More than 600 million people could be threatened by the dangerous Lassa virus in the future. Over the next 50 years, changes in climate and land use will significantly increase the region in which people can contract the often fatal hemorrhagic fever, reports a team led by Raphaëlle Klitting from the Scripps Research Institute. As the working group writes in their publication in »Nature Communications«carries the Natal multi-teat mouse (Mastomys natalensis), carriers of the Lassa virus, the pathogen only in a tiny part of their range. According to the working group’s model, this area will increase dramatically by 2070. Lassa fever could then also spread to Central and East Africa instead of just West Africa.
The natal multi-teat mouse follows cultures and seeks human contact. She most likely transmits the virus through her poo. But while the vector is found throughout almost all of sub-Saharan Africa, Lassa fever is only found in a few small areas of West Africa. According to Klitting’s team, the reason for this is that certain environmental conditions are necessary for the virus to spread. The virus is therefore too demanding for large areas of Africa.
Lassa fever is a serious disease and not uncommon where it occurs. Of the several hundred thousand people who contract Lassa fever in Nigeria and other West African countries, about 80 percent develop very mild or symptom-free disease. However, in the rest of the cases, a severe hemorrhagic fever develops, which can be accompanied by symptoms such as bleeding from the mouth and other orifices. Up to 80 percent of those affected die. There is no vaccination.
On this basis, the group modeled the ecological niche of the Lassa virus – with the result that temperature, precipitation and rangeland determine its distribution. As a second step, she combined this data with projections of future climate and land-use changes to determine the ecological niche of the virus up to 50 years from now. In these projections, the distribution area of the dangerous disease expands considerably.