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Chapter 85 – Soil-transmitted Helminths (Geohelminths)

Simon Brooker,
Donald A. P. Bundy

These are intestinal nematodes, part of the development of which takes place outside the body – in the soil. Infection occurs through contact with parasite eggs or larvae in contaminated soil.

Soil-transmitted helminths (STHs) are among the most common of all chronic human infections, occurring predominanly in areas of poverty and inadequate hygiene and sanitation in the developing world. Unlike many other tropical diseases, infection with STH does not typically result in clinical disease, and the majority of infected individuals exhibit no signs or symptoms. This is because pathology is strongly related to the number of worms present (the intensity of infection), and most individuals harbour only a few worms. In the minority of individuals who harbour a large worm burden, infection results in anaemia, and impaired growth and cognition, as well as overt clinical disease. Fortunately, however, much of this …