Leishmaniasis is one of the diseases most dreaded by pet owners. It is difficult to prevent and for the time being treatment is not successful in curing the disease, which is also transmissible to humans.
The disease is caused by a parasite microorganism belonging to the genus Leishmania. It affects vertebrates that have been bitten by the female of a specific nocturnal mosquito. These mosquitoes transmit the disease from one animal to another when they eat the parasites along with their blood meals. These parasites then develop inside the mosquito, which will inoculate them into another animal the next time it bites, closing the cycle of contagion.
When the parasite spreads through the host’s body it does not do so at random: it has its clear preferences. If it spreads through the skin it causes cutaneous leishmaniasis. If it spreads through other organs, it causes visceral leishmaniasis. When the target is the skin, it causes hair loss, ulcers, excessive nail growth and loss of colouring of the nose. When it affects one or more organs, the symptoms depend on the organs affected.
If you suspect infection you should consult your veterinary surgeon. There is a simple test that, although it is not one hundred percent effective, does permit you to know in the majority of cases if your pet is infected. For good results it is very important to catch the problem in time. This is why performing a quick diagnostic test once a year is recommended in areas where this problem is more frequent, such as the east, south and centre of Spain.
If your pet’s test results are positive you shouldn’t give up. Treatment will be able to keep your pet in good general condition. But it should also be said that, despite all the efforts and treatment combinations, there is no definitive cure. In spite of this, there are increasingly more ill animals that, after individualized treatment and periodic controls, have a good quality of life.
Research being carried out nowadays aims to develop an effective vaccine for this condition. It looks as if it could be ready in two years. If it is finally put on the market its arrival will definitely signal a before and after in the history of this complicated disease.
In Spain, dogs are the proven reservoir. This is a cause of worry because of the large canine population, although the disease is not uniformly present. It is more frequent in the east, south and centre of the Spanish peninsula. It is calculated that between five and ten per cent of dogs are affected by the disease in areas such as Catalonia, Madrid, Murcia, Castile-La Mancha, the Balearic Islands and Navarre. It is difficult to prevent in these animals and the expensive treatment, although it does maintain a good general condition in the animal, does not usually afford a complete cure.
Leishmaniasis presents two clinical forms: one of them causes skin lesions, and the other causes lesions in organs such as the liver or the kidneys. This visceral form of the disease usually appears in persons with a depressed immune system.
It is calculated that there are 12 million cases of human Leishmaniasis worldwide, and that every year there are between one and two million new cases of the cutaneous form and five hundred thousand of the visceral form. However, it is considered that official data underestimate the reality of this human disease caused by protozoan parasites, due to various limiting factors. To begin with, Leishmaniasis is only declared compulsorily in 40 out of 88 of the most affected countries, and most of the official data is obtained exclusively through passive detection. Besides this, there are many undiagnosed or undeclared cases and many people who are infected but show no symptoms.
In Spain, this disease has not been subject to obligatory declaration since 1995. Until then, there were about 100 new cases each year. Nowadays it is still a disease subject to obligatory declaration in some autonomous communities, such as the Valencian one, where there are between 20 and 30 new cases a year, or Madrid, where between ten and 27 new cases are registered.
In short, it is a disease that needs more attention from the health authorities, as much to provide information to dog owners, as to study its real incidence.
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Colegio Oficial de Veterinarios de Alicante
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