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Archives of Medical Research Nov 2022Despite the availability of a safe and effective vaccine, yellow fever remains a major vaccine-preventable disease in endemic regions. Additionally, travelers risk... (Review)
Review
Despite the availability of a safe and effective vaccine, yellow fever remains a major vaccine-preventable disease in endemic regions. Additionally, travelers risk acquiring yellow fever when visiting areas of endemic transmission or locations with ongoing outbreaks. Yellow fever is a viral hemorrhagic fever that has inflicted stigma, illness, and death among human societies. From the 17 to the 19 centuries, yellow fever remained a mysterious illness that predominantly affected tropical regions in Africa, the Caribbean and the Americas. The disease was as feared as cholera or smallpox, and played a significant geopolitical role in shaping modern societies. Epidemics of yellow fever brought out the best and the worst of human nature: the disease spread to new regions during the Atlantic slave trade; while the identification of its causative viral agent and mode of transmission, as well as the development of a vaccine, were made possible by the sacrifice of selfless scientists. Confirmation of the vector transmission of YF paved the way for the development of an effective vaccine in the first half of the 20 century. Encroachment of human settlements into locations with sylvatic transmission has blurred the distinction between the urban and sylvatic cycles. Introduction or expansion of routine immunization activities and reaching hard-to-reach populations consitute public health priorities toward ensuring vaccine equity in endemic areas. It is also critical to ensure the timely immunization of at-risk populations during outbreaks and to promote vaccination of international travelers. We conclude that the threat of YF will linger far into the 21 century as a leading public health emergency of global concern under the International Health Regulations.
Topics: Humans; Yellow Fever; Yellow Fever Vaccine; Yellow fever virus; Disease Outbreaks; Vaccination
PubMed: 36404585
DOI: 10.1016/j.arcmed.2022.10.005 -
Trends in Microbiology Nov 2018Yellow fever (YF) was one of the most dangerous infectious diseases of the 18th and 19th centuries, resulting in mass casualties in Africa and the Americas. The... (Review)
Review
Yellow fever (YF) was one of the most dangerous infectious diseases of the 18th and 19th centuries, resulting in mass casualties in Africa and the Americas. The etiologic agent is yellow fever virus (YFV), and its live-attenuated form, YFV-17D, remains one of the most potent vaccines ever developed. During the first half of the 20th century, vaccination combined with mosquito control eradicated YFV transmission in urban areas. However, the recent 2016-2018 outbreaks in areas with historically low or no YFV activity have raised serious concerns for an estimated 400-500 million unvaccinated people who now live in at-risk areas. Once a forgotten disease, we highlight here that YF still represents a very real threat to human health and economies. As many gaps remain in our understanding of how YFV interacts with the human host and causes disease, there is an urgent need to address these knowledge gaps and propel YFV research forward.
Topics: Africa; Animals; Disease Models, Animal; Disease Outbreaks; History, 18th Century; History, 19th Century; History, 20th Century; History, 21st Century; Host-Pathogen Interactions; Humans; Mosquito Control; RNA, Viral; South America; Vaccination; Vaccines, Attenuated; Yellow Fever; Yellow Fever Vaccine; Yellow fever virus
PubMed: 29933925
DOI: 10.1016/j.tim.2018.05.012 -
Revista Da Associacao Medica Brasileira... Feb 2018The yellow fever (YF) virus is a Flavivirus, transmitted by Haemagogus, Sabethes or Aedes aegypti mosquitoes. The disease is endemic in forest areas in Africa and Latin...
