Żółta febra – Etiologia i przyczyny

Żółta febra (ang. Yellow fever) jest ostrą chorobą wirusową wywoływaną przez wirus żółtej gorączki (Yellow fever virus, YFV), należący do rodzaju Flavivirus z rodziny Flaviviridae. Jest to wirus RNA o dodatniej polarności, posiadający pojedynczą nić RNA i otoczkę lipidową, o średnicy około 50-60 nm.¹² Wirus żółtej gorączki jest blisko spokrewniony z wirusami wywołującymi gorączkę Zachodniego Nilu, japońskie zapalenie mózgu oraz zapalenie mózgu St. Louis.³

Mechanizm transmisji

Żółta febra jest chorobą przenoszoną przez komary i występuje głównie w obszarach tropikalnych i subtropikalnych Afryki oraz Ameryki Południowej i Centralnej.⁴⁵ Transmisja wirusa odbywa się przede wszystkim poprzez ukłucie przez zakażone komary, należące głównie do rodzajów Aedes i Haemagogus.⁶⁷ Głównym wektorem w środowisku miejskim jest komar Aedes aegypti, który żeruje przede wszystkim w ciągu dnia.⁸⁹

Wirus wnika do organizmu człowieka poprzez skórę podczas ukłucia zakażonego komara. Początkowo replikuje się w miejscu ukłucia oraz okolicznych węzłach chłonnych, a następnie rozprzestrzenia się poprzez wiremiię do innych narządów.¹⁰ Komary nabywają wirusa podczas ssania krwi zainfekowanego gospodarza (człowieka lub małpy), po czym wirus namnaża się w tkankach komara, w tym w gruczołach ślinowych. Nowe zakażenia u ludzi mogą nastąpić, gdy ślina zawierająca wirusa zostaje wprowadzona do organizmu nieodpornego gospodarza podczas kolejnych posiłków krwi.¹¹

Wiremia u zainfekowanych osób osiąga wysokie miano na dzień przed wystąpieniem objawów i utrzymuje się na poziomie wystarczającym do zakażenia komarów przez następne cztery dni.¹² Istotne jest, że żółta febra nie przenosi się bezpośrednio z człowieka na człowieka – wyjątkowo rzadko może być przenoszona przez zakażoną krew, organy lub inne płyny ustrojowe, lecz tylko na wczesnym etapie choroby.¹³¹⁴

Cykle transmisji

Wirus żółtej gorączki utrzymuje się w naturze dzięki trzem różnym cyklom transmisji:¹⁵¹⁶¹⁷

Cykl sylwatyczny (leśny, dżunglowy) – występuje w tropikalnych lasach deszczowych Afryki i Ameryki Południowej. Transmisja wirusa zachodzi między nieludzkimi naczelnymi (małpami), które stanowią główny rezerwuar wirusa, a dzikimi komarami z gatunków Aedes i Haemagogus. Ludzie zostają zainfekowanymi, gdy zostają ukąszeni przez zakażone komary podczas pobytu lub pracy w dżungli.¹⁸¹⁹
Cykl pośredni (sawannowy) – występuje głównie na afrykańskich sawannach i obejmuje ludzi mieszkających lub pracujących na obrzeżach dżungli. Transmisja może zachodzić między małpami a ludźmi lub między ludźmi za pośrednictwem komarów, które rozmnażają się zarówno w dzikich, jak i przydomowych środowiskach.²⁰²¹
Cykl miejski – rozpoczyna się, gdy osoba z wiremią, która zaraziła się wirusem w cyklu leśnym lub pośrednim, powraca do obszaru miejskiego. Ludzie rozwijają znaczącą wiremię, co pozwala na zakażenie komarów miejskich, głównie Aedes aegypti, które następnie przenoszą wirusa na innych ludzi. Duże epidemie występują, gdy zakażeni ludzie wprowadzają wirusa do gęsto zaludnionych obszarów o wysokiej gęstości komarów Aedes aegypti, gdzie większość ludzi ma niewielką lub żadną odporność z powodu braku szczepień.²²²³

Pochodzenie geograficzne i historia

Badania epidemiologiczne i genetyczne wskazują, że wirus żółtej gorączki najprawdopodobniej pochodzi z Afryki.²⁴²⁵ Analizy filogenetyczne sugerują, że wirus ten pojawił się około 1500 lat temu wśród naczelnych w lasach Afryki Środkowej.²⁶ Większa różnorodność genetyczna wirusa żółtej gorączki w Afryce potwierdza jego afrykańskie pochodzenie.²⁷

Wirus został prawdopodobnie przeniesiony z Afryki do Ameryki w XVI wieku poprzez handel niewolnikami z endemicznych krajów afrykańskich.²⁸²⁹ Pierwsza udokumentowana epidemia żółtej gorączki w Nowym Świecie miała miejsce w 1647 roku na wyspie Barbados.³⁰ Komary-wektory zostały prawdopodobnie wprowadzone do Ameryki poprzez beczki z wodą na statkach handlowych, przybywających z krajów z endemiczną żółtą gorączką.³¹

Przełomem w zrozumieniu etiologii żółtej gorączki były badania prowadzone pod koniec XIX wieku. W 1881 roku kubański lekarz Carlos Finlay zasugerował, że żółta gorączka może być przenoszona przez komary, a nie przez bezpośredni kontakt między ludźmi, jak wcześniej sądzono.³² Teoria ta została potwierdzona w 1900 roku przez zespół kierowany przez amerykańskiego chirurga Waltera Reeda.³³ Ostatecznie wirus żółtej gorączki został po raz pierwszy wyizolowany w 1927 roku, równocześnie w Ghanie i w Instytucie Pasteura w Dakarze w Senegalu.³⁴

Patogeneza i wirulencja

Wirus żółtej gorączki wykazuje tropizm przede wszystkim do wątroby (viscerotropizm), ale atakuje również nerki, węzły chłonne, śledzionę i szpik kostny.³⁵ Wirus dostaje się do komórek poprzez endocytozę zależną od receptorów. Synteza RNA odbywa się w cytoplazmie, a synteza białek w retikulum endoplazmatycznym. Wiriony są uwalniane przez błonę komórkową, a otoczka wirusowa zawiera dwuwarstwę lipidową pobraną z zainfekowanej komórki.³⁶

Wątroba jest najważniejszym narządem dotkniętym przez żółtą gorączkę. Choroba została nazwana „żółtą” ze względu na głęboką żółtaczkę obserwowaną u zakażonych osób.³⁷ Uszkodzenie wątroby charakteryzuje się stłuszczeniem zrazikowym i martwicą, przy czym najnowsze dane wskazują na apoptozę jako główny mechanizm śmierci komórek w wątrobie, co odpowiada późniejszemu tworzeniu się ciałek Councilmana (zwyrodniałe eozynofilowe hepatocyty).³⁸

Nerki również ulegają znaczącym zmianom patologicznym. Albuminuria i niewydolność nerek rozwijają się na podłożu przednerkowym, a w zaawansowanej chorobie dochodzi do ostrej martwicy kanalików nerkowych.³⁹ Zmiany w ośrodkowym układzie nerwowym można przypisać obrzękowi mózgu i krwotokom, spotęgowanym zaburzeniami metabolicznymi.⁴⁰

Skaza krwotoczna w tej chorobie jest wtórna do zmniejszonej syntezy czynników krzepnięcia w wątrobie, małopłytkowości i dysfunkcji płytek krwi.⁴¹ Końcowy wstrząs można przypisać kombinacji bezpośredniego uszkodzenia miąższu i ogólnoustrojowej odpowiedzi zapalnej. Ta „burza cytokinowa” charakteryzuje się zwiększonym poziomem interleukiny-6 (IL-6), antagonisty receptora IL-1, białka indukowanego przez interferon-10 i czynnika martwicy nowotworu alfa (TNF-alfa).⁴²

