Leishmaniasis, Visceral
Barbara L. Herwaldt, Alan J. Magill
Leishmaniasis is a parasitic disease found in parts of the tropics, subtropics, and southern Europe. Leishmaniasis has several different forms. This section focuses on visceral leishmaniasis (VL), which affects some of the internal organs of the body (such as spleen, liver, and bone marrow).
INFECTIOUS AGENT
VL is caused by obligate intracellular protozoan parasites, particularly by the species Leishmania donovani and L. infantum/L. chagasi.
MODE OF TRANSMISSION
VL is predominantly transmitted through the bite of infected female phlebotomine sand flies, although congenital and parenteral transmission (through blood transfusions and needle sharing) have been reported.
EPIDEMIOLOGY
VL is usually more common in rural than urban areas, but it is found in some periurban areas (such as in northeastern Brazil). In the Old World (Eastern Hemisphere), VL is found in parts of Asia (particularly the Indian subcontinent and southwest and central Asia), the Middle East, Africa (particularly East Africa), and southern Europe. In the New World (Western Hemisphere), most cases occur in Brazil; some cases occur in scattered foci elsewhere in Latin America. Overall, VL is found in focal areas of approximately 65 countries. Most (>90%) of the world’s cases of VL occur in the Indian subcontinent (India, Bangladesh, and Nepal), Sudan, Ethiopia, and Brazil; none of the affected areas in these 6 countries are common tourist destinations.
The geographic distribution of cases of VL evaluated in countries such as the United States reflects travel and immigration patterns. VL is uncommon in US travelers and expatriates. Occasional cases have been diagnosed in short-term travelers (tourists) to southern Europe and also in longer-term travelers (such as expatriates and deployed soldiers) to the Mediterranean region and other areas where VL is found.
CLINICAL PRESENTATION
Among symptomatic people, the incubation period typically ranges from weeks to months. The onset of illness can be abrupt or gradual. Stereotypical manifestations of VL include fever, weight loss, hepatosplenomegaly (especially splenomegaly), and pancytopenia (anemia, leukopenia, and thrombocytopenia). If untreated, severe (advanced) cases of VL typically are fatal. Latent infection can become clinically manifest years to decades after exposure in people who become immunocompromised for other medical reasons.
DIAGNOSIS
Clinicians should consider VL in people with a relevant travel history (even in the distant past) and a persistent, unexplained febrile illness, especially if accompanied by other suggestive manifestations (such as splenomegaly and pancytopenia). Laboratory confirmation of the diagnosis is achieved by detecting Leishmania parasites or DNA in infected tissue (such as in bone marrow, liver, lymph node, or blood), through light-microscopic examination of stained specimens, culture techniques, or molecular methods. Serologic testing can provide supportive evidence for the diagnosis.
CDC can assist in all aspects of the diagnostic evaluation, including species identification. For consultative services, contact CDC Public Inquiries (770-488-7775; parasites@cdc.gov). Additional information can be found on the CDC website (www.cdc.gov/parasites/leishmaniasis).
TREATMENT
Infected travelers should be advised to consult an infectious disease or tropical medicine specialist. Therapy for VL should be individualized with expert consultation. The relative merits of various approaches can be discussed with CDC staff (see the Diagnosis section above for contact information).
Liposomal amphotericin B (AmBisome) is approved by the Food and Drug Administration to treat VL. The pentavalent antimonial compound sodium stibogluconate (Pentostam) is available to US-licensed physicians through the CDC Drug Service (404-639-3670) under an investigational new drug protocol (see www.cdc.gov/laboratory/drugservice/index.html).
PREVENTIVE MEASURES FOR TRAVELERS
No vaccines or drugs to prevent infection are available. Preventive measures are aimed at reducing contact with sand flies (see the Protection against Mosquitoes, Ticks, and Other Insects and Arthropods section in Chapter 2 and Preventive Measures for Travelers in the previous section, Cutaneous Leishmaniasis). In particular, travelers should be advised to avoid outdoor activities, especially from dusk to dawn, when sand flies generally are the most active, and to sleep in air-conditioned or well-screened quarters. Preventive measures also include wearing protective clothing, applying insect repellent to exposed skin, using bed nets treated with a pyrethroid-containing insecticide, and spraying dwellings with residual-action insecticides.
BIBLIOGRAPHY
1.Herwaldt BL. Leishmaniasis. Lancet. 1999 Oct 2;354(9185):1191–9.
2.Malik AN, John L, Bruceson AD, Lockwood DN. Changing pattern of visceral leishmaniasis, United Kingdom, 1985–2004. Emerg Infect Dis. 2006 Aug;12(8):1257–9.
3.Murray HW, Berman JD, Davies CR, Saravia NG. Advances in leishmaniasis. Lancet. 2005 Oct 29–Nov 4;366(9496):1561–77.
4.Myles O, Wortmann GW, Cummings JF, Barthel RV, Patel S, Crum-Cianflone NF, et al. Visceral leishmaniasis: clinical observations in 4 US army soldiers deployed to Afghanistan or Iraq, 2002–2004. Arch Intern Med. 2007 Sep 24;167(17):1899–901.
5.Weisser M, Khanlari B, Terracciano L, Arber C, Gratwohl A, Bassetti S, et al. Visceral leishmaniasis: a threat to immunocompromised patients in non-endemic areas? Clin Microbiol Infect. 2007 Aug;13(8):751–3.
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Leishmaniasis, Visceral - Chapter 3 - 2012 Yellow Book - Travelers' Health - CDC
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