The Study
Amazonian Shuar testosterone levels are related to parasite infection: Immunocompetence Handicap Hypothesis Implications
This study looked at whether boys with higher testosterone levels were more likely to have worms, and it found a link — but only in teens and only for one kind of worm. It didn’t prove that testosterone causes the worms; maybe the worms change how the body works, or maybe teens who are growing fast have both higher testosterone and more exposure to dirt. So it’s like noticing that kids who play outside more get more scratches — but we don’t know if playing outside causes scratches or if kids who get scratched just play outside more.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
In teen boys living where worms are common, higher testosterone makes them more likely to catch one type of worm (whipworm), but if they do get infected, their bodies seem to fight it better.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 542 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this suggests puberty may make boys more vulnerable to infection but also trigger stronger immune responses when worms are already present.
- 2Teens with high testosterone had 11.6x higher chance of getting whipworm, but if infected, they had 1.21 fewer worm eggs per gram of poop.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Evolution, Medicine, and Public Health
Year
2026
Authors
T. Gildner, Aaron D. Blackwell, M. Liebert, S. Urlacher, T. Cepon‐Robins, J. Schrock, R. Bribiescas, F. Madimenos, J. Snodgrass, L. Sugiyama
Related Content
Claims (10)
The theory that high testosterone suppresses immunity to explain parasite resistance does not fully account for human data, because the interaction between testosterone and parasites changes depending on the type of parasite and the age of the person.
In adolescents aged 12–19 infected with Trichuris trichiura, higher testosterone levels are linked to a greater likelihood of infection and a reduced number of parasites.
In adolescent males living in areas with high parasite exposure, higher saliva testosterone levels correlate with a greater likelihood of whipworm infection, but among those infected, higher testosterone levels correlate with fewer whipworm eggs in stool.
In adult males aged 20 and older, testosterone levels do not correlate with infection by the parasite Trichuris trichiura. This relationship only exists during adolescence.
Testosterone levels do not correlate with the likelihood of being infected by Ascaris lumbricoides worms or with the number of worms present, regardless of age. This suggests that hormonal influences on immune responses vary depending on the type of parasite.
In adolescents, higher levels of the Trichuris trichiura parasite are linked to lower testosterone levels, suggesting that energy used for immune defense reduces the resources available for hormone production.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.