Detecting Communicable Disease: Can Humans Smell Sickness?

communicable disease smell

Can our sense of smell stop the spread of communicable disease?

Prior to the 19th century, a commonly held belief was that communicable diseases spread through the air via an ill-defined substance called miasma, which originated from the rotting of diseased matter. According to the theory, miasma, also known as “bad air” or “night air,” is what caused the spread of communicable diseases. Modern germ theory has completely dispelled the notion of miasma, but was there some truth to our ancestor’s logic? Is there such a thing as “bad air?”

Related Article: The Natural, Three-Plant Fresh Air System

According to modern day research, bad air is a reality, but not in the same way that the science of pre-19th century envisioned. Bad air comes in the form of stinky smells, a well documented but only recently focused on aspect of non-communicable and communicable disease. Myriad studies and current practices state that smelling sickness isn’t only possible, it is being achieved.

According to a study published in the journal Psychological Science, humans can more often than not successfully smell the difference between a sick and healthy person. In the study, the difference between a healthy and sick person was defined by the level of activity taking place in the immune system.

Related Article: Alcohol in Moderation Strengthens Immune System

Researcher Mats Olsson of Karolinska Institutet in Sweden headed the study. Olsson notes in the study that a copious amount of scientific and anecdotal evidence already exists regarding the detection of non-communicable and communicable disease through smell. After all, being able to detect communicable disease through our noses alone would be an incredible evolutionary advantage.  Olsson hypothesized that some type of biomarker may be present to allow this detection to take place, explaining that,

There may be early, possibly generic, biomarkers for illness in the form of volatile substances coming from the body.

sweat communicable disease

You sir smell distinctly of an over-active immune system.

He tested his hypothesis by observing the ability of participants to detect a heightened immune response in other participants with only their nose. Eight healthy people were selected to be injected with either a simple saline solution or lipopolysaccharide (LPS), a toxic substance that boosts immune responses in humans. The participants injected with the LPS showed evidence of a heightened immune response in the form of increased body temperatures and a greater number of cytokines, a molecule normally found in the immune system when sick.

For four hours the volunteers sweated into tight fitting t-shirts. 40 new participants were asked to smell the sweat samples gathered from the t-shirts. The authors state that overall the participants rated the LPS group as having a far more intense and unpleasant smell compared to the t-shirts of those injected with saline. Interestingly, the more cytokines present in the blood of people injected with LPS, the more unpleasant their sweat smelled.

Here’s the weird part though: the researchers found no noticeable difference in the amount of odorous compounds between the LPS-filled and LPS-free sweat. This led Olsson to hypothesize that participants were detecting the sickness not through smell, but from detection through an unknown mechanism of the different molecules present in sick and healthy people. Understanding this mechanism would undoubtedly lead to better preventative methods for stopping the spread of communicable diseases.

Related Article: Smelling Calmness: Aromatherapy and Essential Oils

dog smell communicable disease

Dogs are masters of scent. Could their sense of smell be used to detect disease?

It is likely that other mammals such as dogs have the ability to smell illness. Consider what happens when one dog meets another dog. They go right for the butt. Smell is the first and most important sense dogs use to exchange information with other dogs.  Researchers have theorized that this type of stinky exchange of information occurred in human ancestors before they began walking upright. What researchers want to know is specifically what type of information is being exchanged between dogs and human ancestors, and could it lead to the precise detection of communicable diseases?

This type of inquiry is very practical as the earlier we detect a communicable disease the quicker we are able to alert others and stop the seemingly inevitable spread. Luckily for us, this type of super advanced detection is beginning to be widely used for an array of non-communicable and communicable diseases alike.

Many studies note distinctive odors as being a new significant factor contributing to the detection of illness. Although lung cancer can be detected by observing how gold nano particles change in the presence of a person’s breath, it can also be detected simply by the way it makes breath smell. Apparently most of the time a person has lung cancer their breath smells like ammonia and/or fish. In the same vein, urine smells like cheese during a urinary tract infection, while the skin of a person with melanoma usually smells like gasoline. While some people are able to smell the difference, not everyone’s sense of smell is strong enough.

The key to early detection is becoming informed about how different diseases smell, and eventually creating an all-in-one device that can analyze the chemicals and bacteria being emitted from a person’s body and conclude if they have any easily detectable communicable diseases.

communicable disease percentage

Non-communicable vs.communicable disease: There is a major difference in the type of diseases each region of the world dies from.

Perfecting the ability to detect disease, especially by using the nose alone, is an admirable objective. Communicable diseases can be stopped in their tracks by simply stopping the mass spread of such diseases. Communicable diseases account for 55% of all deaths in developing regions of the world, compared to 14% in developed regions. Improved medicinal practices are largely responsible for this dramatic difference in death rates, and detection methods are a major part of improved medicine.

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Millions of lives can be saved through the advanced detection of communicable disease. Early detection is an indispensable tool in the global fight against disease, death, and even poverty. For this reason let us hope that this type of research continues to be funded and supported by the global community.

Who knows, maybe one day there will be an early detection app on our smartphones, or a signpost on each road that changes color in the presence of certain chemicals corresponding to certain communicable diseases. Maybe one day, communicable diseases will become, for all intents and purposes, non-communicable.



Miasma Theory

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