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Blood (Intracellular) and Other Tissue Protozoa 99

(onchocerciasis), all of which are found predominantly in America and the Caribbean Malayan filariasis occurs
parts of Africa and Latin America. In all of these diseases, only in southern and southeastern Asia as well as the
a mosquito first bites an infected individual before biting southern area of the Thai peninsula, Borneo, and the
another uninfected individual, and in the process trans- major islands of the islands of the South China and Java
ferring some of the worm larvae to the new host. Once seas. Filariasis is occasionally found in the United States
within the body, the larvae migrate to a specific area or and most particularly may be present among immigrants
organ of the body where they mature to adult worms. from the Caribbean and Pacific Islands. W. bancrofti was
The two most common types of the disease are actually prevalent in Charleston, South Carolina, at one
bancroftian and Malayan filariasis, which are both dif- point in history and was contracted through slave trade
fering forms of lymphatic filariasis, a parasitic worm that and transmitted by mosquitoes capable of carrying the
lives in human lymph nodes and ducts (Figure 4-16). disease in the region. The disease had largely disap-
The bancroftian variety is found throughout the Africa peared from the region by the early 1920s.
continent, the Pacific Islands, southern and southeastern Lymphatic filariasis is a term that refers to a con-
Asia, and the tropical and subtropical regions of South dition caused by infection with the nematode worms

Source: Centers for Disease Control and Prevention (CDC)

FIGURE 4-16 Life cycle for the microfilaria, Wucheria bancrofti