Science Figures Interpreted and Analyzed by RealClearScience
Lost amongst the din of the holidays was a gem of a study published December 20th in PLoS Neglected Tropical Diseases. Ladies and Gentlemen, I present, "An In-Depth Analysis of a Piece of S***: Distribution of Schistosoma mansoni and Hookworm Eggs in Human Stool."
The title and figures alone make this study an early favorite to be nominated for an Ig Nobel Prize, but it's more than a mere attention grabber. The researchers, led by Stefanie Krauth of the Department of Epidemiology and Public Health at Swiss Tropical and Public Health Institute in Basel, Switzerland, actually tackle a very serious issue: parasitic worms.
Parasitic worm-related disease such as schistosomiasis and helminthiasis affect hundreds of millions of people around the globe, particularly in poor and undeveloped countries. The diseases are fairly easy to treat (the medicine for schistosomiasis costs as little as $0.20 per year), but by and large, the diseases go relatively unchecked. This is due primarily to a lack of interest from the First World and hurdles in diagnosing infections.
The desire to address the latter issue and refine disease detection methods was what prompted the study's researchers to analyze a preponderance of poop. Stool samples were collected from 222 individuals in Cote D'Ivoire, one of the largest sample sizes ever for a study of this nature.
According to the researchers, "one third of all samples (33.8%) were sausage-shaped, 28.8% were mushy, 25.2% were sausage- shaped-but-soft, 7.7% were lumpy, and 4.5% were sausage- shaped-but-lumpy." 125 of the samples (56.3%) were infected with at least one species of parasitic worm. In the infected samples, the researchers sought to determine the location of worm eggs on the stool, whether homogenizing (stirring) the feces boosted detection, and the best way to store stool samples so as to preserve any parasite eggs contained therein. (Above figure: Processing methods for certain stool types. "Kato-Katz" is the test used to detect worms.)
While the researchers found no clear pattern of egg distribution on the stool, they did find that keeping samples on ice or in a wet tissue slowed the disintegration of hookworm eggs. They also found that stirring allowed for more accurate detection of eggs for the species S. mansoni.
Source: Krauth SJ, Coulibaly JT, Knopp S, Traoré M, N'Goran EK, et al. (2012) An In-Depth Analysis of a Piece of S***: Distribution of Schistosoma mansoni and Hookworm Eggs in Human Stool. PLoS Negl Trop Dis 6(12): e1969. doi:10.1371/journal.pntd.0001969