Antygeny wirusowe są znajdowane w całych nerkach, mięśniu sercowym i hepatocytach. U osób, które przeżyją żółtą gorączkę, powrót do zdrowia jest całkowity, bez pozostałego zwłóknienia.⁴³

Czynniki ryzyka i epidemiologia

Żółta gorączka stanowi zagrożenie dla osób podróżujących do lub mieszkających w obszarach endemicznych Afryki i Ameryki Południowej.⁴⁴ Na ryzyko zarażenia się żółtą gorączką wpływają następujące czynniki:⁴⁵⁴⁶⁴⁷

Brak szczepienia przeciwko żółtej gorączce
Podróże do obszarów endemicznych bez odpowiedniej ochrony
Praca lub życie w pobliżu lasu deszczowego, szczególnie w Brazylii i innych krajach Ameryki Południowej
Zmiany środowiskowe, powodujące zwiększoną cyrkulację wirusa wśród małp w ekosystemach leśnych
Bliski kontakt ludzi z komarami
Zmiany w zachowaniu ludzi
Niedostateczne pokrycie szczepieniami w populacjach zagrożonych

Według Światowej Organizacji Zdrowia (WHO), żółta gorączka powoduje rocznie około 200 000 przypadków zachorowań i 30 000 zgonów na całym świecie.⁴⁸⁴⁹ Największą śmiertelność odnotowuje się u niemowląt i osób starszych, które często mają osłabiony układ odpornościowy.⁵⁰

Epidemie żółtej gorączki pojawiają się regularnie w obszarach endemicznych, szczególnie gdy zakażeni ludzie wprowadzają wirusa do gęsto zaludnionych obszarów o wysokiej gęstości komarów i gdzie większość ludzi ma niewielką lub żadną odporność z powodu braku szczepień.⁵¹ Największe współczesne epidemie odnotowano w Brazylii: w sezonie 2016-2017 zarejestrowano 792 przypadki i 274 zgony, a w sezonie od grudnia 2017 do maja 2018 odnotowano 1266 nowych przypadków u ludzi i 415 zgonów.⁵²

Czynniki środowiskowe i klimatyczne

Występowanie i rozprzestrzenianie się żółtej gorączki jest ściśle związane z czynnikami środowiskowymi i klimatycznymi:⁵³⁵⁴

Zmiany klimatyczne – zwiększona temperatura i wysoka wilgotność zwiększają żarłoczność samic komarów, szukających krwi małp i ewentualnie ludzi, co zapewnia sukces składania jaj
Wylesianie – prowadzi do przemieszczania się populacji do obszarów bliskich lasom i zwiększa możliwość kontaktu z komarem
Katastrofy naturalne – powodują przemieszczanie się ludności oraz zaburzenia równowagi środowiskowej
Urbanizacja o wysokiej gęstości – sprzyja rozprzestrzenianiu się komarów w obszarach miejskich
Zmiany w zachowaniach komarów i ludzi – mogą prowadzić do częstszego kontaktu i większej liczby ukąszeń

W Brazylii, zmniejszenie liczby szczepień w latach 1960-2000 doprowadziło do wzrostu liczby ognisk żółtej gorączki w Ameryce Południowej i Afryce. Epidemie te były spowodowane nie tylko niewystarczającym pokryciem szczepieniami z powodu niewystarczających zapasów szczepionek, ale także wzrostem liczby osób bez historii szczepień mieszkających w obszarach endemicznych.⁵⁵

Zapobieganie i kontrola

Najskuteczniejszym sposobem zapobiegania żółtej gorączce jest szczepienie.⁵⁶ Szczepionka przeciwko żółtej gorączce jest wysoce skuteczna – pojedyncza dawka zapewnia odporność na całe życie u 99% osób w ciągu 30 dni od podania.⁵⁷⁵⁸ Szczepienie jest zalecane dla osób podróżujących do obszarów, gdzie występuje ryzyko zarażenia żółtą gorączką.⁵⁹

WHO zaleca utrzymanie co najmniej 80% poziomu zaszczepienia populacji w obszarach zagrożonych żółtą gorączką, aby skutecznie zapobiegać wybuchom epidemii.⁶⁰ Obecnie nie istnieje specyficzne leczenie przeciwwirusowe na żółtą gorączkę, dlatego właściwe postępowanie kliniczne poprawia wskaźnik przeżycia.⁶¹⁶²

Warto podkreślić, że ze względu na niemożność eradykacji żółtej gorączki typu dzikiego, jako że jest to zoonoza dzikich zwierząt, oraz szerokie rozprzestrzenienie A. aegypti w miastach, stałe zagrożenie stanowi ponowne pojawienie się żółtej gorączki w przestrzeniach miejskich.⁶³

