Intestinal worm infections rank among the most common afflictions of people living in extreme poverty, with reports of more than 800 million people who are harboring Ascaris roundworms in their gastrointestinal tract, and approximately 450 million people who are infected with either hookworms or Trichuris whipworms. These numbers suggest that almost every person living in a developing country is infected with worms, a consequence of the fact that the infective egg or larval stages of these parasites are practically ubiquitous in the soil.
“Each type of worm brings its own little shop of horrors,” said Peter Hotez, President of the Sabin Vaccine Institute and Texas Children’s Hospital Endowed Chair in Tropical Pediatrics.
While the World Health Organization (WHO) is leading a global campaign to “deworm” via mass drug administration at schools, Texas Children’s Hospital is pioneering the development of new worm vaccines.
According to Hotez, one of the problems with deworming is rapid post-treatment reinfection. There also is information to suggest that while the drugs work well on some worms, others such as hookworm and Trichuris whipwork are more resistant. And while deworming is one of the world’s largest global public health programs, so far less than 40 percent of the world’s children who could benefit from deworming actually receive the medicines.
“There is a lot of work to do,” said Hotez. “Global deworming needs to continue to scale-up and expand. We also need research into better drugs and vaccines, especially for hookworm.”
The Sabin Vaccine Institute and Texas Children’s Hospital Center for Vaccine Development have been working to do just that. The hookworm vaccine they developed is now in clinical trials in Brazil, and will soon enter clinical testing in Gabon. And a schistosomiasis vaccine is about to undergo phase 1 trials for safety and immunogenicity here in Texas. They are also pursuing the possibility of a vaccine that could target all of the intestinal worms.
Worms can result in severe health consequences for growing children and, in the case of hookworms, also for pregnant women. Recently, the Global Burden of Disease Study that evaluated almost all disease conditions for the year 2010 determined that intestinal worms cause as much or more global disability than better known childhood conditions such as autism, ADHD, or cleft-lip and palate. Hookworms accounted for more than two-thirds of that disability. There have also been occurrences of some unique worm infections here in Texas, including toxocariasis and cysticercosis, which is associated with epilepsy and other brain disorders. It’s important to be aware of these diseases and spread word about their dangers, in order to raise awareness and funding to fight intestinal worm infections in developing countries and at home.
“Worm vaccines would represent important new global health technologies in order to improve the health and vigor of children in the world’s poorest countries,” said Hotez. “A world free of worms would be one in which children achieve their full physical, intellectual and economic potential.”