The hematological status, plasma vitamin B12 and folic acid levels, and intestinal pathology in rats infected with Giardia lamblia.

The purpose of our study was to investigate the hematological status, vitamin B12 and folic acid absorption and intestinal pathology after Giardia lamblia infection in a rat model. Adult Wistar rats were assigned randomly to receive human giardia cysts orally in the amount of 5 x 10(5) or 1.0 x 10(6) cysts, or none in the controls. The results showed that all the rats injected with giardia cysts became infected. The cyst output in the infected rats varied considerably. In rats infected with 5.0 x 10(5) giardia cysts, the incubation period until cyst output was 10 days compared with 4 days in rats infected with the higher amount of 1.0 x 106 giardia cysts. The highest peaks for cysts output in these 2 groups were on days 4-33, which decreased gradually to days 40-58. The hematocrit and hemoglobin levels in the infected rats were statistically significantly lower than in the controls on days 16, 22, 33, and 37 post-infection (p < 0.05). A reverse relationship between giardia cyst output and hemoglobin concentration was found in the infected rats (p = 0.05). There were no significant differences in plasma vitamin B12 and folic acid levels between the infected rats and the control rats. No pathological changes were found in the small intestine of infected rats. These findings suggest that giardiasis did not affect the absorption of plasma vitamin B12 and folic acid but caused anemia in a rat model.