Ticks infected with the bacteria that cause Lyme disease may be considerably more prevalent in the UK than recent estimates indicated, according to new research from the University of Bristol.

Researchers at the university used pet dogs as sentinels for human disease risk.

Transmitted by ticks, Lyme disease is a debilitating chronic infection that affects a number of animals, including humans and dogs. It is caused by the bacterium Borrelia burgdorferi. Clinical signs in humans include a characteristic circular red rash that spreads from the site of the tick bite, followed by a ‘flu-like condition.

In dogs, the symptoms can be much more vague and difficult to diagnose. If untreated, the disease progresses to neurological problems and arthritis; chronic forms of the disease can last for many years.

While only occasionally affecting humans, reported cases in the UK are thought to have increased more than four-fold since the beginning of the century – from 0.38 per 100,000 in 2000 to 1.79 per 100,000 in 2009.

In 2010, there were 953 reported cases in England and Wales, but the level of under-reporting is likely to be considerable.

To obtain a clearer picture of the prevalence of infected ticks, Faith Smith, of the University of Bristol’s School of Biological Sciences, and colleagues recruited vets from across England, Scotland and Wales to examine dogs selected at random as they visited veterinary practices.

Since pet dogs are largely said to share the same environment and visit the same outdoor areas as their owners, exposure to infected ticks in dogs is likely to provide an index for corresponding risks to humans, researchers believe.

Of 3,534 dogs inspected between March and October 2009, 14.9 per cent had ticks. Of the samples that could be tested, 17 were positive for the Borrelia bacteria. Hence, 2.3 per cent of ticks were infected.

The expected prevalence of infected ticks on dogs is 0.5 per cent, or 481 infected ticks per 100,000 dogs. This, say researchers, suggests that the prevalence of Borrelia in the UK tick population is considerably higher than previously thought.

Faith Smith said: “Lyme disease appears to be a rapidly growing problem in the UK, with important health and economic impacts in terms of loss of working hours and potential decrease in tourism to tick hotspots.

“Without considerably better surveillance and routine diagnostic testing, Lyme disease is only likely to become more prevalent. In particular, future warmer winters might well extend the period over which ticks are active seasonally, while growing wild reservoir host populations, such as deer, will allow the tick population to expand.”

The study is published today (January 25) in the journal Comparative Immunology, Microbiology and Infectious Diseases. The research was funded by the Natural Environment Research Council and Merial Animal Health.

The paper is called “Estimating Lyme disease risk using pet dogs as sentinels” by Faith D Smith, Rachel Ballantyne, Eric R. Morgan, and Richard Wall and is in Comparative Immunology, Microbiology and Infectious Diseases.

The figures on reported cases of Lyme disease in the UK came from the Health Protection Agency.

Although not in our small animal remit, this is important enough to cross-post here as well:

UK farm vets urged to remain vigilant for signs of new virus

The BVA is urging farm vets and farmers to familiarise themselves with the clinical signs of the newly discovered Schmallenberg virus, particularly on farms where animals have been imported from affected countries.

BVA president Carl Padgett is calling for vigilance.The virus, of the genus Orthobunyavirus, was initially detected in cattle in Germany and, based on the geographic origin of the sample, was provisionally named Schmallenberg virus (SBV). Since the summer of 2011, clinical signs have also been reported on farms in the Netherlands.

Clinical signs include:

fever,
reduced milk yield (up to 50%),
inappetence,
loss of condition and, in some cases,
diarrhoea.

Clinical signs are generally mild and disappear after a few days but, where pregnant animals are infected, considerable congenital damages, premature births and reproductive disorders may occur.

Since DEFRA’s final report of 2011, Belgium has reported finding viruspositive lambs with congenital
deformities on 11 sheep farms in the North Western region of Antwerp, as well as deformities in a further eight cattle, three more sheep and on one goat farm.

With this in mind, and although no clinical signs or neonatal deformities have been reported in the UK, both DEFRA and the BVA are urging animal keepers to remain vigilant, particularly in areas where consignments of cattle that originated in the affected regions were moved to the UK during July – November 2011 (see map below).

Current countries affected by reports of Schmallenburg virus and recent consignments of live cattle (since July 2011).BVA president Carl Padgett said: “Farmers and vets should be extra vigilant where ruminants have been imported from the affected areas. The symptoms described in adults are quite generic but this disease seems to affect a few animals, not just one.”

He went on: “AHVLA is now looking for reports of signs in newborn ruminants and aborted foetuses of limb or brain defects such as arthrogryposis, jaw deformations and torticollis, and ataxia, paralysis and blindness. They are particularly interested if these offspring were born to animals where there is a history of importation from the Continue reading →