Systemic infection in children usually of begins suddenly with vomiting, diarrhea, fever, and cough. In adults, fever for 2 weeks to 2 months is accompanied by nonspecific symptoms such as fatigue, weakness, and loss of appetite. Weakness increases as the disease progresses. The skin may become grayish, dark, dry and flaky. The parasites damage the immune system by decreasing the numbers of disease fighting cells so death usually results from complications of the disease such as infection rather than from the disease itself.
Death often occurs within two years.
Vaccines and drugs for preventing infection are not currently available. Although sand flies are primarily night-time biters, infection may be acquired during the daytime if resting sand flies are disturbed. Sand fly activity in an area may easily be underestimated because sand flies are noiseless fliers, and rare bites may go unnoticed. Infection by Leishmania have been reported on all the continents except Australia. In the Americas, Leishmania can be found from Mexico south into the South American continent.