Understanding the cryptic nature of Lassa fever in West Africa

Abstract

Lassa fever (LF) is increasingly recognized by global health institutions as an important rodent-borne disease with severe impacts on some of West Africa's poorest communities. However, our knowledge of LF ecology, epidemiology and distribution is limited, which presents barriers to both short-term disease forecasting and prediction of long-term impacts of environmental change on Lassa virus (LASV) zoonotic transmission dynamics. Here, we synthesize current knowledge to show that extrapolations from past research have produced an incomplete picture of the incidence and distribution of LF, with negative consequences for policy planning, medical treatment and management interventions. Although the recent increase in LF case reports is likely due to improved surveillance, recent studies suggest that future socio-ecological changes in West Africa may drive increases in LF burden. Future research should focus on the geographical distribution and disease burden of LF, in order to improve its integration into public policy and disease control strategies.

Evaluation of rodent control to fight Lassa fever based on field data and mathematical modelling

“…However, recent incidence reports suggest a substantial increase in the number and geographical extent of cases, exemplified by an unprecedented 2017-2018 outbreak in Nigeria [9,10]. Although this can partly be explained by the availability of better diagnostic tools and increased public awareness (especially after the 2014-2016 West Africa Ebola epidemic), increased spillover rates and transmission are likely, and can be driven by changes in climate, land use, and human mobility [11,12]. Because of the absence of a human vaccine or efficacious drug, the World Health Organization added LASV to its list of priority pathogens of epidemic potential for which there are no, or insufficient, countermeasures.…”

Large-scale Lassa fever outbreaks in Nigeria: quantifying the association between disease reproduction number and local rainfall

“…Lassa fever (LF), caused by Lassa virus (LASV), is increasingly recognized as an important rodent-borne viral hemorrhagic fever presenting a severe public health threat to some of the communities in sub-Saharan West Africa [1]. Discovered in 1969 [2], LF is endemic to much of rural Nigeria and regions in the Mano River Union [3].…”

“…LASV transmits from human to human, as well as via the zoonotic cycle [1,3,4]. LF has a high case fatality rate ranging from 1% in the community to over 60% in hospital settings [1,4,5]. The common reservoir of LASV is Mastomys natalensis, one of the most widespread rodent species in sub-Saharan Africa [1,3], which exhibit sensitive population dynamics to water level [6,7].…”

“…LF has a high case fatality rate ranging from 1% in the community to over 60% in hospital settings [1,4,5]. The common reservoir of LASV is Mastomys natalensis, one of the most widespread rodent species in sub-Saharan Africa [1,3], which exhibit sensitive population dynamics to water level [6,7]. Previous studies have recognized the ecological connection between the population levels of rodents and rainfall [8][9][10].…”

Potential for Seasonal Lassa Fever Case Exportation from Nigeria

“…Disease transmission is reported yearround, with seasonal peaks typically occurring during the dry season (November to March). 3 In recent years, the case burden has ranged from 25 to 150 cases annually. 4 However, the largest epidemic of Lassa fever in recent history occurred in 2018, with 420 confirmed cases and 106 deaths reported between January 1 and April 29, 2018.…”