Crimean-Congo Hemorrhagic Fever (CCHF)

Crimean-Congo hemorrhagic fever (CCHF) is a disease of significant concern across Africa, much of Asia, and parts of Europe. Spread by ticks, CCHF virus does not seem to cause disease in animals – only humans. People can get CCHF from an infected tick bite, contact with an infected animal (e.g. cattle) or from another sick person. The person-to-person transmission can allow a single case to bubble into a large outbreak, especially if isolation precautions are not taken at the local hospital. In people, CCHF symptoms range from mild flu-like symptoms to severe hemorrhagic fever and the mortality rate is 5-30%.

The risk of a large outbreak of such a high-consequence virus translates to an urgent need to understand how people become infected by CCHF virus, and how to prevent this from occurring. We know that CCHF has a complicated life history. The larval and nymph stage ticks feed on small mammals and ground birds, and when they become adults they switch hosts and feed on larger mammals, such as cattle. In Turkey, CCHF virus had been circulating for decades in animals without causing detectable disease in people until 2002. Within the next two years, over 1800 cases had been detected.  It is believed that CCHF spilling over into people from animal populations was driven by environmental changes, leading to shifts in small mammal communities. A similar risk is present in many other countries where CCHF is known to be present in animals, but has not yet been reported in people.

This complex ecology means we must take a One Health approach to understand current and future risk of CCHF outbreaks in people by evaluating the effects environmental changes may have on ticks and their animal hosts, as well as the latter’s interactions with the virus. EcoHealth Alliance is leading a collaboration with the Kilimanjaro Clinical Research Institute, Tanzania Veterinary Laboratory Agency, University of Glasgow, Washington State University, Tanzania Wildlife Research Institute, One Health Coordination Desk – Prime Minister’s Office, Global Animal Health-Tanzania and Public Health England. This multi-disciplinary team of scientists is working with local people to understand the current risks to people living in northern Tanzania and identify ways to prevent future outbreaks of CCHF. Our One Health serosurvey is collecting samples from cattle, small mammals, ticks and people. Our Tanzanian partner laboratories will conduct the testing and we will share our results with the local government, the local communities and the broader scientific community. We are also spreading the word amongst local communities about the importance of checking for and removing ticks to prevent disease transmission. To do this, we have developed a booklet and are distributing it to all participants.