Households as hotspots of Lassa fever? Assessing the spatial distribution of Lassa virus-infected rodents in rural villages of Guinea

Abstract

The Natal multimammate mouse (Mastomys natalensis) is the reservoir host of Lassa virus (LASV), an arenavirus that causes Lassa haemorrhagic fever in humans in West Africa. While previous studies suggest that spillover risk is focal within rural villages due to the spatial behaviour of the rodents, the level of clustering was never specifically assessed. Nevertheless, detailed information on the spatial distribution of infected rodents would be highly valuable to optimize LASV-control campaigns, which are limited to rodent control or interrupting human-rodent contact considering that a human vaccine is not available. Here, we analysed data from a four-year field experiment to investigate whether LASVinfected rodents cluster in households in six rural villages in Guinea. Our analyses were based on the infection status (antibody or PCR) and geolocation of rodents (n = 864), and complemented with a phylogenetic analysis of LASV sequences (n = 119). We observed that the majority of infected rodents were trapped in a few houses (20%) and most houses were rodent-free at a specific point in time (60%). We also found that LASV strains circulating in a specific village were polyphyletic with respect to neighbouring villages, although most strains grouped together at the subvillage level and persisted over time. In conclusion, our results suggest that: (i) LASV spillover risk is heterogeneously distributed within villages in Guinea; (ii) viral elimination in one particular village is unlikely if rodents are not controlled in neighbouring villages. Such spatial information should be incorporated into eco-epidemiological models that assess the cost-efficiency of LASV control strategies.

Hunting and consumption of rodents by children in the Lassa fever endemic area of Faranah, Guinea

“…Moreover, the LASV prevalence in M . natalensis has been determined in Brissa, Dalafilani, Sonkonia, and Yarawalia, ranging from 15% to 23% of animals infected in 2013–2015 [ 40 , 50 , 51 ]. Moreover, immunoglobulin G (IgG) prevalence in humans was found to be 84% (n = 1302 persons) in the Faranah area, with 62% of 6-year-old children being seropositive [ 52 ].…”

A Sporadic and Lethal Lassa Fever Case in Forest Guinea, 2019

“…In Guinea, numerous LASV sequences have been largely described in rodents, notably in the region of Faranah (221 sequences), Kindia (6 sequences) and Guékedou (9 sequences) [ 9 , 10 , 11 , 20 , 21 ]. However, only 5 sequences are derived from humans, 2 complete from Faranah and Macenta [ 22 , 23 ], and 3 partials from Kissidougou and Nzérékoré [ 14 ].…”

Detection of Lassa virus in wild rodent feces: Implications for Lassa fever burden within households in the endemic region of Faranah, Guinea

“…This study was conducted in the endemic region of Faranah (Guinea), where the LASV prevalence and seroprevalence in the rodent population were 5–10% and 20–40%, respectively. The occupancy of houses with rodents was ±60% at the beginning of the dry season (November) [ 6 ]. All participating house owners gave informed and written consent prior to sampling.…”

“…The multimammate mouse ( Mastomys natalensis ) is the primary reservoir of LASV contributing to human infection. This rodent is widely distributed throughout sub-Saharan Africa where it lives in houses and agricultural fields [ 6 ]. Cohabitation of M. natalensis and humans presents opportunity for viral spillover, as studies show that the rodent sheds viral titers in its urine for up to seven days in laboratory conditions [ 7 ].…”