Hamlet, A. | Search bioRxiv

bioRxiv2023

Serological evidence of high pathogenicity virus infection in Eidolon helvum fruit bats in Nigeria

The Eidolon helvum fruit bat is the most widely distributed fruit bat in Africa and is known to be a reservoir for several pathogenic viruses that can cause disease in humans. To assess the risk of zoonotic spillover, we conducted a serological survey of 304 serum samples from E. helvum bats that were captured for human consumption in Makurdi, Nigeria. Using pseudotyped viruses, we screened the samples for neutralising antibodies against viruses from the Coronaviridae, Filoviridae, Orthomyxoviridae and Paramyxoviridae families. We report the presence of neutralising antibodies against henipavirus lineage GH-M74a virus (odds ratio 6.23; p<0.001), Nipah virus (odds ratio 4.04; p=0.00031), bat influenza H17N10 virus (odds ratio 7.25; p<0.001) and no significant association with Ebola virus (odds ratio 0.56; p=0.375) in the bat cohort. The data suggest a potential risk of zoonotic spillover including the possible circulation of highly pathogenic viruses in E. helvum populations. These findings highlight the importance of maintaining sero-surveillance of E. helvum to monitor changes in virus prevalence and distribution over time and across different geographic locations. Article summary lineThe detection of neutralizing antibodies against henipavirus GH-M74a virus, Nipah virus, and H17N10 virus in Eidolon helvum bat sera from Nigeria using pseudotyped viruses suggests a potential risk of zoonotic spillover.

microbiology↗

bioRxiv2018

Eliminating yellow fever epidemics in Africa: vaccine demand forecast and impact modelling

BackgroundTo counter the increasing global risk of Yellow fever (YF), the World Health Organisation initiated the Eliminate Yellow fever Epidemics (EYE) strategy. Estimating YF burden, as well as vaccine impact, while accounting for the features of urban YF transmission such as indirect benefits of vaccination, is key to informing this strategy.\n\nMethods and FindingsWe developed two model variants to estimate YF burden in sub-Saharan Africa, assuming all infections stem from either the sylvatic or the urban cycle of the disease. Both relied on an ecological niche model fitted to the local presence of any YF reported event in 34 African countries. We calibrated under-reporting using independent estimates of transmission intensity provided by 12 serological surveys performed in 11 countries. We calculated local numbers of YF infections, deaths and disability-adjusted life years (DALYs) lost based on estimated transmission intensity while accounting for time-varying vaccination coverage. We estimated vaccine demand and impact of future preventive mass vaccination campaigns (PMVCs) according to various vaccination scenarios.\n\nVaccination activities conducted in Africa between 2005 and 2017 were estimated to prevent from 3.3 (95% CI 1.2-7.7) to 6.1 (95% CI 2.4-13.2) millions of deaths over the lifetime of vaccinees, representing extreme scenarios of all transmission due to the sylvatic or the urban cycle, respectively. By prioritizing provinces based on the risk of urban YF transmission, an average of 37.7 million annual doses for PMVCs over eight years would avert an estimated 9,900,000 (95% CI 7,000,000-13,400,000) infections and 480,000 (180,000-1,140,000) deaths over the lifetime of vaccinees, corresponding to 1.7 (0.7-4.1) deaths averted per 1,000 vaccine doses.\n\nLimitations include substantial uncertainty in the estimates arising from the scarcity of reliable data from surveillance and serological surveys.\n\nConclusionsBy estimating YF burden and vaccine impact over a range of spatial and temporal scales, while accounting for the specificity of urban transmission, our model can be used to inform the current EYE strategy.

epidemiology↗

bioRxiv2017

International risk of yellow fever spread from the ongoing outbreak in Brazil

The largest Yellow Fever (YF) outbreak in a decade in Latin America is underway in the Southeast of Brazil. In this article we provide a quantitative assessment of the risk of travel-related international spread of YF. We argue that mitigating the risk of imported YF cases seeding local transmission requires heightened surveillance in the southern United States, Latin America (especially Argentina, Chile and Uruguay) and Europe (especially Portugal, Spain, Italy and Germany).

epidemiology↗