New study highlights challenges posed by West Nile virus in Africa
A new Foundation-funded study could bring us closer to preventing this fatal disease.
West Nile virus can cause severe and sometimes fatal neurological disease in humans, including meningitis or encephalitis. The World Health Organization (WHO) has identified the virus as a high-priority, high-risk pathogen, but scientists still lack full insight into how the disease spreads or how to effectively diagnose it.
An exciting new Foundation-funded study aims to improve understanding of the virus in Africa, where it is endemic.
Like other mosquito-borne viruses such as Dengue and Chikungunya, the circulation of West Nile virus could increase and expand into new regions as our climate continues to change.Dr Houriiyah Tegally
Centre for Epidemic Response and Innovation (CERI) at Stellenbosch University
Published recently in The Lancet Microbe and part-funded by the Foundation, the study highlights the challenges researchers face when collecting and analysing data on the West Nile virus.
Currently, there is a lack of accurate data on the extent and spread of the virus, leaving scientists uncertain about its full impact. This data gap means vulnerable communities remain unprotected, and public health systems are ill-prepared for potential outbreaks.
This study, co-authored by Foundation-funded researcher, Dr Houriiyah Tegally from the Centre for Epidemic Response and Innovation (CERI) at Stellenbosch University, South Africa, could play a key role in strengthening the global public health response to the deadly virus.
What is West Nile Virus?
West Nile virus is a type of ‘zoonotic flavivirus’ that can be transmitted from animals to humans, causing severe illness. Birds are the natural host of the virus, but it is mainly transmitted to people through bites from infected mosquitoes.
Zoonotic flaviviruses like this are particularly concerning due to their ability to spill over from animal reservoirs into human populations, potentially causing epidemics.
Despite its ability to cause fatal disease in humans, 80% of people who are infected with the virus do not show any symptoms.
At the moment, treatment for patients whose nervous systems are impacted by the virus involves hospitalisation, intravenous fluids, respiratory support, and prevention of secondary infections. No vaccines have yet been developed for humans.
Strengthening disease and genomic surveillance systems, particularly in areas where data is scarce, is needed to detect outbreaks, reduce their impact on communities, and prevent future outbreaks from occurring.Dr Monika Moir
CERI
What are the key outcomes of this study?
Although West Nile virus is known to be endemic in Africa, scientists know little about the genetic code of the pathogen or its impact on human DNA.[MOU1]
In this project, Dr Tegally and her team from Stellenbosch University explored how effectively advanced techniques, like molecular detection and genomic sequencing, are used in Africa to understand the virus’ spread.
They found that the virus has been detected in 39 African countries, but genomic sequences – which reveal a pathogen’s genetic material – are publicly available for only 16 of these countries.
Dr Tegally explains, “Given its prevalence and evolution in Africa, it is critical for us to understand how West Nile virus was historically transmitted on the continent, to better prepare public health systems and inform resource planning.”
The researchers also observed specific regions of Africa where viral circulation coincided with sites of significant bird diversity and high human population density – i.e. areas more susceptible to spill-over.
Through this work, the team identified key challenges facing the surveillance* of the virus in Africa. These could be useful starting points for addressing knowledge gaps around the disease – for instance, the study highlights a critical need for low-cost diagnostics at the point-of-care, One Health surveillance recommendations, and integration of diverse datasets to better understand how the virus emerges.
Dr Monika Moir from the Centre for Epidemic Response and Innovation (CERI), lead author of the paper, comments, “Understanding the true burden of West Nile virus in Africa is essential for protecting both human and animal health, locally and globally.”
(* see paragraph below on Disease Surveillance.)
Why is it important to more effectively collect and analyse WNV data?
Disease surveillance in general is a crucial public health practice that helps to monitor disease trends and inform public health action.
Dr Moir adds, “Strengthening disease and genomic surveillance systems, particularly in areas where data is scarce, is needed to detect outbreaks, reduce their impact on communities, and prevent future outbreaks from occurring.”
In the context of our changing climate, it may be more important now than ever to understand how the virus circulates. Earlier this summer, for example, the virus was detected for the first time in UK mosquito populations.
"Like other mosquito-borne viruses such as Dengue and Chikungunya, the circulation of West Nile virus could increase and expand into new regions as our climate continues to change,” says Dr Tegally.
“West Nile virus can cause severe neuro-invasive disease in 1% of human cases, and it has already fuelled large outbreaks in North America.”
By improving diagnostics and surveillance for the virus, we could also accelerate vaccine development – bringing us closer to preventing this potentially fatal disease.