Can Probiotics Defeat Intestinal Worms?

Last Friday a team of researchers from the University of California, San Diego presented exciting research on a potential new treatment against intestinal helminths, or worms. The team, lead by Raffi Aroian, PhD, discovered that a slightly modified common dietary supplement was effective in completely curing infected hamsters of hookworm, a parasite that affects between 576-740 million people ever year, according to the CDC. The findings were presented at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH).

The researchers studied how two different versions, one modified and one not, of the bacteria Bacillus subtilis affected the intestinal worm. The first group of hamsters was treated with the common bacteria strain, which is marketed as a probiotic. Probiotics are living microorganisms that aid digestion. Today, they are frequently added to foods like yogurt. The second group of hamsters received a modified version of the same bacteria, which expressed a protein also found in the bacterium Baccillus thuringiensis, or Bt. Bt is safe in humans but, according to this press release on EurekAlert, potentially lethal to intestinal worms.

Upon examination five days later, the hamsters that received the modified version of the bacteria showed no signs of intestinal worms, while those that received the common bacteria strain remained infected with hookworm.

While the results need to be replicated in other animals as well as in humans, Aroian is quoted as saying the findings “are an important development in our effort to find a safe, affordable, and effective way to confront a major global health problem.”

Currently, there are only four anthelminthic drugs recognized on the World Health Organization (WHO) list of essential medicines: albendazole, mebendazole, levamisole, and pyrantel pamoate. While these drugs are commonly prescribed against soil-transmitted helminths, such as hookworm, there is some concern about their efficacy1, 2In addition, a 2008 article published in the Journal of the American Medical Association (JAMA) voices concern that more widespread administration of anthelminthics may cause the emergence and spread of drug-resistant roundworms, an already significant problem in veterinary medicine. The article concludes by stressing “the pressing need for discovery and development of novel anthelminthic drugs.”

Hookworm is one of three soil-transmitted helminths (STHs), the other two are roundworm and whipworm. People become infected with hookworms by coming into contact with contaminated soil. Hookworm larvae, which likely get into the soil through contaminated feces, are capable of penetrating the skin. Once inside the body, the hookworms attach to the small intestine and have the potential to cause a range of discomforts and health problems. Some people show no signs of infection, however others may suffer from diarrhea, anemia, and even developmental delay, among other symptoms. Approximately 1.5 billion people, or almost a quarter of the world’s population, are infected with one or more of these intestinal worms. This type of infection is most common in warm and moist climates where adequate sanitation and hygiene are lacking.

As strides towards a cure for helminthic infections are being made, it is important to remember that proper hygiene and sanitation measures can prevent infection with hookworm, as well as many other soil, water, and food – borne illnesses. In an effort to raise awareness of this global need for access to sanitation, the United Nations designates today, November 19, as the first “World Toilet Day”.  



1. Working group on Soil-transmited helminthiasis. Monitoring Anthelmintic Efficacy for Soil Transmitted Helminths (STH). [Internet]. World Health Organization; 2008 March [cited 2013 November 19]. Available from

2. Kaiser. J. and Utzinger, J. (2008). Efficacy of Current Drugs Against Soil-Transmitted Helminth Infections. Systematic Review and Meta-analysis. JAMA 299(16):1937-1948. Available from 

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