A New Compound Kills the Growth-Stunting Whipworm Parasite That Infects Half a Billion People
Somewhere around 600–800 million people in the world are infected with whipworm (Trichuris trichiura), an infection they got from ingesting soil or water contaminated with feces of infected animals or people containing the parasite's eggs.
Currently, treatment options are limited and not very effective, but a compound has been identified that may pave the way for a new oral drug to fight the infection, as well as a spray to kill eggs on surfaces and the environment.
After evaluating 192 different chemicals, a UK research team from University College London, the University of Manchester, and Oxford University identified a compound called dihydrobenz[e][1,4]oxazepin-2(3H)-one that was active against the parasite. They called it OX02983. Development and preliminary testing of the compound was published in the PLOS journal Neglected Tropical Diseases.
OX02983 paralyzed adult worms and prevented whipworm infections from occurring in mice by inhibiting the ability of the eggs to establish an infection.
The new compound presented several potential routes to treat whipworm infections; It could be developed into a drug to treat whipworm infections, a drug to render eggs passed in feces ineffective, or as a chemical spray to wipe out places were eggs were deposited.
"Dihydrobenzoxazepinones could potentially be developed into a therapeutic agent that acts in the environment, perhaps via a spray utilised at sites of high-parasite density such as communal latrines, to interrupt the parasite lifecycle," according to the study, led by Frederick A. Partridge from the Centre for Respiratory Biology at University College London.
Whipworms live in the large intestine, where they lay eggs that get passed out in the feces of the infected person. In unsanitary conditions where hygiene is poor, such as countries where people defecate outdoors or use human feces as fertilizer, the parasite's eggs end up in the soil. They can then mature into a form that is infective.
People and animals, especially dogs and pigs, can get whipworm from ingesting the eggs that make their way into their mouth. Vegetables or fruits grown in unsanitary conditions that have not been carefully cooked, washed, or peeled can also carry the infective whipworm eggs.
There is some species selection regarding infectivity. Humans can get whipworm from infected dog feces, but pigs cannot. Whipworms that infect dogs and pigs are not the same, so there is no transmission of whipworms between these two species.
Most infections in the world occur in areas where sanitation is bad, and in the tropics where eggs can survive the weather and storms can move whipworm eggs from soil into water. Whipworm infections do occur in the American South, as well.
People infected with whipworm can have very light infections with no symptoms or heavy infections with severe symptoms. Frequent, painful bowel movements that contain mucus, water, and blood are symptoms of a heavy infection—one with many worms. Rectal prolapse, a condition where the bowels extend outside the anus, can also occur.
Infections in children are very serious because the children can become severely anemic due to the loss of blood and experience growth retardation and cognitive impairment.
About 24% of the world's population is infected with soil-transmitted helminths, a group of parasites that includes roundworm, whipworm, and hookworm. The US Agency for International Development—in partnership with private businesses like Johnson & Johnson and GlaxoSmithKline—provides technical and financial support to countries in their efforts to control these infections.
One such program is the Mass Drug Administration program where health officials in at-risk countries try to provide medication to at least 75% of the children once or twice a year. This involves door-to-door and school programs that provide albendazole and mebendazole to treat the infections, as well as hygiene information to prevent transmission and future infections.
It's difficult to manage medication programs of mass numbers of people in poor countries. Besides the obvious obstacle of the sheer numbers of children who must be reached, the medications used, albendazole and mebendazole, have poor efficacy because they were developed to treat animal whipworm infections. Increasing drug resistance also means low cure rates.
So far, that's the only way these types of parasitic infections have been handled—one child at a time. The development of a more effective treatment, along with a spray that has the potential to wipe out mass numbers of eggs before they can develop or infect humans, might stop this rampant infection in its tracks.