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Materiały źródłowe

#1 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
Yellow fever virus is a positive-sense, single-stranded, ribonucleic acid (RNA) enveloped flavivirus with a diameter of about 50-60 nm. The virus is transmitted via the saliva of an infected mosquito. Local replication of the virus takes place in the skin and regional lymph nodes. Viremia and dissemination follow. […] The virus gains entrance through receptor-mediated endocytosis. RNA synthesis occurs in the cytoplasm and protein synthesis takes place in the endoplasmic reticulum. Virions are released through the cell membrane. The viral envelope contains a lipid bilayer taken from the infected cell. Virulence factors include the following: […] Yellow fever is primarily viscerotropic, with the liver being the most affected organ. […] The infection quickly disseminates to the kidneys, lymph nodes, spleen, and bone marrow. Renal failure occurs as renal tubules undergo fatty change and eosinophilic degeneration, likely due to direct viral effect, hypotension, and hepatic involvement.
#2 Yellow Fever Transmission, Symptoms, Treatment, Vaccine
https://www.medicinenet.com/yellow_fever/article.htm
Yellow fever is an acute viral infectious disease transmitted to humans through the bite of infected mosquitoes. […] A virus causes yellow fever. The yellow fever virus is a single-stranded RNA virus that belongs to the Flavivirus genus. […] The bite of infected mosquitoes transmits yellow fever to humans. Various species of Aedes and Haemagogus mosquitoes serve as vectors and are responsible for the transmission to human and nonhuman primates, which serve as reservoirs for the disease. […] There are three transmission cycles for yellow fever: Sylvatic (jungle) cycle, Intermediate (savannah) cycle, and Urban cycle.
#3 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Yellow fever is a mosquito-borne viral illness found in tropical and subtropical areas in South America and Africa. Transmission is primarily via Aedes and Haemagogus mosquitos. […] The virus is an RNA virus of the genus Flavivirus, closely related to the viruses that cause West Nile, St. Louis, and Japanese encephalitis. Tree-hole breeding mosquitoes, such as Aedes aegypti and Haemagogous species, transmit yellow fever during the rainy season. The yellow fever virus has three distinct transmission cycles: jungle, intermediate, and urban. The jungle cycle involves transmission between non-human primates (monkeys) and mosquitoes. Humans are infected through infected mosquito bites while visiting or working in the jungle. The intermediate cycle occurs in the African savannah and involves humans who live or work in jungle border areas. Transmission may be between monkeys and humans or humans via mosquito vectors. The urban cycle involves a viremic human who contracted the virus in either the jungle or intermediate cycle who then returns to an urban area. Humans develop significant viremia to infect mosquitoes, which can then transmit the virus to other humans in urban areas. Person to person or primate to human transmission has not been reported without the involvement of a mosquito vector.
#4 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Yellow fever is a mosquito-borne viral illness found in tropical and subtropical areas in South America and Africa. Transmission is primarily via Aedes and Haemagogus mosquitos. […] The virus is an RNA virus of the genus Flavivirus, closely related to the viruses that cause West Nile, St. Louis, and Japanese encephalitis. Tree-hole breeding mosquitoes, such as Aedes aegypti and Haemagogous species, transmit yellow fever during the rainy season. The yellow fever virus has three distinct transmission cycles: jungle, intermediate, and urban. The jungle cycle involves transmission between non-human primates (monkeys) and mosquitoes. Humans are infected through infected mosquito bites while visiting or working in the jungle. The intermediate cycle occurs in the African savannah and involves humans who live or work in jungle border areas. Transmission may be between monkeys and humans or humans via mosquito vectors. The urban cycle involves a viremic human who contracted the virus in either the jungle or intermediate cycle who then returns to an urban area. Humans develop significant viremia to infect mosquitoes, which can then transmit the virus to other humans in urban areas. Person to person or primate to human transmission has not been reported without the involvement of a mosquito vector.
#5 Yellow Fever – PAHO/WHO | Pan American Health Organization
https://www.paho.org/en/topics/yellow-fever
Yellow fever is an acute viral hemorrhagic disease that is endemic in tropical areas of Africa and Central and South America. […] Large epidemics of yellow fever occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes of the Aedes aegypti species transmit the virus from person to person. […] Some attribute this spread to changes in mosquitoes, and humans. […] The yellow fever virus is transmitted by infected mosquitoes. […] In tropical rainforests, monkeys, which are the primary reservoir of yellow fever virus, are bitten by wild mosquitoes of the Haemagogus and Sabethes species, which pass the virus on to other monkeys.
#6
https://www.who.int/news-room/fact-sheets/detail/yellow-fever
Yellow fever is caused by an arbovirus (a virus transmitted by vectors such mosquitoes, ticks or other arthropods) transmitted to humans by the bites of infected Aedes and Haemagogus mosquitoes. […] Yellow fever is an infectious disease transmitted by mosquitoes that bite mostly during the day.
#7 Yellow fever : symptoms, treatment, prevention – Institut Pasteur
https://www.pasteur.fr/en/medical-center/disease-sheets/yellow-fever
Yellow fever is a viral disease that was first described in the mid-sixteenth century in Yucatn, Mexico. It is caused by yellow fever virus, an arbovirus (a virus transmitted by an insect vector) isolated in 1927, simultaneously in Ghana and at the Institut Pasteur de Dakar, Senegal. […] Yellow fever virus is transmitted to humans via bites from mosquitoes belonging to the Aedes and Haemagogus genera. It also infects forest monkeys in a mosquito-monkey-mosquito cycle, which can occasionally also include humans. Yellow fever is a zoonosis, in all probability dating from ancient times, which was transmitted to humans when they ventured into tropical forests. […] Yellow fever virus is spread by bites from mosquitoes that are mainly active during the day. The mosquito responsible for urban epidemics is Aedes aegypti. […] Yellow fever vaccination is the only mandatory vaccination for travelers to the endemic intertropical regions of Africa and South America.
#8 Yellow fever – Wikipedia
https://en.wikipedia.org/wiki/Yellow_fever
Yellow fever is caused by the yellow fever virus and is spread by the bite of an infected mosquito. […] The disease is caused by Yellow fever virus (YFV), an enveloped RNA virus 4050 nm in width, the type species and namesake of the family Flaviviridae. […] Yellow fever virus is mainly transmitted through the bite of the yellow fever mosquito Aedes aegypti, but other mostly Aedes mosquitoes such as the tiger mosquito (Aedes albopictus) can also serve as a vector for this virus. […] The evolutionary origins of yellow fever most likely lie in Africa, with transmission of the disease from nonhuman primates to humans. […] The virus is thought to have originated in East or Central Africa and spread from there to West Africa. […] The first definitive outbreak of yellow fever in the New World was in 1647 on the island of Barbados.
#9 Yellow fever | World Mosquito Program
https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases/yellow-fever
Yellow fever is caused by a virus transmitted primarily by Aedes aegypti mosquitoes. […] Yellow fever can spread wherever Aedes aegypti and Haemogogus mosquitoes are present. […] Large outbreaks of urban yellow fever tend to occur when infected people introduce the virus into heavily populated areas with a high density of Aedes aegypti mosquitoes, and where most people have little or no immunity, due to lack of vaccination or prior exposure to yellow fever.
#10 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
Yellow fever virus is a positive-sense, single-stranded, ribonucleic acid (RNA) enveloped flavivirus with a diameter of about 50-60 nm. The virus is transmitted via the saliva of an infected mosquito. Local replication of the virus takes place in the skin and regional lymph nodes. Viremia and dissemination follow. […] The virus gains entrance through receptor-mediated endocytosis. RNA synthesis occurs in the cytoplasm and protein synthesis takes place in the endoplasmic reticulum. Virions are released through the cell membrane. The viral envelope contains a lipid bilayer taken from the infected cell. Virulence factors include the following: […] Yellow fever is primarily viscerotropic, with the liver being the most affected organ. […] The infection quickly disseminates to the kidneys, lymph nodes, spleen, and bone marrow. Renal failure occurs as renal tubules undergo fatty change and eosinophilic degeneration, likely due to direct viral effect, hypotension, and hepatic involvement.
#11 Facts about yellow fever
https://www.ecdc.europa.eu/en/yellow-fever/facts
