Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats

Abstract

The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%-47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%-67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses from pregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%-6·66%); M. domesticus: 3·08% (95% CI: 0·11%-6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems.

Small rodents as paratenic or intermediate hosts of carnivore parasites in Berlin, Germany

“…Using the same detection approach, a comparably high prevalence of 40.8% was reported for A . sylvaticus in an area with low cat density suggesting that the contribution of vertical transmission to the epidemiological status of a rodent population may not be negligible [49]. …”

Prevalence and Genetic Characterization of Toxoplasma gondii in Bats in Myanmar

“…T. gondii oocysts can be mechanically transmitted by certain types of insects to insectivorous bats (16,17). Recent studies have shown that congenital transmission may play an important role in sustaining T. gondii infection in some species, including sheep and small mammals (18,19). This transmission mode may be the main infection route in bat species, which needs further investigation.…”

High frequency detection ofToxoplasma gondiiDNA in human neonatal tissue from Libya

“…[16][17][18] However, the frequency of this mode of transmission in natural populations of animals, or humans, is less clear. PCR based studies on the transmission of T. gondii in several mammalian species, e.g., mice, woodmice 17,[19][20][21] and sheep [22][23][24][25] have suggested that congenital transmission may be occurring at a higher frequency than previously thought. Although higher frequencies of congenital transmission are reported in these studies, in many cases there seems to be no measurable disease effect on the neonates in these species.…”