Ascariasis: An Extremely Common Parasitic Infection

Imagine a disease that affects a large percentage of the world's population. It does exist. Perhaps you are thinking of HIV/AIDS or cancer. It is neither of these. It is a disease called ascariasis. Ascariasis affects a huge number of people worldwide. In fact, it is estimated that as many as one-quarter of the world's population is affected by the disease. However, not many people are even aware of the disease. So what exactly is ascariasis?

Ascariasis is an intestinal infection caused by the parasitic roundworm Ascaris lumbricoides. Ascaris lumbricoides causes infections in humans after direct or indirect contact with contaminated soil or through ingestion. Infections occur once the fertilized eggs hatch in their host. The larvae then burrow through the intestine, travel to the liver, and finally to the respiratory system. They are eventually reswallowed and mature in the intestine. They can grow to be quite large, sometimes more than a foot in length. In fact, Ascaris lumbricoides is the largest roundworm that affects humans. The worms can live for nearly two years. The female worms produce more than 200,000 eggs per day. Once the fertilized eggs are shed, the cycle starts all over again. In the United States, approximately two percent of the population is affected by ascariasis. The disease is much more common in other parts of the world. In particular, the disease frequently affects individuals in tropical and developing countries as well as areas with poor sanitation and overcrowding. Children are particularly susceptible to the disease. More than a billion people are affected by ascariasis worldwide.