filtration may not be enough to eliminate cryptosporidium; boiling for at least 1 minute (3 minutes above 6,500 feet (2,000 m) of altitude) will decontaminate it. heating milk at 71.7 °c (161 °f) for 15 seconds pasteurizes it and can destroy the oocysts' ability to infect. water can also be made safe by filtering with a filter with pore size not greater than 1 micrometre, or by filters that have been approved for "cyst removal" by nsf international national sanitation foundation. bottled drinking water is less likely to contain cryptosporidium, especially if the water is from an underground source. people with cryptosporidiosis should not swim in communal areas because the pathogen can reside in the anal and genital areas and be washed off. they should wait until at least two weeks after diarrhea stops before entering public water sources, since oocysts can still be shed for a while. also, they should stay away from immunosuppressed people. immunocompromised people should take care to protect themselves from water in lakes and streams. they should also stay away from animal stools and wash their hands after touching animals. to be safe, they should boil or filter their water. they should also wash and cook their vegetables. the us cdc notes the recommendation of many public health departments to soak contaminated surfaces for 20 minutes with a 3% hydrogen peroxide (99% kill rate) and then rinse them thoroughly, with the caveat that no disinfectant is guaranteed to be completely effective against cryptosporidium. however, hydrogen peroxide is more effective than standard bleach solutions. treatment symptomatic treatment primarily involves fluid rehydration, electrolyte replacement (sodium, potassium, bicarbonate, and glucose), and antimotility agents (e.g., loperamide). supplemental zinc may improve symptoms, particularly in recurrent or persistent infections or in others at risk for zinc deficiency. immunocompetent immunocompetent individuals with cryptosporidiosis typically experience a short (i.e., duration of less than 2 weeks) self-limiting course of diarrhea that may require symptomatic treatment and ends with spontaneous recovery; in some circumstances, antiparasitic medication may be required (e.g., recurrent, severe, or persistent symptoms); however reinfection frequently occurs. as of 2015, nitazoxanide is the only antiparasitic drug treatment with proven efficacy for cryptosporidiosis in immunocompetent individuals; however, it lacks efficacy in severely immunocompromised patients. certain agents such as paromomycin and azithromycin are sometimes used as well, but they only have partial efficacy. immunocompromised in immunocompromised individuals, such as aids patients, cryptosporidiosis resolves slowly or not at all, and frequently causes a particularly severe and persistent form of watery diarrhea coupled with a greatly decreased ability to absorb key nutrients through the intestinal tract. as a result, infected individuals may experience severe dehydration, electrolyte imbalances, malnutrition, wasting, and potentially death. in general, the mortality rate for infected aids patients is based on cd4+ marker counts. patients with cd4+ counts over 180 cells/mm³ recover with supportive hospital care and medication; but, in patients with cd4+ counts below 50 cells/mm³, the effects are usually fatal within 3 to 6 months. during the milwaukee cryptosporidiosis epidemic (the largest of its kind), 73% of aids patients with cd4+ counts lower than 50 cells/mm³ and 36% of those with counts between 50 and 200 cells/mm³ died within the first year of contracting the infection. the best treatment approach is to improve the immune status in immunodeficient individuals using highly active antiretroviral therapy that includes an hiv protease inhibitor along with continued use of antiparasitic medication. antiparasitic drug treatment for immunocompromised individuals usually involves the combination of nitazoxanide, paromomycin, and azithromycin together; these drugs are only partially active in hiv/aids patients compared to their effect in immunocompetent persons. a cochrane collaboration review recommended that nitazoxanide be considered for use in treatment despite its reduced effectiveness in immunocompromised individuals. currently, research is being done in molecular-based immunotherapy. for example, synthetic isoflavone derivates have been shown to fight off cryptosporidium parvum both in vitro and in animal studies. derivates of nitazoxanide, known as thiazolides, have also shown promising results in vitro. rifaximin is also sometimes used for immunocompromised patients/patients with severe disease. epidemiology cryptosporidiosis is found worldwide. it causes 50.8% of water-borne diseases that are attributed to parasites. in developing countries, 8–19% of diarrheal diseases can be attributed to cryptosporidium. ten percent of the population in developing countries excretes oocysts. in developed countries, the number is lower at 1–3%. the age group most affected are children from 1 to 9 years old. in eastern europe cryptosporidiosis in humans and animals is common, but there are considerable gaps in surveillance and a lack of comparable methods which is limit the understanding of the disease and detection of outbreaks. research show a rich diversity of zoonotic subtypes of the parasite in animals indicating a rich potential of animal to human transmission. roughly 30% of adults in the united states are seropositive for cryptosporidiosis, meaning that they contracted the infection at some point in their lives. history the organism was first described in 1907 by tyzzer, who recognised it was a coccidian. research a recombinant cryptosporidium parvum oocyst surface protein (rcp15/60) vaccine has produced an antibody response in a large group of cows and also antibody response in calves fed rcp15/60-immune colostrum produced by these vaccinated cows. this is very promising. human cryptosporidium parvum infections are particularly prevalent and often fatal in neonates in developing countries and to immunocompromised people, such as aids patients. there is no commercially available effective vaccine against cryptosporidium parvum, although passive immunization utilizing different zoite surface (glyco)proteins has shown promise. developmental stages of the life cycle of the