The yellow fever (YF) virus is a Flavivirus, transmitted by Haemagogus, Sabethes or Aedes aegypti mosquitoes. The disease is endemic in forest areas in Africa and Latin America leading to epizootics in monkeys that constitute the reservoir of the disease. There are two forms of YF: sylvatic, transmitted accidentally when approaching the forests, and urban, which can be perpetuated by Aedes aegypti. In Brazil, the last case of urban YF occurred in 1942. Since then, there has been an expansion of transmission areas from the North and Midwest regions to the South and Southeast. In 2017, the country faced an important outbreak of the disease mainly in the states of Minas Gerais, Espírito Santo and Rio de Janeiro. In 2018, its reach extended from Minas Gerais toward São Paulo. Yellow fever has an incubation period of 3 to 6 days and sudden onset of symptoms with high fever, myalgia, headache, nausea/vomiting and increased transaminases. The disease ranges from asymptomatic to severe forms. The most serious forms occur in around 15% of those infected, with high lethality rates. These forms lead to renal, hepatic and neurological impairment, and bleeding episodes. Treatment of mild and moderate forms is symptomatic, while severe and malignant forms depend on intensive care. Prevention is achieved by administering the vaccine, which is an effective (immunogenicity at 90-98%) and safe (0.4 severe events per 100,000 doses) measure. In 2018, the first transplants in the world due to YF were performed. There is also an attempt to evaluate the use of active drugs against the virus in order to reduce disease severity.
Topics: Aedes; Animals; Brazil; Disease Outbreaks; Humans; Insect Vectors; Yellow Fever; Yellow Fever Vaccine
PubMed: 29641667
DOI: 10.1590/1806-9282.64.02.106 -
Revista Da Associacao Medica Brasileira... Apr 2017
Topics: Brazil; Endemic Diseases; Humans; Vaccination; Yellow Fever; Yellow Fever Vaccine
PubMed: 28614526
DOI: 10.1590/1806-9282.63.04.291 -
Revista Da Associacao Medica Brasileira... Jan 2018
Topics: Brazil; Cardiovascular Diseases; Female; Humans; Infant; Male; Middle Aged; Pregnancy; Surveys and Questionnaires; Yellow Fever; Yellow Fever Vaccine; Yellow fever virus
PubMed: 29561932
DOI: 10.1590/1806-9282.64.01.1 -
Communications Biology Jun 2022Yellow fever is transmitted by mosquitoes among human and non-human primates. In the last decades, infections are occurring in areas that had been free from yellow fever...
Yellow fever is transmitted by mosquitoes among human and non-human primates. In the last decades, infections are occurring in areas that had been free from yellow fever for decades, probably as a consequence of the rapid spread of mosquito vectors, and of the virus evolutionary dynamic in which non-human primates are involved. This research is a pathogeographic assessment of where enzootic cycles, based on primate assemblages, could be amplifying the risk of yellow fever infections, in the context of spatial changes shown by the disease since the late 20 century. In South America, the most relevant spread of disease cases affects parts of the Amazon basin and a wide area of southern Brazil, where forest fragmentation could be activating enzootic cycles next to urban areas. In Africa, yellow fever transmission is apparently spreading from the west of the continent, and primates could be contributing to this in savannas around rainforests. Our results are useful for identifying new areas that should be prioritised for vaccination, and suggest the need of deep yellow fever surveillance in primates of South America and Africa.
Topics: Animals; Brazil; Culicidae; Mosquito Vectors; Vaccination; Yellow Fever
PubMed: 35654842
DOI: 10.1038/s42003-022-03492-9 -
Revista de Saude Publica 2022To analyze the number of yellow fever vaccine doses administered before and during the covid-19 pandemic in Brazil.
OBJECTIVE
To analyze the number of yellow fever vaccine doses administered before and during the covid-19 pandemic in Brazil.
METHODS
This is an ecological, time series study based on data from the National Immunization Program. Differences between the median number of yellow fever vaccine doses administered in Brazil and in its regions before (from April/2019 to March/2020) and after (from April/2020 to March/2021) the implementation of social distancing measures in the country were assessed via the Mann-Whitney test. Prais-Winsten regression models were used for time series analyses.
RESULTS
We found a reduction in the median number of yellow fever vaccine doses administered in Brazil and in its regions: North (-34.71%), Midwest (-21.72%), South (-63.50%), and Southeast (-34.42%) (p < 0.05). Series showed stationary behavior in Brazil and in its five regions during the covid-19 pandemic (p > 0.05). Brazilian states also showed stationary trends, except for two states which recorded an increasing trend in the number of administered yellow fever vaccine doses, namely: Alagoas State (before: β = 64, p = 0.081; after: β = 897, p = 0.039), which became a yellow fever vaccine recommendation zone, and Roraima State (before: β = 68, p = 0.724; after: β = 150, p = 0.000), which intensified yellow fever vaccinations due to a yellow fever case confirmation in a Venezuelan State in 2020.
