Resurgence Of Yellow Fever Research Articles

Tackling chikungunya and dengue crisis in Paraguay amidst COVID-19: an epidemiological alert - a correspondence.

Tackling chikungunya and dengue crisis in Paraguay amidst COVID-19: an epidemiological alert - a correspondence.

Aedes mosquitoes in the emerging threat of urban yellow fever transmission.

This last decade has seen a resurgence of yellow fever (YF) in historical endemic regions and repeated attempts of YF introduction in YF‐free countries such as the Asia‐Pacific region and the Caribbean. Infected travellers are the main entry routes in these regions where competent mosquito vectors proliferate in appropriate environmental conditions. With the discovery of the 17D vaccine, it was thought that YF would be eradicated. Unfortunately, it was not the case and, contrary to dengue, chikungunya and Zika, factors that cotribute to YF transmission remain under investigation. Today, all the signals are red and it is very likely that YF will be the next pandemic in the YF‐free regions where millions of people are immunologically naïve. Unlike COVID‐19, YF is associated with a high case‐fatality rate and a high number of deaths are expected. This review gives an overview of global YF situation, including the non‐endemic Asia‐Pacific region and the Caribbean where Aedes aegypti is abundantly distributed, and also proposes different hypotheses on why YF outbreaks have not yet occurred despite high records of travellers importing YF into these regions and what role Aedes mosquitoes play in the emergence of urban YF.

Genotype-specific features reduce the susceptibility of South American yellow fever virus strains to vaccine-induced antibodies

The resurgence of yellow fever in South America has prompted vaccination against the etiologic agent, yellow fever virus (YFV). Current vaccines are based on a live-attenuated YF-17D virus derived from a virulent African isolate. The capacity of these vaccines to induce neutralizing antibodies against the vaccine strain is used as a surrogate for protection. However, the sensitivity of genetically distinct South American strains to vaccine-induced antibodies is unknown. We show that antiviral potency of the polyclonal antibody response in vaccinees is attenuated against an emergent Brazilian strain. This reduction was attributable to amino acidchanges at two sites in central domain II of the glycoprotein E, including multiple changes at the domain I-domain II hinge, which are unique to and shared among most South American YFV strains. Our findings call for a reevaluation of current approaches to YFV immunological surveillance in South America and suggest approaches for updating vaccines.

Yellow Fever in Nigeria: A Review of Past, Current, and Future Strides

Since 1985, there has been resurgence of yellow fever in Africa with outbreaks occurring in more than 33 countries. From that time, thousands of cases have occurred in Nigeria which is the most populous country in Africa. Semi-urban and urban centres across the country are densely populated, with numerous sparsely populated rural settings in every State, some of which contain heavy forests. A wide-range of vegetation zones exists which lead to smooth transition of several tropical climates. As a result, there is preponderance of Aedes species in many parts of the country especially during the rainy season when relative humidity is high. Vector control is not applicable to jungle yellow fever, but infection in human population can be prevented by vaccination. Yellow fever deaths were recently reported in Nigeria, causing panic and public outcry. This review highlights the epidemiological trajectory of yellow fever, the past, and the present and future efforts in the country with a view to providing in-depth knowledge of yellow fever activities in order to enhance public health.

Yellow Fever in Travelers.

This decade has seen a resurgence of yellow fever (YF) that has also affected travelers with a record number of international travelers infected by YF virus including the first documented importation of YF into Asia. The recent resurgence of YF has been attributed largely to sub-optimal vaccination coverage along with waning population-level immunity. New lessons have been learnt with regard to the clinical management of severe YF as a result of the Brazilian outbreak. With increasing YF cases in travelers, travel medicine providers need to familiarize themselves with the diagnosis and clinical management of severe YF. Prevention remains the mainstay, and all efforts need to be taken that travelers do not circumvent the International Health Regulations. More than 80years of experience with YF vaccine reinforce the generally acceptable safety profile of YF vaccine but highlight the unique serious adverse events of viscerotropic and neurotropic disease, in particular in first-time vaccinees. Continued physician and traveler education regarding the risks and benefits of YF vaccination is needed, with an urgent need to better define "significant and unavoidable risk" for improved benefit-risk assessments.

Weakened geomagnetic field, Cosmic rays & the Resurgence of Yellow Fever

Weakened geomagnetic field, Cosmic rays & the Resurgence of Yellow Fever

Yellow fever (YF) remains a public health problem in Cameroon: descriptive analysis of the national database (2010-2016, 50th epidemiological week)

Introduction : there is resurgence of Yellow fever (YF) cases in Africa. In Cameroon, confirmed cases of YF continue being registered (20 cases in 2015), despite several control measures put in place, including, several vaccination campaigns (target > 9 months) conducted nationwide, the last one dating May 2015. We aimed to describe the epidemiological profile of YF cases in Cameroon for the improvement of surveillance and controls strategies. Methods : we analyzed the Expanded Program of Immunization’s YF case database, from 2010 to 2016 with Epi Info 7. Sample transport duration, vaccination status of suspected cases, socio demographics, trends and geographic distribution of confirmed cases were analyzed. A confirmed case, was every positive case at seroneutralisation, with no previous YF vaccination. Differences between the frequencies of cases was determined using Chi-square (X 2 ). Results : a total of 13,837 suspected cases of YF were reported, and 13,807(99.7%) tested. The proportion of samples sent on time to the laboratory decreased from 25% in 2010 to 18% in 2016. In 2016, 56% of suspected cases were unvaccinated or had unknown immunization status. A total of 109 suspected cases were confirmed, giving a predictive positive value of 0.8%. The annual incidence of cases varies, with two peaks in 2011 (1.3/1.000.000hbts) and 2015 (1.1/1.000.000hbts), and a mean of 7 cases/1.000.000hbts/year. Cases were recorded in 58/189 health districts, mostly in rural zones 72 (66%) p Conclusion : these findings highlight that YF remains a public health problem in Cameroon, with probable seasonal trends and low immunisation status of the population. Emphasis should be placed on conducting periodic and high quality vaccination campaigns in order to reduce the risk and prevent outbreaks.

