|A pit latrine in Haiti. Even a simple design|
such as this will do much to reduce
contamination of the environment, and result
in fewer intestinal parasites.
Image by Rémi Kaupp. CC BY-SA 3.0
Contaminated Soil and Intestinal Worms
I submit that there are no surprises here. One acquires hookworm by coming in contact with hookworm larvae from feces contaminating the soil. They penetrate skin. Trichuris trichiura and A. lumbricoides eggs, infective a week or so after being deposited in warm moist soil in feces, must be swallowed. Obviously if feces were deposited in a pit latrine, septic system or other sanitary arrangement, instead of on the ground, those eggs and larvae would not be available to infect new hosts.
The fact that intestinal helminthes are much less common, even rare, in developed countries is no mere accident of climate, especially for the tough A. lumbricoides. It is because the majority of people in developed countries don’t defecate outside on the ground.
Parasite Prevention: Sanitation Works
The best point in this paper, though understated, is that periodically treating people for intestinal worms is perhaps not the best long term approach to getting rid of these parasites. Without good sanitation, people will quickly be reinfected due to contamination of their environment. Lets build toilets.
Read the paper:
Ziegelbauer K, Speich B, Mäusezahl D, Bos R, Keiser J, et al. (2012) "Effect of Sanitation on Soil-Transmitted Helminth Infection: Systematic Review and Meta-Analysis." PLoS Med 9(1): e1001162. doi:10.1371/journal.pmed.1001162