Leishmaniasis is a disease related to the presence, within the organism of an animal, of small parasites: leishmanias. The latter are transmitted to an animal by the bite of a dipterous insect very close to the mosquito.
The disease is common in dogs whereas the cat seems very unresponsive.
The man, like the dog, can be contaminated.
Mode of transmission of the disease
The transmission of the disease is most often related to the sting of a diptera called phlebotome: a female phlebotome pricks a dog carrying leishmanias and absorbs parasites in its blood meal. The latter multiply in the digestive tract of the insect, which, during a new bite, will contaminate another animal by its saliva. The sandfly is particularly present from May to October and its activity is maximum at dusk.
The disease can also be transmitted from a pregnant female to her cubs or even during blood transfusion.
The direct transmission of the dog to the man is not proven: the man is contaminated by the bite of the sandfly present in his environment of life.
Clinical picture in dogs
In a number of dogs, the development of the parasite is limited and does not result in any clinical signs.
In susceptible individuals, Leishmania will progressively infect the cells of the marrow, liver, spleen, lymph nodes, digestive mucosa or the skin of the affected animal causing various symptoms:
In the conventional forms, the animals present:
- A marked abatement and fatigue, first after the effort, then permanently
- Progressive weight loss and heavy muscle wasting (a young animal with the appearance of an old dog)
- anemia and then coagulation disorders
- Several skin disorders with possible ulcerations on the wings of the nose and ears, loss of hair (depilation of the free edge of the ears or the periphery of the eyes), thickening of the pads, lengthening of the claws ...
- Eye disorders
- Urinary disorders, the parasite can generate renal abnormalities leading to severe renal insufficiency.
- A generalized reaction with increase in size of the spleen of the animal and of all the lymph nodes.
The clinical picture is very polymorphic and some dogs may present only one of these symptoms, even a simple fatigue.
In addition, atypical forms of leishmaniasis are described:
- Digestive forms,
- Nerve forms (epileptiform seizures)
- Osteoarticular involvement,
- Generalized forms of lightning, especially in the puppy
- Skin involvement with nodules or pustules on the animal
Finally, dogs initially "resistant" to the disease will be able to express various symptoms of leishmaniasis following a decrease of their immune defenses: in particular in another concomitant disease or general fatigue (as after a bet- For example)
Clinical features in humans
As in dogs, a very large number of humans are carriers of the disease without showing any symptoms. (Truck-Sain)
In France, the various cases of leishmaniasis observed are associated with the leishmania infantum parasite.
Several forms of the disease are encountered:
- The visceral form of the child: Young children (mostly under 5 years of age) have episodes of fever, marked pallor and increased spleen volume.
- Native localized skin leishmaniasis (rare): contaminated individuals have small, painless, crusty skin lesions usually found on the face and forearms. These lesions heal spontaneously.
- Mediterranean visceral leishmaniasis of the adult most commonly encountered in immunocompromised patients (persons with malignant hemopathy, congenital immunosuppression, long corticosteroid therapy or immunosuppressive treatments for transplantation, organs ...)
Diagnosis of the disease in dogs and prognosis
Leishmaniasis should be suspected in an animal with one or more of the symptoms described above and living or having lived in the Mediterranean region. The incubation of the disease can be very long (several months, even several years), it should be considered even for dogs no longer living in the regions concerned for a long time.
Most often, a blood sample taken by your veterinarian will allow the diagnosis of the disease (either directly to the clinic or by various laboratory methods: IFI, ELISA, PCR).
Sometimes the demonstration of the disease will require other types of examinations such as skin tracings or biopsies, punctures or biopsies of the reaction or spleen ganglia, bone marrow aspiration, synovial fluid puncture, etc.
The prognosis depends very much on the stage at which the disease is detected. It will be extremely reserved in dogs for which leishmaniasis is diagnosed when renal function is already impaired or when severe anemia is present.
For animals susceptible to the parasite, the disease will evolve, in the absence of specific treatment, to fatal kidney failure.
The classical treatment of leishmaniasis consists of a meglumine antimonate (Glucantime) treatment administered daily for 1 month by injection, combined with allopurinol (Zyloric) orally administered for long months in order to limit The risk of relapse.
These molecules can aggravate renal lesions already present, which explains the very reserved prognosis of animals in which leishmaniasis has already caused renal lesions.
Miltefosine is a molecule that is also used but is not currently available in France
Regular clinical monitoring of the Leishman animal should be carried out (monitoring of renal function, absence of anemia, symptoms after treatment), and subsequent blood tests Of the disease.
Prevention of leishmaniasis
Leishmaniasis is a serious, life-threatening disease of the animal, the diagnosis of which is not always easy and the treatment is cumbersome and costly. It is rife in more than twenty French departments.
It is, moreover, a disease transmissible to man. The dog, although not necessarily directly responsible for human contamination, is an important reservoir of the parasite (including dogs that carry the parasite but do not express the disease)
The protection of your companion against this parasite is therefore paramount both for the dog itself and to prevent the spread of the disease.
● Prevention of bites
To ensure the best prevention against sandfly pines, it is advisable to:
- To eliminate any source of standing water near the dwellings
- To return the animals in the evening
- To limit the risk of pitting by the application of active pest control products against phlebotomes (insecticide spray, deltamethrin-impregnated collar or permethrin-based pipette to be applied to the animal every 3 weeks)
This treatment should be continued as long as the high heat (up to October in hot regions where leishmaniasis is present)
Please note that not all antiparasitic agents are active against sandflies and those that are to be reserved for the dog (toxic in the cat). Do not hesitate to ask your veterinarian for advice.
A vaccine against canine leishmaniasis is now available.
It is strongly recommended for all dogs living in departments where leishmaniasis is present