Cryptosporidiosis becoming common

Cryptosporidiosis is a parasitic infection of medical and veterinary importance that affects epithelial cells of the digestive, biliary and respiratory tracts of humans as well as over 45 different vertebrate species, including dogs.

Asymptomatic infections are common and constitute a source of infection for others. The major symptom in human patients is diarrhoea, which may be profuse, it may have been preceded by appetite loss and vomiting in children.

The diarrhoea may have associated cramping abdominal pain. General malaise, fever, appetite loss, nausea and vomiting occur less often.

Symptoms will often come and go, but usually clear in fewer than 30 days in most healthy people. Immunodeficient people may be unable to clear the parasite, and the disease in that case has a prolonged course which can contribute to death. Symptoms of cholecystitis may occur in bilial tract infections; the relationship between respiratory tract infections and clinical symptoms is unclear.

Diagnosis is generally made by identification of oocysts (immature protazoan egg cysts) in faecal smears, or stages of the parasites in intestinal biopsy sections. Oocysts are very small and quite hard to identify - they may be confused with natural yeasts unless test samples are stained.

Infection with this organism is not usually detected unless looked for specifically. Serologic assays may be helpful in epidemiologic studies, but when the antibody appears and how long it lasts after infection are not known.

Cryptosporidium parvum is the species associated with human infection. The disease occurs worldwide and has been identified in 50 countries on six continents.

The most effective way to prevent yourself, your family and your dogs from infection with this disease is to be scrupulously clean in your own and your dogs' living quarters. Wash hands well after contact with your dogs (or any other animal you have on the premises) and for breeders, do not bring into the house any boots used while cleaning out the kennel areas.

In a recent New Zealand survey it was found that almost 90% of uncooked chicken was infected with cryptosporidium, whether it was freshly killed or had been frozen, and whether it was sold in a butcher shop or in a supermarket.

Because this infection cannot be identified without tests a trip to the doctor will usually result in a verdict of `flu'. So readers can see how important it is to keep themselves, their dogs and their property free of this debilitating parasite.