A new study shows that signs more subtle than coughing or sneezing can actually indicate that someone is sick and potentially highly contagious.
The study, published in Proceedings of the Royal Society B, shows that upon infection, sick individuals develop paler lips and skin, a swollen face, red eyes, and exhibit other facial cues.
“Our findings suggest that facial cues associated with the skin, mouth and eyes can aid in the detection of acutely sick and potentially contagious people,” the study reads.
Humans tend to avoid peers who exhibit “overt sickness behaviors,” the study says. But we are less adept at detecting sickness by observing human faces for subtle cues.
Twenty-two healthy volunteers were included in the study and received either an injection that causes an inflammatory response and sickness behavior or a placebo.
The subjects were photographed in a controlled environment about two hours after they were injected, and a panel of “raters” was able to detect acutely sick individuals from the photographs.
“We demonstrate that a transient stimulation of the innate immune system affected the human face in a way that allows others to identify acutely sick individuals beyond chance by merely observing facial photographs,” researchers said.
“It would arguably be particularly beneficial to identify sick individuals at an early stage of sickness when risk for contagion is high,” the study concludes.