Leishmaniasis, main information
Leishmaniasis is a disease caused by a protozoan (single-celled) parasite found in dogs, cats and some rodents in many parts of the world, most commonly in rural areas. The parasite is transmitted by small biting sandflies. It is an important disease to be aware of because humans can get it too.
There are 3 main forms of leishmaniasis: visceral (the most severe form because it is almost always fatal without treatment), cutaneous (the most common, usually causing skin ulcers), and mucocutaneous (affecting the mouth, nose and throat). Leishmaniasis is caused by protozoan parasites which are transmitted by the bite of infected female sand flies. The disease is associated with malnutrition, poor housing, a weak immune system and lack of financial resources.
Clinical signs of the cutaneous form most commonly include thickening and hardening of the tissues on the face and footpads, called hyperkeratosis. Many dogs will lose the pigment or dark coloration of these tissues as the disease progresses. Hard lumps or lumps may form on the skin, and the coat often appears dull and brittle with areas of shedding. Nails can become abnormally long and curved.
Clinical signs of the visceral form include fever, anorexia (lack of appetite), weakness, decreased stamina, severe weight loss, diarrhea, vomiting, increased alcohol consumption and urination, and nosebleeds. About a third of dogs will develop enlarged lymph nodes and an enlarged spleen and progress to kidney failure. Muscle pain, joint inflammation, and swelling of the testicles may also be present. Virtually all dogs that acquire leishmaniasis will develop the visceral form of the disease. 90% of those dogs will also have skin involvement. The cutaneous form of leishmaniasis most commonly affects cats.
Leishmaniasis is diagnosed based on a dog's medical and travel history (especially travel to an area with endemic leishmaniasis) and clinical signs. Blood and urine tests are usually done along with tissue biopsies. Occasionally, the organism can be found on lymph node aspirates or skin lesion smears, but these are not very sensitive.
Meglumine antimonate is a medicine used to treat leishmaniasis. This includes the visceral, mucocutaneous and cutaneous form. It is given by injection into the muscle or into the infected area. Side effects include loss of appetite, nausea, abdominal pain, cough, feeling tired, body aches, irregular heartbeat, and kidney problems. It should not be used in people with severe heart, liver or kidney problems. Not recommended during breastfeeding. It is on the World Health Organization's List of Essential Medicines. It is available in Southern Europe and Latin America, but not in the US.
Miltefosine is a drug used primarily to treat leishmaniasis and free-living amoeba infections such as Naegleria fowleri and Balamuthia mandrillaris. This includes the three forms of leishmaniasis: cutaneous, visceral and mucocutaneous. It can be used with liposomal amphotericin B or paromomycin. It is taken orally. Common side effects include vomiting, abdominal pain, fever, headache, and decreased kidney function. More serious side effects can include Stevens-Johnson syndrome or low platelets. Use during pregnancy appears to cause harm to the baby and use while breastfeeding is not recommended. How it works is not entirely clear. Miltefosine was first produced in the early 1980s and studied as a treatment for cancer. A few years later it was found to be useful for leishmaniasis and was approved for this use in 2002 in India.
Allopurinol is indicated for the treatment of canine leishmaniasis, alone or in combination with other compounds (e.g. N-methylglucamine antimonate). The anti-Leishmania action of allopurinol derives from the particular metabolism of Leishmania (as well as of other protozoa belonging to the hemoflagellate group). Allopurinol, while lowering the parasitic load and thus leading to a clinical improvement, is not able to lead to parasitological cure: for this reason, within a short time after the interruption of the therapy, relapses occur almost constantly. The combination treatment between N-methylglucamine antimonate (or meglumine antimonate) and allopurinol is still today the most used therapeutic protocol for the treatment of leishmaniasis in dogs. The animals treated with the two drugs in combination have a more lasting remission than that obtainable with the use of the two substances in monotherapy.
Prevention of Lieshmaniasis
Although the therapy is effective in most cases, it is not definitive, it is very long and can have many side effects. For these reasons, the best solution is to do a good prevention.
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An infected dog must continue to be protected as it can be a reservoir for other animals or humans. Even if a phlebotomist were to sting an infected (but protected) dog, the parasite will not have time to replicate in the phlebotomist because this will die thanks to the action of the pyrethrins.
Prevention should include topical application of slow-release insecticides while the sandflies are active. Furthermore, vaccination should be considered a multimodal approach. Slow-release topical insecticides applied to dogs living in or traveling in endemic areas should be applied throughout the risk period of potential exposure to or activity of sandflies.
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The above information is important to better disseminate the main characteristics of this pathology but it is essential to always contact the Veterinary Doctor for any problem or therapy.