Yellow fever (YF) is an African mosquito-borne infection of primates. It is caused by a virus of the Flavivirus genus of the Flaviviridae family. […] The virus circulates between monkeys in the forest and between humans in village and urban areas. […] Bites by infected mosquitoes are the only mode of transmission. […] Mosquitoes acquire the virus when they feed on a viraemic host, after which (in a susceptible species) the virus infects many tissues, including the salivary glands. […] New infections in humans can occur when saliva that contains the virus is injected into a non-immune host during subsequent blood meals. […] Viraemia reaches high titres on the day before onset of symptoms, and is generally high enough to infect mosquitoes for the next four days.
#12 Facts about yellow fever
https://www.ecdc.europa.eu/en/yellow-fever/facts
Yellow fever (YF) is an African mosquito-borne infection of primates. It is caused by a virus of the Flavivirus genus of the Flaviviridae family. […] The virus circulates between monkeys in the forest and between humans in village and urban areas. […] Bites by infected mosquitoes are the only mode of transmission. […] Mosquitoes acquire the virus when they feed on a viraemic host, after which (in a susceptible species) the virus infects many tissues, including the salivary glands. […] New infections in humans can occur when saliva that contains the virus is injected into a non-immune host during subsequent blood meals. […] Viraemia reaches high titres on the day before onset of symptoms, and is generally high enough to infect mosquitoes for the next four days.
#13 Yellow Fever: Causes, Symptoms, and Prevention
https://www.suburbanmedgroup.com/blog/unraveling-yellow-fever.html
The primary vector of transmission for yellow fever is infected Aedes mosquitoes, namely the Aedes aegypti species. Yellow fever virus is a member of the Flaviviridae family of viruses. […] Infected mosquitoes transmit the yellow fever virus to humans. The Aedes aegypti mosquito is the primary vector, with transmission occurring through bites. […] In rare instances, contaminated blood, organs, or other body fluids can transmit yellow fever to other people. This is a rare mechanism of transmission that usually happens in the early stages of illness.
#14 Yellow Fever – Epidemiology
https://www.vdh.virginia.gov/epidemiology/epidemiology-fact-sheets/yellow-fever/
Yellow fever is a disease caused by a virus that is transmitted by the bite of certain mosquito species. […] The disease is transmitted by the bite of an infected Aedes aegypti mosquito in urban areas, but may also be transmitted by other species of mosquitos in jungle areas. Mosquitoes acquire the virus by feeding on infected primates (human or non-human). […] Yellow fever cannot be transmitted directly from person to person.
#15 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Yellow fever is a mosquito-borne viral illness found in tropical and subtropical areas in South America and Africa. Transmission is primarily via Aedes and Haemagogus mosquitos. […] The virus is an RNA virus of the genus Flavivirus, closely related to the viruses that cause West Nile, St. Louis, and Japanese encephalitis. Tree-hole breeding mosquitoes, such as Aedes aegypti and Haemagogous species, transmit yellow fever during the rainy season. The yellow fever virus has three distinct transmission cycles: jungle, intermediate, and urban. The jungle cycle involves transmission between non-human primates (monkeys) and mosquitoes. Humans are infected through infected mosquito bites while visiting or working in the jungle. The intermediate cycle occurs in the African savannah and involves humans who live or work in jungle border areas. Transmission may be between monkeys and humans or humans via mosquito vectors. The urban cycle involves a viremic human who contracted the virus in either the jungle or intermediate cycle who then returns to an urban area. Humans develop significant viremia to infect mosquitoes, which can then transmit the virus to other humans in urban areas. Person to person or primate to human transmission has not been reported without the involvement of a mosquito vector.
#16 Yellow Fever: Origin, Epidemiology, Preventive Strategies and Future Prospects
https://pmc.ncbi.nlm.nih.gov/articles/PMC8955180/
Yellow fever (YF) virus still represents a major threat in low resource countries in both South America and Africa despite the presence of an effective vaccine. […] Epidemiological and genetic studies sustain the hypothesis that the YF virus originated in Africa and would be introduced in the 16th century by the trading of slaves from endemic African countries into countries of the Western region of America, causing outbreaks there between the 17th and 18th centuries. […] Molecular investigations have highlighted a more marked genetic heterogeneity of YF in Africa supporting here its origin. […] The virus is maintained in nature by transmission between non-human primates (NHP), horizontal transmission via blood-feeding mosquitoes, and transovarial transmission in competent vectors. […] The identification of vectors in different habitats has led to the establishment of three distinct transmission cycles: wild, semi-domestic, and domestic.
#17 Yellow Fever Transmission, Symptoms, Treatment, Vaccine
https://www.medicinenet.com/yellow_fever/article.htm
Yellow fever is an acute viral infectious disease transmitted to humans through the bite of infected mosquitoes. […] A virus causes yellow fever. The yellow fever virus is a single-stranded RNA virus that belongs to the Flavivirus genus. […] The bite of infected mosquitoes transmits yellow fever to humans. Various species of Aedes and Haemagogus mosquitoes serve as vectors and are responsible for the transmission to human and nonhuman primates, which serve as reservoirs for the disease. […] There are three transmission cycles for yellow fever: Sylvatic (jungle) cycle, Intermediate (savannah) cycle, and Urban cycle.
#18 Yellow fever
https://dermnetnz.org/topics/yellow-fever
Yellow fever is a viral disease found in tropical regions of Africa and the Americas. The yellow fever virus, which belongs to the flavivirus group, is spread by the bite of Aedes and Haemogogus mosquitoes. […] Yellow fever has two main transmission cycles: Sylvatic (or jungle) yellow fever In tropical rainforests, yellow fever occurs in monkeys that are infected by wild mosquitoes. […] Urban yellow fever large epidemics occur when migrants introduce the virus into areas with high human population density.
#19 Yellow Fever Fact Sheet | Africa Health Organisation
https://aho.org/fact-sheets/yellow-fever-fact-sheet/
The yellow fever virus is an arbovirus of the flavivirus genus and is transmitted by mosquitoes, belonging to the Aedes and Haemogogus species. […] Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes. The âyellowâ in the name refers to the jaundice that affects some patients. […] Large epidemics of yellow fever occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes transmit the virus from person to person. […] The yellow fever virus is an arbovirus of the flavivirus genus and is transmitted by mosquitoes, belonging to the Aedes and Haemogogus species. […] Sylvatic (or jungle) yellow fever: In tropical rainforests, monkeys, which are the primary reservoir of yellow fever, are bitten by wild mosquitoes which pass the virus on to other monkeys. […] Urban yellow fever: Large epidemics occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes transmit the virus from person to person.
#20 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Yellow fever is a mosquito-borne viral illness found in tropical and subtropical areas in South America and Africa. Transmission is primarily via Aedes and Haemagogus mosquitos. […] The virus is an RNA virus of the genus Flavivirus, closely related to the viruses that cause West Nile, St. Louis, and Japanese encephalitis. Tree-hole breeding mosquitoes, such as Aedes aegypti and Haemagogous species, transmit yellow fever during the rainy season. The yellow fever virus has three distinct transmission cycles: jungle, intermediate, and urban. The jungle cycle involves transmission between non-human primates (monkeys) and mosquitoes. Humans are infected through infected mosquito bites while visiting or working in the jungle. The intermediate cycle occurs in the African savannah and involves humans who live or work in jungle border areas. Transmission may be between monkeys and humans or humans via mosquito vectors. The urban cycle involves a viremic human who contracted the virus in either the jungle or intermediate cycle who then returns to an urban area. Humans develop significant viremia to infect mosquitoes, which can then transmit the virus to other humans in urban areas. Person to person or primate to human transmission has not been reported without the involvement of a mosquito vector.
#21 Yellow fever: View Causes, Symptoms and Treatments | 1mg
https://www.1mg.com/diseases/yellow-fever-348?srsltid=AfmBOoposDyGNpiEYILIp87hOFpIH3VAhyY9M7deRpD4lKhVktJ2zXaF
Yellow fever is a mosquito-borne viral illness commonly seen in tropical and subtropical areas of South America and Africa. […] The yellow fever virus is an arbovirus of the flavivirus genus and is transmitted by mosquitoes, belonging to the Aedes and Haemogogus species. […] There are 3 types of transmission cycles: […] Sylvatic (or jungle) yellow fever: In tropical rainforests, monkeys, which are the primary reservoir of yellow fever, are bitten by wild mosquitoes of the Aedes and Haemogogus species, they pass the virus on to other monkeys. […] Intermediate yellow fever: During this type of transmission, semi-domestic mosquitoes (those that breed both in the wild and around households) infect both monkeys and people. […] Urban yellow fever: Large epidemics occur when infected people introduce the virus into heavily populated areas with a high density of Aedes aegypti mosquitoes and where most people have little or no immunity, due to lack of vaccination or prior exposure to yellow fever.
