Several European countries could be affected by an equine influenza virus transmitted during October horse sales in Ireland, according to the French surveillance center for equine pathologies (RESPE) in Caen. France has already confirmed 19 cases at three different sites.

The disease might have spread as far as northern Africa, where some of the horses from the Irish sales were transported, said RESPE director Christel Marcillaud-Pitel, DVM.

"Animals were purchased at the sales and transported throughout different parts of Europe and even north Africa, but we don’t yet know the extent of the spread of disease outside France," Marcillaud-Pitel said. RESPE only manages alerts within its home country, although it does communicate alerts from other countries when it receives them. "There may be more cases within France that have not yet been reported.

"Unfortunately, the horses arrived in France with three different transporters, so we know it’s linked to the sale itself and not to just one single transport," she said. RESPE has been working closely with Irish sanitary officials to determine exactly which of the recent sales might have been the source of the virus. Irish officials have been helpful and cooperative, she said, but tracking down the origin is difficult due to a general decrease in veterinary care in recent years. "Financially speaking, horse owners in Ireland are giving priority to feeding their horses rather than vaccinating them," she said.

Thus far, investigations have led to undetermined sales occurring in Ireland sometime within the last 10 days of October likely being the source of the outbreaks, Marcillaud-Pitel said. The vast majority of sale horses were Connemara ponies and Irish cobs. Many were sold at traditional "traveler" horse sales, but some were bought and sold between private owners. With the financial crisis severely affecting Ireland, foreign buyers can purchase animals with good breeding at a very low price "and then invest in their care to get them back in shape" to be resold on the continent, she said.

Biosecurity requirements within the European Union specify that horses must have a passport and traceable identification (microchip), but not that they be vaccinated against equine influenza, Marcillaud-Pitel said.

Despite more or less severe clinical signs in the unvaccinated adult animals at the three affected French sites, most of the animals are expected to fully recover, said Marcillaud-Pitel. One pony died due to complications of the disease, but he was already in "very poor condition." Another pony had already died at the time of laboratory testing and was unavailable for autopsy.

The specific clinical signs affected French horses displayed were not noted. However classic clinical signs of influenza include a sudden onset of a high fever (up to 106°F); a dry, deep cough that helps spread the virus; a serous (clear, runny) nasal discharge; and sometimes mild swelling of the submandibular (under the jaw) lymph nodes. Rarely, veterinarians might note edema (swelling) of the distal limbs and trunk in affected horses. In some horses a secondary bacterial infection can develop, resulting in pneumonia. In these cases the nasal discharge usually changes from serous to mucoid (green, yellow, and thick), breathing becomes difficult, and such a sequel can be fatal if left untreated.