Diarrhea is the second major killer of children under the age of 5 in developing countries (second to pneumonia). We know much less than we should about the causative agents, severity, burden etc. of diarrhea in developing countries. Funded by Bill and Melinda Gates Foundation, A Global Enteric Multicenter Study (GEMS) picked up the task of learning more about diarrhea in children in developing countries with high incidence (Gambia, Mali, Mozambique, Kenya, India, Bangladesh and Pakistan) and did an extensive 3 year-long case-control study. I won’t go to details about their magnificent work but just mention one rather surprising finding. They found the 4 top pathogens causing diarrhea in children under 5 to be: 1. Rotavirus 2. Cryptosporidium 3. Shigella 4. Enterotoxigenic Escherichia coli producing heat-stable toxin (ST-ETEC). Rotavirus has long been known as a major cause of diarrhea in children and there are effective vaccines against it who have significantly reduced its incidence in developed countries. Shigella and ST-ETEC were also previously known. But the high incidence of Cryptosporidium has come out as a surprise to everyone. Crypto is an apicomplexan protozoan parasite, kin to other famous parasites Plasmodium and Toxoplasma. It’s durable cysts are shed in the stool and can be ingested in contaminated food and water. Compared to the other top pathogens and with regards to the high mortality it is causing, Crypto is relatively unpopular and extremely understudied (even reflected in its Wikipedia page). Now GEMS calls for more research on Crypto and better therapies against it. Hopefully this would mean more funding for studying this bizarre parasite and more exciting knowledge learnt from its biology and pathophysiology.
Find and share GEMS infographic about their findings from here.
Cryptosporidium trophozoite bound to the small intestine epithelium, inducing actin accumulation at its binding site. From Elliott and Clarck, Infection and Immunity, 2000
Kotloff, K., Nataro, J., Blackwelder, W., Nasrin, D., Farag, T., Panchalingam, S., Wu, Y., Sow, S., Sur, D., Breiman, R., Faruque, A., Zaidi, A., Saha, D., Alonso, P., Tamboura, B., Sanogo, D., Onwuchekwa, U., Manna, B., Ramamurthy, T., Kanungo, S., Ochieng, J., Omore, R., Oundo, J., Hossain, A., Das, S., Ahmed, S., Qureshi, S., Quadri, F., Adegbola, R., Antonio, M., Hossain, M., Akinsola, A., Mandomando, I., Nhampossa, T., Acácio, S., Biswas, K., O’Reilly, C., Mintz, E., Berkeley, L., Muhsen, K., Sommerfelt, H., Robins-Browne, R., & Levine, M. (2013). Burden and aetiology of diarrhoeal disease in infants and young children in developing countries (the Global Enteric Multicenter Study, GEMS): a prospective, case-control study The Lancet DOI: 10.1016/S0140-6736(13)60844-2
Elliott, D., & Clark, D. (2000). Cryptosporidium parvum Induces Host Cell Actin Accumulation at the Host-Parasite Interface Infection and Immunity, 68 (4), 2315-2322 DOI: 10.1128/IAI.68.4.2315-2322.2000