Predicting the evolution of Lassa Virus endemic area and population at risk over the next decades

Abstract

Lassa fever is listed among the diseases that pose the greatest risks to public health by the World Health Organization. This severe viral hemorrhagic fever is caused by Lassa virus, a zoonotic pathogen that repeatedly spills over to humans from its rodent reservoirs. It is currently not known how climate change, transformations in land use, and human population growth could affect the endemic area of this virus, currently limited to parts of West Africa. By exploring the environmental data associated with virus occurrence, we show how temperature, precipitation and the presence of pastures determine ecological suitability for virus circulation. We project that regions in Central and East Africa will likely become suitable for Lassa virus over the next decades and estimate that the total population living in areas suitable for Lassa virus may grow from about 100 million to 700 million by 2070. By analysing geotagged viral genomes, we find that in the event of Lassa virus being introduced into a new suitable region, its spread might remain spatially limited over the first decades. Our results highlight how the endemic area of Lassa virus may expand well beyond West Africa in the next decades due to human impact on the environment, putting hundreds of million more people at risk of infection.

Lassa fever in Nigeria: Social and Ecological Risk Factors Exacerbating Transmission and Sustainable Management Strategies

“…Hansen, et al [24] and Abdullahi, et al [25], stated that other rodent species such as Hylomyscus pamfi, Rattus rattus, Praomys daltoni, Mus minutoides, Crocidura spp., and Mastomys erthrocyclus may likely be carriers of Lassa virus although their impact in the spread of the virus. M. natalensis is a widespread rodent in urban and semi-urban settlements in Nigeria: where it was discovered and Sierra Leone, Liberia, and Guinea [26], the rodent has been reported in Mali, Ghana, Benin, Togo, and Ivory Coast [27][28][29]. LASV is transmitted mainly from rodent reservoirs to humans [14,16,17,27,29] and sometimes through personto-person contact [12,14,15], sexual and in-utero transmission have been reported by WHO [8].…”

“…M. natalensis is a widespread rodent in urban and semi-urban settlements in Nigeria: where it was discovered and Sierra Leone, Liberia, and Guinea [26], the rodent has been reported in Mali, Ghana, Benin, Togo, and Ivory Coast [27][28][29]. LASV is transmitted mainly from rodent reservoirs to humans [14,16,17,27,29] and sometimes through personto-person contact [12,14,15], sexual and in-utero transmission have been reported by WHO [8].…”

“…This is at par with other developing and developed countries and regions of the world. These rapid changes are mainly due to anthropogenic activities in pursuit of the development of humans that are in turn exacerbating climate change as the average temperature has increased whereas a decrease in rainfall over time is expected [27]. Zoonotic diseases have also been predicted to increase as several forecasts indicate that higher temperatures in the subregion and making it suitable for increased growth in the M. natalensis population [26].…”

“…Zoonotic diseases have also been predicted to increase as several forecasts indicate that higher temperatures in the subregion and making it suitable for increased growth in the M. natalensis population [26]. While other regions around the world have tropical climates, M. natalensis is mainly found in sub-Saharan Africa and it has been established that LASV is found only in the West African region [27]. This could be the reason why the LASV like other arenaviruses has enveloped and are sensitive to high temperatures or low humidity more than its host, which may trigger the reliance of LASV transmission on rainfall and humidity in West Africa [27,71].…”

“…Tewogbola and Aung [96] suggest that the Yoruba ethnic group of Nigeria to some extent has formed resistance to LASV when compared to other endemic areas. Klitting, et al [27] also predict that in the next few decades, LASV may extend beyond its current geographical borders as its predecessor Ebola virus if it is introduced to a new habitat that is fitting for its needs.…”