Ancylostomiasis

Ancylostomiasis

Article
Digestive Health
Kids' Zone
+4
Contributed byMaulik P. Purohit MD MPHMar 08, 2020

What are the other Names for this Condition? (Also known as/Synonyms)

  • Ancylostoma Duodenale Hookworm Infection
  • Ground Itch
  • Necator Americanus Infection

What is Ancylostomiasis? (Definition/Background Information)

  • Ancylostomiasis is an infection of the intestines caused by hookworms. There are many species of hookworms, but the main species responsible for human Ancylostomiasis include Ancylostoma duodenale and Necator americanus
  • Hookworms are parasites that can infect the small intestine of a host, including humans. They are found worldwide, but are most common in tropical and subtropical climates
  • Regions where hookworms are especially common include Africa, Latin America, the Mediterranean region, South East Asia, and the Western Pacific. It is estimated that the infection affects millions worldwide, without any racial or ethnic bias 
  • Ancylostomiasis can be difficult to diagnose, as specific symptoms are often not seen. The possible symptoms include itching, the presence of a localized skin rash, abdominal pain, and diarrhea. If the infection is severe, blood loss can occur because of the blood sucking action of the hookworm
  • A microscopic examination of stool samples is the chief mode of diagnosis. Following a diagnosis, Ancylostomiasis is treated with anti-parasitic drugs that kill the infecting worms
  • The best prevention for Ancylostomiasis is to avoid walking barefoot in areas that may be contaminated with human feces, especially in places where hookworms are common
  • The prognosis for individuals with Ancylostomiasis is generally positive after adequate treatment. Most individuals are completely cured of the infection 

Who gets Ancylostomiasis? (Age and Sex Distribution)

  • Ancylostomiasis is very common throughout the world, and it is estimated that over 700 million people worldwide have the disease. No racial or ethnic predilection is reported in the occurrence of this infection
  • Individuals of all ages can be affected; however, children are more likely to be infected by hookworm, owing to playing or participating in outdoor activities to a larger extent
  • Although both males and females are susceptible to infection, men are more likely to be infected owing to more outdoor activities (in many communities)
  • Ancylostomiasis is reported worldwide; but, the regions most affected include Africa, Latin America, the Mediterranean, South East Asia, and Western Pacific regions

Individuals in the United States and many other developed nations typically do not develop Ancylostomiasis, unless the infection sets in from travel to the endemic regions, or if it spreads from contact with infected individuals.

What are the Risk Factors for Ancylostomiasis? (Predisposing Factors)

Some risk factors of Ancylostomiasis include: 

  • Living in a warm and moist environment where sanitation and hygiene facilities are poor or lacking, which is especially observed in some developing countries  
  • Walking around barefoot outside/outdoors: This can result in direct skin contact with soil that may be contaminated from human feces of infected individuals. This may be a result of defecating outdoors or using human feces as fertilizer
  • Childhood: Children playing outdoors in contaminated soils have a higher risk for infection
  • Having pets at home: People with dogs or cats infected with hookworms can develop a skin condition called cutaneous larva migrans (larvae infection under the skin), if their bare skin contacts soil contaminated having pet excrement (feces). The hookworms that cause this condition are Ancylostoma braziliense, Ancylostoma caninum, and Uncinaria stenocephala. Dogs and cats carrying these parasites are often only found in developing countries.  This infection does not result in Ancylostomiasis 

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Ancylostomiasis? (Etiology)

Ancylostomiasis is caused by infection with hookworms belonging predominantly to Ancylostoma duodenale and Necator americanus species.

  • Ancylostomiasis and other hookworm infections are caused through skin contact with soil containing infected human feces. This commonly occurs while walking barefoot in contaminated areas. A. douodenale can also infect humans orally
    • Contaminated human feces contain hookworm eggs that hatch in favorable soil conditions. The hatched larvae become infectious after 2 months. Hookworms are typically around 1 centimeter long
    • After entering the host through contact with bare skin, the larvae move through the bloodstream to the lungs. Once there, they can pass into the airway and travel up the windpipe to the throat, from where they are then swallowed
    • When hookworms enter the stomach, they migrate into the small intestine. If ingested orally, A. duodenale can enter the stomach directly
    • The intestines provide nutrients that allow the larvae to grow into adult hookworms. They take up nutrients by sucking the blood of the host. Once in the intestines, the adult hookworms may stay in place for years
  • A. duodenale typically takes 28 to 50 days to cause infection, while N. americanus takes between 40 to 50 days 
  • Ancylostoma ceylanicum can also infect humans, though it is more commonly observed to infect animals such as dogs

Ancylostoma braziliense, Ancylostoma caninum, and Uncinaria stenocephala are other species of hookworms that can penetrate human skin, but are not known to cause any further infection. The worms embed themselves into the skin, stay in place and cause cutaneous larva migrans (not Ancylostomiasis). However, there have been rare cases of A. caninum migrating to the intestine and causing an inflammation.

