Leishmaniasis is a long-lasting, severe and protozoan (parasitic) disease of humans, dogs and other animals. Dogs act as the main source of infection (“reservoir host”) and cats are rarely infected. The single-celled parasite is transmitted through the bite of a mosquito that has previously bitten an infected animal or person. The disease is potentially fatal in dogs and humans.
It is important to note that leishmaniasis is not transmitted directly from one dog to another and from one dog to another human. The mosquito is the only carrier of the disease, which means preventing mosquito bites is the key to preventing leishmaniasis.
The prevalence in cats is usually lower than in dogs in the same area. Cats living with humans can become infected, keeping parasites available for transmission to carriers. However, their role as reservoir hosts is still controversial.
Types of leishmaniasis
- Cutaneous leishmaniasis
This form of leishmaniasis primarily affects the skin and mucous membranes.
- Visceral leishmaniasis
This type of disease can affect various internal organs such as the spleen, liver and kidneys and can be fatal if not properly treated.
Symptoms of leishmaniasis
The response of the dog’s immune system can be effective against this disease and prevent the active form of the disease for months to years. It may take up to 7 years after the onset of symptoms.
Some of the most common symptoms associated with leishmaniasis in dogs:
- Loss of weight and appetite
- Weakness and lethargy
- Intermittent fever
- Anemia
- Flaking and hair loss around the eyes, ears and nose.
- Skin lesions, such as nodules, ulcers, and scaling (in the case of cutaneous leishmaniasis)
- Difficulty breathing
- diarrhea and vomiting
- Spleen and liver enlargement
- Difficulty walking or running
- Bleeding from the nose, gums or skin
- Conjunctivitis (eye inflammation)
- Kidney and liver problems
Feline leishmaniasis is a chronic disease with clinical signs and clinicopathological abnormalities similar to those seen in dogs.
Two common clinical findings in cats are mucocutaneous lesions and lymphadenopathy, and the most common clinical pathological abnormality is hypergammaglobulinemia. The most common skin lesions are areas of baldness with severe shedding of dry skin that usually starts on the head and spreads to the rest of the body. Ulcers can also occur, especially on the head and limbs. A wound on the ear can bleed significantly. .
Diagnosis of leishmaniasis
Some of the most common tests used to diagnose leishmaniasis:
a) Serological tests
Serological tests are useful for diagnosing infection, but they don’t always tell if a dog is sick. It is important to note that dogs can have positive antibodies to Leishmania without being sick, as they can be asymptomatic carriers.
b) Cytology
This test involves taking a sample of skin lesions, lymph nodes, or bone marrow for examination under a microscope. Cytology can detect the presence of amastigotes (intracellular form of Leishmania) in tissues.
c) Biopsy
This test involves removing a tissue sample for examination under a microscope to detect the presence of Leishmania amastigotes.
d) PCR
This test detects the genetic material of Leishmania in samples of blood, bone marrow or other tissues.
- It is important to note that no single diagnostic test is completely accurate, so several tests are often used in combination to increase diagnostic accuracy. Furthermore, diagnosis of leishmaniasis in dogs can be difficult due to the variety of symptoms and the possibility that dogs may be asymptomatic carriers. For this reason, regular diagnostic tests are recommended for dogs living in leishmaniasis endemic areas.
Leishmaniasis treatment
One of the most serious consequences of leishmaniasis is kidney failure. Prompt treatment reduces the risk of kidney failure.
Treatment of leishmaniasis in dogs focuses on reducing the parasite load and repairing skin damage in case of ulceration. The drugs of first choice for the treatment of Leishmania are meglumine antimonate, allopurinol, amphotericin B or a combination of both. In case of resistance to treatment, miltefosine can be prescribed. These drugs are expensive to use and must be used with caution as they are highly toxic. Once the patient is stabilized, they should be monitored because there is a high risk of relapse.
In the treatment of cats for leishmaniasis, empiric therapy using allopurinol (10 mg/kg), PO, twice daily for at least 6 months has been used. (No side effects are often reported.)
Prevention of leishmaniasis
1) Stay away from high-risk areas
2) Use of mosquito repellents.
3) Vaccination
4) periodic diagnostic tests
5) Proper hygiene
- It is important to remember that no preventive measure is 100% effective, but a combination of several of them can significantly reduce the chance of infection.
Overall, leishmaniasis is a serious disease in dogs that can affect many body systems and requires specialized veterinary care and preventative measures to reduce the risk of infection. However, dogs infected with leishmaniasis can lead normal and happy lives and live for many years with proper treatment.