Hookworm Infections In Human: Causes, Symptoms, Treatments, Prevention, Diagnosis

Hookworms are parasites and live on other living things including humans. In human body, they affect the lungs and small intestine. As per the Centers for Disease Control and Prevention, hookworm infections occur in about 576 to 740 million people worldwide. This infection mainly affects people in developing nations in the tropics and subtropics, because of poor sanitation and rarely may occur in the United States.

Read below to know about the causes, symptoms and treatments.

Hookworm Infections In Human

Hookworm Infections In Human: An Overview

Hookworm larvae or the immature worms are present in soil that has been contaminated with human feces. The larvae can infect humans if their bare skin comes in contact with the soil; for example while walking on the soil barefoot. Most hookworm infections occur in Africa, China, America and Southeast Asia.

Children are at a greater risk of getting hookworm infection as they often play outside barefoot. Hookworm infection during pregnancy in women can cause retarded growth of the fetus and result in premature baby birth or children with low birth weight. Hookworms may also cause intellectual, cognitive and physical growth issues in small children.

Growth And Development of The Hookworm:

The larvae and the adult hookworms live in the small intestine of an infected animal or an infected person. If an infected person defecates outside or if their stools are used as fertilizer, the eggs of the hookworm present in the stools will contaminate the soil. These hookworm eggs hatch in the soil after 1 to 2 days and release larvae, which are too small to be visible. These larvae develop into their mature form in 5 to 10 days, which can penetrate the human skin. This happens when you walk barefoot on the contaminated soil. Even eating raw and unwashed vegetables that are contaminated with eggs of the hookworm or by drinking contaminated water, you allow room for the worms to enter inside your body.

Let us see the pathological phases of hookworm infections.

Cutaneous or Invasis Phase:

There may be irritation and itching on the skin when the larvae penetrate the skin initially. If these larvae fail to locate a blood capillary, they can wander through the skin, resulting in a condition known as cutaneous larval migrans, leaving a track visualized under the skin, by the presence of the host inflammatory reaction.

Pulmonary Phase:

This is the phase when the larvae are bursting out of the capillaries in the lungs into the alveolar spaces. This results in local hemorrhaging at the site. This is rarely symptomatic, except when there is a heavy infection and when it can cause pneumonitis and can also result in cough and sore throat.

Intestinal Phase:

The adult hookworms are usually restricted to the anterior third of the small intestine. However, where infections are very heavy, they can occupy the whole length of the small intestine. These hookworms clamp into the mucosa, abrading the surface and sucking the blood. Proteolytic enzymes from the dorsal pharyngeal gland are released in the buccal cavity which help in digestion.

Causes of Hookworm Infections In Human

Hookworm is generally caused by unhygienic environmental conditions and habits. Pregnant women, small children, farmers and sanitation workers are at high risk for getting the hookworm infection. Hookworm eggs are passed on to the soil by the infected human feces or animals. These eggs contaminate the soil from where they can be ingested or get into the host through their skin or direct ingestion.

Through Skin:

The hookworm eggs penetrate the skin through several ways. Some of them include, while walking barefoot in the contaminated soil, touching the contaminated soil in the fields (especially the farmers), coming in contact with sewage water (by workers or during rains), bathing in the water source into which sewage is disposed, lying on beach sand that is contaminated by the infected feces.

Direct Ingestion:

Direct ingestion of the eggs can also occur when animals like pet dogs eat the weeds or leftovers from the contaminated soil, eating raw foods like fruits and vegetables without properly washing, ingestion of food with contaminated hands, especially after playing in the contaminated soil, drinking contaminated water.

Symptoms of Hookworm Infections In Human

Usually the symptoms of hookworm infection are general and most patients may have no symptoms or may have symptoms of intestinal inflammation, iron deficiency anemia, and protein deficiency. The two different stages of the disease; i.e., early stage or late stage show different symptoms. Below we will know about some of the symptoms of hookworm infections in human.

Symptoms of The Lungs:

Usually these symptoms occur after one week of exposure. Wheezing, pneumonitis, Cough, and in rare cases, severe infections may result in Loffler syndrome that is characterized by Paroxysmal attacks of a cough, dyspnea, pleurisy, little or no fever, eosinophilic pulmonary infiltrates that last for some weeks after the initial infection.

Symptoms Of Skin Disease:

These symptoms generally occur after one or two weeks of cutaneous infection. Some of the symptoms include itching of the skin, skin rashes, pale skin, creeping eruption or cutaneous larvae migrans, etc.

Symptoms of Intestine Due To Eosinophilic enteritis:

These symptoms are common with initial exposures and peak between 4 to 6 weeks after exposure to the hookworm infection. Indigestion, abdominal pain, constipation that changes to diarrhea, nausea and vomiting, emaciation or extreme weight loss and loss of adipose tissue or fat under the skin, abdominal distension with ascites, etc. are some of the intestinal symptoms of the infection.