#22 Yellow Fever – PAHO/WHO | Pan American Health Organization
https://www.paho.org/en/topics/yellow-fever
Yellow fever is an acute viral hemorrhagic disease that is endemic in tropical areas of Africa and Central and South America. […] Large epidemics of yellow fever occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes of the Aedes aegypti species transmit the virus from person to person. […] Some attribute this spread to changes in mosquitoes, and humans. […] The yellow fever virus is transmitted by infected mosquitoes. […] In tropical rainforests, monkeys, which are the primary reservoir of yellow fever virus, are bitten by wild mosquitoes of the Haemagogus and Sabethes species, which pass the virus on to other monkeys.
#23 Yellow fever | World Mosquito Program
https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases/yellow-fever
Yellow fever is caused by a virus transmitted primarily by Aedes aegypti mosquitoes. […] Yellow fever can spread wherever Aedes aegypti and Haemogogus mosquitoes are present. […] Large outbreaks of urban yellow fever tend to occur when infected people introduce the virus into heavily populated areas with a high density of Aedes aegypti mosquitoes, and where most people have little or no immunity, due to lack of vaccination or prior exposure to yellow fever.
#24 Yellow fever – Wikipedia
https://en.wikipedia.org/wiki/Yellow_fever
Yellow fever is caused by the yellow fever virus and is spread by the bite of an infected mosquito. […] The disease is caused by Yellow fever virus (YFV), an enveloped RNA virus 4050 nm in width, the type species and namesake of the family Flaviviridae. […] Yellow fever virus is mainly transmitted through the bite of the yellow fever mosquito Aedes aegypti, but other mostly Aedes mosquitoes such as the tiger mosquito (Aedes albopictus) can also serve as a vector for this virus. […] The evolutionary origins of yellow fever most likely lie in Africa, with transmission of the disease from nonhuman primates to humans. […] The virus is thought to have originated in East or Central Africa and spread from there to West Africa. […] The first definitive outbreak of yellow fever in the New World was in 1647 on the island of Barbados.
#25 Yellow Fever: Origin, Epidemiology, Preventive Strategies and Future Prospects
https://pmc.ncbi.nlm.nih.gov/articles/PMC8955180/
Yellow fever (YF) virus still represents a major threat in low resource countries in both South America and Africa despite the presence of an effective vaccine. […] Epidemiological and genetic studies sustain the hypothesis that the YF virus originated in Africa and would be introduced in the 16th century by the trading of slaves from endemic African countries into countries of the Western region of America, causing outbreaks there between the 17th and 18th centuries. […] Molecular investigations have highlighted a more marked genetic heterogeneity of YF in Africa supporting here its origin. […] The virus is maintained in nature by transmission between non-human primates (NHP), horizontal transmission via blood-feeding mosquitoes, and transovarial transmission in competent vectors. […] The identification of vectors in different habitats has led to the establishment of three distinct transmission cycles: wild, semi-domestic, and domestic.
#26 What Is Yellow Fever? Disease and Causation in Environmental History | Environment & Society Portal
https://www.environmentandsociety.org/arcadia/what-yellow-fever-disease-and-causation-environmental-history
What is yellow fever? At its most basic, yellow fever results from a virus invading a susceptible human body. Recent phylogenetic analyses suggest that the yellow fever virus is approximately 1,500 years old and emerged among primates in the forests of Central Africa. From there the virus spread to humans, making its way to West Africa where it eventually boarded ships, likely during the slave trade, and traveled to Europe and the Americas. […] Yellow fever was also a product of the human ecologies of Atlantic World port cities. […] What then is yellow fever? It is a set of clinical conditions caused by a virus, which developed and spread quite recently in the larger scheme of earth history, and a mosquito vector with a particular historical ecology and co-evolutionary history with humans. […] Yellow fever may be substantially caused by nonhuman forces, but to treat it merely as a product of nature that shaped human history is to miss all of the ways in which its nature has history.
#27 Yellow Fever: Origin, Epidemiology, Preventive Strategies and Future Prospects
https://pmc.ncbi.nlm.nih.gov/articles/PMC8955180/
Yellow fever (YF) virus still represents a major threat in low resource countries in both South America and Africa despite the presence of an effective vaccine. […] Epidemiological and genetic studies sustain the hypothesis that the YF virus originated in Africa and would be introduced in the 16th century by the trading of slaves from endemic African countries into countries of the Western region of America, causing outbreaks there between the 17th and 18th centuries. […] Molecular investigations have highlighted a more marked genetic heterogeneity of YF in Africa supporting here its origin. […] The virus is maintained in nature by transmission between non-human primates (NHP), horizontal transmission via blood-feeding mosquitoes, and transovarial transmission in competent vectors. […] The identification of vectors in different habitats has led to the establishment of three distinct transmission cycles: wild, semi-domestic, and domestic.
#28 Yellow Fever: Origin, Epidemiology, Preventive Strategies and Future Prospects
https://pmc.ncbi.nlm.nih.gov/articles/PMC8955180/
Yellow fever (YF) virus still represents a major threat in low resource countries in both South America and Africa despite the presence of an effective vaccine. […] Epidemiological and genetic studies sustain the hypothesis that the YF virus originated in Africa and would be introduced in the 16th century by the trading of slaves from endemic African countries into countries of the Western region of America, causing outbreaks there between the 17th and 18th centuries. […] Molecular investigations have highlighted a more marked genetic heterogeneity of YF in Africa supporting here its origin. […] The virus is maintained in nature by transmission between non-human primates (NHP), horizontal transmission via blood-feeding mosquitoes, and transovarial transmission in competent vectors. […] The identification of vectors in different habitats has led to the establishment of three distinct transmission cycles: wild, semi-domestic, and domestic.
#29 History of Yellow Fever in the U.S.
https://asm.org/articles/2021/may/history-of-yellow-fever-in-the-u-s
Yellow fever is caused by a virus in the family Flaviviridae, and it is transmitted by the Aedes aegypti mosquito. The yellow fever virus most likely originated in Africa and arrived in the Western Hemisphere in the 1600s as a result of slave trade. The mosquito vector was likely introduced to the U.S. via water barrels on trade ships arriving from countries with endemic yellow fever. The virus followed when slaves from areas with endemic disease arrived. The hungry mosquitos then spread the virus from infected to uninfected in the New World. […] The discovery of the causative agent of yellow fever was a decades-long process. While Cuban physician Carlos Finlay first described the Aedes aegypti mosquito as the carrier of the disease in 1886, he was ridiculed for this theory. Finlays discovery was accepted 20 years later only after U.S. Army scientists working with U.S. Army surgeon, Major Walter Reed, confirmed that this was in fact correct. The work of Reeds team also confirmed that yellow fever was caused by an agent small enough to pass through bacteria filters, but it was more than 25 years before the virus was first isolated.
#30 Yellow fever – Wikipedia
https://en.wikipedia.org/wiki/Yellow_fever
Yellow fever is caused by the yellow fever virus and is spread by the bite of an infected mosquito. […] The disease is caused by Yellow fever virus (YFV), an enveloped RNA virus 4050 nm in width, the type species and namesake of the family Flaviviridae. […] Yellow fever virus is mainly transmitted through the bite of the yellow fever mosquito Aedes aegypti, but other mostly Aedes mosquitoes such as the tiger mosquito (Aedes albopictus) can also serve as a vector for this virus. […] The evolutionary origins of yellow fever most likely lie in Africa, with transmission of the disease from nonhuman primates to humans. […] The virus is thought to have originated in East or Central Africa and spread from there to West Africa. […] The first definitive outbreak of yellow fever in the New World was in 1647 on the island of Barbados.
#31 History of Yellow Fever in the U.S.
https://asm.org/articles/2021/may/history-of-yellow-fever-in-the-u-s
