Complement fixation tests for equine piroplasmosis (Babesia equi and B caballi) performed in the UK during 1976 to 1979.

The research article presents an investigation into the presence of equine piroplasmosis (caused by Babesia equi and B caballi) in horses in UK and Ireland for international travel during 1976-1979, with findings revealing none of the locally born and residing horses carried the antibodies against these parasites.

Study Context and Overview

• The study focuses on complement fixation (CF) tests for equine piroplasmosis. This disease affects horses and is caused by two types of parasites, Babesia equi and Babesia caballi. The test aims to identify the presence of antibodies against these parasites in the blood of horses.
• The research was conducted considering horses from Great Britain and Ireland, earmarked for international movement. This meant the study examined horses intended for export to different countries.

Key Findings

• The study found that horses born and continuously living in the British Isles did not carry CF antibodies to Babesia equi or B. caballi. This implies that these horses were not infected with either type of Babesia, suggesting these parasites are not common or endemic in the British Isles.
• However, some horses with positive tests were found to be associated with countries known to have tick vectors for these diseases. These include Spain, Portugal, Belgium, France, Poland, USSR, and Arabian Gulf countries. This suggests that horses from these countries are more likely to be infected with Babesia equi or B. caballi.
• The research also tracked the persistence of CF antibodies in horses that were repeatedly tested. It was found that some animals lost their CF titre (a measure of antibodies) within a few months of their first test, while others retained a titre for periods up to 13 months for B. caballi and 28 months for B. equi.
• Interestingly, some horses regained their antibody levels on subsequent tests after initially showing negative results. It proposed that removing horses from exposure to infection or any treatment did not necessarily eradicate the CF titre predictably, suggesting variability in the immune response.

Implications

• This study highlights the importance of regular testing for equine piroplasmosis, especially in horses intended for international transport, to check for infection and monitor the persistence of CF antibodies.
• It underscores the necessity of understanding infection patterns in different geographies, especially in countries with known tick vectors.