CONCLUSION
The reduced number of yellow fever vaccine doses administered during the covid-19 pandemic in Brazil may favor the reemergence of urban yellow fever cases in the country.
Topics: Brazil; COVID-19; Humans; Pandemics; Vaccination; Yellow Fever; Yellow Fever Vaccine; Yellow fever virus
PubMed: 35703600
DOI: 10.11606/s1518-8787.2022056004503 -
Microbiology Spectrum Jun 2022Quick and accurate detection of neutralizing antibodies (nAbs) against yellow fever is essential in serodiagnosis during outbreaks for surveillance and to evaluate...
Quick and accurate detection of neutralizing antibodies (nAbs) against yellow fever is essential in serodiagnosis during outbreaks for surveillance and to evaluate vaccine efficacy in population-wide studies. All of this requires serological assays that can process a large number of samples in a highly standardized format. Albeit being laborious, time-consuming, and limited in throughput, the classical plaque reduction neutralization test (PRNT) is still considered the gold standard for the detection and quantification of nAbs due to its sensitivity and specificity. Here, we report the development of an alternative fluorescence-based serological assay (SNT) with an equally high sensitivity and specificity that is fit for high-throughput testing with the potential for automation. Finally, our novel SNT was cross-validated in several reference laboratories and against international WHO standards, showing its potential to be implemented in clinical use. SNT assays with similar performance are available for the Japanese encephalitis, Zika, and dengue viruses amenable to differential diagnostics. Fast and accurate detection of neutralizing antibodies (nAbs) against yellow fever virus (YFV) is key in yellow fever serodiagnosis, outbreak surveillance, and monitoring of vaccine efficacy. Although classical PRNT remains the gold standard for measuring YFV nAbs, this methodology suffers from inherent limitations such as low throughput and overall high labor intensity. We present a novel fluorescence-based serum neutralization test (SNT) with equally high sensitivity and specificity that is fit for processing a large number of samples in a highly standardized manner and has the potential to be implemented for clinical use. In addition, we present SNT assays with similar performance for Japanese encephalitis, Zika, and dengue viruses, opening new avenues for differential diagnostics.
Topics: Antibodies, Neutralizing; Antibodies, Viral; Encephalitis, Japanese; Humans; Neutralization Tests; Yellow Fever; Yellow fever virus; Zika Virus; Zika Virus Infection
PubMed: 35670599
DOI: 10.1128/spectrum.02548-21 -
The Brazilian Journal of Infectious... 2017
Topics: Brazil; Disease Outbreaks; Humans; Risk Factors; Vaccination; Yellow Fever
PubMed: 28336123
DOI: 10.1016/j.bjid.2017.02.004 -
Emerging Microbes & Infections Jul 2018Yellow fever (YF) remains a public health issue in endemic areas despite the availability of a safe and effective vaccine. In 2015-2016, urban outbreaks of YF were... (Review)
Review
Yellow fever (YF) remains a public health issue in endemic areas despite the availability of a safe and effective vaccine. In 2015-2016, urban outbreaks of YF were declared in Angola and the Democratic Republic of Congo, and a sylvatic outbreak has been ongoing in Brazil since December 2016. Of great concern is the risk of urban transmission cycles taking hold in Brazil and the possible spread to countries with susceptible populations and competent vectors. Vaccination remains the cornerstone of an outbreak response, but a low vaccine stockpile has forced a sparing-dose strategy, which has thus far been implemented in affected African countries and now in Brazil. Accurate laboratory confirmation of cases is critical for efficient outbreak control. A dearth of validated commercial assays for YF, however, and the shortcomings of serological methods make it challenging to implement YF diagnostics outside of reference laboratories. We examine the advantages and drawbacks of existing assays to identify the barriers to timely and efficient laboratory diagnosis. We stress the need to develop new diagnostic tools to meet current challenges in the fight against YF.
Topics: Animals; Brazil; Disease Outbreaks; Endemic Diseases; Humans; Mass Vaccination; Mosquito Control; Vaccination; Yellow Fever; Yellow Fever Vaccine; Yellow fever virus
PubMed: 30002363
DOI: 10.1038/s41426-018-0128-8