Source: Monell Chemical Senses Center
Summary: New findings suggest that odor cues associated with sickness can cause biological changes in healthy individuals, potentially impacting social contacts and perhaps even patterns of disease spread.
Odors surround us, providing cues about many aspects of personal identity, including health status. Now, research from the Monell Center extends the scope and significance of personal odors as a source of information about an individual’s health. The study reveals that the bodily odors of otherwise healthy animals sharing an environment with sick animals become like the odors of the sick animals. The findings suggest that odor cues associated with sickness can cause biological changes in healthy individuals, potentially impacting social contacts and perhaps even patterns of disease spread. Previous Monell work had demonstrated that inflammation leads to bodily odor changes, suggesting that immune-activated odors might signal the presence of disease risk (or possible contagion) to other members of a species. The study findings were published in the journal Scientific Reports.
In the current study, the researchers injected mice with lipopolysaccharide (LPS), a non-infectious bacterial toxin that causes inflammation, activation of the immune system, and other symptoms associated with sickness. The LPS-injected “sick” animals were then housed in the same cages as healthy animals. Results from bioassays using “sniffer” mice trained to differentiate between urine odors from LPS-injected and healthy animals indicated that healthy partners of sick animals smelled more like sick, as compared to healthy, animals. A parallel analysis using statistical predictive modeling of urinary odor compounds identified via analytical chemistry confirmed the behavioral bioassay findings: models were more likely to classify odor compounds from healthy mice as sick rather than healthy when the healthy mice were co-housed with sick animals. The combined findings reveal that body odors of healthy animals can change in the presence of odor-based sickness signals.
Senior author Gary Beauchamp said, This work shows not only that odors signal disease but that they can have strong effects on individuals that detect them.”
More Information: Stephanie S. Gervasi et al, “Sharing an environment with sick conspecifics alters odors of healthy animals”, Scientific Reports (2018). www.nature.com/articles/s41598-018-32619-4