Resurgence of yellow fever in Brazil: Overview and possible control options.

Resurgence of yellow fever in Brazil: Overview and possible control options.

Resurgence of Yellow Fever in Angola, 2015-2016.

To the Editor: Yellow fever virus (YFV) is endemic in tropical and subtropical Africa and South America, and it is transmitted to humans and nonhuman primates through the bites of infected mosquitoes. The virus, a member of the family Flaviviridae, causes yellow fever, which in severe cases manifests as fulminant hemorrhagic fever. Outbreaks of yellow fever in humans occur mostly in the urban cycle of the virus, which involves its transmission through the bites of the day-feeding infected Aedes aegypti mosquitoes (1). As many as 130,000 cases with fever and jaundice or hemorrhage may occur annually with a concomitant 78,000 deaths (2). A low capacity for yellow fever diagnosis and lack of surveillance in disease-endemic countries likely contribute to case underreporting (1).

US$58 million grant to fight yellow fever in Africa

Efforts to contain the resurgence of yellow fever in 12 West African states have been boosted by a US$58 million grant from the GAVI Alliance to support special immunization campaigns in countries at high risk of yellow fever epidemics. The disease was almost wiped out in the 1960s but many nations

Resurgence of Yellow Fever in Africa Prompts a Counterattack

INFECTIOUS DISEASEExperts tracking the resurgence of yellow fever across Africa worry about one scenario in particular: simultaneous outbreaks in several of the continent's teeming megacities. In response, a major initiative to protect the populations at highest risk was announced at the World Health Assembly last week.

The changing epidemiology of yellow fever and dengue, 1900 to 2003: full circle?

Yellow fever and dengue are old diseases, having caused major epidemics in centuries past. Both were effectively controlled in the mid 1900s, yellow fever in Francophone Africa by vaccination and yellow fever and dengue in the Americas by effective control of the principal urban vector of both viruses, Aedes aegypti. In the last 25 years of the 20th century, however, there was a resurgence of yellow fever in Africa, and of dengue worldwide. The factors responsible for this resurgence are discussed, as are current options for prevention and control.

Fiebre amarilla en Africa: su impacto en salud pública y perspectivas para su control en el siglo XXI

In the last two decades, yellow fever re-emerged with vehemence to constitute a major public health problem in Africa. The disease has brought untold hardship and indescribable misery among different populations in Africa. It is one of Africa's stumbling blocks to economic and social development. Despite landmark achievements made in the understanding of the epidemiology of yellow fever disease and the availability of a safe and efficacious vaccine, yellow fever remains a major public health problem in both Africa and America where the disease affects annually an estimated 200,000 persons causing an estimated 30,000 deaths. Africa contributes more than 90% of global yellow fever morbidity and mortality. Apart from the severity in morbidity and mortality, which are grossly under reported, successive outbreaks of yellow fever and control measures have disrupted existing health care delivery services, overstretched scarce internal resources, fatigued donor assistance and resulted in gross wastage of vaccines. Recent epidemics of yellow fever in Africa have affected predominantly children under the age of fifteen years. Yellow fever disease can be easily controlled. Two examples from Africa suffice to illustrate this point. Between 1939 and 1952, yellow fever virtually disappeared in parts of Africa, where a systematic mass vaccination programme was in place. More recently, following the 1978-1979 yellow fever epidemic in the Gambia, a mass yellow fever vaccination programme was carried out, with a 97% coverage of the population over 6 months of age. Subsequently, yellow fever vaccination was added to the EPI Programme. The Gambia has since then maintained a coverage of over 80%, without a reported case of yellow fever, despite being surrounded by Senegal which experienced yellow fever outbreaks in 1995 and 1996. The resurgence of yellow fever in Africa and failure to control the disease has resulted from a combination of several factors, including: 1) collapse of health care delivery systems; 2) lack of appreciation of the full impact of yellow fever disease on the social and economic development of the affected communities; 3) insufficient political commitment to yellow fever control by governments of endemic countries; 4) poor or inadequate disease surveillance; 5) inappropriate disease control measures, and 6) preventable poverty coupled with misplaced priorities in resource allocation. Yellow fever can be controlled in Africa within the next 10 years, if African governments seize the initiative for yellow fever control by declaring an uncompromising resolve to control the disease, the governments back up their resolve with an unrelenting commitment and unwavering political will through adequate budgetary allocations for yellow fever control activities, and international organisations, such as WHO, UNICEF, GAVI, etc., provide support and technical leadership and guidance to yellow fever at risk countries. Over a ten-year period, of stage-by-stage mass yellow fever vaccination campaigns, integrated with successful routine immunisation, Africa can bring yellow fever under control. Subsequently, for yellow fever to cease being a public health problem, Africa must maintain at least an annual 80% yellow fever vaccine coverage of children under the age of 1 year, and sustain a reliable disease surveillance system with a responsive disease control programme. This can be achieved at an affordable annual expenditure of less than US$1.00 per person per year, with a reordering of priorities.