The scent of disease

Ability to detect diseases in conspecifics would be advantageous for the individual. In line with this, rodents avoid body odors of infected individuals. Two studies (Olsson et al. 20014; in prep.) indicated that this is possible by way of human smell and human observers. T-shirts from donors (worn for 4 hours) that had received an injection of endotoxin [0.8ng lipopolysaccharide (LPS) / kg body weight], which causes systemic inflammation, smelled more unpleasant, intense, and sick than shirts from donors that had received a placebo (Saline) injection. GC/MS analysis of the shirts suggested that the change of body odor was not due to a general increase of odorous compounds in the “sick shirts” compared to “placebo shirts” but rather to a qualitative change. Study 2 (ongoing) further investigated the nature of this perception. In a first experiment, we compared the body odor of 30 endotoxin (0.6ng LPS / kg body weight) and 21 placebo (Saline) donors. Again, body odors were sampled during 4 hours using T-shirts. Observers then smelled the shirts and rated intensity, pleasantness, and disgust. In a second experiment, urine from these donors were collected and was investigated in the same way with subjective ratings. Altogether the data suggest that systemic inflammation makes body odors more aversive within a few hours.