Canine Leishmaniasis: First Case of Non-Vector-Borne Infection Between Two Dogs Across the Channel

In the United Kingdom, a Shih Tzu exhibiting vomiting, diarrhea, and weight loss died of leishmaniasis within three weeks. The dog lived with another dog that had been imported from Spain, where this chronic disease—which is usually transmitted through the bite of an infected female sandfly—is endemic. In the British case, transmission occurred directly, from dog to dog, without the involvement of a biting insect. Veterinary researchers are calling for measures to protect the canine and human populations of the United Kingdom against leishmaniasis.

Dogs are the primary reservoir hosts for the protozoan Leishmania infantum and therefore play a major role in the transmission cycle of the infection, which also affects rabbits, hares, cats, wolves… and humans. A dog carrying the parasite thus poses a real danger to other dogs, other mammals, and humans alike. Although this anthropozoonosis used to affect primarily areas around the Mediterranean, it is now spreading toward northwestern Europe. In recent years, veterinarians have observed an increasing number of cases of canine leishmaniasis.

The Shih Tzu that died of leishmaniasis was three years old, lived in Hertfordshire, and had never left the British Isles. This is the first case of visceral leishmaniasis reported in the United Kingdom in a dog that had not previously traveled to an endemic area. The dog lived with a seropositive dog from Spain that had developed the disease six months earlier and had to be euthanized. Infected dogs thus pose a risk of infection to other dogs through direct contact, even in the absence of natural vectors. Direct transmission from dogs to humans, however, has yet to be proven.

According to the British Small Animal Veterinary Association, the increase in the number of seropositive dogs imported into the United Kingdom makes accidental transmission via these infected dogs increasingly likely. Although rare, leishmaniasis is on the rise and is a cause for concern among British veterinarians. More than a quarter of the practitioners surveyed by the British Veterinary Association last year

have reported cases of this disease among their clients. However, canine leishmaniasis remains little known across the Channel. At the same time, cases have become more frequent over the past fifteen years or so, as it has become easier for pets to travel throughout Europe.

Faced with the difficulty of diagnosing and treating the disease, veterinary researchers recommend adopting four measures aimed at protecting the canine and human populations of the United Kingdom against leishmaniasis:

- screening of both dogs imported from regions of endemicity and dogs that have been “in contact” with infected dogs;

- veterinary monitoring of at-risk dogs to ensure the absence of seroconversion;

- exclusion of subclinically infected dogs from blood donation;

- vaccination and the use of topical insecticides in dogs traveling to areas of endemicity. The combination of vaccination and insecticides may contribute, if not to the elimination, then at least to a reduction in the significance of this source of infection, and thus to a decrease in human cases.

Further Reading

‘Huge concern’ over leishmaniasis prompts new advice, https://veterinaryrecord.bmj.com/content/184/14/425

https://vetitude.fr/leishmaniose-canine-des-progres-en-termes-de-diagnostic-et-de-gestion-de-la-maladie-sur-le-terrain/

https://vetitude.fr/leishmaniose-canine-efsa-la-caracterisation-de-la-maladie-et-prevention/