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Updated: May 26, 2026
Sampling and Analysis of Animal Scent Signals
Published on: February 13, 2021
Scent recognition of infected status in humans
Mikhail Moshkin1, Nadezhda Litvinova, Ekaterina A Litvinova
1Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia. mmp@bionet.nsc.ru
Introduction:
There is a body of experimental evidence that mice and rats use chemical signals to avoid sexual contact with infected conspecifics. In contrast to animals, body scent of sick humans is employed only in medical diagnostics. A modification of human body odor, due to an infection, has not been studied as a potential signal for choice of a sexual partner. It might, however, be especially important for sexually transmitted infections (STI) because many such infections have no obvious external manifestations.
Aim:
In this study, we have investigated odor pleasantness of young men infected with gonorrhea, Neisseria gonorrhoeae.
Methods:
We collected armpit sweat and saliva from young men (17-25 years old) belonging to three groups: healthy persons (N = 16), young men infected with gonorrhea, Neisseria gonorrhoeae (N = 13), and persons recovered due to specific therapy (N = 5). The sweat samples odor was then assessed by healthy young women (17-20 years old). Concentrations of cortisol, testosterone, immunoglobulin A (IgA), and immunoglobulin G (IgG) were measured in saliva by means of enzyme-linked immunosorbent assay.
Main Outcome Measures:
Subjective rates of odor pleasantness, association of scent of armpit sweat with odor descriptors, stepwise regression of odor pleasantness and salivary cortisol, testosterone, IgA, and IgG.
Results:
The odor from infected individuals was reported as less pleasant in comparison with the odor of healthy and recovered young men. The scent of infected men was more frequently associated by raters with the descriptor "putrid." Odor pleasantness of the male sweat correlated negatively with concentration of the nonspecific salivary IgA and IgG, which was measured as an indicator of current immunoenhancement.
Conclusion:
Perhaps, the immune-dependent reduction of the scent pleasantness in the acute phase of STI is part of an evolutionary mechanism ensuring, unconsciously, avoidance of a risky romantic partner.
Insights
Human body odor may signal infection, influencing partner choice. Gonorrhea infection in men alters sweat odor, making it less pleasant and potentially signaling illness to deter sexual contact.
Area of Science:
- Human behavior and chemical signaling
- Immunology and infectious disease
- Olfactory perception
Background:
- Animals use chemical signals to avoid mating with infected individuals.
- Human body odor changes during illness are not well-studied for partner selection.
- Sexually transmitted infections (STIs) often lack obvious external symptoms, making olfactory cues potentially crucial.
Purpose of the Study:
- To investigate the odor pleasantness of young men infected with gonorrhea (Neisseria gonorrhoeae).
Main Methods:
- Collected armpit sweat and saliva from healthy, gonorrhea-infected, and recovered young men.
- Assessed sweat odor pleasantness by healthy young women.
- Measured salivary cortisol, testosterone, immunoglobulin A (IgA), and immunoglobulin G (IgG) via ELISA.
Main Results:
- Odor from gonorrhea-infected men was perceived as less pleasant than from healthy or recovered men.
- Scent of infected men was more often described as "putrid."
- Odor pleasantness negatively correlated with salivary IgA and IgG levels.
Conclusions:
- Reduced scent pleasantness during acute STIs may be an evolutionary mechanism.
- This mechanism could unconsciously promote avoidance of partners with potential infections.
- Immune responses appear to influence body odor perception and partner selection.