Yellow fever is caused by a virus in the family Flaviviridae, and it is transmitted by the Aedes aegypti mosquito. The yellow fever virus most likely originated in Africa and arrived in the Western Hemisphere in the 1600s as a result of slave trade. The mosquito vector was likely introduced to the U.S. via water barrels on trade ships arriving from countries with endemic yellow fever. The virus followed when slaves from areas with endemic disease arrived. The hungry mosquitos then spread the virus from infected to uninfected in the New World. […] The discovery of the causative agent of yellow fever was a decades-long process. While Cuban physician Carlos Finlay first described the Aedes aegypti mosquito as the carrier of the disease in 1886, he was ridiculed for this theory. Finlays discovery was accepted 20 years later only after U.S. Army scientists working with U.S. Army surgeon, Major Walter Reed, confirmed that this was in fact correct. The work of Reeds team also confirmed that yellow fever was caused by an agent small enough to pass through bacteria filters, but it was more than 25 years before the virus was first isolated.
#32 Yellow fever – Wikipedia
https://en.wikipedia.org/wiki/Yellow_fever
Carlos Finlay, a Cuban-Spanish doctor and scientist, proposed in 1881 that yellow fever might be transmitted by previously infected mosquitoes rather than by direct contact from person to person, as had long been believed. […] Yellow fever was the first virus shown to be transmitted by mosquitoes.
#33 History of Yellow Fever in the U.S.
https://asm.org/articles/2021/may/history-of-yellow-fever-in-the-u-s
Yellow fever is caused by a virus in the family Flaviviridae, and it is transmitted by the Aedes aegypti mosquito. The yellow fever virus most likely originated in Africa and arrived in the Western Hemisphere in the 1600s as a result of slave trade. The mosquito vector was likely introduced to the U.S. via water barrels on trade ships arriving from countries with endemic yellow fever. The virus followed when slaves from areas with endemic disease arrived. The hungry mosquitos then spread the virus from infected to uninfected in the New World. […] The discovery of the causative agent of yellow fever was a decades-long process. While Cuban physician Carlos Finlay first described the Aedes aegypti mosquito as the carrier of the disease in 1886, he was ridiculed for this theory. Finlays discovery was accepted 20 years later only after U.S. Army scientists working with U.S. Army surgeon, Major Walter Reed, confirmed that this was in fact correct. The work of Reeds team also confirmed that yellow fever was caused by an agent small enough to pass through bacteria filters, but it was more than 25 years before the virus was first isolated.
#34 Yellow fever : symptoms, treatment, prevention – Institut Pasteur
https://www.pasteur.fr/en/medical-center/disease-sheets/yellow-fever
Yellow fever is a viral disease that was first described in the mid-sixteenth century in Yucatn, Mexico. It is caused by yellow fever virus, an arbovirus (a virus transmitted by an insect vector) isolated in 1927, simultaneously in Ghana and at the Institut Pasteur de Dakar, Senegal. […] Yellow fever virus is transmitted to humans via bites from mosquitoes belonging to the Aedes and Haemagogus genera. It also infects forest monkeys in a mosquito-monkey-mosquito cycle, which can occasionally also include humans. Yellow fever is a zoonosis, in all probability dating from ancient times, which was transmitted to humans when they ventured into tropical forests. […] Yellow fever virus is spread by bites from mosquitoes that are mainly active during the day. The mosquito responsible for urban epidemics is Aedes aegypti. […] Yellow fever vaccination is the only mandatory vaccination for travelers to the endemic intertropical regions of Africa and South America.
#35 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
Yellow fever virus is a positive-sense, single-stranded, ribonucleic acid (RNA) enveloped flavivirus with a diameter of about 50-60 nm. The virus is transmitted via the saliva of an infected mosquito. Local replication of the virus takes place in the skin and regional lymph nodes. Viremia and dissemination follow. […] The virus gains entrance through receptor-mediated endocytosis. RNA synthesis occurs in the cytoplasm and protein synthesis takes place in the endoplasmic reticulum. Virions are released through the cell membrane. The viral envelope contains a lipid bilayer taken from the infected cell. Virulence factors include the following: […] Yellow fever is primarily viscerotropic, with the liver being the most affected organ. […] The infection quickly disseminates to the kidneys, lymph nodes, spleen, and bone marrow. Renal failure occurs as renal tubules undergo fatty change and eosinophilic degeneration, likely due to direct viral effect, hypotension, and hepatic involvement.
#36 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
Yellow fever virus is a positive-sense, single-stranded, ribonucleic acid (RNA) enveloped flavivirus with a diameter of about 50-60 nm. The virus is transmitted via the saliva of an infected mosquito. Local replication of the virus takes place in the skin and regional lymph nodes. Viremia and dissemination follow. […] The virus gains entrance through receptor-mediated endocytosis. RNA synthesis occurs in the cytoplasm and protein synthesis takes place in the endoplasmic reticulum. Virions are released through the cell membrane. The viral envelope contains a lipid bilayer taken from the infected cell. Virulence factors include the following: […] Yellow fever is primarily viscerotropic, with the liver being the most affected organ. […] The infection quickly disseminates to the kidneys, lymph nodes, spleen, and bone marrow. Renal failure occurs as renal tubules undergo fatty change and eosinophilic degeneration, likely due to direct viral effect, hypotension, and hepatic involvement.
#37 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The liver is the most important organ affected in yellow fever. The disease was labeled „yellow” based on the profound jaundice observed in affected individuals. Hepatocellular damage is characterized by lobular steatosis and necrosis, with recent data indicating apoptosis as the primary mechanism of cell death in the liver, corresponding with subsequent formation of Councilman bodies (degenerative eosinophilic hepatocytes). […] The kidneys also undergo significant pathologic changes. Albuminuria and renal insufficiency evolve secondary to the prerenal component of yellow fever; consequently, acute tubular necrosis develops in advanced disease. […] Central nervous system (CNS) findings can be attributed to cerebral edema and hemorrhages compounded on metabolic disturbances. The bleeding diathesis of this disease is secondary to reduced hepatic synthesis of clotting factors, thrombocytopenia, and platelet dysfunction.
#38 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The liver is the most important organ affected in yellow fever. The disease was labeled „yellow” based on the profound jaundice observed in affected individuals. Hepatocellular damage is characterized by lobular steatosis and necrosis, with recent data indicating apoptosis as the primary mechanism of cell death in the liver, corresponding with subsequent formation of Councilman bodies (degenerative eosinophilic hepatocytes). […] The kidneys also undergo significant pathologic changes. Albuminuria and renal insufficiency evolve secondary to the prerenal component of yellow fever; consequently, acute tubular necrosis develops in advanced disease. […] Central nervous system (CNS) findings can be attributed to cerebral edema and hemorrhages compounded on metabolic disturbances. The bleeding diathesis of this disease is secondary to reduced hepatic synthesis of clotting factors, thrombocytopenia, and platelet dysfunction.
#39 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The liver is the most important organ affected in yellow fever. The disease was labeled „yellow” based on the profound jaundice observed in affected individuals. Hepatocellular damage is characterized by lobular steatosis and necrosis, with recent data indicating apoptosis as the primary mechanism of cell death in the liver, corresponding with subsequent formation of Councilman bodies (degenerative eosinophilic hepatocytes). […] The kidneys also undergo significant pathologic changes. Albuminuria and renal insufficiency evolve secondary to the prerenal component of yellow fever; consequently, acute tubular necrosis develops in advanced disease. […] Central nervous system (CNS) findings can be attributed to cerebral edema and hemorrhages compounded on metabolic disturbances. The bleeding diathesis of this disease is secondary to reduced hepatic synthesis of clotting factors, thrombocytopenia, and platelet dysfunction.
#40 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The liver is the most important organ affected in yellow fever. The disease was labeled „yellow” based on the profound jaundice observed in affected individuals. Hepatocellular damage is characterized by lobular steatosis and necrosis, with recent data indicating apoptosis as the primary mechanism of cell death in the liver, corresponding with subsequent formation of Councilman bodies (degenerative eosinophilic hepatocytes). […] The kidneys also undergo significant pathologic changes. Albuminuria and renal insufficiency evolve secondary to the prerenal component of yellow fever; consequently, acute tubular necrosis develops in advanced disease. […] Central nervous system (CNS) findings can be attributed to cerebral edema and hemorrhages compounded on metabolic disturbances. The bleeding diathesis of this disease is secondary to reduced hepatic synthesis of clotting factors, thrombocytopenia, and platelet dysfunction.
