An Overview of Hookworm

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Hookworm is an intestinal parasite that affects roughly half a billion people globally. Once widespread in the United States, hookworm infections now disproportionately impact poor areas with limited access to sanitation and medical care. The worm's larvae live in contaminated soil, primarily infecting people by burrowing through the bottoms of their bare feet.

Despite a safe and effective treatment available, there are an estimated 576–740 million people currently infected with hookworm worldwide, making it one of the most common neglected tropical diseases impacting humans.

While most people with hookworm infections don't have any symptoms, those with long-term infections can experience lifelong issues as a result—especially children.

hookworm symptoms
Illustration by JR Bee, Verywell

Symptoms

Not everyone infected with hookworm will get symptoms. When they do, it’s often itchiness or a rash at the site where the larvae penetrated the skin (typically on the bottom of the foot). Those heavily infected, however, might experience:

  • Fatigue
  • Diarrhea
  • Weight loss
  • Lack of appetite
  • Abdominal pain
  • Anemia

While most people who are infected don't experience any symptoms at all, the disease can cause serious damage if left untreated—especially for pregnant women and young children. Over time, the worms feed on human tissue, resulting in internal blood loss, malnutrition, and anemia. The long-term impact of which can result in serious consequences for children's physical growth and cognitive development.

Causes

Two types of hookworm infect humans: Ancylostoma duodenale and Necator americanus. The adult and larvae stage of the worm live in the human intestine and can spread through contaminated soil.

There are two primary ways people become infected with hookworms: skin-to-soil and ingestion through contaminated food or water sources.

  • Skin-to-soil: Hookworms live in soil contaminated with fecal matter. When humans walk barefoot in the soil, the worm’s larvae burrow their way through the foot and into the body.
  • Ingestion: When people defecate outside in the soil or use their stool as fertilizer, hookworm eggs can contaminate food or water sources and be re-ingested or ingested by others.

The Life Cycle of the Hookworm

The life cycle of the hookworm looks a lot like those of other intestinal parasites. The eggs of the worm are present in infected individuals’ feces. When they defecate out in the open (rather in than in a toilet or latrine) or the stool is collected to use as fertilizer, the eggs get into the soil.

Over time, the eggs hatch and release larvae, which then continue to mature. When people place their skin in contact with the soil—such as walking barefoot or when children play in the dirt—the larvae penetrate the skin to get inside the human body. The same can happen if people eat food or drink water that has been contaminated with eggs that might have been in the soil. In either case, the larvae make their way to the intestines, where they mature into adults and lay eggs, continuing the cycle.

Diagnosis

Diagnosing hookworm is a relatively straightforward and simple process. Doctors or other health care providers take a stool sample and look for hookworm eggs under a microscope. Because it can be tough to spot the eggs if the infection is light, the CDC recommends that health care providers or lab techs use a concentration procedure to increase the chances the eggs will be seen.

Treatment

Multiple treatment options are available for hookworm, including some that can treat the infection in just one dose. Because these treatment options are safe and effective, they are often given preemptively to individuals without a diagnosis or delivered to whole communities on an annual basis to keep infections under control.

Medications

Hookworm can be treated easily with a number of anthelminthic medications—like albendazole, mebendazole, and pyrantel pamoate—designed to rid the body of the parasites. These drugs are taken by mouth over the course of one or three days, depending on the type of medication and its dose, and can be given to kids as young as one year old.

Iron Supplements

For kids, pregnant women, or others who develop anemia as a result of a hookworm infection, health care providers will often prescribe an iron supplement in addition to an anti-worm medication. These supplements help restore the body's iron stores, which are essential to making red blood cells responsible for carrying oxygen throughout the body.

Preventive Chemotherapy

An important part of treating hookworm is preventing future infections. Unlike viruses or other germs, you can get sick with hookworm over and over again throughout your lifetime. The best way to prevent hookworm is for people to defecate in toilets or outhouses rather than open soil and avoid using human feces as fertilizer. That, however, isn’t always practical for some communities.

Instead of (and in addition to) better sanitation, high-risk groups like kids and pregnant or nursing women are treated preemptively. These individuals have not yet been diagnosed with hookworm, but because the risks of the parasite are greater than the risks of the medication, they are given the treatment to treat any infections they might have.

Mass Drug Administrations

Another tactic used to treat hookworm and other worms transmitted via contaminated soil is to give medications to whole communities proactively. The drugs used to treat these infections are inexpensive, often donated, and safe with few side effects.

As a result, countries can slow or halt the spread of the worm in a given population by providing medication periodically, such as once a year. Health care providers, community health workers, or others visit households one by one to administer treatment for hookworm and other neglected tropical diseases.

A Word From Verywell

While no longer common in the United States, hookworm—along with other soil-transmitted helminths—continues to be a major cause of illness worldwide, especially among those with poor access to sanitation and effective treatment. It's relatively uncommon for travelers to areas with hookworm to become infected, so long as they wear shoes while walking outside and thoroughly wash uncooked food. That said, if you have any symptoms of hookworm, see your doctor right away to be tested for the worm and, if necessary, get treatment.

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