Cotton rats (Sigmodon hispidus) from a pineapple plantation in Costa Rica were studied searching for parasites. Seventy four animals were trapped, sex and pregnant condition determined and dissected to study all their organs. The presence of nematodes and protozoa was determined and classification of these parasites was performed. Eimeria oocysts were kept in presence of 2.5% potasium dichromate for sporocyst and sporozoites development. Most of the organisms were intestinal parasites and all the rats have at least one nematode, wihle 57.4% presented some protozoa. The parasites found were: Longistriata adunca (95.9%), Angiostronylus costaricensis (42.3%), Eimeria sigmodontis (28.4%), Trichomonas sp. (23.0%), E. tuskegeensis (10.8%), E. roperi (5.4%) y E. webbae (1.4%). There was a significative difference between protozoa infection in pregnant female rats (60.5%) as compared with non-pregnant animals. This study is a contrtibution to the knowledge of the parasitological fauna of S. hispidus in Costa rica.Cotton rats (Sigmodon hispidus) from a pineapple plantation in Costa Rica were studied searching for parasites. Seventy four animals were trapped, sex and pregnant condition determined and dissected to study all their organs. The presence of nematodes and protozoa was determined and classification of these parasites was performed. Eimeria oocysts were kept in presence of 2.5% potasium dichromate for sporocyst and sporozoites development. Most of the organisms were intestinal parasites and all the rats have at least one nematode, wihle 57.4% presented some protozoa. The parasites found were: Longistriata adunca (95.9%), Angiostronylus costaricensis (42.3%), Eimeria sigmodontis (28.4%), Trichomonas sp. (23.0%), E. tuskegeensis (10.8%), E. roperi (5.4%) y E. webbae (1.4%). There was a significative difference between protozoa infection in pregnant female rats (60.5%) as compared with non-pregnant animals. This study is a contrtibution to the knowledge of the parasitological fauna of S. hispidus in Costa rica.
