Cryptosporidium are single-celled parasites which infect hosts including humans and farm animals. Cryptosporidium infect the cells that line the small intestine. The parasites sit right at the edge of these intestinal cells, located directly between the contents of the digestive tract (mostly food and the microbiome) and the host. Cryptosporidium grow and multiple in the small intestine leading to destruction of the cells in the gut. In the short term this causes diarrhoea. For young children and adults with compromised immune systems this diarrhoea can become chronic and life-threatening. In young children this contributes to malnutrition which reduces growth and learning ability.

The most common form of parasite spread is when a host swallows water contaminated with faeces from an infected gut. Even low numbers of Cryptosporidium in water sources can lead to large outbreaks of infection. This is because Cryptosporidium are transmitted through the environment in a protective “shell” called the oocyst. The oocyst wall protects parasites from disinfectants, including bleach, making it very difficult and expensive to sanitise water free from Cryptosporidium.

Unfortunately, there are no medicines that can treat the symptoms of cryptosporidiosis for young children or immunocompromised adults. Additionally, providing water clean of Cryptosporidium is a great challenge. The transmission form of this parasite, the “oocyst” is responsible for both continuous, chronic infection of the current host, and transmission to the next host via the faeces. Mattie Pawlowic’s group wish to understand how Cryptosporidium build the protective “shell” that protects them during transmission. By better understanding what the oocyst wall is made of and how it is constructed, we may illuminate new targets for therapeutics that can both limit transmission and stop chronic infections.


We will use genetic and biochemical techniques to understand which genes are involved in this process, and how exactly they contribute to buying the oocyst wall and protecting Cryptosporidium parasites during transmission.