No abstract

In order to assess the impact of Cryptosporidium parvum on host intestinal physiology, we investigated absorption of the two principal amino acids in dam's milk (leucine, glutamate), using Ussing chambers and RT-PCR analyses. Experiments were performed in both heavily (ileum) and mildly (duodenum) infected segments of the small intestine at the peak of infection [day 8 post-infection (PI)] and after spontaneous clearance of the parasite (day 17 PI). At day 8 PI, amino acid fluxes across the mucosa were decreased throughout the small intestine (P<0.01) and EAAT3 mRNA expression was reduced ( from -49% to -28%). At day 17 PI, leucine and glutamate fluxes were normalized but the decrease in EAAT3 mRNA levels persisted (from -31% to -46%). Our results demonstrate that cryptosporidiosis induces major amino acid malabsorption involving the entire small intestine which is not counterbalanced by any up-regulation, even after spontaneous clearance of the parasite.

This study aimed to explore the metabolic consequences of cryptosporidiosis in an acute experimental model both at the peak of infection and after parasite clearance. Four-day-old suckling rats were infected with 10(6) oocysts of Cryptosporidium parvum. At the peak of infection (day 8 PI), C. parvum resulted in a dramatic reduction both in nutrient intake (-50%) and body weight (16.3+/-5.2 vs 27.3+/-1.0 g, P<0.01) with a decrease in both lean body mass and adipose tissue. Muscular fractional and absolute synthesis rate were reduced (-15 and -55%, respectively). After parasite clearance (day 17 PI), body weight remained reduced in formerly infected animals (37.8+/-8.0 vs 47.8+/-4.2 g, P<0.01) whereas nutrient intake normalized and fractional synthesis rate slightly increased (+22%) compared to controls. Overall, our results show that the impact and consequences of cryptosporidiosis are far greater than generally appreciated, leading to major malnutrition in suckling rats.