Leishmaniasis and Other Protozoan Infections at a Glance
- A complex of diseases caused by the protozoa Leishmania and transmitted by the bite of infected phlebotomine sandflies.
- Four major human diseases: (1) localized cutaneous leishmaniasis, (2) diffuse cutaneous leishmaniasis, (3) mucocutaneous leishmaniasis, and (4) visceral leishmaniasis.
- Resulting disease dependent mainly on interaction between Leishmania species and the immunologic status of the host.
- Diagnosis by organism isolation or by serology but species identification only possible with isoenzyme analysis and new molecular techniques.
- Management ranging from observation to systemic therapy, primarily with antimonials, and vaccines in development.
Leishmaniasis, a truly ancient disease,2 was recognized on Amerindian pottery drawings dating back to the first century ad.3 It was named after W.B. Leishman who identified organisms in smears taken from the spleen of a patient who died from “dum-dum fever” in India in 1901. The disease burden remains important in the twenty-first century with up to 2 million individuals developing systemic disease annually and accounting for around 70,000 deaths per year.4
The various types of leishmaniasis are confined primarily to the Mediterranean basin, Southern Europe, Central Africa, and parts of Southern and Central Asia [Old World (OW)], and Central and South America [New World (NW)]. The infection is endemic in 88 countries, 72 of which are developing countries.
In Western countries, the incidence is increasing due to human immunodeficiency virus (HIV)-Leishmania coinfection, military appointment, and tourism in endemic countries.5,6 New Zealand, Antarctica, and the Pacific islands are Leishmania-free. Australia was thought to be devoid of Leishmania species until 2004, when it was discovered in red kangaroos that had developed ulcers over their limbs or ears, raising the possibility of imported species becoming endemic, or of a current still unrecognized human form of the disease.7
More than 90% of localized cutaneous leishmaniasis (LCL) cases occur in Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, Syria, Brazil, and Peru.8 In the United States, most LCL cases are imported; however, the Southern and Central parts of Texas are considered endemic for Leishmania mexicana.9,10
The World Health Organization (WHO) has classified leishmaniasis as a category 1 disease (emerging and uncontrolled). The recent geographic spread is attributed to massive rural-urban migration and agro-industrial development projects that bring nonimmune urban residents into endemic rural areas. Other incriminated factors include natural disasters, cessation of malaria spraying leading to increased sandfly population, reconstructions, control programs, global warming, wars, and deforestation.
Risk factors for contracting the disease include residing in an endemic area and in a ground floor, the design and construction material of the house, and the presence of domesticated animals. The prevalence of the disease increases until the age of 15 then seems to stabilize, probably reflecting development of immunity.11 In general, males have greater likelihood of ...