Bloodsucker Hookworm
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Synonyms
Ankylostomiasis or ancylostomiasis, miner’s disease, tunnel disease, intertropical hyphemia, uncinariasis, necatoriasis.
Any other types?
- Ancylostoma caninum found predominantly in dogs.
- Ancylostoma tubaeforme found predominantly in cats.
- Ancylostoma braziliense found predominantly in dogs and cats.
- Ancylostoma ceylanicum found in civet cat of Ceylon (Sri Lanka).
- Uncinaria stenocephala found predominantly in dogs and cats.
Though these are predominantly found in pets, they have been implicated in human cutaneous larva migrans. A deviation of the larvae from its usual trajectory to locate under the skin is called cutaneous larva migrans. See below for details.
Epidemiology
Hookworm is an endemic in many tropical and subtropical areas, especially in areas where human feces are not disposed off in a sanitary manner.
Ancylostomiasis is the most prevalent hookworm infection and is second only to ascariasis in infections by parasitic worms. Necator americanus is most common in the Americas, central and south Africa, south Asia, Indonesia, Australia and Pacific Islands. Ancylostoma duodenale is the dominant species in the Mediterranean region and north Asia.
Symptoms
Symptoms usually vary according to the severity of infection. It is common for people with light infections to be asymptomatic. Heavy infections may cause a person to become anemic due to worms feeding on the host’s blood. Other symptoms include fever, abdominal pain, weight loss, constipation, or diarrhea. Chronic infections in children may retard growth and thinking ability, and may cause a potbelly appearance. Occasionally coughing and upper respiratory tract infections may occur from the worms moving through the lungs.
Diagnosis
Cases of hookworm are diagnosed by finding eggs in stool samples using a microscope. However, no eggs may be present in the early stages of infection, and other tests like blood examination or endoscopy may be required to confirm hookworm presence.
Spread
Anybody can get hookworm. However, agricultural workers in endemic areas have a higher risk of being infected. The illness can be more serious in babies, children, pregnant women and people with poor diets. People can become infected with hookworm by walking bare foot on soil that contains infective larvae. Other infection routes include drinking water or eating food contaminated with larvae. Cases of mother to baby transfer of the hookworm Ancylostoma duodenale have also been reported. Hookworm larvae are capable of penetrating the skin in a few seconds. Hence even sunbathing in the beaches or bathing/swimming/wading in pools, reservoirs or contaminated waters in the epidemic areas can quickly contract the larvae.
Life cycle
- Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall with resultant host blood loss.
- Eggs are passed in the stool, and under favorable conditions (right soil type, moisture, warmth, shade), hatch into noninfective larvae (rhabditiform larvae) in one to two days.
- These larvae take seven to ten days to become infective (filariform larvae) and then penetrate human skin, usually the foot. Itchy skin or ground itch occurs where the larvae penetrate the skin.
- On entry, the larvae make their way to the lungs by the blood and immune systems. Then they are coughed up and swallowed into the digestive system. The larvae attach to the small intestine wall by hooks and develop into adults (in six to seven weeks). Adults produce 15,000 to 20,000 eggs a day which exit in the feces.
The worms penetrate the skin and may migrate locally in the skin instead of migrating to the lungs. This condition is called cutaneous larva migrans.
Contagious?
Hookworm is not transmitted from person to person. Infected people can contaminate soil for several years if the right conditions are present. Larvae can survive in dirt for several weeks but do not survive in clay, dry or hard packed soils, or in temperatures that are freezing or higher than 45ºC.
Hibernation period?
Symptoms can take weeks or months to develop depending on the severity of infection, and the amount of iron in an infected person’s diet. Ancylostoma duodenale can stay dormant in the body for eight months.
Prevention
- Disposing of human feces in a sanitary way so that it doesn’t contaminate soil.
- Wearing covered footwear in areas where the disease is endemic.
- Washing hands after going to the toilet and before handling or eating food. (Be aware of the importance of washing hands.)
- Using safe drinking water and safe food preparation practices.
Keeping pets out of areas used for sleeping and eating and avoiding close contacts with them. - Deworm if necessary or as directed by your primary physician.
Medications
Pyrantel pamoate and mebendazole are used with good results and anemia is treated with iron supplements.
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