Abstract

Forty-nine field rats collected from six municipalities of Northern Samar through the use of rat traps were necropsied, examined for schistosome infection, assessed for macroscopic lesion characteristics, and evaluated for parasite burden. Evaluation showed that out of the 49 field rats clinically examined, a prevalence rate of 42.86% was obtained. From this infection rate, 24.49% were males and 18.57% were females parasitized. Rats collected from Catarman had the highest prevalence rate (14.28%) of schistosoma infection. Schistosome burden was low with one adult schistosome on the average per infected field rat. All schistosomes recovered were retrieved from the mesenteric veins. Majority (42.86%) of the schistosome infected field rats demonstrated granulomatous liver surfaces with edematous intestines. About 23.81% infected rats showed multiple lesions with fibrosis and nodular mass (granulomas) of the liver and edematous intestine as prominent lesions. These findings attest to the fact that about 43% of the field rat population in Northern Samar is infected with S. japonicum. It can therefore be concluded that field rats in the province may play as one of the multiplier hosts of schistosomiasis among humans and animals.

Key words: Schistosoma Japonicum, fibrosis, infected rats, edematous intestines, granulomatous.