#41 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The liver is the most important organ affected in yellow fever. The disease was labeled „yellow” based on the profound jaundice observed in affected individuals. Hepatocellular damage is characterized by lobular steatosis and necrosis, with recent data indicating apoptosis as the primary mechanism of cell death in the liver, corresponding with subsequent formation of Councilman bodies (degenerative eosinophilic hepatocytes). […] The kidneys also undergo significant pathologic changes. Albuminuria and renal insufficiency evolve secondary to the prerenal component of yellow fever; consequently, acute tubular necrosis develops in advanced disease. […] Central nervous system (CNS) findings can be attributed to cerebral edema and hemorrhages compounded on metabolic disturbances. The bleeding diathesis of this disease is secondary to reduced hepatic synthesis of clotting factors, thrombocytopenia, and platelet dysfunction.
#42 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The terminal event of shock can be attributed to a combination of direct parenchymal damage and a systemic inflammatory response. This cytokine storm has been characterized by increased levels of interleukin (IL)-6, IL-1 receptor antagonist, interferon-inducible protein-10, and tumor necrosis factor (TNF)alpha. Viral antigens are found diffusely in kidneys, myocardium, and hepatocytes. In individuals who survive yellow fever, the recovery is complete, with no residual fibrosis.
#43 Yellow Fever: Practice Essentials, Background, Etiology
https://emedicine.medscape.com/article/232244-overview
The terminal event of shock can be attributed to a combination of direct parenchymal damage and a systemic inflammatory response. This cytokine storm has been characterized by increased levels of interleukin (IL)-6, IL-1 receptor antagonist, interferon-inducible protein-10, and tumor necrosis factor (TNF)alpha. Viral antigens are found diffusely in kidneys, myocardium, and hepatocytes. In individuals who survive yellow fever, the recovery is complete, with no residual fibrosis.
#44 Yellow fever | NHS inform
https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/yellow-fever/
Yellow fever is a serious viral infection that is spread by certain types of mosquito. […] The virus that causes yellow fever is passed to humans through the bites of infected mosquitoes. […] The yellow fever vaccine protects you from infection when you travel to a country where yellow fever virus occurs and prevents the disease from spreading between countries. […] The countries that require proof of vaccination are those where either the disease occurs, or where it could occur because they have the correct mosquito and monkey species that could harbour the infection.
#45 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Vaccination has decreased worldwide epidemics of yellow fever, but the infection has reemerged in many parts of Africa and South America. No one is immune from yellow fever, and it occurs in people of all ages and races. The highest mortality rates are reported in infants and the elderly, who often have depressed immune systems. yellow fever is very rare in the United States. Most cases are diagnosed in unvaccinated travelers to sub-Saharan Africa or South America.
#46 Yellow Fever: Symptoms and Treatment
https://www.webmd.com/a-to-z-guides/yellow-fever-symptoms-treatment
Yellow fever is a viral infection transmitted by a bite from infected mosquitoes most commonly found in parts of South America and Africa. […] The World Health Organization estimates there are 200,000 cases of yellow fever worldwide each year, resulting in 30,000 deaths. Yellow fever appears to be on the rise internationally, due to a decreased immunity to infection among local populations, deforestation, climate change, and high-density urbanization. […] Yellow fever is typically spread to humans from bites by infected mosquitoes. […] A few different species of mosquitoes transmit the yellow fever virus; some breed in urban areas, others in jungles. […] The yellow fever vaccine is advised for adults and children over age 9 months who are traveling to or living in countries with a known risk of yellow fever. […] Vaccination is the most important measure you should take when traveling to areas where exposure to the yellow fever virus is possible.
#47 Epidemics That Didn’t Happen | Yellow Fever
https://etdh.resolvetosavelives.org/2021/yellow-fever/
The yellow fever virus, which spreads between mosquitoes and primates (human and non-human), was brought to the Americas from Africa by the Atlantic slave trade. One of the earliest recorded outbreaks was in the mid-17th century in the Yucatan, and between 1693 and 1905 it killed more than 100,000 people in the United States. Outbreaks continue to occur in tropical areas of Africa and South America, where it cannot be fully eliminated as it circulates between mosquitoes and non-human primates indigenous to the forest. Brazil was able to eliminate urban yellow fever in 1942. […] There is no cure for yellow fever, and 30-60% of those with severe infections die. […] In Brazil, people living or working in or near the rainforest are most at risk for yellow fever infection. In recent years, environmental changes have led to higher circulation of the yellow fever virus among monkeys in forest ecosystems which, along with closer contact of humans and mosquitoes and changes in human behavior, led to an explosion of infections in nearby human populations.
#48 WHO EMRO | Yellow fever | Health topics
https://www.emro.who.int/health-topics/yellow-fever/index.html
Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes, mainly Aedes aegypti. […] Globally, yellow fever causes around 200,000 cases and 30,000 deaths per year. […] Sudan conducted a yellow fever risk assessment exercise in early 2013 and confirmed that the yellow fever virus was circulating in all parts of the country. […] Recommendations to control yellow fever included conducting preventive campaigns with the yellow fever vaccine, of which a single dose provides lifelong protection. […] There is currently no specific treatment for yellow fever, although proper case management improves survival rate. Use of yellow fever vaccine which offers life-long immunity can protect one from yellow fever.
#49 Yellow Fever: Symptoms and Treatment
https://www.webmd.com/a-to-z-guides/yellow-fever-symptoms-treatment
Yellow fever is a viral infection transmitted by a bite from infected mosquitoes most commonly found in parts of South America and Africa. […] The World Health Organization estimates there are 200,000 cases of yellow fever worldwide each year, resulting in 30,000 deaths. Yellow fever appears to be on the rise internationally, due to a decreased immunity to infection among local populations, deforestation, climate change, and high-density urbanization. […] Yellow fever is typically spread to humans from bites by infected mosquitoes. […] A few different species of mosquitoes transmit the yellow fever virus; some breed in urban areas, others in jungles. […] The yellow fever vaccine is advised for adults and children over age 9 months who are traveling to or living in countries with a known risk of yellow fever. […] Vaccination is the most important measure you should take when traveling to areas where exposure to the yellow fever virus is possible.
#50 Yellow Fever – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK470425/
Vaccination has decreased worldwide epidemics of yellow fever, but the infection has reemerged in many parts of Africa and South America. No one is immune from yellow fever, and it occurs in people of all ages and races. The highest mortality rates are reported in infants and the elderly, who often have depressed immune systems. yellow fever is very rare in the United States. Most cases are diagnosed in unvaccinated travelers to sub-Saharan Africa or South America.
#51 Yellow Fever – PAHO/WHO | Pan American Health Organization
https://www.paho.org/en/topics/yellow-fever
Yellow fever is an acute viral hemorrhagic disease that is endemic in tropical areas of Africa and Central and South America. […] Large epidemics of yellow fever occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes of the Aedes aegypti species transmit the virus from person to person. […] Some attribute this spread to changes in mosquitoes, and humans. […] The yellow fever virus is transmitted by infected mosquitoes. […] In tropical rainforests, monkeys, which are the primary reservoir of yellow fever virus, are bitten by wild mosquitoes of the Haemagogus and Sabethes species, which pass the virus on to other monkeys.
#52 Epidemics That Didn’t Happen | Yellow Fever
https://etdh.resolvetosavelives.org/2021/yellow-fever/
The largest outbreak of yellow fever in Brazil in modern times was emerging, just as the global yellow fever vaccine supply was running dangerously low. […] During the 2016-2017 season, cases climbed to 792, with 274 deaths. In the December 2017-May 2018 season, cases and deaths continued to rise, with 1,266 new human cases, and 415 deaths. […] Brazil was uniquely able to respond to yellow fever, as it had developed scientific expertise on the endemic disease starting in the late 19th century and was a part of developing the yellow fever vaccine in the 1930s, motivated by national risk.
#53 Yellow Fever: Symptoms and Treatment
https://www.webmd.com/a-to-z-guides/yellow-fever-symptoms-treatment
