Catching up to Crypto
“Cryptosporidium is a leading cause of severe diarrheal disease in children under the age of five.”
For people who think about diarrheal disease, this is an obvious fact. However, the knowledge that cryptosporidiosis is an important childhood disease is relatively new. Although Cryptosporidium was discovered in 1907, it wasn’t until 1970s that scientists realised it caused diarrhea in people. Then, the AIDS epidemic of the 1980’s saw a monumental increase in cryptosporidiosis cases. Sadly, many patients coming into the clinic with chronic diarrhea were diagnosed simultaneously with cryptosporidiosis and AIDS, previously unware of their HIV status. Cryptosporidiosis became synonymous with immunocompromised adults.
More recently, global epidemiological studies revealed that young children, rather than immunocompromised adults, are the largest group of cryptosporidiosis patients.
The GEMS Study (Global Enteric Multicenter Study), MAL-ED (Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development), GBD (Global Burden of Diseases, Injuries, and Risk Factors), and several smaller scale birth-cohort studies have recently produced a growing amount of evidence that cryptosporidiosis has a significant impact on child health.
Nutrition is critically important during the first years of growth. Gut infections affect whether or not children are able to absorb nutrients, both when they have acute infections (short bouts of diarrhea) and longer-lasting, asymptomatic infections. Malnutrition and gut infections are a kind of “chicken and egg” story, where being malnourished makes you more susceptible to infection, and infection decreases your ability to absorb nutrients. The real problem is that poor nutrition during the first five years of life has life-long consequences. These include things that are easy to see, like reduced height, but also more serious things like impaired cognitive development, higher rates of obesity, and decreased earning potential.
A recently published analysis looked at epidemiological studies investigating Cryptosporidium and malnutrition in young children and estimated that the burden of Cryptosporidium infection is 2.5 times larger than previously reported when considering long-term health outcomes.
What is hopeful is that Cryptosporidium research has finally caught up with our understanding of its impact. New tools and technologies allow scientists to accurately model Cryptosporidium infection for the first time. Tools like CRISPR allow us to make specific changes to the genome of the parasite to understand how genes work. Organoid technology, miniature organs that grow in the lab, may allow us to model the complex environment of the gut including human cells, Cryptosporidium, and the microbiome.
Investments in drug discovery efforts have identified several new drugs that are very promising in treating Cryptosporidium. At the Wellcome Centre for Anti-Infectives Research at the University of Dundee, our investigations into basic parasite biology influence our collaboration with drug discovery scientists. Thanks to investments in research to better characterize this threat, we have a stronger foundation to tailor solutions and achieve the greatest health impact.