In last month's 'summer series' article, we discussed the topic of pet travel abroad and looked into the key exotic parasites. This second article will consider some of the key parasitic hotspots in and around the UK and provide practical advice and information to enable veterinary professionals to effectively advise pet owners on the best methods of protection against these parasites.

The summer holidays are well under way and British holidaymakers are out and about making the most of the season’s best. When travelling around the UK, or taking short trips abroad, it is easy to forget about the parasite hotspots located within the British Isles and surrounding areas. Whether choosing to holiday in the UK this year, or just enjoying day trips out and about, it is important that pet owners do not become complacent about the parasitic threats to themselves and their accompanying pets.

Cheaper, easier and quicker transport links abroad have seen a rise in the number of people travelling abroad for short trips or for the day. However, it is vital to remember that pets are still at risk of contracting exotic parasitic diseases even on a short trip overseas.

Despite having to abide by the PETS derogation – even when taking pets abroad for short periods – pet owners should still be strongly encouraged to further protect against parasites, such as Dirofilaria repens and Echinococcus multilocularis, and vector-borne diseases, such as babesiosis and ehrlichiosis, which may be found in areas such as northern France, Belgium and the Netherlands. Veterinary professionals should also remain vigilant for signs of infection in animals returning from abroad.

Closer to home, since we believe that these infections have not yet become established in the UK, we do not currently need to worry about our pets contracting these exotic diseases. It is important to remember, however, that the UK is home to a number of potentially dangerous parasites, Echinococcus granulosus and Angiostrongylus vasorum to name but two.

Veterinary professionals should inform pet owners about the importance of regularly treating their pets for parasites and raise awareness about the various parasitic hotspots explored next in this article.

Echinococcus granulosus

Echinococcus granulosus, also known as the hydatid tapeworm, is a potentially lethal zoonotic disease (Figure 1). The sheep strain is historically endemic within the areas of mid-Wales, West Herefordshire and the Outer Hebrides. The definitive host of E. granulosus is the dog, but the disease also infects the intermediate hosts of, primarily, sheep, but also humans.

Figure 1: Echinococcus granulosus

Dogs become infected with E. granulosus when they scavenge or feed from an infected sheep carcass containing hydatid cysts. A cyst contains larvae which develop in the intestine of the dog into an adult tapeworm. The prepatent period of E. granulosus is five to eight weeks and, once the worm is fully developed, segments containing microscopic worm eggs will be passed in the dog’s faeces. These eggs are then immediately infective to the intermediate hosts and, when digested, will develop into hydatid cysts within the intermediate host’s organs.

E. granulosus eggs are able to survive for up to a year – and sometimes longer – in the right environment, thus increasing the risk of further infection. Cysts which develop in humans cause a major impact on the health of the individual and a substantial cost to the health service. Owing to the seriousness of this parasite, the Welsh Assembly Government launched the Hydatid Disease Campaign, now in its third year. The aim of the campaign is to raise awareness about the disease and promote good dog worming practices and personal hygiene.

The campaign has also piloted a quarterly worming scheme for dogs on farms in South Powys. A spokesperson for the campaign explained: “The pilot scheme ran over one year and continues to be monitored by randomly sampling dogs on 200 to 250 holdings every three months, in order to help establish a trend of infection.

Initial indications of the first quarterly sampling, prior to first treatment, are that one in 10 dogs on farms in South Powys, irrespective of whether or not they were pet or working dogs, were carriers of adult E. granulosus and could, therefore, potentially pass on hydatid infection to humans or livestock.” Further information about the Hydatid Disease Campaign can be found at www.wales.gov.uk/topics/ environmentcountryside.

One of the concerns with E. granulosus is the lack of awareness about the disease elsewhere in the UK. Anna Judson, member of ESCCAP UK and partner in Camlas Veterinary Practice in Welshpool, Powys, explained: “Practices in areas of the country where the risk of hydatid disease is low may not think to warn people bringing their dogs to this area on holiday to alter their dog’s worming programme to include praziquantel. It doesn’t take long for a dog to snaffle a bit of dead sheep in a ditch when they are out in the fields on a walk.

