Oxidative stress and clinico-pathological alterations induced by Cryptosporidium parvum infection in a rat model

Cryptosporidium parvum is an apicomplexan zoonotic enteric protozoa that is principally responsible for severe necrotizing enteritis in immunocompromised hosts and has been associated with diarrhoea in a wide variety of animal species. The work was carried out on 48 rats which were equally divided into four groups: GI, GII, GIII and GIV. Rats in GI worked as healthy control. Rats in GII were administered C. parvum oocysts orally, GIII received dexamethasone, whereas GIV were given dexamethasone along with C. parvum oocysts. The maximum severity of experimental infection and oocyst shedding was observed on 8^th DPI in Group IV rats who exhibited depression, inappetance, poor fur condition, decreased weight gain, bloody diarrhoea and highest mortality rate. Significant increase in LPO and decrease in SOD, CAT and GSH concentrations were seen in intestine in GIV rats at 8^th DPI indicating the involvement of free radical induced oxidative stress in the pathogenesis of C. parvum infection. Severe necrotizing and haemorrhagic enteritis was seen in Group IV rats, whereas Group II animals had mild enteritis. Pathological examination of intestines in Group IV animals revealed extensive necrosis, blunting, fusion and sloughing of intestinal villi. Severe lymphocytic infiltration in lamina propria and submucosa was also observed. The diarrhoea and oocyst shedding gradually subsided after 8^th DPI and completely resolved in GII whereas mild enteritis was still seen in GIV animals at 12^thDPI. It was inferred from the present study that C. parvum strains prevalent in Jammu were capable of causing severe enteric infection in immunosuppressed rats.