Hookworms infected about 428 million people in 2015, mostly through bare feet
Hookworm infection rarely kills, yet in 2015 it affected around 428 million people. Larvae living in contaminated soil slip through the skin of anyone walking barefoot where sanitation is poor. Heavy infections drain iron and protein, slowing children's mental and physical growth, which makes it a classic neglected tropical disease.
Two species cause most human cases. Ancylostoma duodenale, responsible for ancylostomiasis, is more common in the Middle East, North Africa and India and was once found in southern Europe. Necator americanus, behind necatoriasis, prevails across the Americas and sub-Saharan Africa as well as in China, Indonesia and the rest of Southeast Asia. Eggs leave the body in stools; if they reach the soil, they hatch into larvae that can burrow through skin, and one species can also spread through contaminated food.
People carrying only a few worms may notice nothing beyond an itchy rash where larvae entered. Heavy burdens bring abdominal pain, diarrhoea, weight loss and fatigue, and no symptom is unique to hookworm. The underlying damage is gut inflammation combined with steadily worsening iron-deficiency anaemia and protein loss. Severe infection can cause coughing, wheezing and fever, and advanced cases show wasting, heart failure and fluid swelling in the abdomen. Incubation ranges from weeks to many months, depending largely on how many parasites someone carries. Heavy infections occur in adults too, but are less common than in children.
Hookworms of dogs and cats can also reach people. Larvae of A. braziliense, mostly in the Americas, cannot mature in humans but wander through the outer skin layers, tracing winding, blistered tracks known as creeping eruption, or ground itch when they strike the foot or lower leg. The trailing ends of the tracks dry and crust as the larvae move on.
Diagnosis is by examining a stool sample under a microscope. Treatment usually means one to three days of albendazole or mebendazole, with iron supplements for anaemia. Individuals can cut their risk by wearing shoes where the disease is common, while communities benefit from ending open defecation, not using raw faeces as fertiliser and mass deworming programmes.
Source: Hookworm infection
