''Cryptosporidium'', sometimes informally called crypto, is a genus of

apicomplexa The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. Th ...

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

alveolates The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major clade and superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochond ...

that can cause a respiratory and

gastrointestinal illness Gastrointestinal diseases (abbrev. GI diseases or GI illnesses) refer to diseases involving the gastrointestinal tract, namely the oesophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the liver, ...

(

cryptosporidiosis Cryptosporidiosis, sometimes informally called crypto, is a parasitic disease caused by '' Cryptosporidium'', a genus of protozoan parasites in the phylum Apicomplexa. It affects the distal small intestine and can affect the respiratory tra ...

) that primarily involves watery diarrhea (intestinal cryptosporidiosis), sometimes with a persistent cough (respiratory cryptosporidiosis). Treatment of gastrointestinal infection in humans involves fluid rehydration, electrolyte replacement, and management of any pain. ,

nitazoxanide Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is ind ...

is the only drug approved for the treatment of

in immunocompetent hosts. Supplemental zinc may improve symptoms, particularly in recurrent or persistent infections or in others at risk for

zinc deficiency Zinc deficiency is defined either as insufficient zinc to meet the needs of the body, or as a serum zinc level below the normal range. However, since a decrease in the serum concentration is only detectable after long-term or severe depletion, s ...

. ''Cryptosporidium'' oocysts are 4–6

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...

in diameter and exhibit partial

acid-fast Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sam ...

staining. They must be differentiated from other partially acid-fast organisms including '' Cyclospora cayetanensis''.

General characteristics

''Cryptosporidium'' causes

, an infection that may present as a

diarrhoea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

, sometimes with a persistent cough in immunocompetent hosts. Other

apicomplexan The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. The ...

pathogens include the

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. ...

parasite ''

Plasmodium ''Plasmodium'' is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of ''Plasmodium'' species involve development in a blood-feeding insect host which then injects parasites into a ve ...

'' and the

toxoplasmosis Toxoplasmosis is a parasitic disease caused by '' Toxoplasma gondii'', an apicomplexan. Infections with toxoplasmosis are associated with a variety of neuropsychiatric and behavioral conditions. Occasionally, people may have a few weeks or mont ...

parasite ''

Toxoplasma ''Toxoplasma gondii'' () is an obligate intracellular parasitic protozoan (specifically an apicomplexan) that causes toxoplasmosis. Found worldwide, ''T. gondii'' is capable of infecting virtually all warm-blooded animals, but felids, such as ...

''. Unlike ''Plasmodium'', which transmits via a

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...

vector, ''Cryptosporidium'' does not use an insect vector, and is capable of completing its lifecycle within a single host, resulting in

cyst A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

stages that are excreted in feces or through inhalation of coughed on

fomites A fomite () or fomes () is any inanimate object that, when contaminated with or exposed to infectious agents (such as pathogenic bacteria, viruses or fungi), can transfer disease to a new host. Transfer of pathogens by fomites A fomite is any ...

and are capable of transmission to a new host. A number of ''Cryptosporidium'' species 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. Cryptosporidiosis is typically an acute, short-term infection, can be recurrent through reinfection in immunocompetent hosts, and become severe or life-threatening in immunocompromised individuals. In humans, it remains in the lower intestine and may remain for up to five weeks. The parasite is transmitted by environmentally hardy

s (oocysts) that, once ingested, exist in the

small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...

and result in an infection of intestinal

epithelial tissue Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

. Transmission by ingestion or inhalation of coughed on fomites is a second, less likely route of infection. The

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

of ''Cryptosporidium parvum'', sequenced in 2004, was found to be unusual amongst

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacter ...

s in that the

mitochondria A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

seem not to contain DNA. A closely related species, ''C. hominis'', also has its genome sequence available.

Life cycle

Cryptosporidium has three developmental stages: meronts, gamonts and

oocysts Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

. They reproduce within the intestinal

epithelial cells Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellu ...

. The ''Cryptosporidium''

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

phase (

oocyst Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

) can survive for lengthy periods outside a host. It can also resist many common

disinfectant A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than s ...

s, including

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

-based disinfectants.

Water treatment and detection

Many treatment plants that take raw water from

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s, and

reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...

for public

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...

production use conventional filtration technologies. Direct filtration, which is typically used to treat water with low

particulate Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The te ...

levels, includes coagulation and filtration but not sedimentation. Other common filtration processes including

slow sand filter Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water. The length and bre ...

s, diatomaceous earth filters, and membranes will remove 99% of ''Cryptosporidium''. Membranes and bag- and cartridge-filter products remove ''Cryptosporidium'' specifically. ''Cryptosporidium'' is highly resistant to chlorine disinfection; but with high enough concentrations and contact time, ''Cryptosporidium'' inactivation will occur with

chlorine dioxide Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually ...

and

ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the l ...

treatment. In general, the required levels of chlorine preclude the use of chlorine disinfection as a reliable method to control ''Cryptosporidium'' in drinking water. Ultraviolet light treatment at relatively low doses will inactivate ''Cryptosporidium''.

Calgon Carbon Calgon Carbon Corporation is a Pittsburgh, Pennsylvania based company that manufactures and markets products that remove contaminants and odors from liquids and gases, both for industrial, municipal, and consumer markets. Calgon Carbon's product l ...

-funded research originally discovered UV's efficacy in inactivating ''Cryptosporidium''. One of the largest challenges in identifying outbreaks is the ability to verify the results in a

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physi ...

. The oocytes may be seen by microscopic examination of a stool sample, but they may be confused with other objects or artifacts similar in appearance. Most cryptosporidia are 3–6 μm in size, although some reports have described larger cells. Boiling is believed to be the safest option for water contaminated by ''Cryptosporidium''.

Epidemiology

Exposure risks

* People who swim regularly in pools with insufficient sanitation (certain strains of ''Cryptosporidium'' are chlorine-resistant) * Child-care workers * Parents of infected children * People caring for other people with cryptosporidiosis * Backpackers, hikers, and campers who drink unfiltered, untreated water * People who visit petting farms and open farms with public access * People, including swimmers, who swallow water from contaminated sources * People handling infected cattle * People exposed to human feces * People who turn

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting ...

that has not gone through its phase where temperatures over 50ºC are reached Dealing with stabilized compost - i.e. composting material that has gone through the phases where micro-organisms are digesting the organic matter and the temperature inside the composting pile has reached temperature up to 50-70ºC - poses very little risk as these temperatures kill pathogens and even make oocysts unviable. Like many fecal-oral pathogens, the disease can also be transmitted by contaminated food, poor hygiene or turning compost in a local

site. Testing of water, as well as

epidemiological Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evid ...

study, are necessary to determine the sources of specific infections. ''Cryptosporidium'' typically does not cause serious illness in healthy people. It may chronically sicken some children, as well as adults exposed and

immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

. A subset of the immunocompromised population is people with

AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

. Amongst

men who have sex with men Men who have sex with men (MSM) are male persons who engage in sexual activity with members of the same sex. The term was created in the 1990s by epidemiologists to study the spread of disease among all men who have sex with men, regardless of ...

who have AIDS, insertive anal sex is an increased risk factor. Analingus and oral-genital sex after anal-genital sex are known transmission routes. Other transmission routes include exposure to laboratory specimens.

References

External links

CryptoDB: The ''Cryptosporidium'' Genome Resource
{{Taxonbar, from=Q133078 Apicomplexa genera Conoidasida