In man there are two species of hookworm capable of causing intestinal infections, Ancylostoma duodenale native to parts of Southern Europe, North Africa ,Northern Asia and parts of Western South America, and Necator americanus in Central and Southern Africa, Southern Asia, Australia and the Pacific Islands. It is estimated that there are 1200 million cases of hookworm infection in man per year, of which about 100 million cause symptoms.
Hookworms eggs are passed in the faeces, and once exposed to air they mature rapidly, given favourable conditions.
These larvae live in the soil. Infection takes place by penetration of the skin, for example when walking with bare feet over contaminated soil, this is followed by entry into the blood stream, from where the larvae are carried to the lungs. Once in the lungs, they burrow into the air spaces and migrate upwards and are then swallowed. Once swallowed they pass into the intestine and bury themselves in the intestinal wall. About thirteen days after the initial infection they turn into immature adult worms, which mature over three to four weeks, then mate and commence egg laying to complete the lifecycle.
The hookworm feeds on blood in the intestinal wall and depending on the level of infestation produces varying degrees of anaemia. In some cases, the infected person may have no symptoms however in extreme cases the chronic loss of blood and resulting anaemia may result in death. Other symptoms include abdominal pain, diarrhoea, loss of appetite, and weight loss. Itching and a rash at the site of where skin touched soil or sand is usually the first sign of infection. These symptoms occur when the larvae penetrate the skin.
Hookworm infestation is diagnosed by finding the eggs in a sample of faeces. In the UK the infection is usually treated with a short course of Mebendazole which should be obtained from you doctor.
You can help to avoid infection by not walking barefoot or handling soil or sand in areas where hookworm is common.
This article published on
04 December 2005
Next review date 12/12/2013
Stomach and digestion