Hookworms: The Dracula of Parasitic Worms

It is burrowing up through your feet, floating in your blood, climbing into your lungs and crawling up your throat, where you'll swallow it, to live and grow with teeth buried in the lining of your intestine! Sounds scary doesn't it? This may sound like a tale of fiction, but it is fact.

Hookworms are a type of parasitic nematode worm (helminth) that live in, and suck blood from, the small intestine of host; Ancylostoma duodenale and Necator americanus the two species that commonly infect humans.

How Common is Hookworm Infection?

Although it is difficult to know the actual infection rate, since many cases go treated and unreported, it is thought that these parasitic worms are infecting more than 600 million worldwide, primarily in the tropics. There is very little risk of contracting the disease in North America and other developed regions that have modern sanitation systems.

How Do Hookworms Get Inside the Body?

Eggs of the parasite can be present in fecally-contaminated, moist soil. If the temperature of the ground is warm, the eggs will hatch and mature into larvae. Hookworm larvae penetrate skin of foot to enter the body, sometimes causing the affected skin to become irritated, an condition called "ground itch."

Once inside the body, hookworm larvae migrate through the bloodstream to lungs, and up the windpipe. After emerging into the throat they are swallowed, and introduced into the digestive system, maturing into adult worms in the intestine.

Health Problems Caused by Hookworm

Mature worms sink their teeth into the lining of the intestine where they greedily suck blood. The loss of blood from a hookworm infestation can result in anemia, iron and protein deficiency, and damage to the lining of the intestines.

How Serious Is a Hookworm Infection?

In developing tropical counties, hookworm infection is common. Although hookworm infection is hardly ever fatal, the severe anemia can significantly impact the health of those infected. Most people show no direct symptoms. The impact of infestation is an insidious slow decline in health. In children, hookworm can result in slowed mental and physical development, and the babies born to infected mothers are often underweight.

Hookworm Infestation in Pets

Although hookworm infections in humans are no longer common in the northern hemisphere, these intestinal parasites commonly infect our pet dogs and cats. The hookworm species that plague pets include Ancylostoma braziliense and A. tubaeforme in cats, A. caninum in dogs, and the versatile Uncinaria stenocephala that infects both. Like human hookworm infections, the young are at highest risk, with anemia and diarrhea a threat to vulnerable puppies and kittens.

Hookworm infection in pets can be easily detected through veterinary examination of a stool sample. For treatment, most of the medications that kill roundworms will also kill hookworms. But since wormers only kill adult worms in the intestine, two or more treatments are usually required, so that migrating larvae will be exposed to wormer once mature.

Sources

Hotez PJ, Bethony J, Bottazzi ME, Brooker S, Buss P (2005) "Hookworm: The Great Infection of Mankind". PLoS Med 2(3).

Hookworm, Wikipedia, October 2009.

Hookworm, MedlinePlus, Natonal Library of Medicine and National Institute of Health, August 2009.