How your smell can reveal if you're sick

By Meera Senthilingam, for CNN

Updated 2034 GMT (0434 HKT) January 20, 2016

Subtle differences occur in body odor when someone is sick or infected, changing their odors from pleasant to aversive. When picked up by others, these differences can inform them to protect themselves and avoid becoming infected.
Photos: How humans smell disease to stay healthy
Subtle differences occur in body odor when someone is sick or infected, changing their odors from pleasant to aversive. When picked up by others, these differences can inform them to protect themselves and avoid becoming infected.
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The change in odor is thought to be caused by activation of the body's immune system in response to a new infection. Scientists at the Karolinska institute in Sweden injected volunteers with a compound mimicking the presence of bacteria, and changes in smell were detected.
Photos: How humans smell disease to stay healthy
The change in odor is thought to be caused by activation of the body's immune system in response to a new infection. Scientists at the Karolinska institute in Sweden injected volunteers with a compound mimicking the presence of bacteria, and changes in smell were detected.
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Everyone has their own "odorprint" made up of select compounds combining to release a unique odor. But this scent is based on various factors including age, gender and health.
Photos: How humans smell disease to stay healthy
Everyone has their own "odorprint" made up of select compounds combining to release a unique odor. But this scent is based on various factors including age, gender and health.
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Smelling sickness can help people avoid infection from others, but research has also revealed that sniffing an infection in others could initiate an immune reaction and prepare the body for attack.
Photos: How humans smell disease to stay healthy
Smelling sickness can help people avoid infection from others, but research has also revealed that sniffing an infection in others could initiate an immune reaction and prepare the body for attack.
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Several diseases have been discovered to have signature scents: People with typhoid fever are said to smell like baked bread, people with yellow fever smell like a butcher's shop, and those with the glandular disease scrofula smell like stale beer. Pictured, a patient with typhoid fever.