Cryptosporidiosis is a parasitic disease affecting the intestines of mammals that is caused by Cryptosporidium, a protozoanparasite 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.
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. The high resistance of Cryptosporidium oocysts to disinfectants like chlorine bleach facilitates transmission of the disease. Some outbreaks have happened in day care related to diaper changes.
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.
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.
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.
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.
In 1993, a waterborne cryptosporidiosis outbreak occurred in Milwaukee, Wisconsin. An estimated 403,000 people became ill, including 4,400 people hospitalized.
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. 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.
In March 2007, a suspected outbreak occurred in Galway, Ireland, after the source of water for much of the county, Lough Corrib, was suspected to be contaminated with the parasite. A large population (90,000 people) including areas of both Galway City and County were advised to boil water for drinking, food preparation and for brushing teeth. On 21 March 2007, it was confirmed that the city and county's water supply was contaminated with the parasite. The area's water supply was finally given the all-clear on 20 August, 2007; five months after it was first detected. Around 240 people contracted the disease, however experts say the true figure could be anything up to 5,000. 
As of June 20, 2007, Anglian Water Services prepared an alert confirming the possibility that cryptosporidium might have entered the drinking water supply in North Walsham, Anglia, England.. Customers in North Walsham and in the North Walsham Road area of Felmingham are being advised to boil their tap water before drinking it or using it in cooking.
As of August 9 2007, there is an outbreak of Crypto in Montgomery County, PA. There are 20 confirmed cases, and the Health Department is keeping close watch on local swimming pools. The Spring Valley YMCA has been under closest watch as all 20 of the cases have been to it. They have been closing the pools for extra disinfection after accidents. Other local pools have been affected and most are taking the same steps to assure safety, whether they have crypto or not.
Hundreds of public pools in 20 Utah counties were closed to young children in 2007, as children under 5 are most likely to spread the disease, especially children wearing diapers. As of September 10, 2007 the Utah State health department had reported 1302 cases of cryptosporidiosis in the year; a more usual number would be 30. On September 25, the pools were re-opened to those not requiring diapers, but hyperchlorination requirements were not lifted.
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^ Hawkins S, Thomas R, Teasdale C (1987). "Acute pancreatitis: a new finding in cryptosporidium enteritis.". Br Med J (Clin Res Ed)294 (6570): 483-4. PMID 3103738.
^ Corso P, Kramer M, Blair K, Addiss D, Davis J, Haddix A (2003). "Cost of illness in the 1993 waterborne Cryptosporidium outbreak, Milwaukee, Wisconsin.". Emerg Infect Dis9 (4): 426-31. PMID 12702221.
^ State Health Department Issues Update on Seneca Lake State Park Gastrointestinal Outbreak. New York State Health Dept. Retrieved on 2006-09-29.
^ RTÉ News - Galway water now safer than ever - HSE
^ Anglian Water Services: alert. Anglian Water Services, June 20, 2007. Retrieved on 2007-06-20.