Leishmaniasis

skin-lesions-leishmania

skin lesions in a dog with leishmania

Leishmaniasis is a prevalent disease in much of Europe and warmer areas of the world. It is an infection that is caused by a protozoal (single celled) organism which lives in host bodies and is spread by female sandflies . Dogs are the principal reservoir hosts for this infection. Although it is not currently commonly seen in the UK, dogs that are travelling abroad are at risk of contracting the disease.

Mechanism of infection:

  • Female sandfly becomes infected by drinking blood from infected dog
  • Organism grows and develops inside the sandfly
  • The sandfly bites a new dog and injects it with the parasite
  • Local white blood cells attack and try to kill the organism but it has evasive mechanisms to enable survival. Organism grows and bursts out of white cells spreading further within the body

The outcome following infection depends on the host dog’s immune system. Once infected, dogs will either clear the infection, have subclinical infection (harbour the parasite for a number of months/years before any signs become apparent) or develop signs of active disease. It is not possible to predict an individual’s response to infection with the parasite. Another complicating factor is that the signs of leishmaniasis are quite varied it can be difficult to diagnose the condition. Once a dog has been diagnosed with leishmaniasis active infection it is not possible to cure the infection and long term medication and monitoring is usually required to control the clinical signs and maintain good quality of life. Active infections if left untreated can be fatal.

If your dog is travelling abroad please contact us so we can advise you about appropriate measures to reduce the risk of contracting this disease.

Signs of Leishmania

There are a wide variety and combination of clinical signs that can be seen and active infection can be quite debilitating. Dogs can develop skin lesions such as baldness with sores and itchy broken skin that is slow to heal. This usually occurs over prominent bony areas like elbows and knees but can also occur around the face. There is also a visceral form of the disease where the leishmania organisms affect organ systems like the liver, kidneys and bone marrow. Severe cases can lead to liver or kidney failure and can be fatal.

Additional signs that are sometimes seen are shifting or intermittent lameness, weightloss, anaemia, fever and lethargy.

Can Leishmaniasis be transmitted to humans or other dogs?

Although some forms of the disease can be carried by humans, direct dog-to-human transmission has never been reported, even among veterinarians who have handled hundreds of dogs with leishmaniasis. Where the disease is managed at low levels there is a negligible risk of any kind of transmission and the canine strain of the disease is different to the strain that affects humans in other parts of the world. Direct canine to canine transmission is very rare and the vast majority of canine cases are infected directly via sandfly bites.

Where are dogs most at risk?

Dogs are at risk from the disease anywhere where there are sandflies present. They are most abundant in gardens, around houses in the countryside, parklands and woodland. The period of activity of all sand fly vectors is from sunset to sunrise. The dangerous times of year are different in different countries. Around the Mediterranean, leishmaniasis is transmitted from May to September, or later if there is a warm summer we can see increased activity into October. It is endemic in most of Greece, much of Italy, the Balkans, Malta, southern France, many parts of Portugal and Spain (particularly in the south east and the Balearic islands) and in the humid parts of North Africa. Among the safe places are the Scandinavian countries, the UK including the Channel Islands, Belgium, Luxembourg, the Netherlands, Germany, Northern France, and the mountains of Switzerland. There have also been recent reports of cases in warmer parts of the USA.

How can we prevent Leishmania infection in our pet dogs?

Prevention is a 2 part process:

  1. vaccination to strengthen the immune response before infection occurs
  2. reducing exposure to sandfly bites.

If your dog is travelling abroad we would recommend vaccination prior to travelling. The Canileash vaccine is manufactured by Virbac and is the first vaccine for this disease to be available in Europe.

Dogs require a course of three injections given at three weekly intervals from the age of six months. A single annual booster is required to maintain immunity. Dogs that have previously travelled abroad should be tested for Leishmania antibodies prior to vaccination to ensure they have not been exposed to the disease previously. If positive titres are found then vaccination is not recommended.

We can also reduce exposure to sandfly bites with appropriate anti-parasite measure. It is advisable to avoid wooded areas at dawn and dusk as these are peak activity times for the sandflies. Additionally keeping dogs indoors at night time is beneficial to reduce the risk of infection. Scalibor collars and advantix flea treatment both act to kill sandflies and help reduce the chance of dogs getting bitten. These products are available from us, please come and ask us about appropriate parasite control for dogs travelling abroad.

In May 2014, we had a case of leishmania diagnosed at Vet4life in Teddington. As a lot of our clients and pets travel abroad we would like everyone to be aware of this disease. It is of particular concern to us as once dogs are infected they cannot be cured of the disease. Treatment can be initiated but is expensive and patients require longterm monitoring. If caught late the disease can be fatal. So prevention of infection is definitely preferable!

Please contact us at Vet4life if you would like more information about Leishmania prevention for your canine companion.