Prevalence of Onchocerca species and Thelazia lacrimalis in horses examined post mortem in Normandy.

The researchers examined horses post mortem in Normandy for the presence of Onchocerca species and Thelazia lacrimalis, finding low prevalence rates compared to those reported in the United Kingdom and North America.

Objective of the Research

• The researchers sought to determine the incidence of Onchocerca species and Thelazia lacrimalis (types of nematodes) in horses from Normandy, France which had died of various causes. They aimed to compare the frequencies of these infections with those documented in different regions like UK and North America.

Methodology

• Post-mortem examinations were performed on 368 horses.
• The team focused primarily on two regions: umbilical skin and the ligamentum nuchae (a ligament that runs along the back of the neck).
• The presence of nematodes, the parasites from Onchocerca species and Thelazia lacrimalis, were checked.

Findings

• Only four of the horses were found to be infected with Onchocerca species. Among them, pathological changes in the skin were reported in two cases.
• Thelazia lacrimalis was found in 38 horses, which represents 10.3% of the total sample. Interestingly, horses between the ages of six months and two years were found to be more commonly infected.
• Despite the presence of Thelazia lacrimalis, no ocular (eye-related) lesions were reported in any of the cases.

Comparison with Other Regions

• The prevalence of these two types of nematodes in Normandy was noticeably lower than the infection rates previously recorded in the United Kingdom and North America.

Implications

• The low prevalence of these parasites indicates that they might not be a major veterinary concern in this part of France.
• However, the infection rate in younger horses (between six months to two years) suggests a potential vulnerability in this age group that might require further investigation or targeted treatment strategies in future.