Helminths

Helminths are parasitic worms that infest animals, humans included. Adult helminths continue to live in their host until it dies. The lifespan of adult helminths varies widely from species to species. Some helminths live up to 17 years in the body of their host. These parasitic worms are active reproducers throughout their lives. Helminths have a history dating back to the Egyptian culture around 1550 B.C., when a medical manuscript contained observations about parasitic worms.

Helminths migrate through the body to infect different organs, causing hypersensitivity reactions. Most commonly infected organs are the lungs, liver, and intestines. Common symptoms of helminth infections include pneumonia, eosinophilia, granulomatous lesions, and petechial hemorrhages. Helminth infections are extremely common in developing countries.

A variety of helminths infect different species of animals. The most common species of hookworm is Ascaris lumbricoides, which lives in soil. Ascaris lumbricoides passes eggs through the feces of its host. Eggs from contaminated food are ingested and continue the life cycle. While Ascariasis may not be symptomatic, it can be fatal if the worms are allowed to block the intestines.

Some helminths are free-living. Others occur as parasites in humans and other animals. About half of helminth species are parasitic. The worms are classified by their physiology and their habitat. Among the most common are Ascaris lumbricoides, Trichuris trichiura, and Enterobius vermicularis. These organisms can cause disease in the digestive system and in many other parts of the body.