''Cryptosporidium hominis'', along with ''

Cryptosporidium parvum ''Cryptosporidium parvum'' is one of several species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. Primary symptoms of ''C. parvum'' infection are acute, watery, and nonbloody diarrhea. ''C. parvum'' in ...

'', is among the medically important '' Cryptosporidium'' species. It is an obligate parasite of humans that can colonize the gastrointestinal tract resulting in the gastroenteritis and

diarrhea 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 ...

characteristic of

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 ...

. Unlike ''C. parvum'', which has a rather broad host range, ''C. hominis'' is almost exclusively a parasite of humans. As a result, ''C. hominis'' has a low zoonotic potential compared to ''C. parvum''. It is spread through the fecal-oral route usually by

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, a ...

contaminated with oocyst laden feces. There are many exposure risks that people can encounter in affected areas of the world. Cryptosporidium infections are large contributors of child death and illness in heavily affected areas, yet low importance has been placed on both identifying the species and finding more treatment options outside of nitazoxanide for children and AIDS patients.

Characteristics

''C. hominis'' shares many similar characteristics with ''C. parvum'' including identical oocyst morphology and life-cycle. The different cryptosporidium species share nearly identical morphological features, so differentiation is only seen at the molecular level. As a result, ''C. hominis'' is most easily differentiated from ''C. parvum'' through genetic analysis via time-intensive PCR-restriction fragment length polymorphism or gene sequencing.

Life cycle

The

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesis ...

of ''Cryptosporidium hominis'' is similar to that of others of the genus with infective

sporozoites 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 ...

from ingested

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 i ...

invading gut epithelium. From there, they undergo

merogony 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 i ...

and generate merozoites, which escape and can reinvade additional cells and form a secondary

meront 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 ...

. The secondary meront then releases secondary merozoites which reinvade and undergo gametogony forming micro and macrogametocytes. The

gametocyte A gametocyte is a eukaryotic germ cell that divides by mitosis into other gametocytes or by meiosis into gametids during gametogenesis. Male gametocytes are called ''spermatocytes'', and female gametocytes are called ''oocytes''. Development ...

s can then fuse, forming a

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicell ...

, which starts the cycle again.

Treatment

Though symptoms in most immunocompetent persons will resolve without treatment,

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 ...

has been approved for treatment of diarrhea resulting from cryptosporidiosis. The effectiveness of nitazoxanide in

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 ...

patients, however, is uncertain and current treatments revolve around boosting the host immune system to aid in symptom resolution. Current avenues for treatment include scanning the ''Cryptosporidium hominis'' genome for possible targets for vaccine development.

References

{{Taxonbar, from=Q5191063 Conoidasida Waterborne diseases