Necator americanus: The Hookworm

Necator americanus is a nematode, a type of parasitic worm, that is a common cause of infection in tropical and subtropical climates. often plays an unnoticed yet substantial role in public health in many parts of the world. Necator americanus is the most common type of hookworm found in the Americas, though there are numerous other species of hookworm, such as the common Ancylostoma duodenale more commonly found in Asia. In this article, we will discuss what Necator americanus is, how it is transmitted, the symptoms of infection, and common methods of treatment.

What Is Necator americanus? 

Necator americanus is a type of parasitic worm that can infect the human digestive tract. It thrives in environments where sanitation is poor and is a common cause of iron-deficiency anemia and malnutrition due to chronic blood loss. 

Necator americanus is a parasitic hookworm that is known for causing hookworm disease in humans. It predominantly resides in the small intestine, where it attaches to the mucosal lining and feeds on the host's blood, often resulting in conditions of anemia and malnutrition. (1) This parasitic infestation is most prevalent in tropical and subtropical regions of the world, particularly in areas with warm, moist climates that facilitate the hookworm's life cycle. Necator americanus is the most common type of hookworm infection, representing 85% of all hookworm infections. (2)

The Start of a Cycle: Necator americanus Egg

The lifecycle of Necator americanus begins with the egg. These eggs are microscopic and hardy, laid in the intestines of an infected person and passed into the environment through feces. Once in the soil, they hatch into larvae where they can be transmitted by skin to skin contact – typically through walking barefoot on contaminated soil. (3)

The Necator americanus Life Cycle

The complete life cycle of Necator americanus is a journey that begins in contaminated soil and can end in a human host:

• Hatching: The eggs require warm, moist soil to hatch into larvae.
• Larvae: These larvae mature into a form that can penetrate human skin.
• Migration: After skin penetration, they travel through the bloodstream to the lungs.
• Getting Swallowed: They ascend the bronchial tree of the lungs to the throat, where they are eventually swallowed.
• Maturation and Reproduction: In the small intestine, larvae mature into adult worms and reproduce, completing their life cycle. (1)

Necator americanus Symptoms

Infection with Necator americanus can lead to a variety of symptoms, many of which are common to other intestinal parasites and can therefore go unnoticed or be misdiagnosed. Initial symptoms are often dermatological, where the larvae enter the skin. However, as the worms migrate through the body and begin to feed on the host's blood, more systemic symptoms can develop:

• Skin Itching: Dermatitis and localized itching develop at the site of larval entry.
• Respiratory Symptoms: Cough and wheezing as larvae pass through the lungs.
• Gastrointestinal Symptoms: Pain, nausea, and diarrhea once the worms reach the intestines.
• Nutritional Deficits: Long-term infections can lead to iron-deficiency anemia and protein malnutrition due to blood loss at the site where the worms attach to the intestinal wall. (1)

Children, in particular, can experience stunted growth and cognitive delays if the infection and its resultant nutritional deficiencies are not addressed.

Necator americanus Disease

The disease caused by Necator americanus is often referred to simply as hookworm disease. It’s an ailment that can affect an individual's overall health, particularly if the burden of worms is high. Chronic infection can lead to:

• Anemia: A significant reduction in red blood cells due to the worms' blood-feeding habits.
• Protein Loss: The loss of blood proteins which can result in a condition known as hypoalbuminemia.
• Physical and Cognitive Development Delays: In children, the effects of anemia and malnutrition may result in delayed growth and development.

Treatment of Necator americanus Infection

Treatment for Necator americanus primarily involves antiparasitic medications that effectively kill the adult worms. (4) The most commonly prescribed medications are:

• Albendazole
• Mebendazole
• Ivermectin
• Pyrantel Pamoate

Some people opt for natural antiparasitic herbs as alternatives to supporting the elimination of hookworm and other parasites. While these herbs may be effective, it is recommended to speak with your doctor to determine what is the best course of treatment for you if you have a hookworm infection.

Preventing Infection

While treatment is possible and generally effective, it is best to avoid getting a hookworm infection in the first place if possible. Some essential preventive measures include:

• Improving Sanitation: Access to proper toilets and waste management systems to prevent soil contamination.
• Health Education: Teaching communities about the risks of walking barefoot in endemic areas and the importance of handwashing.
• Soil Treatment: In some areas, treating the soil can help to reduce the incidence of hookworm larvae.
• Regular Deworming: In endemic regions, mass deworming programs have been effective in reducing the prevalence of hookworm infections. Regular parasite cleanses may also be helpful.

The Bottom Line

Necator americanus may be a small worm, but its impact on your health can be substantial. By learning about this parasite, from recognizing its eggs to understanding the illness it can cause, you can take proactive measures to protect your health and stay parasite-free.

References

1 https://www.ncbi.nlm.nih.gov/books/NBK546648/

2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806429/

3 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978129/

4 https://www.cdc.gov/parasites/hookworm/treatment.html