Cryptosporidium

Cryptosporidium

Cryptosporidium (Crypto) is a microscopic parasite (4–6 µm in diameter) that causes the diarrheal disease cryptosporidiosis. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very tolerant to chlorine disinfection. While this parasite can be spread in several different ways, water (drinking water and recreational water) is the most common way to spread the parasite. Cryptosporidium is a leading cause of waterborne disease among humans in the United States.

Crypto lives in the intestines of people and a wide variety of animals, especially young cattle and is transmitted when people or animals ingest food or water contaminated with its oocysts (the infectious particles of the parasite). An infected person or animal spreads Crypto parasites in their feces and can shed 10,000,000 to 100,000,000 Crypto germs in a single bowel movement. Shedding of Crypto in feces begins when symptoms like diarrhea begin and can last for weeks after symptoms stop.

The infective stage of Cryptosporidium is called an oocyst. The oocyst consists of a very tough “shell” surrounding four individual parasites. After the oocyst is swallowed, the shell breaks open and the parasites are released. This process is called excystation (the action of an organism escaping from its “envelope”). The parasites enter the cells that line the lower small intestine and begin to develop. After the parasite cells reproduce, two kinds of oocysts are produced:

1.Thin-walled oocysts that start another cycle of infection
2. Thick-walled oocysts that enter the environment in the feces and can then infect other animals.

Crypto is found in every part of the United States and throughout the world, and is commonly found in waters such as streams, canals, lakes or ponds that have been contaminated with feces from infected humans or animals. Water can be contaminated through sewage overflows, sewage systems that are not working properly, polluted storm water runoff, and agricultural runoff.

Crypto oocysts are able to live in nature for 18 months, provided the environment is cool and damp/wet, and are, therefore, quite common in lakes and other water sources that have at one time been contaminated with sewage or manure. Oocysts that dry out appear to die in just a few hours, therefore if fecal matter completely dries out before coming into contact with water meant for human/animal consumption, the oocysts presumably cannot cause infection.

Young children, pregnant women, and people with a weakened immune system are more at risk from cryptosporidiosis and are likely to develop more serious illness. The effects of prolonged diarrhea and dehydration caused by cryptosporidiosis can be dangerous, especially for young children, the elderly, and the frail. In persons with healthy immune systems, symptoms usually last about 1 to 2 weeks and causes a self-limited diarrheal illness. The symptoms may go in cycles in which you may seem to get better for a few days, then feel worse before illness ends. Treatment of gastrointestinal infection in humans involves fluid rehydration, electrolyte replacement, and management of any pain.

Water treatment

The best ways to prevent getting sick with cryptosporidiosis are to practice good hygiene, avoid water and food that might be contaminated. Effective treatment methods for water suspected of being contaminated with protozoa such as cryptosporidium and/or giardia include filtration and boiling.

Filtration: Maintain strict standards for water purification and filtration by using filters with a pore size of one to two micrometers or smaller. (This will block the four to five micrometer C. parvum spores from entering the water supply). The filters should be labeled ‘Absolute’ and meet ‘Cyst Removal’ standards. The filter should be changed according to recommended intervals and the immunocompromised should either wear gloves while changing the filter, or get someone else to change the filter for them. Let utensils dry for a few hours before re-use as drying is a very effective way of killing Cryptosporidium.

Boiling: Boil water that is intended for consumption for at least one minute. (Heating to 72.4°C (162.3°F) or higher for one minute makes C. parvum oocysts non-infectious).

Factoids about Cryptosporidium

· Contaminated drinking water is the main method of transmission of C. parvum to cause widespread human infection

· One study of surface water in 14 U.S. states and one Canadian province demonstrated that 87% of the sites had Cryptosporidium species in raw water.

· It has been shown that even one oocyst can withstand pure bleach for 24 hours and still cause an infection. Disinfection with iodine or chlorine is not effective in killing Cryptosporidium;

· Some people with Cryptosporidiosis will have no symptoms at all. Most people with healthy immune systems will recover without treatment.

References

www.kdheks.gov/epi/Fact_Sheets/Cryptosporidious_factsheet.doc

https://www.cdc.gov/healthywater/drinking/private/wells/disease/cryptosporidium.html

https://www.safewater.org/fact-sheets-1/2017/1/23/detailed-cryptosporidium