At Home with Mastomys and Rattus: Human-Rodent Interactions and Potential for Primary Transmission of Lassa Virus in Domestic Spaces

Abstract

The multimammate mouse (Mastomys natalensis) is the reservoir for Lassa virus (LASV). Zoonotic transmission occurs when humans are directly or indirectly exposed to fluids of the multimammate mouse, such as urine, saliva, and blood. Housing characteristics and domestic organization affect rodent density in and around households and villages, and are likely to be a risk factor for Lassa fever in humans where the reservoir exists. We use semi-structured interviews (N = 51), a quantitative survey (N = 429), direct observations, and a rodent ecology study to provide new insights into how the organization of domestic spaces brings together humans and rodents and creates pathways for infection in rural settlements in Bo District, Sierra Leone. Rodents were frequently reported inside houses (92.4% of respondents), in which we predominantly trapped M. natalensis (57% of trapped rodents) and Rattus rattus (38% of trapped rodents). Building design and materials provide hiding and nesting places for rodents and lead to close proximity with humans. Patterns of contact are both unintentional and intentional and research participants reported high levels of contact with rodents (34.2% of respondents) and rodent fluids (52.8% of respondents). Rodents are also perceived as a serious threat to food security. These results present detailed knowledge about how humans live with and come into contact with rodents, including the LASV reservoir. Our results argue for further collaborative research in housing and environmental modification such as ceiling construction, food storage, and sanitation as prevention against zoonotic LASV transmission.

Density dependence and persistence of Morogoro arenavirus transmission in a fluctuating population of its reservoir host

“…Although survival outside the host is arguably important to explain intraspecies transmission for many arenaviruses (e.g. LASV is most likely transmitted from rodents to humans by the environment; Bonwitt et al, ), empirical data to support a free‐living stage are rare. The only available data come from laboratory experiments where LASV was deposited on solid surfaces in the dark and aerosolized, (>50% inactivation at 60 hr) (Sagripanti, Rom, & Holland, ; Stephenson et al, ).…”

Lassa fever infection from West Africa, dynamic and epidemiology of the virus on the population 1969–2019: a systematic review and meta-analysis

“…LF is transmitted to humans when they ingest food contaminated by the feces and urine of Mastomys spp. Once humans are infected, transmission also occurs from human to human through contact with fluid and aerosol secretions in the form of sneezing, sputum, seminal fluid, stool, urine and blood [5].…”

“…). In the period 2009-2019 we had a prevalence of 17.53% (548/3159) in 8 countries Benin (1), Ghana (6), Ivory Coast (4), Liberia(14), Mali (240), Sierra Leone(40), Nigeria (238) and Togo(5)…”

Climate Change and the Neglected Tropical Diseases

“…Transmission occurs when humans come into close contact with the mouse specifically through ingestion or inhalation of mouse urine, faeces or blood. Risk factors include living in close proximity to the mice, butchering and consumption (Bonwitt et al, 2016(Bonwitt et al, , 2017.…”