A hookworm is a small parasitic worm that lives in the human intestine, where it attaches to the gut wall and feeds on blood. Hookworms infect an estimated 406 to 480 million people worldwide, mostly in tropical and subtropical regions with poor sanitation. The infection is rarely fatal, but chronic cases cause iron-deficiency anemia that can be especially damaging to children and pregnant women.
How Hookworms Get Into Your Body
Hookworm larvae live in warm, moist soil contaminated with human feces. The most common way they enter your body is straight through the skin of your bare feet. When you walk on contaminated ground, the microscopic larvae burrow in, often causing an itchy rash at the entry point sometimes called “ground itch.” One species can also be swallowed through contaminated food or water.
From the skin, the larvae travel through the bloodstream to the lungs. They climb up the airways, get swallowed, and finally reach the small intestine. There, they molt twice and mature into adult worms roughly 1 centimeter long. The adults latch onto the intestinal lining using sharp teeth or cutting plates built into their mouths, and they begin feeding on blood. A female hookworm can produce thousands of eggs per day, which pass out in feces and hatch in soil to restart the cycle. The entire journey from skin penetration to egg-laying adult takes several weeks.
Two Main Species That Infect Humans
The two classic human hookworm species are Necator americanus and Ancylostoma duodenale. Necator is the more common worldwide and predominates in the Americas, sub-Saharan Africa, and Southeast Asia. Ancylostoma duodenale is more prevalent in the Middle East, North Africa, and parts of southern Europe. A third species, Ancylostoma ceylanicum, primarily infects animals but is increasingly recognized as an emerging human parasite in certain regions of Asia.
The two main species differ slightly in how they attach: Ancylostoma has sharp teeth in its mouth, while Necator uses flat cutting plates. Ancylostoma duodenale is also considered more aggressive. It tends to cause greater blood loss per worm and can infect through oral ingestion, not just skin penetration.
Symptoms at Each Stage
Many light infections produce no noticeable symptoms at all. When symptoms do appear, they tend to follow the worm’s path through the body.
At the entry site, usually the feet, you may notice an itchy, red rash within a day or two of exposure. As larvae pass through the lungs, some people develop a dry cough, wheezing, or a mild sore throat. These respiratory symptoms are typically brief and easy to dismiss as a cold.
The real damage happens once the worms settle in the intestine. Abdominal pain, diarrhea, nausea, and loss of appetite are common. Because hookworms feed on blood, the hallmark of a significant infection is iron-deficiency anemia. You might feel unusually tired, short of breath during light activity, or notice pale skin. In heavily infected individuals, blood loss can reach up to 9 milliliters per day. Most of that blood isn’t consumed by the worms themselves; it leaks from the wounds they leave in the intestinal wall even after they shift to a new attachment site.
Long-Term Effects of Chronic Infection
A short-lived, light hookworm infection in an otherwise healthy adult is unlikely to cause lasting harm. The real concern is chronic, untreated infection, particularly in children and pregnant women who already have limited iron stores.
In children, ongoing blood loss leads to protein malnutrition and severe anemia, which can impair physical growth and cognitive development. Kids with heavy hookworm burdens often perform worse in school and have lower energy levels than their peers. In pregnant women, hookworm-related anemia raises the risk of low birth weight and complications during delivery. In adults, chronic fatigue and reduced work capacity are the most common consequences.
How Hookworm Is Diagnosed
Diagnosis is straightforward: a stool sample examined under a microscope. Lab technicians look for the distinctive oval eggs, which are visible in standard preparations. The number of eggs found in a given amount of stool helps estimate how heavy the infection is, which guides treatment decisions. Because egg output can vary from day to day, your doctor may request more than one sample.
Treatment
Hookworm is treated with antiparasitic medications taken by mouth. A single dose is often enough for mild infections, while moderate to heavy infections may require a short course over three days. The same dosing applies to adults and children. These drugs paralyze or kill the adult worms, which then pass out of the body naturally.
If anemia is significant, iron supplements or dietary changes may be recommended alongside the antiparasitic treatment to help rebuild your red blood cell count. Most people recover fully once the worms are cleared, though it can take weeks for iron levels to normalize.
Who Is Most at Risk
Hookworm thrives in warm, humid climates where sanitation infrastructure is limited. Sub-Saharan Africa, South and Southeast Asia, and parts of Central and South America carry the highest burden. People who walk barefoot on soil that may be contaminated with human waste face the greatest risk. Agricultural workers, children who play outside without shoes, and communities without access to toilets are disproportionately affected.
In higher-income countries, hookworm is rare but not nonexistent. Pockets of transmission have been documented in rural areas of the southeastern United States where poverty and inadequate sewage systems overlap.
Prevention
The single most effective personal measure is wearing shoes. A systematic review published in PLOS Neglected Tropical Diseases found that regular footwear use was associated with roughly half the odds of hookworm infection compared to going barefoot. That said, shoes alone aren’t a complete solution. Experts emphasize that lasting reductions in hookworm depend on a combination of strategies: improved sanitation (so feces don’t contaminate soil in the first place), access to clean water, periodic community-wide deworming programs, and health education.
If you’re traveling to an area where hookworm is common, wearing closed-toe shoes outdoors, avoiding sitting or lying directly on bare soil, and using a mat or towel as a barrier are practical steps that significantly lower your risk.