Useful information on Schistosomiasis and STH
STH (Continued)
Who is most at risk?
From the time children stop breastfeeding and start crawling around the ground – frequently putting their hands in their mouths – they are at risk of STH infections. Without treatment, they become repeatedly reinfected and the number of worms living in them steadily increases. By the time they reach school, they can be harbouring hundreds of worms.
Because STHs do not multiply in the human host (as with viruses, bacteria, fungi and protozoa),
reinfection is always the result of new contact with an infected environment.
Why should school-age children be targeted for treatment?
- They typically have the highest worm loads.
- They are at a particularly important time of their lives for growing.
- High levels of worm infections make them less able to resist other infections.
- It may be the only time in their lives they have a chance to go to school and learn.
- If the infection rates are reduced in this group, the environment becomes less contaminated, benefiting the whole community.
Treatment
There are four drugs to treat STH infections: albendazole and mebendazole, which are particularly attractive because they are so easy to administer, or pyrantel and levamisole, the doses of which are based on the weight of the child.
All four drugs produce excellent egg reduction rates:
- for roundworms, the reduction rate is over 95%;
- for hookworms, the drugs are nearly as effective, being >90%;
- for whipworms, these drugs are less effective. Albendazole and mebendazole have a 50–80% egg reduction rate and levamisole between 10% and 50%. Pyrantel has very little effect on whipworms.
Albendazole and mebendazole tablets are chewable, normally fruit flavoured and children like them. For small children, the tablet can be crushed between two spoons and offered to the child with a glass of water.
Drug Costs
- Albendazole costs only US$ 0.02 per dose.
- Therefore, US$ 1 will buy one dose for 50 children.
- US$ 2000 will buy one dose for 100 000 children.