On the lookout for Lyme

Lyme disease remains a threat to both horses and humans in the UK. It is a constant concern, and can seriously affect quality of life.

- Adam Jackson MRCVS

INFECTION by the bacterium Borrelia burgdorferi, which causes Lyme disease, is becoming more recognisable and more common in regions in which types of ticks (Ixodes spp.), which carry the bacterium, are endemic.

Lyme disease is referred to as a vector-borne disease, because the spread of the bacteria relies on the tick (the vector) to transmit the disease to various host animals when it feeds. It is thought to be the most common disease spread by ticks in the northern hemisphere and commonly occurs in the spring and early summer.

Within the UK, research in horses has observed high levels of seropositivity (presence of the antibodies that combat the disease) in East Anglia and on the south coast, but low seropositivity in Newmarket, Yorkshire, Scotland and Ireland.

Similar trends have been seen in human medicine and in dogs. Not all horses with antibodies develop signs, and those clinical signs that are evident are often described by owners as vague and mysterious.

THE TICK’S LIFE CYCLE

IT is important to understand the tick’s life cycle in order to take measures to reduce the risk of your horse contracting the disease.

Ticks need to have a new host at each stage of their life.

In spring, female ticks detach from hosts and lay thousands of eggs in warm spots on the ground. With the arrival of summer, the eggs hatch and produce six-legged larvae. The larvae may be infected with B. burgdorferi but more commonly, ticks become infectious once they have absorbed the pathogen from one of their hosts.