Parasitic Infection (PI)
Parasitic infections can be spread in a number of ways. For example, protozoa and helminths can be spread through contaminated water, food, waste, soil, and blood. Some can be passed through sexual contact. Some parasites are spread by insects that act as a vector, or carrier, of the disease. For example, malaria is caused by parasitic protozoa that are transmitted by mosquitos when they feed on humans.
Parasitic infections are a big problem in tropical and subtropical regions of the world. Malaria is one of the deadliest parasitic diseases.