Cryptosporidium parvum: infectivity and pathogenicity of the ‘porcine’ genotype

Abstract

Genetic studies have demonstrated profound differences between the 'porcine' genotype of Cryptosporidium parvum, versus 'human' and 'bovine' genotypes. The study analysed infectivity and pathogenicity of the 'porcine' genotype (CPP-13 isolate) of C. parvum, and compared the results with published data on the 'bovine' genotype (CPB-0 isolate). This was investigated in calves and piglets from commercial herds. Piglets were mildly affected by the CPP-13 isolate, contrary to piglets infected with the CPB-0 isolate, which caused diarrhoea of a mean duration of 3.5 days. CPP-13 produced no or very mild clinical signs in piglets despite the excretion of high numbers of oocysts. Concomitant infection with rotavirus, however, caused a dramatic aggravation of the clinical signs, and 5 of 6 experimentally infected piglets died. CPP-13 appeared to be adapted to porcine hosts as illustrated by the lack of infectivity to 1 experimentally inoculated calf, and the absence of clinical signs, the long pre-patent period (15 days), and the excretion of very low numbers of oocysts following experimental infection of another calf. Thus, in accordance with other molecular studies, our results support the genetic evidence for the existence of a new species of Cryptosporidium adapted to pigs.

Matched case-control study evaluating the frequency of the main agents associated with neonatal diarrhea in piglets

“…Cryptosporidium spp. was diagnosed in only one litter of very young piglets (1-2 days old), agreeing with previous results showing that the beginning of fecal oocysts excretion of this agent varies from 2 to 9 days after infection (Enemark et al 2003).…”

“…It has been previously demonstrated that there is no relationship between the occurrence of diarrhea and the detection of oocysts of Cryptosporidium in feces, especially in piglets with low levels of infection (Enemark et al 2003). The possible explanation is that diarrhea is caused by pathogens other than Cryptosporidium sp.…”

Epidemiological Studies on Intestinal Protozoa in Pigs in Saitama, Japan

“…In humans and cattle, unformed stools in Cryptosporidium infection reportedly contained as many as 10 5 to 10 6 oocysts per gram of stools 28,29 . Experimental Cryptosporidium infection can cause serious diarrhea, loss of appetite and vomiting in suckling pigs 4 . Diarrhea caused by C. suis in outdoorgrown suckling pigs has also been reported 21 , suggesting C. suis infection as a potential cause of diarrhea in the five pigs in our study that produced partly unformed or unformed stools with oocysts per gram of stools of 10 4 to 10 5 .…”

“…Diarrhea caused in pigs by Cryptosporidium allows increased superinfection with other pathogens such as rotavirus (Rota V), porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, and Escherichia coli 4,13,26 . Rota V infection facilitates the growth of Cryptosporidium in the digestive tract of the pig and increases mortality rates 4 .…”

“…Cryptosporidium species (C. suis, C. pig genotype II) has been reported as having weakly pathogenic results in pigs 4,20,21,27 . However, the pathogenicity of Cryptosporidium species remains unclear, and there have been only a few pathological …”