Serologic detection of Toxoplasma gondii infection in Rattus spp collected from three different sites in Dasmariñas, Cavite, Philippines.

Acute and chronic cases of toxoplasmosis in Rattus norvegicus and Rattus rattus mindanensis caught in agricultural, commercial and residential sites in Dasmariñas, Cavite, Philippines were determined serologically. Fifty-eight percent of R. norvegicus and 42.0% of R. r. mindanensis were positive for anti-T. gondii antibodies (Abs). Infection was higher in male rats, and those caught in the commercial site had 100.0% seropositivity. Thirty percent of the R. norvegicus and 51.0% R. rattus mindanensis had acute infection, with 1:64-1:128 Abs titer. Seventy percent of the R. norvegicus and 49.0% of R. rattus mindanensis were chronically-infected with Abs titer 1:256-1:2048 and 1:256-1024, respectively. The association between the presence of infection with the rat gender and species and their collection sites was insignificant (p>0.05). In a related study, however, mice experimentally-inoculated brain tissue homogenate obtained from chronically-infected Rattus spp, manifested differences in the onset as well as, severity of infection which was histopathologically evaluated, suggestive of a possible difference in T. gondii parasite strain(s) infecting different rat populations.

Parasite biodiversity in Rattus spp caught in wet markets.

Rattus spp trapped in wet markets in Quiapo, Manila and Balayan, Batangas had ectoparasites, Echinolaelaps echidnius (mite), and Polyplax spinulosa (louse). The endoparasites identified were Hymenolepis diminuta; the acanthocephalan Moniliformis moniliformis; Taenia taeniaeformis strobilocercus larvae and Capillaria hepatica in liver; Trichosomoides crassicauda of the urinary bladder; Sarcocystis sp of muscle tissue; and two different species of stronglyloid-looking intestinal nematodes. Rats had 100% infection with C. hepatica and T. taeniaeformis, exhibiting high parasitemia. The co-existence of rats with diverse parasitic species is reflective of the host's capability to support parasites' behavioral, physiological, and developmental needs. Despite heavy infection with intestinal parasites, and marked hepatic tissue damage owing to severe capillariasis and strobilocercus larval infection, all rats appeared healthy and agile, suggestive of a well-established rat host-parasite relationship. In view of the diversity and zoonotic nature of rat parasites, and the impoverished conditions prevailing in communities where Rattus spp survive and proliferate, they can readily facilitate parasite transmission to humans and other susceptible animal hosts.