How important are leptospiral infections as a cause of equine disease?

This research explores the controversial topic of leptospiral infection and its relation to equine disease, specifically equine abortion. The study indicates that leptospiral infection is a significant cause of equine abortion, and emphasizes the need for further research and the potential development of a vaccine to counteract this issue.

Association of Leptospiral Infection and Equine Disease

• The article discusses the ongoing debate about the connection between leptospiral infection and equine diseases. The infection often remains insidious or sub-clinical, and laboratory culturing might take as long as six months.
• Research works have produced inconsistent results regarding this correlation. Some studies have pointed out pathogenic associations while others have not. However, it is now understood that leptospiral infection is an important cause of equine abortion, particularly in Kentucky.
• The study cites the identification of 71 abortion cases over six years in Kentucky due to leptospiral infection, which averaged around 2.5% of all investigated abortions.
• Other significant causes of infectious equine abortion, like the Equid herpesvirus-1 (EHV-1), are also mentioned for comparison. Overall, the infection rates seem to suggest that leptospiral abortion deserves more research attention.

Serological Data and Serovar Distribution

• The paper provides important serological data, namely the concentration of antibodies in the blood due to leptospiral infection in horses. Specifically, most of the abortion cases were linked to one serovar – pomona type kennewicki, which had a seroprevalence of around 15.99%.
• Other serovars, although more prevalent, were not related to the abortion cases. Serovar pomona has also been linked to both abortion and neonatal foal disease in other studies.

Reservoir Hosts and Vaccine Development

• Pigs and wildlife are reported to be reservoir hosts for the pomona serovar. Type kennewicki has frequently been found in wild rodents and skunks, especially in the farms of central Kentucky.
• However, serovar pomona has negligible seroprevalence in England and Ireland, suggesting a potential absence of well-adapted reservoir hosts in these regions.
• The study emphasizes that more work is needed to assess the significance of leptospira as a cause of foetal infection globally. This research should focus primarily on the type of serotype and serovar involved.
• If leptospira are detected in a significant number of cases, there may be an internationally recognized need for a commercially available vaccine to combat this issue.