What is it?
Leishmaniasis is a parasitic disease spread by a species of sandfly, the female phlebotomine sandfly. The disease has two main forms – the cutaneous form which affects the skin and the visceral form that affects the internal organs. Cutaneous leishmaniasis is seen when lesions form on the skin weeks to months after the possible insect bite. Visceral leishmaniasis causes swelling and enlargement of the spleen and liver in addition to anaemia.
Leishmaniasis is a disease that usually takes on epidemic proportions when it occurs. Kala-azar (visceral leishmaniasis) is the commonest form found in India and the last major epidemic occurred in 1977 when more than 100,000 cases were reported from Bihar. However, the states of both Bihar and West Bengal regularly report cases of Kala-azar.
What are the causes and risk conditions?
Leishmaniasis is a protozoal infection transmitted by the bite of the female phlebotomine sandfly. The sandfly needs the Leishmania parasites to obtain a protein necessary to develop her eggs. This parasite grows inside the fly and when it next bites a human being, the infection is transmitted. The incubation period i.e., the time lapse between the actual infection and the manifestation of symptoms, is usually 1-4 months but may range from 10 days to upto 2 years.
The disease occurs twice as many times in men as in women. It occurs most commonly among the lower socio-economic status and in migrant populations. People who work in open places in close proximity with animals are more prone to sandfly stings and thus the infection.
What are the symptoms?
Cutaneous leishmaniasis – this is the form of leishmaniasis that manifests itself in the form of lesions on the skin. These lesions may be open or closed and may sometimes be confused with leprotic lesions. The ulcers may be painful and may reduce an individual's ability to work. The main symptoms for this form are:
Painful ulceration of skin
The main ulcer surrounded by smaller lesions that may itch and pain
Discolouration of skin in some cases.
Visceral leishmaniasis (kala-azar) – this is the form that affects the internal organs like the liver and spleen causing a variety of symptoms like:
Swelling and enlargement of the spleen and liver
Fatigue, weakness and loss of appetite
Persistent abdominal discomfort
Nausea and vomiting
Unexplained weight loss
Darkening of skin of face, hands, feet and abdomen (kala-azar = black illness).
How is it diagnosed?
The disease is diagnosed by a series of laboratory tests. Various skin tests may be done:
The Montenegro skin test – result based on skin reaction
Biopsy of the spleen
Lymph node biopsy
Bone marrow biopsy
Aldehyde test widely used in India for the diagnosis of Kala-azar
Serological tests – ELISA and IFAT (Indirect Fluorescent Antibody Test) are the commonly done diagnostic tests.
Other complementary tests are:
Complete blood count (CBC)
What is the treatment?
Once the disease is contracted, it can be treated with a tight vaccination schedule which involves a daily injection of sodium stibogluconate for 20 days for adults. To patients who do not respond to this form of therapy, a stronger and more toxic compound is administered under supervision. For cutaneous leishmaniasis, Amphotericin B, a potent antibiotic, is also used as a measure of treatment. However, since this drug is very toxic and has to be carefully administered, it is used only when the patient fails to respond to any other form of treatment.
However, the best method of treatment of the condition is prevention. Sandflies should be controlled with the help of insecticides, with DDT being sprayed at regular intervals. Insect repellents should be lit in the room at night. Popel who are more prone to insect stings can try rubbing insect repellant gels on the exposed parts of their body. Sanitation should be maintained in the neighbourhood with elimination of breeding places like garbage, rodent burrows, bricks or rubbish near houses and the like.
Animal reservoirs like dogs should be inoculated regularly. Health education becomes a necessary tool to be acquired to cope with the disease. Since once contracted, the disease has a high mortality rate, utmost care should be taken to avoid the breakout of Leishmaniasis.