Infectious Diseases
Hookworm Life Cycle

Understanding the symptoms and treatments of hookworms



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Hookworm Life Cycle
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"Understanding the symptoms and treatments of hookworms"
Caption: Hookworm Life Cycle
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Imagine a blood-sucking creature that penetrates your skin and travels through your veins to your lungs. It then rips holes in your air sacs and crawls into your throat where it is swallowed into your gut. Attaching itself to the wall of your intestine, it spends the rest of its life drinking your blood and laying eggs. Sound like a horror story? For those unlucky enough to be infected by the parasite called "hookworm," it can be.

The two most common species of hookworm are Ancylostoma duodenale and Necator americanus. According to the Centers for Disease Control, Ancylostoma duodenale is found mainly in the southern parts of Europe, Northern Africa, Asia, and parts of South America. Necator americanus is seldom seen these days, but  early in the 20th century it was a common health problem in the southeastern United States.

Hookworm infection is fairly common in areas of the world where there is warm, moist, sandy soil and sanitary conditions are poor. The eggs are passed in feces from infected persons, hatch in the soil, grow into infectious larva and wait to penetrate a victim.

In only 24 hours, the eggs have hatched into infectious larvae. When a barefoot person steps on one, it penetrates the skin of the foot and finds its way into the bloodstream. Once it gets inside a person, it makes its way through the blood vessels to the heart, and from there, into the lungs. Pushing through an air sac  and into the bronchial tubes, it is swept up into the throat and swallowed. After passing through the stomach, it attaches itself to the intestinal wall and begins feeding on the unlucky person's blood.

The worms take approximately a week to reach the intestine. There, they take another six weeks to mature into adult worms, mate, and produce eggs. These eggs are then passed in the feces of the host, and the cycle begins again. Because of this life cycle, they are confined to areas where people routinely defecate outdoors and go barefoot.

Adult worms are round, whitish in color, and 8 to 13 millimeters in length. Hookworm infection can be confirmed by recovering the eggs from a patient's feces using a routine laboratory procedure. The adult worms are seldom seen in feces, as they remain attached to the intestinal wall. In underdeveloped countries where infection is high, the diagnosis is often made on the basis of the patient's symptoms, which include fatigue, nausea, abdominal pain, diarrhea and pallor.

Many people who become infected by hookworm never show any signs of illness, but for others, especially children, it can lead to serious disease and, although rarely, even death. For persons with a heavy infection, there can be considerable blood loss leading to a loss of iron and protein which can cause iron deficiency anemia. Women, with their greater need for iron, are especially at risk. The loss of nutrition due to intestinal problems caused by hookworms can lead to mental and physical developmental problems, as well.

Albendazole is the usual treatment for hookworm infection and is generally effective. However, in countries where reinfection is likely, treatment is sometimes not given if the infection is light and not causing serious symptoms.

Prevention of hookworms is relatively simple:

  • Institute sanitary measures in areas where the infection rate is high
  • Dig pit privies so that the ground isn't contaminated by feces
  • Educate the people of these areas about how hookworm is transmitted so that they can avoid the conditions that lead to infection

Hookworm infection may sound like something out of a horror story, but some day scientists and public health workers, through treatment, education, and sanitation measures, will put an end this parasitic menace.

Reference: The Centers for Disease Control and Prevention, Parasites and Health, http://www.dpd.cdc.gov/dpdx/HTML/Hookworm.htm


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