Disease: Risks

Rabies

Close up of a table with veterinary records and stethoscope

In western countries rabies poses little threat to people and, in general, to their pets. In case of exposure, rabies can be effectively treated if the treatment is initiated at an early stage. Many countries, such as Australia, the British Isles (although occasional cases are recorded in bats), Hawaii, Japan, New Zealand, and parts of Scandinavia are rabies free; strict quarantine prevents new infections being brought into these countries. Worldwide, however, rabies causes 30,000-70,000 human deaths, the majority of which are in Asia, Africa and South America. If you are travelling to these countries, you should avoid any contacts with wild and domestic animals. Always contact your local health authority before travelling. More information on rabies can be found on the links to the left and on the World Rabies Day website.

Mange

Mangy fox sitting on slabs
Fox affected by mange; © J. Bowry

The parasite causing sarcoptic mange in foxes, scientific name Sarcoptes scabiei, exists in a variety of strains which are specific to different animals. For example Sarcoptes scabiei var. canis can infect both foxes and domestic dogs. The disease can be fatal in foxes but can be easily treated in dogs. Contact your veterinarian for advice on how to treat your dog for mange.

However, the chances of dogs catching mange from foxes are pretty slim. In Bristol, only when fox density was very high (one the highest ever recorded in the world, i.e. 37 adult foxes/km2) was mange transmitted from foxes to dogs. Since then, fox density has decreased but it is still higher than in rural areas. At this lower, more usual, fox density the number of cases of mange in dogs has fallen to negligible levels.

The fox strain (Sarcoptes scabiei var. canis) can be transmitted to humans but cannot persist, so infected people develop a rash that naturally dies away in a few weeks. The chances of infection increase with the degree of contact, so it is not advisable to handle mangy foxes without protection. The mange strain that causes scabies in humans is called Sarcoptes scabiei var. hominis.

TopFox tapeworm

The fox tapeworm (scientific name Echinococcus multilocularis) is a parasite present in much of the northern hemisphere, although not in the British Isles. Foxes are one of the potential definitive hosts for this parasite and where fox populations have increased, there has been a parallel increase of the prevalence of the fox tapeworm in fox populations. When pets come into contact with fox faeces (droppings), pets and their owners are at risk of contracting echinococcosis, a disease caused by the fox tapeworm. To be infected, humans as well as pets need to ingest the parasite eggs, for instance by eating berries contaminated with fox faeces containing fox tapeworm eggs. This disease can be fatal in humans. In mainland Europe, the disease prevalence has increased due to the increase in fox numbers, but baiting campaigns with anti-parasitic drugs have been successful in reducing the prevalence of fox tapeworm in foxes.

TopToxocariasis

Toxocara canis is a kind of roundworm (parasitic nematode) that inhabits the intestine of dogs and foxes. The roundworm sheds its eggs via dog faeces and humans can be infected through direct contact or via contaminated soil. Young children are particularly at risk because they tend to explore the world by mouthing objects and infection with toxocariasis occurs through ingestion of contaminated material such as dog and cat faeces or cat litter. Contamination cannot happen simply through handling pets and their faeces, the eggs must be ingested. Pet cats harbour a different species of worm, Toxocara cati, which can also infect humans.

TopCanine heartworm

A young girl sitting on an armchair hugging a small dog
De-worming is an effective way to protect your pet from parasites

There are several kinds of heartworms widespread in different parts of the world. Dirofilaria immitis is a nematode (parasitic roundworm) commonly found in domestic and wild canids in Africa, Asia, Australia, South America, southern Europe and the USA but is absent in the British Isles. It is transmitted by several species of mosquitoes and adult worms live in the heart and lung arteries. It is common in domestic dogs and less common in cats, ferrets and a variety of other wild carnivores. In dogs, light infestations are easily treated but heavy infestations can be fatal. The disease is easily treated in humans.

Angiostrongylus vasorum is also a nematode (parasitic roundworm) commonly found in domestic dogs, foxes and other canids in North and South America, southern England and in many parts of Europe. The heartworm lives in the lung arteries of foxes and dogs. The disease has severe consequences for the infected animal, including heart failure and death. The disease is not easily treated in dogs and the fact that foxes could act as reservoir is a matter of concern.

However, a regular de-worming protocol for your pets is effective in preventing all diseases due to nematodes (roundworms). Please consult your veterinarian for de-worming advice.

Question & answer

TopWhat can I do to avoid contracting the fox tapeworm?

In the country where it is present (not in Britain) it is simple to avoid infection. You need to take a few simple measures:

  • Avoid touching fox faeces with your bare hands
  • Regularly de-worm your pet with a product suggested by your veterinarian
  • Wash your garden and fruit vegetables thoroughly, especially those to be eaten raw, such as lettuce or berries

TopWhat can I do to avoid contracting toxocariasis?

Children, especially young children, are particularly at risk. To prevent your child from contracting toxocariasis you need to take a few simple measures:

  • Keep your child away from cat and dog faeces
  • Maintain good hygiene standards: wash children's hands frequently and teach them to avoid putting dirty hands in their mouths
  • Prevent your child from accessing the cat litter
  • Regularly de-worm your pet with a product suggested by your veterinarian

TopWhat can I do to prevent my dog from contracting canine heartworm?

Regularly de-worm your pet with a product suggested by your veterinarian. There are a variety of options for preventing heartworm infection; ask your veterinarian for advice.

References

  • Bellamy, R. & Salmon, R. (1999) Risk of importation of diseases exotic to Great Britain following the relation of quarantine regulations. Quarterly Journal of Medicine 92, 683-687.
  • Deplazes, P., Hegglin, D., Gloor, S. & Romig, T. (2004) Wilderness in the city: the urbanization of Echinoccocus multilocularis. Trends in Parasitology 20, 77-84.
  • Ferasin, L. (2004) Disease risks for the travelling pet: heartworm disease. In Practice 26, 350-357.
  • Morgan, E.R., Shaw, S.E., Brennan, S.F., De Waal, T., Jones, B.R. & Mulcahy, G. (2005) Angiostrongylus vasorum: a real heartbreaker. Trends in Parasitology 21, 49-51.
  • Ridyard, A. (2005) Heartworm and lungworm in dogs and cats in the UK. In Practice 27, 147-153.
  • Smith, G.C., Gangadharan, B., Taylor, Z.,Laurenson, M.K., Bradshaw, H., Hide, G., Hughes, J.M., Dinkel, A., Romige, T. & Craig, P.S. (2003) Prevalence of zoonotic important parasites in the red fox (Vulpes vulpes) in Great Britain. Veterinary Parasitology 118, 133142.