What are the Signs and Symptoms of Ancylostomiasis?

Many individuals with mild cases of Ancylostomiasis may not display any signs and symptoms. However, in moderate and severe cases, the symptoms may include: 

  • Itching and a localized rash: This is often the first sign of infection, and they occur because of the larvae entering the skin 
  • Pale skin appearance
  • Loss of appetite, fatigue and weight loss
  • Nausea and vomiting
  • Abdominal pain; passing gas
  • Diarrhea
  • Coughing
  • Fever
  • Anemia, due to fewer red blood cells

How is Ancylostomiasis Diagnosed?

The diagnosis of Ancylostomiasis is made through the following tests and exams:

  • A complete physical examination and review of medical and/or travel history
  • Assessment of symptoms
  • Analysis of stool samples: The samples are viewed under a microscope to check for the presence of hookworm eggs
  • Blood tests to check for anemia

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Ancylostomiasis?

The complications of Ancylostomiasis may include the following: 

  • Nutritional deficiencies
  • Significant loss of proteins from the body
  • Ascites or fluid buildup in the abdomen
  • Iron-deficiency anemia: This occurs due to blood loss, caused by hookworms sucking blood from the intestines. Typically, an infection by A. duodenale causes more severe blood loss than N. americanus infection
  • Stunted growth in children with severe infections due to malnutrition. This can lead to intellectual and cognitive deficits, causing poor performance in school
  • Pregnant women with severe infections may give birth to low birth-weight babies. They may also have poor milk production. In such cases, there is higher risk for the babies of severe malnutrition or mortality

Generally, infected pregnant women are more than 3-times as likely to die during childbirth because of anemia, than uninfected women.

How is Ancylostomiasis Treated?

The following are potential treatment options for Ancylostomiasis:

  • Administration of anti-parasitic medications
  • Iron supplements, in case of anemia
  • Ensuring proper and balanced nutrition, with an increase in the amount of protein in the diet, to avoid malnutrition

How can Ancylostomiasis be Prevented?

The following are some tips for prevention of Ancylostomiasis: 

  • Avoid walking barefoot in areas that may be contaminated with human feces, especially in places where hookworms are known to be common
  • Avoid skin contact with potentially contaminated soil and avoid ingesting contaminated soil. Properly washing hands and food, such as fruits and vegetables, can help in avoiding a contamination
  • Practicing good hygiene and maintain a clean-living environment, including taking proper care of pets
  • Avoiding defecating outdoors (building suitable toilet facilities, if it is not available)
  • Having effective waste and sewage disposal systems to limit the chance of infection

Those at an elevated risk for infection (including children of preschool age and upwards, pregnant women, and adults with outdoor jobs) in developing countries, where Ancylostomiasis and other hookworm infections are common, should consider getting prophylactic treatment even without a stool examination. This can help prevent transmission of infection and spread of hookworm parasites.

What is the Prognosis of Ancylostomiasis? (Outcomes/Resolutions)

The prognosis of Ancylostomiasis is generally positive with proper treatment. The possible outcomes of Ancylostomiasis include the following: 

  • With treatment, hookworm infections can be cured very successfully
  • Without treatment, Ancylostomiasis may result in severe anemia, which can cause complications. Children and pregnant women are especially vulnerable to severe complications of anemia that may result in a reduced quality of life or even death

Additional and Relevant Useful Information for Ancylostomiasis:

  • Ancylostomiasis is the world’s leading cause of anemia and protein malnutrition. This is especially true for pregnant women and children
  • Children with hookworm infections are at an increased risk of performing poorly in school, due to cognitive disabilities from malnutrition. It is shown that there is a 23% drop from school attendance in children with Ancylostomiasis. Treating the disease is the most effective way to get children back into school in the developing countries 
  • Pregnant women are more susceptible to complications of Ancylostomiasis, such as anemia, because they have an already low reserve of iron in their blood

In developed countries, such as the United States, hookworm infection is comparatively rare. Although, in the early 20th century, Necator americanus was widespread in the Southeastern United States. Hookworm infection was a big problem during this time, but advances in waste disposal and sanitation techniques have largely eradicated this disease from United States.

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Maulik P. Purohit MD MPH

Assistant Medical Director, Medical Editorial Board, DoveMed Team

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