Cryptosporidium Life Cycle


Cryptosporidium is a genus of parasitic alveolates that can cause gastrointestinal or respiratory diseases. The gastrointestinal illness causes watery diarrhoea and is known as Cryptosporidiosis. This parasite present in respiratory lines also causes concurrent coughing in human hosts. Several species of Cryptosporidium exist and infect mammals all over the world. Water is the most common medium of transmission for this parasite. This parasite lives inside one host and resides in the linings of the intestine and respiratory tract.

Let’s look at the life cycle of cryptosporidium to get a better understanding.

Life Cycle of Cryptosporidium

Life Cycle of Cryptosporidium

1) The Egg – Stage 1 –

This infection in human beings starts when the Cryptosporidium parasite is transmitted through contact with contaminated water. It is transmitted via exposure to water contaminated by faeces of infected animals. Food items may also act as a catalyst for the transmission of this parasite into the host.

2) The Ingestion – Stage 2 –

Human beings might become hosts to Cryptosporidium parasites by either inhaling or consuming water contaminated by the faeces of infected animals. After the parasite enters the human host, the excystation process begins.

3) The Excystation – Stage 3 –

In the excystation stage, the sporozoites are released and infect all epithelial cells. Epithelial cells include cells found on the surface of the body like the skin, urinary tract and so on. But, the parasite Cryptosporidium targets mainly the gastrointestinal lining and respiratory tract. In the epithelial cells, the parasite Cryptosporidium undergoes two types of asexual reproduction namely schizogony and merogony. Schizogony is an asexual reproduction in certain protozoa that occurs through multiple fission. Merogony is an asexual reproduction process, where a protozoan replicates in its own nucleus inside the host’s cell. Gametogony is the process by which male and female gametes are produced. Male gamete is called microgamonts and female gamete is called macrogamonts. After fertilization, the oocysts sporulate inside the infected human host.

Two types of oocyst are produced, the thick-walled oocysts are excreted from the human host. The thin walled oocysts undergo autoinfection, where the cyst wall breaks once they are separated from the epithelium and later the cycle begins again.

4) The Host – Stage 4 –

After excretion, the oocysts become infective. This gives rise to direct or indirect faecal-oral transmission of the infected oocysts into the host. Once the parasite enters the host, the life cycle begins again.


The diarrheal disease known as Cryptosporidiosis and the parasite Cryptosporidium is commonly called ‘Crypto’. The primary symptoms of this disease are watery diarrhoea and vomiting. The transmission of this disease is easy, as its primary transmitters include water, food and contact with surfaces contaminated with infected animals or human beings.

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Frequently Asked Questions on Cryptosporidium Life Cycle


How long does Cryptosporidium parasite stay in the body?

The Cryptosporidium parasite causes watery diarrhea that might last a week or two in a healthy person. But if a Cryptosporidium parasite enters a host with weak immunity, then the infection can be life threatening.


How do you treat Cryptosporidiosis?

Anti parasitic drugs will help in reducing watery diarrhea. Fluid replacement and using anti motling agents will reduce the symptoms of diarrhea.


Is crypto disease contagious?

Yes, the disease Cryptosporidiosis or commonly called crypto is highly contagious. Infected individuals must take drastic measures to ensure that it does not spread to other people. Infected individuals are advised to frequently wash their hands after any household activity.


What are the types of oocysts produced? How are they formed?

The two types of oocysts formed are the thick-walled oocysts and the thin-walled oocysts. They are formed by the fertilization of microgamont and macrogamont.

Define schizogony and merogony?

Schizogony is an asexual reproduction in certain protozoa that occurs through multiple fission. Merogony is an asexual reproduction process, where a protozoan replicates in its own nucleus inside the host’s cell.
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