Lassa Fever in Guinea and Sierra Leone: rodent control, and seasonality of human exposure to rodents

• Applicants: Matthias Borchert, Ph.D.; Dr. Elisabeth Fichet-Calvet
• Co-Applicants: Dr. Lamine Koivogui; Professor Foday Sahr, Ph.D.
• Subject Area: Virology
• Term: from 2012 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 214436063

Lassa fever is a viral haemorrhagic fever, endemic in parts of rural West Africa including Guinea and Sierra Leone, affecting 200,000-300,000 persons with 5,000-10,000 fatalities per year. Lassa virus has a rodent reservoir, Mastomys natalensis, and is transmitted to humans through contact with Mastomys, their body fluids or droppings. Treatment options are limited. There is no vaccine, so that prevention has to be based on reducing the contact between humans and infectious Mastomys. From earlier studies in Guinea we know that Mastomys aggregates in houses during the dry season, thus presumably increasing the risk for transmission to humans. Mathematical modelling has shown that transmission between rodents occurs predominantly between adults, and less so between pregnant females and foetuses. Therefore, reducing the abundance of rodents could decrease the occurrence of Lassa fever in humans by decreasing the exposure of humans to Mastomys, and by decreasing the proportion of infectious Mastomys. In Guinea, we suggest evaluating rodent trapping as intervention to reduce the abundance of Mastomys, the prevalence of Lassa virus in Mastomys, and the incidence of Lassa infection in humans. We will explore whether rodent trapping could be complemented by other means of rodent control like environmental hygiene. In Sierra Leone, we suggest to investigate whether the same seasonal pattern of Mastomys aggregation occurs as in Guinea.

• DFG Programme: Research Grants
• International Connection: Guinea, Sierra Leone
• Participating Person: Professor Dr. Stephan Günther