You get hookworm when microscopic larvae in contaminated soil burrow through your bare skin, most commonly through the soles of your feet. The infection affects an estimated 406 to 480 million people worldwide, concentrated in tropical and subtropical regions where warm, moist soil and poor sanitation allow the parasite to thrive.
How Hookworm Enters Your Body
Hookworm infection starts on the ground. An infected person passes hookworm eggs in their stool. In warm, moist soil, those eggs hatch into larvae that can survive for weeks waiting for a human host. When you walk barefoot on contaminated soil, or sit on it with exposed skin, the larvae latch on and actively burrow in. You won’t necessarily feel it right away, though many people develop an itchy, red rash at the entry site within a few days. This reaction is sometimes called “ground itch.”
The larvae need specific conditions to survive. They do best in shaded soil at temperatures around 86°F (30°C) and can’t tolerate direct sunlight, freezing temperatures, or anything above 113°F (45°C). Sandy, loamy soil in tropical climates is ideal. Dry, sun-baked ground is not. This is why hookworm is overwhelmingly a problem in warm regions with poor sanitation, where human waste contaminates soil that people regularly contact with bare skin.
What Happens After the Larvae Get In
Once hookworm larvae penetrate your skin, they don’t stay there. They enter your bloodstream and travel to your heart, then to your lungs. In the lungs, they break into the tiny air sacs, crawl up your airways to your throat, and get swallowed. From there, they travel down to your small intestine, where they attach to the intestinal wall, mature into adult worms, and begin feeding on blood.
This entire journey, from skin to intestine, takes several weeks. During the lung phase, some people develop a cough or mild wheezing. Once the worms settle in the intestine, they can live there for years. A light infection might cause no obvious symptoms at all. Heavier infections cause persistent blood loss from the intestinal wall, which over time leads to iron-deficiency anemia, fatigue, and in children, developmental and growth problems. Abdominal pain, diarrhea, and loss of appetite are also common with significant worm burdens.
Animal Hookworm and Skin Infections
Dogs and cats carry their own species of hookworm, and those larvae can also burrow into human skin. The difference is that animal hookworms can’t complete their life cycle in a human body. They get stuck in the skin and can’t migrate to the intestine the way human hookworms do. Instead, they tunnel through the upper layers of skin, creating red, raised, intensely itchy tracks that creep forward over days or weeks. This condition is called cutaneous larva migrans.
It’s most common in people who’ve walked barefoot or sat directly on sand or soil in tropical areas, particularly beaches where dogs and cats roam. The tracks are distinctive enough that a doctor can usually diagnose it on sight. The infection is self-limiting since the larvae eventually die, but treatment speeds up recovery and relieves the itching.
Who Is Most at Risk
Geography and daily habits determine your risk more than anything else. People living in tropical and subtropical areas with inadequate sanitation carry the highest burden. Farming, mining, and any occupation that involves regular contact with potentially contaminated soil increases exposure. Children who play barefoot outdoors in endemic areas are especially vulnerable, both to initial infection and to the cumulative effects of chronic blood loss during critical years of growth.
Travelers to tropical regions also pick up hookworm, particularly the animal variety from contaminated beaches. You don’t need a wound or a cut for the larvae to get in. Intact skin on your feet, legs, buttocks, or hands is enough.
How Hookworm Is Diagnosed
Diagnosis relies on finding hookworm eggs in a stool sample under a microscope. Because eggs don’t appear until the worms have matured in the intestine, testing too early after exposure can produce a false negative. If your doctor suspects hookworm based on your symptoms and travel or exposure history, they may also check your blood count for signs of anemia or an elevated level of a specific white blood cell type that rises during parasitic infections. For cutaneous larva migrans from animal hookworms, the visible skin tracks are usually enough for diagnosis without lab tests.
How to Avoid Infection
The single most effective prevention measure is not walking barefoot in areas where hookworm is common and soil may be contaminated with human or animal feces. Wear shoes, and use a towel, mat, or other barrier when sitting on soil or sand. This applies especially to tropical beaches, rural farming areas, and anywhere sanitation infrastructure is limited.
On a broader scale, hookworm transmission drops dramatically when communities have access to proper sanitation. Preventing human waste from reaching soil breaks the parasite’s life cycle entirely. In areas with endemic animal hookworm, regular deworming of dogs and cats also reduces the amount of larvae in the environment.