Yellow fever is a viral infection transmitted by a bite from infected mosquitoes most commonly found in parts of South America and Africa. […] The World Health Organization estimates there are 200,000 cases of yellow fever worldwide each year, resulting in 30,000 deaths. Yellow fever appears to be on the rise internationally, due to a decreased immunity to infection among local populations, deforestation, climate change, and high-density urbanization. […] Yellow fever is typically spread to humans from bites by infected mosquitoes. […] A few different species of mosquitoes transmit the yellow fever virus; some breed in urban areas, others in jungles. […] The yellow fever vaccine is advised for adults and children over age 9 months who are traveling to or living in countries with a known risk of yellow fever. […] Vaccination is the most important measure you should take when traveling to areas where exposure to the yellow fever virus is possible.
#54 Yellow Fever: Outbreak and Possible Causes Involved
https://biomedres.us/fulltexts/BJSTR.MS.ID.002624.php
Yellow fever (YF) is an acute infectious disease caused by an arbovirus, transmitted by mosquitoes of the genera Homologues, Sabethas and Aedes. The YF has two mechanisms of transmission: urban and wild and has now gained relevance for outbreaks in large urban centers. Aedes aegypti is the main vector in both South America and Africa. […] YF epidemics are directly related to climate and social changes. Increased temperature and high humidity increase the voracity of the female mosquito by blood from monkeys and eventually humans to ensure the success of oviposition. Deforestation, natural disasters or the direct action of man, determine population displacements to areas close to forests, in addition to environmental imbalances, increase the possibility of contact with the mosquito. […] In the past, yellow fever was one of the major problems for Brazilian public health but was controlled with the elimination of urban transmission in the country in 1942. However, with the impossibility of eradicating wild-type yellow fever, as it is a zoonosis of wild animals, and the wide dispersion of A. aegypti in Brazilian cities, the possibility of re-emergence of yellow fever in urban spaces is a threat constant. […] It is concluded that studies on the environmental changes and adaptation of the contaminated vectors in the non-endemic regions should be carried out and new forms of prevention should be discussed.
#55 Yellow Fever: Origin, Epidemiology, Preventive Strategies and Future Prospects
https://www.mdpi.com/2076-393X/10/3/372
Although the domestic cycle plays a limited role in YF transmission, especially in South America, urban outbreaks have been registered in Angola and DRC. […] If massive vaccination programs during the 1940sâ1950s and the 2000s significantly reduced YF virus outbreaks, the reduction in vaccination coverage between the 1960s and the mid-2000s led to a rise in YF outbreaks in South America and Africa. […] These outbreaks are not only due to insufficient vaccine coverage for insufficient vaccine supply, but also to the increase in people without history of vaccination living in endemic areas.
#56 Yellow Fever – Infectious Diseases – Merck Manual Professional Edition
https://www.merckmanuals.com/professional/infectious-diseases/arboviruses-arenaviridae-and-filoviridae/yellow-fever
Yellow fever is a mosquito-borne flavivirus infection endemic in tropical South America and sub-Saharan Africa. […] In urban yellow fever, the virus is transmitted by the bite of an Aedes aegypti mosquito infected about 2 weeks previously by feeding on a person with viremia. In jungle (sylvatic) yellow fever, the virus is transmitted by Haemagogus and Sabethes forest canopy mosquitoes that acquire the virus from wild primates. […] The most effective way to prevent yellow fever outbreaks is to maintain 80% vaccination coverage of the population in areas at risk of yellow fever. […] A single dose of vaccine can provide life-long immunity against yellow fever. […] An effective vaccine is available; a single dose provides adequate lifetime protection.
#57 History of Yellow Fever in the U.S.
https://asm.org/articles/2021/may/history-of-yellow-fever-in-the-u-s
Prevention of yellow fever primarily relies on vaccination, as there is no antiviral treatment available for the disease. While the live-attenuated vaccine has been demonstrated to be safe and effective (lifelong protection offered from one shot within 30 days of immunization in 99% of people who receive it), production can be slow and result in a low vaccine supply for areas in need.
#58 WHO EMRO | Yellow fever | Health topics
https://www.emro.who.int/health-topics/yellow-fever/index.html
Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes, mainly Aedes aegypti. […] Globally, yellow fever causes around 200,000 cases and 30,000 deaths per year. […] Sudan conducted a yellow fever risk assessment exercise in early 2013 and confirmed that the yellow fever virus was circulating in all parts of the country. […] Recommendations to control yellow fever included conducting preventive campaigns with the yellow fever vaccine, of which a single dose provides lifelong protection. […] There is currently no specific treatment for yellow fever, although proper case management improves survival rate. Use of yellow fever vaccine which offers life-long immunity can protect one from yellow fever.
#59
https://www.nhs.uk/conditions/yellow-fever/
Yellow fever is a serious infection spread by mosquitoes. It’s found in certain areas of Africa and South and Central America. You can get yellow fever if you’re bitten by an infected mosquito. The mosquitoes that carry the yellow fever virus bite during the day. […] Yellow fever is not found in the UK, Europe, Asia, Australia, New Zealand or the Pacific Islands. […] The yellow fever vaccine is recommended if you’re travelling to an area where yellow fever is found. Some people at risk of yellow fever through their work should also get vaccinated. […] There’s no specific treatment for yellow fever.
#60 Yellow Fever – Infectious Diseases – Merck Manual Professional Edition
https://www.merckmanuals.com/professional/infectious-diseases/arboviruses-arenaviridae-and-filoviridae/yellow-fever
Yellow fever is a mosquito-borne flavivirus infection endemic in tropical South America and sub-Saharan Africa. […] In urban yellow fever, the virus is transmitted by the bite of an Aedes aegypti mosquito infected about 2 weeks previously by feeding on a person with viremia. In jungle (sylvatic) yellow fever, the virus is transmitted by Haemagogus and Sabethes forest canopy mosquitoes that acquire the virus from wild primates. […] The most effective way to prevent yellow fever outbreaks is to maintain 80% vaccination coverage of the population in areas at risk of yellow fever. […] A single dose of vaccine can provide life-long immunity against yellow fever. […] An effective vaccine is available; a single dose provides adequate lifetime protection.
#61 WHO EMRO | Yellow fever | Health topics
https://www.emro.who.int/health-topics/yellow-fever/index.html
Yellow fever is an acute viral haemorrhagic disease transmitted by infected mosquitoes, mainly Aedes aegypti. […] Globally, yellow fever causes around 200,000 cases and 30,000 deaths per year. […] Sudan conducted a yellow fever risk assessment exercise in early 2013 and confirmed that the yellow fever virus was circulating in all parts of the country. […] Recommendations to control yellow fever included conducting preventive campaigns with the yellow fever vaccine, of which a single dose provides lifelong protection. […] There is currently no specific treatment for yellow fever, although proper case management improves survival rate. Use of yellow fever vaccine which offers life-long immunity can protect one from yellow fever.
#62 Yellow Fever: International History, U.S. Risk, Vaccines
https://www.verywellhealth.com/yellow-fever-7511482
Yellow fever is not contagious, meaning it causes illness but is not spread from person to person. Instead, it transmits via mosquitoes, disease vectors that spread the virus after biting an infected person and then biting an uninfected person. […] While the yellow fever vaccine prevents it, it does not treat or cure an active infection. […] There is no medicine or cure for yellow fever. However, for mild cases, at-home comfort measures can help. […] Most people survive yellow fever. Severe yellow fever occurs in about 15% of infected people. Of them, it is fatal 30% to 60% of the time.
#63 Yellow Fever: Outbreak and Possible Causes Involved
https://biomedres.us/fulltexts/BJSTR.MS.ID.002624.php
Yellow fever (YF) is an acute infectious disease caused by an arbovirus, transmitted by mosquitoes of the genera Homologues, Sabethas and Aedes. The YF has two mechanisms of transmission: urban and wild and has now gained relevance for outbreaks in large urban centers. Aedes aegypti is the main vector in both South America and Africa. […] YF epidemics are directly related to climate and social changes. Increased temperature and high humidity increase the voracity of the female mosquito by blood from monkeys and eventually humans to ensure the success of oviposition. Deforestation, natural disasters or the direct action of man, determine population displacements to areas close to forests, in addition to environmental imbalances, increase the possibility of contact with the mosquito. […] In the past, yellow fever was one of the major problems for Brazilian public health but was controlled with the elimination of urban transmission in the country in 1942. However, with the impossibility of eradicating wild-type yellow fever, as it is a zoonosis of wild animals, and the wide dispersion of A. aegypti in Brazilian cities, the possibility of re-emergence of yellow fever in urban spaces is a threat constant. […] It is concluded that studies on the environmental changes and adaptation of the contaminated vectors in the non-endemic regions should be carried out and new forms of prevention should be discussed.