The number of people at risk of exposure to Lassa fever in Africa would increase by 600%, according to new study
The Natal multimammate rat. Photo: iStock Climate change will aid the spread of Lassa fever, a zoonotic disease endemic to parts of west Africa, to the central and eastern parts of the continent in the next 50 years, a recently published study has found.
A team of scientists from the Scripps Research Institute in the United States and the University of Brussels in Belgium projected that there would be a 600 per cent jump in the number of people exposed to the virus that causes Lassa fever.
The number of people at risk of exposure would rise to 453 million by 2050 and 700 million by 2070, up from about 92 million in 2022.
Lassa fever is caused by the Lassa virus, a member of the Arenaviridae family. Humans usually become infected through direct contact or exposure to the excreta of infected Natal multimammate rat (Mastomys natalensis) rats.
An estimated 80 per cent of infections are mild or asymptomatic. But the remaining 20 per cent can cause haemorrhaging from the mouth and gut, low blood pressure and potential permanent hearing loss.
The fatality rate for hospitalised patients is generally high and can reach 80 per cent at times. There is currently no vaccine approved to prevent the disease. Lassa fever is currently reported mostly from Guinea, Liberia, Nigeria and Sierra Leone, all of which are in west Africa.
The scientists analysed environmental data on Lassa virus outbreaks over the decades. This showed that temperature, rainfall and the presence of pastureland areas were key factors that contributed to the transmission of the Lassa virus.
They combined an ‘ecological niche’ model with projections of climate and land use changes in Africa over the next several decades, along with the known range of the Natal multimammate rat.
Africa is at the frontline of the global climate emergency.
Up to 118 million extremely poor people or those living on less than $1.90 per day will be exposed to drought, floods and extreme heat in Africa by 2030, according to State of the Climate in Africa 2020 report.
Countries of sub-Saharan Africa are expected to contribute more than half of the increase in the global human population anticipated through 2050, according to World Population Prospects 2022 released in July this year.
The scientists found that several regions would likely become ecologically suitable for viral spread in central Africa, including in Cameroon and the Democratic Republic of the Congo and also in Uganda, east Africa.
They also found that if the virus was successfully introduced and propagated in a new ecologically suitable area, its growth would be limited over the first decades.
The study Predicting the evolution of the Lassa virus endemic area and population at risk over the next decades was published September 27, 2022 in the journal Nature Communications
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