Altered body odor indicates malaria even if microscope doesn't | Hacker News Reader

Altered body odor indicates malaria even if microscope doesn't

medicalxpress.com

64 pointsdnetesn10 comments

Reminds me about the woman who can smell Parkinson's:

> She sniffed six sweaty tees from people diagnosed with Parkinson’s, and six from healthy controls. Milne correctly identified which six had Parkinson’s, but she also tagged one of the control subjects as having the disease.

> Despite that error, Barran was intrigued—all the more so eight months later, when the same supposedly healthy control subject Milne had identified was diagnosed with Parkinson’s.

https://news.nationalgeographic.com/2018/01/smell-sickness-p...

This is both excellent and at the same time _terrible_, because it appears to be an adaptation on the part of the malaria parasite to be more virulent:

> "Our previous work in a mouse model found that malaria infection altered the odors of infected mice in ways that made them more attractive to mosquitoes, particularly at a stage of infection where the transmissible stage of the parasite was present at high levels[...]"

In turn, this reminds me of a spate of articles that hit ~2y ago on T. Gondii, which appears to alter the scent of host cats' urine to make it more appealing to prey animals: https://en.wikipedia.org/wiki/Toxoplasma_gondii

Huh. My first reaction is "well, duh" but then I remember that most people on HN and elsewhere have no experience with these things.

Malaria has this smell. I can't describe it, I can only say that it's not unpleasant, but anyone who's tended to someone with the disease knows what I mean. The sweat, the breath, even the room the person lay in, it just has this smell.

I'm inferring that you've done this in the first person. Were you surrounded by people with the same experience, ie. was this detectable by everyone, or was this something that some people picked up on more than others?

Curious for two reasons: the top-level comment here on some people being able to diagnose Parkinson's by smell, and my own experience being exposed to people experiencing malaria (albeit in a non-clinical setting with _plenty_ of other overwhelming smells) and not registering a common olfactory experience.

A recent article that goes into how unique our sweat and body odors are.

https://www.theverge.com/2018/5/14/17352044/sweat-science-he...

What kind of (cheap) instruments exist to measure odor objectively?

Is there such a thing as odor in an objective sense? Olfaction is just the detection of chemical volatiles in the air/water going through an animal’s nose/gills. We “notice” smells that we’ve evolved chemosensors for; everything else just goes on through.

So, if you want to replicate smell, are you talking about replicating the particular suite of chemosensors all humans have in common? Some particular human? All animals? Or, are you not so much talking about odor (the thing that anythinghas evolved to detect) as chemical volatiles generally?

Even then, we need to manufacture something much like chemosensors to detect any particular chemical volatile—we have to be explicit about what we’re looking for, and won’t see anything we don’t know to look for. (You can use a mass spectrometer, but you’re not getting molecules from that, just atomic isotopes; and you’re not getting just volatiles, but the whole fluid containing the volatiles.)

There is https://en.wikipedia.org/wiki/Electronic_nose. Think of breathalyzers as another example of an objective way to measure the smell of alcohol.

> So, if you want to replicate smell, are you talking about replicating the particular suite of chemosensors all humans have in common? Some particular human? All animals? Or, are you not so much talking about odor (the thing that anythinghas evolved to detect) as chemical volatiles generally?

I guess, depending on context, you can answer these question like for the other senses. E.g. humans cannot hear above a certain frequency, where some animals can. Some humans have reduced ability to see "green" (the most common form of colorblindness), etc. That doesn't mean we can't measure or reproduce audio and video in a meaningful way, of course.

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