Global Health Travel Health Tropical Medicine

Hookworms and why to wear your shoes!

Image: berbercarpetTropical climates are hot and sweaty.  A hot and sweaty environment, for me, usually means sandals or no shoes at all.  Aside from cuts and scrapes to delicate feet used to being protected by shoes, there are infections that can be acquired from going barefooted on your travels. 

Hookworm is a slang term used to describe a pair of intestinal parasites called Ancylostoma duodenale and Necator Americanus.  These parasites belong to the phylum Nematoda and are commonly found in the victim (or host) intestinal tract.  Evidence of the parasites can be found in literature as far back as ancient Egypt.  It was the ancient Egyptians who made a connection between anemia, a very common symptom, and the parasite. 

Hookworm under microscopy

Helminthitic infection of the intestines that frequently causes iron deficient anemia secondary to blood loss. Two species exist: Ancylostoma Duodenale and Necator Americanus. Acquired by direct contact with infected soil, usually walking barefoot. Characteristic “ground itch” is common at site of penetration. The life cycle is simple:  penetration of skin to blood stream, migration through the lungs, coughed up in phlegm and swallowed to stomach where they make their final home.  Eggs from the worms are passed into the soil through improper disposal of feces.  In the soil, the eggs mature into a form that can directly penetrate the human skin.

Tropical countries in areas with moist soil and poor hygiene in respect to fecal waste management. Both species are found in Africa, Asia, South Pacific and South America.  Americanus is most common in South/Central America. 

Transmission/ Incubation:
Transmitted via contact with infected soil containing 3rd stage larvae. Larvae directly penetrate skin. Most commonly acquired through human waste but some other species can transmit via cat/animal feces. Incubation can take weeks to months, as the parasites develop. Larger burdens of infection present quicker.

Hookworm egg under 400x microscope, in fecal smear
Hookworm egg under 400x microscope, in fecal smear

Use of shoes when walking, sanitary disposal of feces

Isolation of eggs in a fecal smear

Albendazole or Mebendazole. Studies done to show benefits of treatment based on number of eggs per gram of feces.

 Overall, this parasitic infection is a major health concern in developing nations causing anemia, pregnancy complications and malnourishment, espcially in growing children.  Fortunately, the infection typically responds well to medicine and elimination is possible provided there is adequate acces to healthcare.

For other trop med geeks (like me), you can visit the CDC DpDX website for some great pics on how to tell the difference between the two species.  Necator has cutting plates on the mouth while Ancylostoma has teeth, when viewed unuder a microscope.


  1. Hey…those are my exact Keene sandals at the top! So ugly but the most functional travel shoes I’ve ever owned. 🙂

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