Researchers: African Horse Sickness Could Shift North

 As the global climate changes gradually, an equine disease that was once limited to sub-Saharan Africa could reach as far north as England in the near future, according to several European animal health networks.

African horse sickness (AHS) is a vector-transmitted viral disease with a mortality rate of 90% in horses. It is spread via the Culicoides species of biting midges. Scientists believe that because of climate change these midges are now able to survive in more northern European climates. And if AHS-infected horses or midges that have had exposure to infected horses are shipped to these areas, the virus could potentially spread.

Equine Center

A horse with the peracute form of horse sickness, in which froth fills the bronchial tract.

Recent European outbreaks of bluetongue, a disease affecting cattle and sheep via the same species of midge, have caused various European animal health organizations to create surveillance groups and lobby for government action to prevent the spread of the deadly diseases.

Medreonet, an animal disease surveillance and study network, was developed by the European Union in 2006. Coordinated by the Center of International Cooperation in Agricultural Research for Development (CIRAD), based in Marseille, France, Medreonet studies the three major diseases transmitted by Culicoides: bluetongue, African horse sickness, and epizootic hemorrhagic disease (EHD), which primarily affects deer. While all three of these illnesses have been documented in Africa for more than a century, bluetongue and EHD have begun to spread to other continents, including Europe, North America, and Australia, according to Medreonet spokesperson Florence Vigier.

African horse sickness is currently threatening southern Europe, Vigier said, along with every other country where Culicoides midges have been shown to survive.

According to the Swiss Federal Veterinary Office (OVF), until recently, Culicoides midges remained between latitudes of 40°N and 35°S. Now, however, the OVF states that the midge is capable of surviving the winter in Portugal, Italy, Corsica, and southern Spain. If blown by the wind or transported with animals, the midges are capable of surviving milder seasons as far north as England.

In the United Kingdom The Horse Trust, a 120-year-old horse charity program and the largest provider of horse welfare grants in the country, is soliciting the government to create a strategy for a U.K. outbreak of AHS, assess the impact of such an outbreak, and support research for prevention and control of AHS. They are also creating an education program for horse owners, an information campaign for equine veterinarians and a research program to develop appropriate control measures.

Despite these actions, The Horse Trust's Chief Executive and Veterinary Director Paul Jepson stated that there is not yet cause for panic.

In Spain, Madrid and Andalusia were affected by AHS from 1987 to 1990 following the importation of infected African zebras, and an outbreak was reported in Portugal in 1989. The disease was completely eradicated in these regions through movement restrictions, vector eradication, vaccination, and slaughter policies.

African horse sickness exists in four forms and can cause fever, respiratory difficulties, edema, and frequently death within a week. Horses are most likely to succumb to the illness, whereas zebras and donkeys usually survive and serve as a source for further infections.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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