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Cryptosporidium parvum​ is a leading pathogen that causes diarrhea in young
children and immunocompromised patients. In 1976 ​Cryptosporidium ​ (crypto) the
protozoan waterborne parasite was first acknowledged as a diarrhea agent (Navin).
Severe infection by crypto causes damage to the small intestine epithelium(), this blocks
important processes in the small intestine and causes mild-to-severe diarrhea ().
Crypto is an important pathogen that upon infection causes morbidity and mortality in
malnourished children and children with AIDS(). In young children who are infected
diarrhea is severe and can lead to complications or even death. However, in adults
diarrhea typically last for several weeks but usually self-cures itself. This parasite can
gets transmitted via oral-fecal route.Due to the size of the oocyst it is hard to detect
when water is contaminated. Another disadvantage is that the oocysts are resistant to
chlorinated water. It only takes one gulp of contaminated water for individuals that come
in contact with it suffer infection.
This parasite is zoonotic and can infect not just humans but it also infects calves.
Its main host is calves at the age of 7-12 days, infection by crypto causes severe
diarrhea. Which is why this parasite is a prominent veterinary pathogen. The route of
infection for calves is the same as human through oral uptake. This is because that
oocysts shed into the feces and contaminate the environment around the cattle.
Locations where there are calves the likelihood of infection by crypto rises. It is
recommended by the CDC that if there is any contact with animals, children and adults
should wash their hands.
It is important to take precautions when visiting aquatic centers. If children or
adults have diarrhea or recently had diarrhea it is recommended to stay out of the water
to prevent any contamination. Outbreaks of crypto normally occur during the summer in
aquatic centers such as pools or in areas were there are farms.
Cryptosporidium life cycle
Sporulated oocysts get released in the feces of the calves or humans. These
oocysts are thick-walled and contain four sporosites inside. The sporosites inside the
oocyst are highly infectious once they excyst from the oocyst. The excystation of the
sporozoites happens once an individual is infected and the oocyst has made its way to
the small intestine. The sporozoites forms a trophozoite that starts to propagate and
leads to the formation of meronts that contain six to eight merozoites inside (Figure 1).
When these merozoites get release they begin to invade other enterocytes.
The merozoites II are form gametocytes as the invasion of the enterocytes
progresses. Once the macrogamonts get fertilized two different oocysts are produced, a
thick-walled and thin-walled oocyst. The thick-walled oocysts are shed into the feces
and the thin-walled are thought to auto-infection.
Figure 1: ​The life cycle of ​Cryptosporidium parvum ​upon infection.
Limitation in crypto research
Research on crypto has faced limitations that have been it difficult to fully study
the parasite. Although there are in vitro methods to study this parasite, timewise there is
a small time period in which the parasite can be study in vitro. One way is the parasite
can be studied in cell culture however the parasite can not be passage continous in cell
culture (). The parasite can be passage and observe for 2-3 days in cell culture using
human ileocaecal adenocarcinoma cells (HCT-8) ().
Genetic tools in crypto research
With the use of genetics and molecular biology new tools have been developed
to facilitate the study of crypto.
Figure 2: ​The pipeline for the propagation of transgenic oocyst.
Drug efficacy