TDK conference 2013

In young foals, diseases with clinical sign of diarrhoea can lead to debilitation, growth retardation, and - in severe cases - to death. Treatment of the disease is often complicated and associated with high cost, especially if the disease is infectious and occurs in stock level. Although diarrhoea is one of the main problems in young foals, the aetiology of the disease is not clear in all cases. In foals, pathological changes of the small intestine, for example rotavirus infections, can also lead to diarrhoea. Rotaviruses are the members of the Reoviridae family, having segmented double-stranded RNA genome. The Rotavirus genus is divided into five serological groups from A to E. Horses typically infected by group A rotaviruses. Though inflammation of the small intestine can occur with high morbidity (50%), the mortality is low (1%). The virus is shed by faeces, and foals are infected via oral way from the environment, where rotaviruses can survive for even one year. According to this, those animals can be most affected, which grow up in unsatisfactory hygienic circumstances, or were born on studfarms, which working for decades so the environment could have enriched virus contamination.

The aim of our research was to assess rotavirus prevalence in Hungarian foal-populations. To investigate this question, we used direct and indirect diagnostic methods. We collected faecal-samples from foals, aged of two months with clinical signs of diarrhoea. We used RT-PCR to detect rotaviruses. None of the tested samples gave positive result. Antibodies against rotaviruses were detected with competitive ELISA method. We collected blood samples from foals aged between 8 and 15 months. To reflect the general situation in Hungary we collected samples from different parts of the country with sufficient geographical diversity. During the examination of 94 samples, we found high antibody level in only one serum, which was higher than 80%, compared to the positive control. Two more samples showed medium level of antibodies (60-80%), and further 17 samples showed low levels (20-40%). The rest of the samples were negative (<20%). The examination and evaluation of samples from foals, borne in 2013 (aged between 1 and 7 months), are in progress.

In practice, the aetiology of the disease is not identified in most of the cases, despite the fact, that treating foals for weeks with antibiotics is often ineffective. The results of our study imply, that the prevalence of rotaviruses in Hungarian foal-populations is low. Introduction and spread of particular rotavirus strains adapted to horses with higher virulence can be expected related to intensive international horse movements between countries all over the world. Therefore the definitive diagnosis of presumably infectious, epidemically occurring enteric diseases still remains an important task for us.