Definition | Cryptosporidiosis – cryptosporidium parvum – intestinal parasite

Cryptosporidiosis is a parasitosis due to protozoan microscopic Cryptosporidium. The parasite lives in theintestine from some mammals, mainly cattle, as well as in humans. Thespecies Cryptosporidium parvum is the only one to be pathogenic for the human. She is regularly responsible forepidemics in France, the most recent took place in November 2024 in the Grasse region.

Transmission of cryptosporidiosis

The parasite is transmitted by drinking water contaminated with faeces from infected animals or from direct contact with a contaminated surface or food. In the environment, Cryptosporidium parvum is in the form of a oocyst, a physiological state of resistance. Oocysts resist heat and cold as well as chlorinated detergents which makes it very difficult to eradicate. It is the infectious form of parasite. Once ingested, the sporozoites, the mobile form of the parasite, break free from the oocyst and infect theepithelium intestinal. They replicate inside cells and produce new infectious oocysts which are excreted by thehost.

Here is the parasitic cycle in detail (the letters and numbers refer to the diagram below): a sporulated oocyst, containing four sporozoites, is excreted by an infected host (1). The contamination is generally done via contaminated drinking water (2). After infection of the host, the sporozoites are released and infect the epithelial cells (a, b, c) of the intestine. Inside these cells, the parasites reproduce asexually (d, e, f) then sexual reproduction (g) produces a male microgamont (g) and a female macrogamont (h). The fertilization of the macrogamont by gametes (i) forms a zygote which will give two types of oocysts: the thick-walled oocyst (j) secreted into the environment and the thin-walled oocyst (k) which remains on the body.

Symptoms of cryptosporidiosis

The first ones symptoms appear between one and twelve days after infection and may last fifteen days. Infected people present with a wide range of intestinal disorders such as diarrhea acute, colic, vomiting, dehydration or even weight loss. Some people have no symptoms, they are healthy carriers, but can transmit the disease.

This parasitosis is diagnosed by examining the stool for oocysts. In healthy subjects, the disease disappears spontaneously. In immunocompromised subjects, infection with Cryptosoridium parvum may have severe complications and requires follow-up. To prevent the spread of the disease, wash your hands properly after the bowel movement or after any contact with a risky surface, and do not drink tap water if it is contaminated.