Several neglected tropical diseases (NTDs) are transmitted by infected insects. For example, Chagas disease is transmitted by the triatomine, or “kissing,” bug and can lead to life-long cardiac problems; leishmaniasis is transmitted by infected sand flies and can lead to sores that cause permanent scarring; onchocerciasis is transmitted by infected black flies and can lead to blindness; and dengue fever, which can lead to circulatory failure, and lymphatic filariasis, which can lead to extreme swelling of the genitalia or limbs, are both transmitted by infected mosquitoes.
Other NTDs are transmitted through consumption of water or food that harbors parasites. Guinea-worm disease, fascioliasis, and schistosomiasis are examples of NTDs that infect people through contaminated water or food.
Most NTDs are not transmitted from person to person, although there are exceptions. Leprosy—although not highly contagious—can be transmitted through respiratory droplets in coughs and sneezes and can lead to thick skin lesions and nerve damage. Trachoma, which can lead to blindness, can be transmitted through personal contact and the sharing of personal items that harbor the bacteria.