Leishmaniasis – The Dog Disease in Focus

It sounds like a scene from a horror film: tiny little parasites that literally devour their host from the inside out, without the host being able to stop the little pests. But this is not about a creepy fantasy creature, but about a very real parasite infestation: leishmaniasis.

Leishmaniasis – a tropical disease on the move

Leishmaniasis was long regarded as a purely tropical disease. It can occur in many different mammals, humans included. Most cases here, however, occur in the domestic dog. The tiny leishmania are transmitted through the bite of the sandfly, which was long regarded as an insect of the tropics. However, this fly is now also spreading in the Mediterranean region – and with it the leishmania. This is one reason why leishmaniasis is often wrongly associated in a blanket way with animal welfare abroad. But the sandfly and its pathogens are on the advance: specimens of the sandfly have already been caught in Germany too, proving that leishmaniasis has long since arrived in our climes as well.

Typical leishmaniasis symptoms and course of the disease

The leishmania themselves are tiny pathogens. No sooner have they entered the body through the bite than they begin to destroy their host's cells. They multiply within the cells and then attack them from the inside. In doing so, they are chiefly out to target the animal's immune defences, so that as the course progresses there are increasingly diffuse immune reactions: non-specific inflammations, ulcers and cell degenerations are typical symptoms. Diarrhoea, seemingly groundless lameness and loss of appetite are further signs of illness in the initial phase.

While at the beginning it is normally mainly the skin that is affected, the symptoms spread further and further over time, until finally the whole body is affected and internal organs too increasingly sustain damage. The reactions are so confused that liver inflammation, kidney failure, bone marrow inflammation, nerve inflammation and many other illnesses can occur, which can be not only extremely painful but also fatal. In fact, in the long term leishmaniasis almost always ends fatally, because there is still no complete cure for infestation with leishmania; only alleviation is possible.

Therapy and treatment options

Since there is currently still no complete cure for animals suffering from leishmaniasis, most treatment approaches focus on alleviating the symptoms, halting the spread of the leishmania in the body, as well as supporting the body's own defences.

If the illness is noticed in time, the vet can, depending on tolerability, administer various pharmaceutical agents which, if taken consistently, prevent the leishmania from spreading further in the body and infesting further organs and body regions. As a result, even a sick dog can often still lead a good life with the parasites. No further precautions need to be taken here, especially since infection through dog-to-dog contact is almost impossible in the early stage. However, close veterinary supervision is always absolutely necessary in the case of leishmaniasis in order to keep the disease under control.

Dogs from abroad and leishmaniasis

Since the spread of the sandfly is currently leading to a strong increase in leishmaniasis cases, especially in the Mediterranean region, the disease is often also associated with animal welfare abroad. Many a person turns up their nose at the fact that sick animals enter the country and carry the pathogens within them. Of course, every responsible animal welfare organisation should test its dogs (and of course cats too) in advance for various illnesses and also for leishmaniasis infestation – but a risk to the domestic animal population is hardly to be feared. Because the leishmania actually spread almost exclusively via the bite of an infected sandfly; a direct transmission from dog to dog is normally ruled out. However, especially in open skin lesions that can occur in the late stage, there are many active pathogens. If these are brought directly into the bloodstream (for example through contact with open wounds), they can likewise cause infections.

Far more problematic is the increasing spread of the sandfly: because even though currently only isolated sandflies are being discovered in our latitudes, it is nonetheless concerning, in view of the current climate development, how an insect of the tropics can become native here. The only truly effective protection against infection is to safeguard yourself and your animal from the bite through insect repellents (repellents). In this connection, it is also strongly advised against taking a healthy dog along if the holiday is to be spent in a known leishmaniasis area with a strong sandfly population.