Leishmaniasis, a disease transmitted by infected sand fly bites, presents in several forms, with cutaneous and visceral being the most prevalent. Cutaneous leishmaniasis results in skin lesions, while visceral leishmaniasis targets internal organs such as the spleen and liver and can be life-threatening. Skin sores from cutaneous leishmaniasis vary in size and appearance, often resembling a volcano due to their raised edges and central craters, and can be painless or painful. Swollen glands near the lesions are common, such as those under the arm if the sores are on the arm or hand.Visceral leishmaniasis is characterized by fever, weight loss, and an enlarged spleen and liver, with the spleen typically being more swollen. Patients may also exhibit abnormal blood tests, including low red blood cell counts. Annually, there are approximately two million new leishmaniasis cases, with 1.5 million being cutaneous and 0.5 million visceral. The disease is prevalent in regions such as Mexico, Central and South America (except Uruguay, Chile, and Canada), Southern Europe, Asia (excluding Southeast Asia), the Middle East, and Africa, particularly East and North Africa. Over 90% of visceral leishmaniasis cases occur in India, Bangladesh, Nepal, Sudan, and Brazil. The disease is absent in Australia and Oceania and is rare in the USA, though rural southern Texas has reported a few cases of cutaneous leishmaniasis, with no known visceral cases.Leishmaniasis is transmitted by certain phlebotomine sand flies, which acquire the parasite from infected animals or humans. These flies are silent and tiny, about a third the size of typical mosquitoes, and are most active between dusk and dawn, though they may bite during the day if disturbed. Rarely, leishmaniasis can be passed from a mother to her baby or through blood transfusions or contaminated needles. People in affected areas, particularly rural regions, are at risk, with higher susceptibility for those engaging in nighttime outdoor activities, such as adventure travelers, Peace Corps volunteers, missionaries, ornithologists, and soldiers.Cutaneous leishmaniasis typically develops within weeks to months after being bitten, while visceral leishmaniasis may take several months to manifest. Untreated, cutaneous leishmaniasis can result in disfiguring scars, and in rare cases, the infection may spread to the nose or mouth, causing mucosal leishmaniasis, particularly in Central and South America. Visceral leishmaniasis can be fatal if not treated. Travelers can reduce their risk by protecting themselves from sand fly bites, as no vaccines or preventive drugs are available.To minimize the risk of bites, travelers should stay in well-screened or air-conditioned areas, avoid outdoor activities from dusk to dawn, wear protective clothing, and use insect repellents with DEET. Clothing can be treated with permethrin, which should be reapplied after five washes. Living and sleeping areas should be sprayed with insecticides, and bed nets (preferably treated with permethrin) should be used if sleeping in unscreened areas. Sand flies are smaller than mosquitoes, requiring fine-mesh netting for effective protection, though this may be uncomfortable in hot weather.
