Intestinal worms

Intestinal worms (soil transmitted helminthiasis) are extremely common and widespread infections of humans, with in the order of one billion people infected worldwide. The effect of the infection depends very much on “worm burden” i.e. how many worms an individual is harbouring. Transmission is very much associated with poor sanitation and hygiene as worm eggs are passed out in the faeces of infected individuals. Eggs of the roundworm and whipworm are extremely hardy and can contaminate soil for many years.[/caption]

Key Facts

  • The main intestinal worm species infecting humans are the roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura) and hookworms (Necator americanus and Ancylostoma duodenale)
  • Intestinal worm infections are found worldwide but are particularly common in low and middle income countries
  • Infections cause gut problems, anaemia, stunting and wasting in children and poor school performance
  • Humans become infected through ingesting worm eggs/larvae contaminating food, on hands or on utensils, or through penetration of the skin by hookworm larvae in contaminated soil
  • Intestinal worm disease is controlled through regular treatment of young children, school-aged children and pregnant women with deworming drugs

Unmet needs/challenges?

Recently, there has been a scale up in control of intestinal worms using deworming drugs and increasing focus on eliminating intestinal worm from humans. This highlights a number of knowledge gaps and challenges:

  • The role of animals in transmission of intestinal worms. It has been shown that roundworms and whipworms in pigs, and whipworms and hookworms in dogs can infect humans. However, it is unclear what contribution animal worms make to the total burden of worm infection in humans. Reservoirs of intestinal worms in animals will make it more difficult to eliminate them from humans.
  • Resistance to deworming drugs. As distribution of deworming drugs is increased, there is a growing concern that drug resistance will arise. Indeed, there are already reports of reduced efficacy of deworming drugs in certain areas. New tools to monitor emergence of resistance are needed as well as an improved understanding of the mechanisms underlying resistance to deworming drugs.
  • No sensitive and simple diagnostic tools to diagnose worm infections. The current microscopy-based methods are not sensitive and will miss low-level infections. As control is scaled-up and infection levels decrease, sensitive, simple and cost-effective diagnostic methods are needed which can be used in resource-poor settings.

What is NTDhub doing?

  • Assessing the contribution of animal and environmental reservoirs to the burden of human intestinal worm infection in the Philippines
  • Investigating the role of β-tubulin genes in resistance to deworming drugs in the roundworm and developing new tools to assess resistance
  • Developing new sensitive and field-friendly diagnostic tests for the roundworm

External sources (links)