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

Abstract

A key aim in wildlife disease ecology is to understand how host and parasite characteristics influence parasite transmission and persistence. Variation in host population density can have strong impacts on transmission and outbreaks, and theory predicts particular transmission–density patterns depending on how parasites are transmitted between individuals. Here, we present the results of a study on the dynamics of Morogoro arenavirus in a population of multimammate mice (Mastomys natalensis). This widespread African rodent, which is also the reservoir host of Lassa arenavirus in West Africa, is known for its strong seasonal density fluctuations driven by food availability. We investigated to what degree virus transmission changes with host population density and how the virus might be able to persist during periods of low host density. A seven‐year capture–mark–recapture study was conducted in Tanzania where rodents were trapped monthly and screened for the presence of antibodies against Morogoro virus. Observed seasonal seroprevalence patterns were compared with those generated by mathematical transmission models to test different hypotheses regarding the degree of density dependence and the role of chronically infected individuals. We observed that Morogoro virus seroprevalence correlates positively with host density with a lag of 1–4 months. Model results suggest that the observed seasonal seroprevalence dynamics can be best explained by a combination of vertical and horizontal transmission and that a small number of animals need to be infected chronically to ensure viral persistence. Transmission dynamics and viral persistence were best explained by the existence of both acutely and chronically infected individuals and by seasonally changing transmission rates. Due to the presence of chronically infected rodents, rodent control is unlikely to be a feasible approach for eliminating arenaviruses such as Lassa virus from Mastomys populations.

Experimental Morogoro Virus Infection in Its Natural Host, Mastomys natalensis

“…Our findings also match observations made by Borremans et al, where Mastomys neonates infected with MORV develop a long-lasting viremia in the presence of antibodies. Evidence for MORV persistence in Mastomys has also been found in field studies, and mathematic modeling of the data suggests that chronic infections are important for virus maintenance within the host population [ 34 ]. We found a clear correlation between the age and the duration of the infection.…”

Impacts of biodiversity and biodiversity loss on zoonotic diseases

“…There is less evidence evaluating the effect of host abundance on emergence, but some studies suggest abundance is a key factor (e.g., ref. 42 ). The “zoonotic host diversity and abundance” model thus appears to be more realistic than the model that considers only “zoonotic host diversity”, and it is far more appropriate than the “total host diversity” model ( Fig.…”

Linking Behavior, Co-infection Patterns, and Viral Infection Risk With the Whole Gastrointestinal Helminth Community Structure in Mastomys natalensis

“…This explanation may also suggest that the negative correlation between exploration and MORVab presence, found in Vanden Broecke et al (59), is potentially indirect, where less explorative individuals are more likely to become infected with P. muricola, which reduces their immune system making them more vulnerable to MORV infection. Nonetheless, experimental studies are needed to confirm this link between P. muricola and MORV infection and should take other factors, such as population density, sequence of infection and immunological responses to helminth and MORV infection into account (58,68,118).…”