“Many owners will keep their dogs on leads when they are around a field of sheep, but sometimes carcasses get missed in fields when the sheep are moved off the pasture and in the extensive grazing of the hills and mountains, farmers may not find, or be aware of, dead sheep in order to remove them.

“Pet owners thinking of visiting the countryside with their dogs, particularly those areas known historically to be endemic, should be advised to worm their dogs with a praziquantel-based wormer at least every six weeks.

Moreover, particularly as cases of hydatic infection have been found elsewhere in the UK, dog owners should take care to prevent their dogs having access to sheep carcases throughout the UK.”

.Angiostrongylus vasorum

Angiostrongylus vasorum, also known as lungworm or French heartworm (Figure 2), is a potentially lethal roundworm which usually inhabits the pulmonary artery of the heart and adjacent blood vessels supplying the lungs.

Figure 2: Angiostrongylus vasorum worms showing their characteristic 'barber's pole' appearance. (Image courtesy of John McGarry, Liverpool University.)

The definitive host of A. vasorum is dogs, with molluscs (snails and slugs) acting as intermediate hosts. Recent debates and interest surrounding lungworm infestations in pets have arisen from concerns over the rising population of slugs and snails in the UK’s increasingly warm and damp seasons. A. vasorum was previously known to be endemic in areas of South Wales and Cornwall. However, research over recent years has shown that the parasite is becoming more widely found in pockets throughout the UK and cases of lungworm in dogs are on the increase.

Dogs become infected with A. vasorum when they ingest molluscs infected by the larvae. These larvae then mature into adult worms and shed eggs into the blood stream of the infected dog. When these eggs hatch into larvae they penetrate the host’s airway and are then coughed up, swallowed and excreted in the faeces of the infected dog. Slugs and snails then become infected by these larvae as they feed on infected dog faeces – and the life cycle begins again.

The prevention of a
ngiostrongylosis can be ensured by regular worming of dogs with an effective wormer. It is important to note that many standard dog wormers will not protect against lungworm and pet owners should be encouraged to seek veterinary advice if they are visiting endemic areas or believe that their dog is at risk.

Since transmission is largely through contaminated faeces, it is important that pet owners are encouraged to pick up faeces after their dog in order to prevent the spread of lungworm.

Ticks

Ticks are a threat to both animal and human health because of the vector- borne diseases (VBDs) that they can pass on to their host. Some high-risk areas for tick occurrence are grass and moor land, hills and mountains, parks, woods and forests. People who live in lower risk areas, such as towns and cities, may not consider the increased risk of ticks when visiting more rural areas on holiday with their pets.

Veterinary professionals should raise awareness within pet owners about the risks of contracting ticks and the possibility of becoming infected with dangerous zoonotic diseases, such as Lyme Disease transmitted by Ixodes ricinus. Pet owners should be advised to use suitable repellents or acaricides if visiting any areas with a high risk of tick occurrence, and to thoroughly examine their pets – and themselves – for ticks, and safely remove any that are found with a proprietary tick removal device.

Resources and further information

In order to assist veterinary professionals and pet owners with protecting pets from parasitic diseases in the UK, ESCCAP has developed a range of key information resources. There are a number of leaflets, designed for pet owners, about ticks, worms and fleas and about being aware of parasitic diseases. There is also a ‘Dog Worm Parasite Wheel’, specifically designed for vet nurses as a source of reference and a learning aid about the parasitic worm infections currently found in dogs in the UK.

ESCCAP UK has two websites providing advice and information for both veterinary and animal care professionals (www.esccapuk.org.uk) and pet owners (www.petparasites.co.uk).

Author

Laura Yeadon BA(Hons)

Laura Yeadon graduated from the University of Worcester in 2009 with a BA Joint Honours in Media and Cultural Studies with Sociology. Whilst studying for her degree, she began working part time as an administrator for a parasitology consultancy in Malvern, assisting with the development of Expert Reports and Guidelines in Parasitology. Laura is currently ESCCAP UK Manager and runs the organisation's Secretariat.

• VOL 25 • No8 • August 2010 • Veterinary Nursing Journal