Article: Cryptosporidiosis

Cryptosporidiosis is a parasitic disease affecting the intestines of mammals that is caused by Cryptosporidium, a protozoan parasite in the phylum Apicomplexa. It is a disease spread through the fecal-oral route; the main symptom is self-limiting diarrhea in people with intact immune system. In immunocompromised individuals, such as AIDS patients, infection can cause permanent & life-threatening diarrhea. Despite not being identified until 1976 it is one of the most common waterborne diseases and is found worldwide. The disease and parasite name are sometimes abbreviated to just Crypto.

Infection is through contaminated material such as earth, water, uncooked or cross-contaminated food that has been in contact with the feces of an infected individual or animal. Contact must then be transferred to the mouth and swallowed. It is especially prevalent amongst those in regular contact with bodies of fresh water whether through work or recreation.The source can be recreational water like swimming pools, contaminated water supplies, or contaminated food. Some outbreaks have happened in day care related to diaper changes.

Symptoms

Symptoms appear from two to ten days after infection and last for up to two weeks or so. As well as watery diarrhea there is often stomach pains or cramps and a low fever. Some individuals are asymptomatic (have no symptoms) but are still infective and thus can pass on the infection to others. Even after symptoms have finally subsided that individual is still infective for some weeks.

Severe disease, including pancreatitis, can occur (Br Med J 1987, 294).

Treatment is primarily supportive. Fluids need to be replaced with oral rehydration. A lactose free diet should be taken as tolerated. In rare situations, intravenous fluids may be required. Antibiotics are not usually helpful, and are primarily reserved for persons with severe disease and a weak immune system. Sometimes relapses happen.

Prevention is through washing hands carefully after going to the bathroom or contacting stool, and before eating. If the water supply is in question, the water can be boiled or carefully filtered before drinking.

Treatment

The majority of immuno-competent individuals suffer a short (less than 2 weeks) self limiting course that requires supportive care with re-hydration and occasionally anti-diarrhoeal medication. In immuno-incompetent individuals (including some with HIV/AIDS) anti-retroviral therapy has been associated with improved outcomes. Several drug trials with high dose azithromycin look promising.

Infectious agents

A number of species of Cryptosporidium infect mammals. In humans the main causes of disease are C. parvum and C. hominis (previously C. parvum genotype 1). C. canis, C. felis, C. meleagridis, and C. muris can also cause disease in humans.

Notable cases

In 1993 a waterborne cryptosporidiosis outbreak occurred in Milwaukee, Wisconsin. An estimated 403,000 people became ill, including 4,400 people hospitalized[1].

In the summer of 2005, after numerous reports by patrons of gastrointestinal upset, a water park at Seneca Lake State Park, in the Finger Lakes region of upstate New York, was found to have two water storage tanks infected with Cryptosporidium. By early September of 2005, over 3,800 people reported symptoms of a Cryptosporidium infection[2]. The "Sprayground" was ordered closed for the season on August 15.

In October 2005 Gwynedd and Anglesey areas of North Wales (UK) suffered an outbreak of Cryptosporidiosis. The outbreak may be linked to the drinking water supply from Llyn Cwellyn but this is yet to be confirmed. This has resulted in over 200 people falling ill and the company Welsh Water (Dwr Cymru) advising 61000 people to boil their water before use. The UK's biggest outbreak occurred in Torbay in Devon in 1995 when 575 people fell ill.