Zoonotic hookworms are hookworms that live in animals but can be transmitted to humans. Dogs and cats can become infected with several hookworm species, including Ancylostoma brazilense, A. caninum, A. ceylanicum, and Uncinaria stenocephala. The eggs of these parasites are shed in the feces of infected animals and can end up in the environment, contaminating the ground where the animal defecated. People become infected when the zoonotic hookworm larvae penetrate unprotected skin, especially when walking barefoot or sitting on contaminated soil or sand. This can result in a disease called cutaneous larva migrans (CLM), when the larvae migrate through the skin and cause inflammation.

Zoonotic hookworms are hookworms that live in animals but can be transmitted to humans. Dogs and cats can become infected with several hookworm species, including Ancylostoma brazilense, A. caninum, A. ceylanicum, and Uncinaria stenocephala. The eggs of these parasites are shed in the feces of infected animals and can end up in the environment, contaminating the ground where the animal defecated. People become infected when the zoonotic hookworm larvae penetrate unprotected skin, especially when walking barefoot or sitting on contaminated soil or sand. This can result in a disease called cutaneous larva migrans (CLM), when the larvae migrate through the skin and cause inflammation.

Image: L: Filariform (L3) hookworm larvae. These L3 are found in the environment and infect the human host by penetration of the skin. Center: Two dogs playing. Worming your pet regularly will prevent zoonotic hookworm infection. R: Extreme magnification of the anterior end of an adult of Ancylostoma caninum, a dog parasite that has been found to produce a rare human infection known as eosinophilic enteritis. Credit: DPDx

What is animal (zoonotic) hookworm infection in people?

There are many different species of hookworms, some are human parasites and some are animal parasites. People can be infected by larvae of animal hookworms, usually dog and cat hookworms. The most common result of animal hookworm infection is a skin condition called cutaneous larva migrans.

What are the clinical manifestations of animal (zoonotic) hookworm in people?

Cutaneous larval migrans (CLM) in a person's foot. Courtesy Vince Conte, MD, Miami-Dade County Health Department

Most animal hookworm infections result in a skin condition called cutaneous larva migrans. People are infected when animal hookworm larvae penetrate the skin, causing a local reaction that is red and itchy. Raised, red tracks appear in the skin where the larvae have been and these tracks may move in the skin day to day, following the larvae’s movements. The symptoms of itching and pain can last several weeks before the larvae die and the reaction to the larvae resolves. In rare cases, certain types of animal hookworm may infect the intestine and cause abdominal pain, discomfort, and diarrhea.

What should I do if I think I have hookworm infection?

See your health care provider to discuss the possibility of infection and, if necessary, to be examined. There is no blood test for animal hookworm infection.

What is the treatment for animal hookworm infection?

The animal hookworm larvae that cause cutaneous larva migrans (CLM) usually do not survive more than 5 – 6 weeks in the human host. In most patients with CLM, the signs and symptoms resolve without medical treatment. However, treatment may help control symptoms and help prevent secondary bacterial infections. Antiparasitic treatments may be prescribed by your health care provider.

Can I get hookworm from my pet?

Yes, but not directly. Puppies and kittens are especially likely to have hookworm infections. Animals that are infected pass hookworm eggs in their stools. The eggs can hatch into larvae, and both eggs and larvae may be found in dirt where animals have been. People may become infected while walking barefoot or when exposed skin comes in contact with contaminated soil or sand. The larvae in the contaminated soil or sand will burrow into the skin and cause the skin to become irritated in that area. For example, this can happen if a child is walking barefoot or playing in an area where dogs or cats have been (especially puppies or kittens).

How can I prevent animal hookworm infection?

Wearing shoes and taking other protective measures to avoid skin contact with sand or soil will prevent infection with zoonotic hookworms. Travelers to tropical and subtropical climates, especially where beach exposures are likely, should be advised to wear shoes and use protective mats or other coverings to prevent direct skin contact with sand or soil.

Routine veterinary care of dogs and cats, including regular deworming, will reduce environmental contamination with zoonotic hookworm eggs and larvae. Prompt disposal of animal feces prevents eggs from hatching and contaminating soil — which makes it important for control of this parasitic infection.

This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health care provider.

Regular veterinary care will protect your pet and your family.

Dog and cat hookworms are found throughout the world, especially in warmer climates. In the United States, zoonotic hookworms are found everywhere but more commonly along the East Coast than the West Coast. Worldwide, zoonotic hookworms are found in tropical and subtropical regions where the parasite is better able to survive because of environmental conditions. However, there is one type of dog and cat hookworm that is more commonly found in cooler climates.

