Tick-borne Encephalitis Virus in Horses, Austria, 2011

James O. Rushton, Sylvie Lecollinet, Zdenek Hubálek, Petra Svobodová, Helga Lussy, and Norbert Nowotny

Author affiliations: University of Veterinary Medicine, Vienna, Austria (J.O. Rushton, H. Lussy, N. Nowotny); Agence Nationale de Sécurité Sanitaire, Maisons-Alfort, France (S. Lecollinet); Academy of Sciences of the Czech Republic, Brno, Czech Republic (Z. Hubálek, P. Svobodová); Sultan Qaboos University, Muscat, Oman (N. Nowotny)

Abstract

An unexpectedly high infection rate (26.1%) of tick-borne encephalitis virus (TBEV) was identified in a herd of 257 horses of the same breed distributed among 3 federal states in Austria. Young age (p<0 .001="" and="" associated="" infection.="" male="" p="" positively="" sex="" were="" with="">

Tick-borne encephalitis (TBE), which is caused by tick-borne encephalitis virus (TBEV), is a potentially fatal disease of the central nervous system, mainly in humans, but also in monkeys, dogs (1), and horses. Ruminants such as goats, sheep, and cattle are considered to be sporadically infected subclinically. However, they might be the source of disease in humans who consume nonpasteurized milk and milk products (2). TBEV-associated central nervous system disease in ruminants is rare (3).
TBEV occurs in natural foci and is endemic to many countries in Europe and parts of central and eastern Asia (4). The principal vectors for transmission are ticks of the genus Ixodes. Although TBEV in humans has been studied extensively, there are only a limited number of reports on TBEV in animals (5), especially horses. Only 2 reports were found in the German literature on the epidemiology of TBEV infection in horses (6,7), and 1 case report was found on clinical symptoms of TBE in a mare (8). The purpose of this study was to determine the status of TBEV infection in a large population of a single horse breed in Austria.