Visceral leishmaniasis generally conforms to the following cardinal signs of prolonged fever, anemia, leukopenia, splenomegaly and hypergammaglobulinemia. Cutaneous leishmaniasis may or may not present as a nodule at the site of the sandfly bite.
Generally, these presenting signs and symptoms governs the majority of leishmaniasis cases:
The presence of the cardinal signs mentioned above and the history of travel to endemic areas for leishmaniasis clinches the diagnosis of the disease. The following additional tests may be used to determine the presence of leishmania in a host:
The use of antiparasitic pentavalent antimonial like sodium stibogluconate and meglumine antimonate are the mainstay in the treatment of all forms of leishmaniasis . Pentavalent antimonials have cure rate of 90%-97% for leishmaniasis. However, the liposomal form of Amphoteracin B is the drug of choice for visceral leishmaniasis .
The oral antineoplastic drug miltefosine has been advocated to halt the proliferation of leishmania in the cutaneous tissues . In India, meltifosine has become the drug of choice for visceral leishmaniasis . Other treatment options available for the cutaneous disease includes: cryotherapy, reconstructive surgery, local heat therapy and topical paromomycin preparations.
The localized cutaneous forms of leishmaniasis are expected to resolve within 3 to 6 months without therapy. The disseminated cutaneous form of leishmaniasis are often associated with treatment resistance and are extremely disfiguring to the face although mortality rates remains low.
The mucocutaneous forms are more disfiguring for it attacks the mid-facial structures like the palate, lips and the nose. Mortality is evident due to the secondary bacterial infection of the respiratory system. Visceral leishmaniasis is potentially serious and lethal especially in those with poor immune resistance and poor nutritional status.
The majority of the complications in leishmaniasis is due to the relative anemia, leukopenia and thrombocytopenia in patients. The following clinical conditions are the more common complications of leishmaniasis:
The primary reason of leishmaniasis transmission is the eventual migration of human population to the natural habitat of sandflies in the jungle because of urban expansion to the wild. There is a close correlation with leishmaniasis and poverty, malnutrition, the unavailability of vaccines, and the limited access of first line medical care.
Persons with AIDS have a 100 fold risk of acquiring leishmaniasis in endemic areas of the globe. Old world leishmaniasis is primarily caused by Leishmania donovani endemic in China, India and Bangladesh, Leishmania tropica in the Middle East and the Mediterranean and in Africa caused by Leishmania aethiopica. The new world leishmaniasis is dominated by Leishmania brazilienses in Central and South America and Leishmania chagasi in Central and South America.
Transmission of the disease through the bite of the sandfly is the most common mode of transmission but less common routes include congenital transfer, blood transfusion, sexual intercourse and sharing of infected needles, which only occurs in endemic countries .
Leishmaniasis is fairly rare in the United States with sporadic cases of cutaneous leishmaniasis found in southern Texas and Oklahoma bordering Mexico . During the Persian Gulf War at least 400 US service men acquired cutaneous leishmaniasis from their tour of duty .
Approximately 1% of US forces serving the Western Asia are infected with the Old World leishmaniasis . The World Health Organization (WHO) reports that there is an annual incidence of 220,000 cases of cutaneous Leishmaniasis and 58,000 cases of visceral forms occurring worldwide .
Males has double the risk of the disease compared to the females due to occupational exposures to the sandfly’s habitat. The adolescent and young adults are the more susceptible group in Colombia and Afghanistan while the infant group are more prone in Iran.
Leishmania is introduced to the human skin in its flagellated form (mastigote) from the salivary glands of the sandfly. When the protozoan enters the blood stream they lose their flagella and become an amastigote where a majority are extinguished by the body’s natural defense and the minority are engulfed by the macrophages where they multiply and evolve. The fast proliferation of the leishmania species within the cell incapacitates it till it explodes and releases the active form of the parasite (promastigote) to infect other healthy cells.
They have a predisposition in infecting the reticuloendothelial cells rendering the host vulnerable to any cell mediated immunity breach. Parasitized macrophages abound the spleen and the bone marrow. Engorgement of the vascular vessels of the spleen leads to enlargement. Bone marrow becomes hyperplastic and the hematopoetic tissues are subsequently replaced by the parasitized macrophages. The disseminated cutaneous spread of leishmaniasis is due to the relative anergy of the system to immunologically react to the protozoal antigen.
The early diagnosis and treatment is still the most important guiding principle in the treatment of the disease. Vaccination against leishmania seems to be a promising option but may not offer adequate protection against the visceral forms. Insect repellants must always be applied to the skin to prevent insect bites.
Leishmaniasis is generally divided into two categories:
Leishmaniasis may also be conveniently classified as to geographical origin. The Old World Leishmaniasis from Asia, Africa and Middle East and the New World Leishmaniasis occurring in Central and South America . Latent disease may express after 2-6 months of incubation and may present with relapse after 10 years.
Patients bitten by the Phlebotomus sandfly must submit to immediate medical therapy to circumvent the advancement of the clinical course. Any potentially disfiguring lesions in the middle face must be brought in immediately for surgical evaluation and care. A patient infected with leishmania must take absolute care not to contract secondary infections because he is categorically immune-compromised.