When we think of parasites, we often think of tiny--even microscopic--organisms.  But ascariasis, also known as roundworm, is not only the most common NTD but also the largest in size.  Ascaris lumbricoides worms can reach 5-14 inches in length, causing immense damage: intestinal obstruction, anemia, and impairment of child growth and development.

Having trouble visualizing what a host of 14-inch worms looks like?  Take this tiny girl from Paraguay, infected with a particularly heavy load of ascariasis:

As you can see, her abdomen is grossly distended--the tell-tale sign of a major worm infection.  In many severe cases like hers, you can even physically palpate the worms on the outside of the abdomen.

But what's even more shocking is to see the worms themselves.  These are the actual worms that were expelled from her body:

When you see a worm burden of this magnitude, it's not hard to understand why kids who have worm infections are stunted and malnourished and perform less well in school.

More about ascariasis:


Parasitic eggs are ingested and hatch into larvae, which travel through the body and can cause pulmonary symptoms such as coughing and wheezing. Once the larvae settle in the small intestine, they feed on food from the human host and can live for up to two years. A small number of ascaris worms may not necessarily be harmful, but large numbers of worms can be extremely damaging to the body.

Control Efforts

Ascariasis infects over 807 million people.  In 2001, the World Health Organization (WHO) adopted a resolution aimed at the “deworming” of 75 percent of all at-risk school-age children by 2010, the largest public health program ever attempted to date. The program is currently underway and has been able to achieve some success in reducing the severity of worm infections in some areas, particularly in Africa. Education efforts aimed at prevention though proper sanitation, hand washing and food preparation techniques are also critical to reducing incidence of the disease.

Prevention and Treatment

  • Anti-helminthic drugs albendazole (Albenza) or mebendazole (Vermox) on an annual basis
    • 50 million tablets of mebendazole donated per year by Johnson & Johnson
    • Albendazole available from GlaxoSmithKline for 2¢ per pill
  • In some cases, surgery may be required to repair intestinal blockages or bowel obstruction