Soil-Transmitted Helminths

Soil-transmitted helminths, or STHs, which include hookworm, roundworm and whipworm infections, have plagued humans since the earliest recorded history and are estimated to infect one billion people worldwide. These chronic, disabling and often disfiguring infections contribute to a downward cycle of poverty and deprivation and are considered a Neglected Tropical Disease (NTD). For more information about NTDs, click here.

School-aged children bear the greatest burden from these infections, which are associated with anemia, malnutrition, growth and cognitive delays, and inflammatory bowel disease and can negatively impact physical development and school performance. Helminth infections can also negatively impact the progression of malaria and HIV/AIDS by increasing the severity of malaria-induced anemia and contributing to decreased hemoglobin levels, which in turn, increase the risk of mortality.   

Ascariasis, roundworm, is the most common human worm infection. Infection is most prevalent in tropical and subtropical areas where sanitation and hygiene are poor. Infection occurs when food contaminated with feces containing Ascaris eggs is ingested. The larvae hatch, burrow through the intestine, reach the lungs, and finally migrate up the respiratory tract. They are then re-swallowed and mature in the intestine, growing up to 12 inches (30 cm.) in length. Children are most vulnerable; roundworm infection adversely affects childhood growth and physical fitness and impairs intellectual and cognitive development. There are 1.2 billion people infected with roundworms and 60,000 deaths are attributed to the disease each year

Hookworm infection affects 740 million in tropical developing countries. The larvae develop and survive in moist dirt, particularly sandy and clay-like soil. They enter the body through the skin (often through bare feet), and travel to the small intestine, where they begin to feed. Children and women of reproductive age are the most vulnerable to hookworm-associated blood loss leading to iron-deficiency anemia and protein malnutrition. Hookworm infection is estimated to cause a 40% reduction in an infected person’s future wage earnings.

Trichuriasis is caused by the human whipworm; the worms' eggs enter the body on food or on hands that have come into contact with contaminated soil. The parasites' eggs hatch in the small intestine and attach to the large intestine, where they cause blood loss and deplete the host of nutrients. It is estimated that 800 million people are infected with the parasite and that 10,000 deaths result each year.

Since school children bear the highest infection loads, HKI implements school-based de-worming programs that can have an enormous positive impact on the community. STHs can also be prevented through improved hygiene and sanitation practices, measures that also help combat blinding trachoma and schistosomiasis.  HKI implements de-worming programs to control STHs in Cameroon, DRC, Guinea, Mali, Niger, Senegal, Sierra Leone and Tanzania.