An obligate intracellular protozoan parasitic disease transmitted by the bite of some species of sandflies.
Leishmania anre obligate intracellular parasites that invade and multiply within hosts phagocytes.
The global prevalence is estimated to be 6 million cases, and approximately 0.7 to 1 million new cases occur annually.
CD4 positive T cells are critical for host defense since they produce interferon gamma, a key cytokine that activates sacrifices to kill parasites.
Most leishmania species that cause human disease also infect domestic and wild animals which serve as zoonotic reservoirs.
Most cases occur where inadequate evening shelter, and limited personal protective measures are present.
Other factors contributing to the high prevalence of leishmaniasis include malnutrition, lack of awareness of disease, , co-infections with HIV and helminths, and forced population displacement due to conflicts.
Other contributing factors in increasing the spread of infection include expansion of vector and zoonotic reservoirs from climate change and increase vector feeding on humans owing to urbanization and deforestation.
The number of cases of cutaneous leishmaniasis is increasing, particularly in the Mediterranean region,and the prevalence of visceral leishmaniasis is decreasing globally.
Infected sandflies are responsible for most cases of transmission, but visceral leishmania is can also occur through blood, transfusion, organ transplantation, congenital transmission, needle stick injuries, or sharing of contaminated syringes.
Parasites persist throughout the life of the patient after clinical cure, and infection can cause disease recrudescence in persons at higher risk in those in the overall population.
Most commonly manifests either in a cutaneous or in a visceral form.
Cutaneous leishmaniasis is the most common form.
The number of cases of cutaneous’s Leishman is increasing.
Mucosal leishmaniasis causes destructive nose, mouth, and throat lesions.
Visceral leishmaniasis is a potentially life-threatening process that results from blood-borne dissemination of the parasites.
Transmitted mostly by infected sandflies which are noiseless fliers that prefer dark places and are active in the evening, but can be transmitted congenitally and parenterally.
Leishmania is endemic in 98 countries or territories worldwide.
More than 90% of the world’s cases of cutaneous leishmaniasis occur in Afghanistan, Algeria, Brazil, Peru, and the middle east.
More than 90% of the world’s cases of visceral leishmaniasis occur in Bangladesh, India, Brazil, Nepal, and the Sudan.
Leishmaniasis is endemic in Africa, the Americas, Asia, and Europe.
More than 1 billion people are at risk for contracting the disease.
Estimated yearly incidence of Leishmania infection is 1.5 million cases of cutaneous form and 500,000 cases of visceral Leishmaniasis.
75% of cases in the U.S. originate in Latin America.
Travelers who are active in the evenings are at risk.
The type of clinical symptoms and timing of their onset depend on mode of transmission, the Leishmania species and the nutritional or immune status of the host.
The incubation period after the bite of the sand fly, infected with leishmania ranges from 2 to 4 weeks or more for a cutaneous leishmaniasis from a few weeks to 1 to 2 years for visceral disease.
Most patients with cutaneous leishmaniasis have a history of residence in or recent travel to an area where the disease is endemic and present with nodular or ulcerating skin lesions near the sand-fly bites.
Cutaneous form is characterized by one or more skin lesions that develop weeks to months after a person is bitten by infected sandflies.
Skin lesions may be single or multiple and can be small dry lesions to large ulcerating ones and usually occur on exposed areas of the body.
Cutaneous form results from the paratization of skin macrophage and manifest as a papule that enlarges to a nodule that often ulcerates within 1 to 3 months.
The skin lesions can last from weeks to years and may develop raised edges and a central ulcerations.
Cutaneous leishmaniasis resolves without treatment in a few months to several years, depending on the infecting species.
Cutaneous form leads to morbidity due to presence of skin ulcer and presence of disfigurement.
Post kala-agar dermal leishmaniasis (PKDL) is a dermal form of disease reported months or years after treatment in some patients with visceral leishmaniasis caused by Leieshmania donovani.
Mucosal leishmaniasis develops with dissemination of the parasites to the mucosa and concomitantly with cutaneous leishmaniasis or several years after the resolution of the cutaneous infection.
Visceral form can cause fever, weight loss, hepatosplenomegaly and anemia.
Visceral form, if left untreated, is fatal.
Diagnosis based on history and skin lesions and demonstration of parasite on Geimsa stained slides of the lesions.
Most cases of cutaneous disease are self-limited and heal within weeks to 3 years without being treated.
Multiple species cause cutaneous Leishmaniasis.
May be transmitted via transfusion and can cause severe clinical illness and immunosuppressed and newborns.
Molecular methods that test tissue samples of skin or bone marrow are used to identify infecting species.
Detection of Giemsa stained anmastigotes in the edge of tissue from a skin lesion on microscopic exam or isolation of parasites establishes a diagnosis.
Detection of Lashman DNA by PCR is a sensitive diagnostic test.
Treatment with pentavalent antimony agents are the main treatments, but amphotericin B and pentamidine are alternative drugs.