Parasite Infection (Leishmaniasis) in Cats

Leishmaniasis in Cats

Brought on by the protozoan parasite Leishmania, leishmaniasis causes two types of disease in cats: a cutaneous (skin) reaction and a visceral (abdominal organ) reaction, which is also known as black fever, the most severe form of leishmaniasis.

The infection is acquired when sandflies transmit the flagellated parasites into the skin of a host. The incubation period from infection to symptoms is generally between one month to several years. Although relatively rare in cats, when it does occur it often localizes in the skin. There is no age, gender, or breed predilection; however, males are more likely to have a visceral reaction.

The main organ systems affected are the skin, kidneys, spleen, liver, eyes, and joints. There is also commonly a skin reaction, with lesions on the skin, and hair loss. There is marked tendency to hemorrhage.

Affected cats in the U.S. are frequently found to have acquired the Leishmania infection in another country, notably the Mediterranean basin, Portugal, and Spain. There have also been sporadic cases confirmed in Switzerland, northern France, and the Netherlands, and endemic areas found in South and Central America, and in southern Mexico. Endemic cases in Texas have also been reported in cat populations there as well.

It is important to note that leishmaniasis is a zoonotic infection, and the organisms residing in the lesions can be communicated to humans.

Symptoms and Types

Visceral – affects organs of the abdominal cavity

• Severe weight loss
• Loss of appetite (anorexia)
• Diarrhea
• Tarry feces (less common)
• Vomiting
• Nose bleed
• Exercise intolerance

Cutaneous - affects the skin

• Hyperkeratosis — most prominent finding; excessive epidermal scaling with thickening, depigmentation (loss of skin color), and chapping of the muzzle and footpads
• Alopecia — dry, brittle hair coat with symmetrical hair loss
• Nodules usually develop on the skin surface

Causes

Traveling to endemic regions (usually the Mediterranean), where the cat can be exposed to sandflies -- a Leishmania host  -- is the most common way of contracting the infection. However, receiving a transfusion from another infected animal can also lead to leishmaniasis.

Diagnosis

Your veterinarian will perform a thorough physical exam on your cat, taking into account the background history of symptoms and possible incidents that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. Your doctor will be looking for evidence of such diseases as lupus, cancer, and distemper, among other possible causes for the symptoms. Tissue samples from the skin, spleen, bone marrow, or lymph nodes will be taken for laboratory culturing, as well as fluid aspirates. Since there are often related lesions on the skin's surface, a skin biopsy will be in order as well.

Most animals with leishmaniasis have high levels of protein and gammaglobulin, as well as high liver enzyme activity. Even so, your veterinarian will need to eliminate tick fever as the cause of the symptoms, and may test specifically for lupus in order to rule it out or confirm it as a cause.

Treatment

Unless your cat is extremely ill, it will be treated as an outpatient. If it is emaciated and chronically infected, you may need to consider euthanasia because the prognosis is very poor for such animals. If your cat is not severely infected, your veterinarian will prescribe a high-quality protein diet, one that is designed specifically for renal insufficiency if necessary. If your cat has a single dermal nodule, it is best to surgically remove it.

This is a zoonotic infection, and the organisms residing in the lesions can be communicated to humans. These organisms will never be entirely eliminated, and relapse, requiring treatment, is inevitable.

There are medications that can be helpful in treating symptoms and in addressing the disease. Your veterinarian will advise you on the best course.

Living and Management

Your veterinarian will want to monitor your cat for clinical improvement and for identification of organisms in repeat biopsies. You can expect a relapse a few months to a year after the initial therapy; your veterinarian will want to recheck your cat's condition at least every two months after completion of the initial treatment. The prognosis for a successful cure is very guarded.