Blood Chemical Changes in Cotton Rats, Sigmodon hispidus, Infected with Parastrongylus costaricensis (Nematoda: Angiostrongyloidea)

Abstract. Serum analytes of adult laboratory-raised cotton rats, Sigmodon hispidus, infected with Parastrongylus costaricensis were compared with those of ageand sexmatched control animals. Parasitism produced significant longand short-term changes in some analytes. Long-term changes included reductions in levels of sodium, chloride, creatinine, triglycerides, and calcium as well as elevation of lactate dehydrogenase (LDH) levels that occurred during the first 32 days of the infection. Short-term changes were correlated to specific developmental stages of the life cycle of the parasite. Thus, immediately after infection (when the third-stage larvae occur in mesenteric lymph nodes and vessels), an increase occurred in the levels of bilirubin, globulins, and proteins. As young juvenile worms matured in the mesenteric vasculature, globulin levels had a tendency to rise, and the elevation became significant at day 16. Egg laying was accompanied by decreases in levels of alkaline phosphatase (AP) and alanine aminotransferase (ALT). Hatching of eggs and passage of first-stage larvae through gut tissues had the most profound effect. At day 24, a dynamic decrease occurred in LDH, ALT, and aspartate aminotransferase (AST) while a downward drift in AP occurred. An electrolyte disturbance occurred in which potassium (K+ ) levels decreased (day 24) and then rebounded (day 28) while sodium (Na+) levels normalized and then declined. Changes were not observed in levels of creatinine phosphokinase (CPK), uric acid, carbon dioxide (CO2), glucose, protein, and cholesterol.