Ground itch
Ground itch also called cutaneous larva migrans or sandworm disease, is a skin infection caused by hookworm larvae that usually infest cats, dogs and other animals. ground itch causes severe itching, blisters, and a red growing, winding rash. The rash can grow up to 1 to 2 centimeters per day. The infection usually appears on areas of the body that have been exposed to the contaminated ground. These include the feet, legs, buttocks, or back.
Hookworm is an intestinal parasite of humans. The larvae and adult worms live in the small intestine can cause intestinal disease. Hookworm eggs are passed in the feces of an infected person. If an infected person defecates outside (near bushes, in a garden, or field) or if the feces from an infected person are used as fertilizer, eggs are deposited on soil. They can then mature and hatch, releasing larvae (immature worms). The larvae mature into a form that can penetrate the skin of humans. Hookworm infection is transmitted primarily by walking barefoot on contaminated soil. One kind of hookworm (Ancylostoma duodenale) can also be transmitted through the ingestion of larvae. An estimated 576-740 million people in the world are infected with hookworm 1. Hookworm was once widespread in the United States, particularly in the southeastern region, but improvements in living conditions have greatly reduced hookworm infections.
People of all ages, sex and race can be affected by creeping larva migrans if they have been exposed to hookworm larvae. It is most commonly found in tropical or subtropical geographic locations. Groups at risk include those with occupations or hobbies that bring them into contact with warm, moist, sandy soil. These may include:
- Barefoot beachcombers and sunbathers
- Children in sandpits
- Farmers
- Gardeners
- Plumbers
- Hunters
- Electricians
- Carpenters
- Pest exterminators.
People are rarely exposed to hookworms in the U.S. This is because most cats and dogs are dewormed. Public areas are also kept clean. Infection is more likely in tropical and semitropical countries. Most larva migrans seen in United States are reported in people who have traveled to the Caribbean, Africa, Asia, and South America. Since the hookworm larvae often enter the body through bare feet, wearing shoes will help stop infection.
How can I prevent ground itch hookworm infection?
Do not walk barefoot in areas where hookworm is common and where there may be fecal contamination of the soil. Avoid other skin-to-soil contact and avoid ingesting such soil. Fecal contamination occurs when people defecate outdoors or use human feces as fertilizer.
The infection of others can be prevented by not defecating outdoors or using human feces as fertilizer, and by effective sewage disposal systems.
Public sanitation and deworming of dogs and cats have decreased hookworm infestation in the United States.
Ground itch causes
Ground itch is caused by hookworms. Hookworm eggs are found in the infested animals feces such as dogs and cats on warm, moist, sandy soil, where the larvae hatch. After the eggs hatch, they mature into worms. The infection can be spread to people from skin contact with the worms in the feces. Hookworms may be found in moist, sandy areas. Walking barefoot on contaminated grounds in warm climates is how most people get ground itch. On contact with human skin, the larvae can penetrate through hair follicles, cracks or even intact skin to infect the human host. Between a few days and a few months after the initial infection, the larvae migrate beneath the skin. In an animal host, the larvae are able to penetrate the deeper layers of the skin (the dermis) and infect the blood and lymphatic system. Once in the intestine, they mature sexually to create more eggs that are then excreted to start the cycle again. However, in a human host, the larvae can rarely penetrate the basement membrane to invade the dermis so the disease usually remains confined to the outer layers of the skin.
Many types of hookworm can cause cutaneous larva migrans. Common causes are:
- Ancylostoma braziliense: hookworm of wild and domestic dogs and cats found in central and southern US, Central and South America, and the Caribbean
- Ancylostoma caninum: dog hookworm found in Australia
- Uncinaria stenocephala: dog hookworm found in Europe
- Bunostomum phlebotomum: cattle hookworm.
Ground itch symptoms
A non-specific rash occurs at the site of penetration of the hookworm larvae. The rash usually shows up 1 to 5 days after you have been exposed to the hookworms. But sometimes it can take more than 1 month to show up. Each person may have slightly different symptoms. Symptoms may include:
- There may be a tingling or prickling sensation within 30 minutes of the larvae penetrating. The larvae can then either lie dormant for weeks or months or immediately begin creeping activity that creates 2–3 mm-wide, snakelike tracks stretching 3–4 cm from the penetration site.
- Winding, snake-like rash. This is because the hookworm burrows along a path that creates a winding rash. These are slightly raised, flesh-colored or pink and cause intense itching. Tracks advance a few millimeters to a few centimeters daily and if many larvae are involved a disorganized series of loops and tortuous tracks may form.
- Itching
- Blisters
Sites most commonly affected by cutaneous larva migrans are the feet, spaces between the toes, hands, knees and buttocks.
The symptoms of ground itch may look like other skin conditions. Always see your healthcare provider for a diagnosis.
Ground itch possible complications
Ground itch may lead to these complications:
- Bacterial skin infections caused by scratching
- Spread of the infection through the bloodstream to the lungs or small intestine (rare)
Ground itch diagnosis
Your healthcare provider can often diagnose this condition by looking at your skin. In rare cases, a skin biopsy is done to rule out other conditions. In very rare cases, a blood test is done to see if you have increased eosinophils (a type of white blood cell).
Ground itch treatment
Ground itch or cutaneous larva migrans is self-limiting. Humans are an accidental and ‘dead-end’ host so the hookworm larvae eventually die. The natural duration of the disease varies considerably depending on the species of larvae involved. In most cases, lesions will resolve without treatment within 4–8 weeks.
However, effective antiparasitic medicines (orally or topical creams) are available to shorten the course of the disease.
Anthelmintics such as tiabendazole, albendazole, mebendazole and ivermectin are used. Topical thiabendazole is considered the treatment of choice for early, localized lesions. Oral treatment is given when the cutaneous larva migrans is widespread or topical treatment has failed. Itching is considerably reduced within 24–48 hours of starting antihelmintic treatment and within 1 week most lesions/tracts resolve.
If these are unavailable, physical treatments such as liquid nitrogen cryotherapy or carbon dioxide laser may be used to destroy the larvae.
Antihistamines and topical corticosteroids may also be used with anthelminthics to provide symptomatic relief of itch.
Secondary bacterial infection may require treatment with appropriate antibiotics.
Ground itch prognosis
Ground itch often goes away by itself over weeks to months. Treatment helps the infection go away more quickly.
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