The global burden of zoonotic hookworm in dogs and cats is not known; also, the amount of disease in people caused by these parasites is also unknown. Cutaneous larva migrans (CLM) is most often reported by returning travelers to tropical regions who have had soil and/or sand exposures in places where dogs and cats are likely to have hookworms. However, CLM is likely causing significant problems for the people who live in less developed parts of the world, even though the disease is not reported regularly. In less developed areas of the world, dogs and cats are often free-ranging and have high rates of infection with hookworm which leads to widespread contamination of sand and soil. In a survey of a rural population in Brazil, the prevalence of CLM during the rainy season was 14.9% among children less than 5 years old and 0.7% among adults aged 20 years and older.

Causal Agents

Some zoonotic hookworm species are capable of infecting humans, but they typically do not develop in the intestine (see intestinal hookworms) and instead infect extraintestinal sites like the skin. Cutaneous larva migrans (CLM) has been associated with Ancylostoma caninum, A. braziliense, and Uncinaria stenocephala, which are all hookworms of dogs and cats. Bunostomum phlebotomum, a cattle hookworm, is also capable of causing short-lived CLM in humans.

Life Cycle

Cutaneous larva migrans (also known as creeping eruption) is a zoonotic infection with hookworm species that do not use humans as a definitive host, the most common being Ancylostoma braziliense and A. caninum. The cycle in the definitive host is very similar to the cycle for the human species, which involves tracheal migration to the small intestine. Some larvae become arrested in the tissues and serve as the source of infection for pups via transmammary (and possibly transplacental) routes. Mature hookworms reproduce in the small intestine, and eggs are passed in the animal definitive host’s stool 1 , and under favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. The released rhabditiform larvae grow in the feces and/or the soil 2 , and after 5 to 10 days (and 2 molts) they become filariform (third-stage) larvae that are infective 3 . These infective larvae can survive 3 to 4 weeks in favorable environmental conditions. On contact with the animal host 4 , the larvae penetrate the skin and are carried through the blood vessels to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed. The larvae reah the small intestine, where they reside and mature into adults. Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall. Some larvae become arrested in the tissues, and serve as source of infection for pups via transmammary (and possibly transplacental) routes 5 . Humans become infected when filariform larvae penetrate the skin 6 . With most species, the larvae cannot mature further in the human host and migrate aimlessly within the epidermis, sometimes as much as several centimeters a day. Some larvae may become arrested in deeper tissue after skin migration.

Zoonotic hookworm infections usually result in a skin condition called cutaneous larva migrans, or CLM. When people walk or sit on beach sand or soil where infected dogs or cats have defecated, the dog or cat hookworm larva can penetrate the skin of the foot or body and migrate in the top layers of the skin. This migration causes severe itchiness and raised red lines can form as part of the reaction to the larva in the skin. The larva will die in the skin after several weeks without developing any further, and the itchiness and red lines will go away. Scratching at the lines can cause a bacterial infection. Your doctor may decide to treat you to control the symptoms and prevent a bacterial infection. In rare cases, certain types of animal hookworm may infect the intestine and cause abdominal pain, discomfort, and diarrhea.

Cutaneous larva migrans (CLM) in a patient’s foot over the course of one week. Photos courtesy of Florida Department of Health, Duval County Epidemiology

Cutaneous larva migrans (CLM) is a clinical diagnosis based on the presence of the characteristic signs and symptoms, and exposure history to zoonotic hookworm. For example, the diagnosis can be made based on finding red, raised tracks in the skin that are very itchy. This is usually found on the feet or lower part of the legs on persons who have recently traveled to tropical areas and spent time at the beach. There is no blood test for zoonotic hookworm infection. Persons who think they have CLM should consult their health care provider for accurate diagnosis.

The zoonotic hookworm larvae that cause cutaneous larva migrans (CLM) usually do not survive more than 5 – 6 weeks in the human host. In most patients with CLM, the signs and symptoms resolve without medical treatment. However, treatment may help control symptoms and help prevent secondary bacterial infections. Antiparasitic treatments may be prescribed by your health care provider.

Avoiding skin contact with sand or soil, and regular veterinary care for your pets -- including deworming -- will help ensure healthy pets and healthy people.

Wearing shoes and taking other protective measures to avoid skin contact with sand or soil will prevent infection with zoonotic hookworms. Travelers to tropical and subtropical climates, especially where beach exposures are likely, should be advised to wear shoes and use protective mats or other coverings to prevent direct skin contact with sand or soil. Routine veterinary care of dogs and cats, including regular deworming, will reduce environmental contamination with zoonotic hookworm eggs and larvae. Prompt disposal of animal feces prevents eggs from hatching and contaminating soil — which makes it important for control of this parasitic infection.