Leishmaniasis

What is Leishmaniasis?

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.

How is it caused?

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.

• Swelling and enlargement of the spleen and liver
  
• Persistent fever
  
• 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.

• Complete blood count (CBC)
  
• Haemoglobin check
  
• Serum albumin
  
• Serum protein

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.