Serologically Confirmed Toxoplasma gondii
Infection in Philippine Rattus spp. and its Histopathology in Mus musculus
Cristina C. Salibay1* and Florencia G. Claveria2
1Biological Sciences Department, College of Science
De La Salle University-Dasmariñas, Dasmariñas, Cavite, Philippines
2Biology Department, College of Science
De La Salle University-Manila, Taft Avenue, Manila, Philippines
corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Toxoplasma gondii infection that was serologically confirmed in Rattus norvegicus and Rattus rattus mindanensis caught in agricultural (AGR), commercial (COM), and residential (RES) sites in Dasmarinas, Cavite, Philippines was bioassayed in mice. Mouse infection was serologically determined and presence of tachyzoites was examined post-inoculation (p.i.) with 0.5-1.0 mL brain tissue suspension. Histopathologic manifestations for 4 wk p.i. were evaluated in vital organs. Infection rate was significant (p<0.05) in mice inoculated with brain tissue of seropositive AGR and COM-inhabiting Rattus spp. While the severity of histopathologic manifestations in mice exposed to T. gondii from Rattus spp. caught in AGR and COM sites were comparable, tissue injury at later stage of infection was more acute/severe and extensive in mice infected with T. gondii parasites from R. norvegicus. Mice inoculated with brain tissue from RES-dwelling rats manifested generally less severe tissue damage. Tissue cysts were detected only in mice inoculated with higher (0.75-1.0 mL) inoculum doses of T. gondii from RES-caught R. rattus mindanensis. Present observations suggest the existence of different isolates/strains presumably the virulent to low virulent types infecting AGR and COM-inhabiting R. norvegicus and R. rattus mindanensis. Early detection of tissue cysts in muscles and brain of mice exposed to parasites obtained only from RES-inhabiting R. rattus mindanensis is indicative of avirulence, where the parasite undergoes encystation even without prolonged proliferation as an effective strategy of evading host response. Present biological and histopathological data suggestive of the existence of intraspecific types of T. gondii parasites infecting Philippine rats need to be validated using molecular markers and gene analysis.
INTRODUCTION
A wild range of wild and domestic mammals, including humans (Tenter et al. 2001; Hove & Dubey 1999; Dubey & Beattie 1998) and birds (Szabo et al. 2004; Dubey et al. 2004a) are infected with the apicomplexan zonootic parasite . . . .
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