Basic Information on Leishmaniasis

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Leishmaniasis is a common infectious disease.

Infectious agent:
Protozoal parasites family Trypanasomatidae, genus Leishmanania:

L. donovani and L. infantum may cause visceral leishmaniasis while L. tropica and L. major may cause cutaneous leishmaniasis.

Incubation period:
Considered to be at least a week but may extend up to several months. For zoonotic type it is considered to be about 4 months and for the anthroponotic type it ranges from 6-12 months

Case Definition:
Two types of leishmaniasis occur in Pakistan: – cutaneous and visceral.

Suspected case
In cutaneous leishmaniasis, there are lesions on the face, neck, arms, and legs, which begin as nodules and turn into skin ulcers, eventually healing but leaving a depressed scar.

In visceral leishmaniasis, the parasite invades the spleen, liver, bone marrow, and lymph nodes.

Symptoms include mainly irregular fever, splenomegaly and weight loss; also fatigue, enlargement of the lymph nodes and the liver, secondary infections such as pneumonia, and it can be fatal if left untreated.

Confirmed case
Suspected cases with positive parasitological evidence from a stained smear by microscopy or culture from the lesion.

Management:

Intra-lesional Treatment:

Intra-lesional treatment means carefully infiltrating the area around the lesion and the base, with a fine gauge (25g) needle and injecting the Glucantime / pentostam pentavalent antimony under pressure as the needle advances. Treatments are every week up to five times.

Systemic (intra-muscular) treatment:

Injections should be given daily (with a break of one day for a week-end) for 14 days into the upper, outer quadrant of the buttock, alternating sides. If the response is poor by the 14th day, the treatment can be continued for 7 more days. Here is a table showing the correct doses for Glucantime and Pentostam on a scale based on a simplified formula relating body weight to surface area whereby a 20 Kg child receives 20 mg/kg of antimony.

Prevention:

Prevention of Anthroponotic Cutaneous Leishmaniasis is very similar to malaria prevention, as sandflies bite at night and sleeping indoors, using permethrin treated bednets, etc. are useful. Sandflies are generally more sensitive than mosquitoes to insecticide, i.e. residual spraying of indoor rooms (vector control). The use of insecticide is unlikely to work in prevention of Zoonotic Cutaneous as the sandfly vector tends to bite outdoors, so the most effective strategy is to poison or dig up the burrows of reservoir rodents.

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The writer enjoys medical education and has special interest in community medicine.