Symptoms of The Eye:

The hookworms migrate to the eye and result in Diffuse Unilateral Subacute Neuroentinitis or a parasitic disease that affects the retina, vitritis or inflammation of the vitreous body, visual loss, consecutive crops of multiple, evanescent retinal lesions, also the condition may progress to retinal arterial narrowing, optic atrophy and electroretinographic changes.

Other Symptoms of Hookworm Infection:

Some of the other symptoms of the infection include cardiac failure in severe cases, hypoproteinemia or low level of protein in the blood that leads to peripheral edema, slow physical and cognitive growth, symptoms of infections like fever, chest pain, wheezing, etc. when the infection is long term, it can cause symptoms of iron deficiency and anemia presenting with pallor, chlorosis, hypothermia, tachycardia and spooning nails. Though these are some of the symptoms of hookworm infection, some people who are infected with hookworm, do not have any symptoms.

Diagnosis of Hookworm Infections In Human

Hookworm infections are diagnosed by inspecting a stool sample of the infected person under a microscope in a laboratory and looking for the hookworm eggs. In case there is an infection, the number of eggs will be counted so as to see how severe it is.

Apart from this, anemia should also be checked through complete blood count and there must be a requirement of differential count to look for eosinophilia. These tests would be done to evaluate the level of hookworm infection. A high blood count will indicate the presence of infection.

Even Specific diagnosis with PCR can be employed for confirming hookworm infection.

Endoscopy is rarely done that would reveal the presence of adult hookworms in the intestine. This is done to identify the species of the work that has infected the person. In order to check lung involvement in hookworm infection, Chest X-rays is to be done.

Treatment of Hookworm Infections In Human

The treatment for this infection aims to get rid of the parasite, improve nutrition and treat complications from anemia. Let us look at some of the treatments for hookworm infection.


You will be prescribed with specific medications by your doctor that would help destroy the hookworm. Albendazole (Albenza) and mebendazole (Emverm) are some of the medications used to destroy the hookworm. These medications are generally to be taken 1 to 3 days so as to treat the infection. These medicines are effective in treating the infection while the worm is on the skin or in the intestine. Other antihelminthic drugs like levamisole, pyrantel pamoate etc, are also used for treating the hookworm infection. It must be noted that medicines prescribed for pregnant or lactating women would differ according to the sensitivity of the drug and severity of the hookworm infection.


Your doctor might also prescribe you to take an iron supplement, in case you have anemia. Folic acid and vitamin B12 supplements are also given for treating anemia. The physician will also help you recover from any nutritional deficiencies if you have. You will be asked to add additional protein to your diet in case you have ascites.

Other Treatments For Hookworm Infection:

The abendazole is topically applied for destroying the larvae in the skin. Local cryotherapy is used for destroying the hookworms while the parasite is still in the skin, that causes itching and skin rashes. It must be mentioned that after 2 weeks of the treatment, stool examination should be repeated.

Appropriate Diet and Nutrition For The Patient With Hookworm Infection:

Hookworm grows in the intestine and absorbs nutrients so as to grow. This in turn affects the human host which harbors the worm and this develops nutrient deficiencies in the affected individual. The affected person may rapidly lose weight and may have deterioration in the health. So, it is essential that the patient suffering from a hookworm infection must have a proper diet and nutrients and the diet must include iron, protein, fiber, vitamin C, vitamin B12, folic acid, etc.

Preventing Hookworm Infections In Human

You can prevent or at least lower your risk of getting infected with hookworm by following ways:

  • Wear shoes while you walk outside, especially in areas that might have feces in the soil.
  • Drink safe water.
  • Clean your food properly and then cook it well.
  • Practice good hygiene, especially have a habit of washing hands when you come from outside, before and after meal, etc.

Apart from these, in areas where these infections are common, sanitation should be improved, which includes using better sewage disposal systems and reducing human defecation outside. This can reduce the number of hookworm infections.

FAQs Related To Hookworm Infections In Humans:

Can Your Pet Make You Infected With Hookworm?

Hookworm infections also occur in pets, especially in kittens and puppies. If you have a pet that has a hookworm infection, you can indirectly get the infection from it. However, you won’t get it from petting your cats or dogs. The eggs are passed in the pet’s stool and hatch into larvae. These eggs and larvae are found in the diet where pets leaves stools. You can get the infection if you touch contaminated dirt with your bare feet or bare hands. You can also get it by accidentally eating the contaminated soil. In order to reduce the risk of hookworm infections from your pets, make sure your pets are vaccinated and dewormed. Apart from this, avoid walking barefoot in areas where your pets leave stools.

How Serious is a hookworm infection?

Hookworm infection that last for a long time can make the affected person anemic. Anemia is characterized by a low red blood cell count, and this can lead to heart failure in a severe cases. Anemia is caused because hookworm feeds on your blood. You are more at a risk of having severe anemia in case you do not eat well, if you have malaria, in case you are pregnant.

Nutritional deficiencies and ascites are some other complications of hookworm infection. Ascites is caused by a serious loss of protein and it results in fluid buildup in your abdomen.

Children having frequent hookworm infections can experience slow physical growth and mental development from losing protein and iron.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:October 3, 2018

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