parasite might act as possible targets for vaccine development. the organism is detected in 65–97% of the surface-water supply in the united states and is resistant to most disinfectants used for the treatment of drinking water. antibodies in the serum of humans and animals infected with cryptosporidium parvum react with several antigens, one of which is a 15 kda protein (cp15) located on the surface of the organism. this protein is a good candidate for use as a molecular vaccine because previous studies have shown that a monoclonal antibody to cp15 confers passive immunity to mice. currently, there is no vaccine or completely effective drug therapy against cryptosporidium parvum in hiv/aids individuals. a summary of discoveries presented at the most recent (june 2019) international symposium on cryptosporidium has been published in 2020. other animals the most important zoonotic reservoirs are cattle, sheep and goats. in addition, in recent years, cryptosporidiosis has plagued many commercial leopard gecko breeders. several species of the cryptosporidium family (c. serpentes and others) are involved, and outside of geckos it has been found in monitor lizards, iguanas and tortoises, as well as several snake species. notable cases before 2000 in 1987, 13,000 people in carrollton, georgia, united states, became ill with cryptosporidiosis. this was the first report of its spread through a municipal water system that met all state and federal drinking water standards. in 1993, a waterborne cryptosporidiosis outbreak occurred in milwaukee, wisconsin, us. an estimated 403,000 people became ill, including 4,400 people hospitalized. the source of the cryptosporidium is believed to be overflow from the milwaukee area combined sanitary and storm sewer system into lake michigan, which was then taken into the howard avenue water purification plant and distributed to an estimated 880,000 residents (of the 1.61 million residents in the milwaukee area who receive their drinking water from lake michigan). these residents, who receive their drinking water from lake michigan, were told to boil their water before drinking it. more people were affected in this one outbreak than the combined number of people affected in every cryptosporidiosis outbreak in the 24 years since then. an estimated 69 people died during the outbreak, according to the cdc. the uk's biggest outbreak occurred in torbay in devon in 1995. in the summer of 1996, cryptosporidium affected approximately 2,000 people in cranbrook, british columbia, canada. weeks later, a separate incident occurred in kelowna, british columbia, where 10,000 to 15,000 people got sick. 2001–2009 in april 2001, an outbreak occurred in the city of north battleford, saskatchewan, canada. between 5800 and 7100 people had diarrheal illness, and 1907 cases of cryptosporidiosis were confirmed. equipment failures at the city's antiquated water filtration plant following maintenance were found to have caused the outbreak. 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 2005, over 3,800 people reported symptoms of a cryptosporidium infection. the "sprayground" was ordered closed for the season on 15 august. in october 2005, the gwynedd and anglesey areas of north wales, the united kingdom, had an outbreak of cryptosporidiosis. the outbreak may have been linked to the drinking water supply from llyn cwellyn, but this is not yet confirmed. as a result, 231 people fell ill and the company welsh water (dwr cymru) advised 61,000 people to boil their water before use. 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 approval on 20 august 2007, five months after cryptosporidium was first detected. around 240 people are known to have contracted the disease; experts say the true figure could be up to 5,000. 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 10 september 2007 the utah department of health had reported 1302 cases archived 25 september 2007 at the wayback machine of cryptosporidiosis in the year; a more usual number would be 30. on 25 september the pools were reopened to those not requiring diapers, but hyperchlorination requirements were not lifted. on 21 september 2007, a cryptosporidium outbreak attacked the western united states: 230 idaho residents, with hundreds across the rocky mountain area; in the boise and meridian areas; utah, 1,600 illnesses; colorado and other western states — montana, decrease. on 25 june 2008, cryptosporidium was found in england in water supplies in northampton, daventry, and some surrounding areas supplied from the pitsford reservoir, as reported on the bbc. people in the affected areas were warned not to drink tap water unless it had been boiled. anglian water confirmed that 108,000 households were affected, about 250,000 people. they advised that water might not be fit for human consumption for many weeks. the boil notice was lifted for all the affected customers on 4 july 2008. throughout the summer of 2008; many public swimming areas, water parks, and public pools in the dallas/fort worth metroplex of texas had an outbreak of cryptosporidiosis. burger's lake in fort worth was the first to report such an outbreak. this prompted some, if not all, city-owned and private pools to close and hyperchlorinate. to the 13 august 2008 there were 400 reported cases of cryptosporidium. in september 2008, a gym in cambridge, the united kingdom, was forced to close its swimming pool until further notice after health inspectors found an outbreak of cryptosporidiosis. environmental health authorities requested that the water be tested after it was confirmed that a young man had been infected. 2010 and later in may 2010, the behana creek water supply south of cairns, australia, was found to be contaminated by cryptosporidium. in july 2010, a local sports center in cumbernauld (glasgow, uk) detected traces of cryptosporidium in its swimming pools, causing a temporary closure of the swimming pools. in november 2010, over 4000 cases of cryptosporidiosis were reported in östersund, sweden. the source of contamination was the tap water. in mid december 2010 the number of reported cases was 12,400 according to local media. as of april 2011, there has been an ongoing outbreak in skellefteå, sweden. although many people have been diagnosed with cryptosporidiosis, the source of the parasite has not yet been found. several