 |
| © Turtleman Dreamstime.com |
The tick Ixodes ricinus, commonly known as the sheep tick,
deer tick, or castor bean tick, is the
most widespread tick species in the
United Kingdom and across much of Europe. It is medically and veterinary
important because it can transmit a wide range of disease-causing microorganisms,
known as tick-borne pathogens (TBPs), to humans, horses, livestock, wildlife,
and pets.
In the UK, I. ricinus is found mainly in areas with moist vegetation, rough grazing, heathland, woodland, and upland pasture. Large populations occur in southern England, Norfolk, the Scottish Highlands, Wales, the Lake District, and the North York Moors, although the species is spreading into new regions. The tick is considered a common and increasing problem in Britain, partly because warmer temperatures and milder winters linked to climate change improve tick survival.
Expanding deer populations, increased outdoor recreation, and greater contact between wildlife, horses, pets, and people also contribute to rising exposure.
The most important disease carried by I. ricinus in the UK is Lyme disease, caused by bacteria from the Borrelia burgdorferi group. Lyme disease is the most common tick-borne infection affecting humans in Britain. Horses can also become infected, although clinical disease is less commonly recognised. Symptoms in horses may include lethargy, stiffness, lameness, muscle tenderness, behavioural changes, and poor performance.
The tick can also carry Anaplasma phagocytophilum, which causes equine granulocytic anaplasmosis. This disease may lead to fever, depression, limb swelling, jaundice, and reluctance to move. In addition, I. ricinus is capable of transmitting Babesia parasites, which infect red blood cells and can cause anaemia. Tick-borne encephalitis virus (TBEV), a virus affecting the nervous system, has also recently been identified in parts of the UK, although human cases remain rare.
A recent Polish study led by Anna Rymaszewska investigated the occurrence of several TBPs in I. ricinus ticks collected from recreational forest areas, from ticks feeding on horses, and from red deer blood samples. The researchers used molecular diagnostic methods to identify the microorganisms present.
The study examined both “questing” ticks and feeding ticks. A questing tick is a tick actively searching for a host. Rather than jumping or flying, ticks climb vegetation and hold out their front legs in a behaviour called “questing.” When an animal or person brushes past, the tick attaches itself and begins feeding.
The study found several pathogens in the ticks, including Borrelia afzelii, Borrelia garinii, Anaplasma phagocytophilum, and species of Rickettsia. B. afzelii and B. garinii are important causes of Lyme disease in Europe. B. afzelii is commonly associated with skin infections, while B. garinii is linked more closely with neurological disease. Rickettsia helvetica and related species may cause flu-like illness, fever, headache, and occasionally more serious disease in humans.
An important finding was the detection of multiple pathogens within single ticks or animals. Some ticks carried two, three, or even four pathogens simultaneously. This is significant because co-infections may increase disease severity, complicate diagnosis, and allow animals or humans to become infected with several diseases from one tick bite.
The study highlights the growing importance of tick surveillance and tick control in both veterinary and human medicine. Forest recreation areas, horse grazing land, and wildlife habitats can all act as hotspots for exposure. Understanding tick ecology and disease transmission is increasingly important for protecting horse health.
For more details, see:
Anna Rymaszewska, Katarzyna Kubiak, Małgorzata Dmitryjuk, Izabella Rząd, Lucyna Kirczuk.
Occurrence of tick-borne pathogens in questing ticks, ticks from riding horses, and red deer blood in Western Pomerania, Poland,
Veterinary Microbiology,(2026), Vol 315,110932,
No comments:
Post a Comment