Migratory Birds Can Spread Haemorrhagic Fever

Researchers have now studied the dissemination mechanisms of this potentially fatal disease. The study is multidisciplinary, with bird experts, tick experts, molecular biologists, virologists, and infectious disease physicians from Uppsala University and Uppsala University Hospital in collaboration with colleagues from the Swedish Institute for Communicable Disease Control, Kalmar and Linköping. Ornithologists and volunteers also helped gather birds.

During two spring seasons in 2009-2010, a total of 14 824 birds were captured at the two ornithological stations Capri (Italy) and Anticythera (Greece), on their way from Africa to Europe. A total of 747 ticks were gathered and analysed for the virus.

Some 30 different bird species were examined, and one species, the woodchat shrike, which winters in southern Africa and nests in Central Europe, proved to be a carrier of virus-infected ticks.

“This is the first time ticks infected with this virus have been found on migratory birds. This provides us with an entirely new explanation of how this disease, as well as other tick-borne diseases, has spread to new areas, where new mammal populations can be infected by the infected ticks”, says Erik Salaneck, one of the authors of the study.

The Hyalomma tick, which spreads the disease, does not thrive in northern Europe, preferring warmer latitudes. But with a warmer climate, the boundary for both the tick species and the disease could move northward with the help of migratory birds.

The article will appear in print in December.

Reference: Lindeborg M, Barboutis C, Ehrenborg C, Fransson T, Jaenson TGT, Lindgren P-E, et al. Migratory birds, ticks, and Crimean-Congo hemorrhagic fever virus [letter]. Emerg Infect Dis [Internet]. 2012 Dec

Contacts and sources:
Erik Salaneck
Uppsala University