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Plasmodium-associated changes in human odor attract mosquitoes (pnas.org)
73 points by tosh 6 months ago | hide | past | web | favorite | 31 comments



""" Malaria parasites (Plasmodium) can change the attractiveness of their vertebrate hosts to Anopheles vectors, leading to a greater number of vector–host contacts and increased transmission. Indeed, naturally Plasmodium-infected children have been shown to attract more mosquitoes than parasite-free children. """


Were those mosquitoes parasite-free?

To maximize infectiousness, the Plasmodii would then manipulate infected mosquitoes to ignore that smell and feed on uninfected humans...


Thank you for posting this; I was trying to find a concise article about this phenomenon.


The community of microbes resident on skin (or rather, their metabolites) has also been shown to influence attractiveness to mosquitos[1]. Interestingly, some taxa were associated with decreased attraction, which the authors of the linked study hypothesize is due to a masking effect. Skin probiotics may be on the horizon for mosquito deterrence and other applications (think acne, eczema, etc.). The composition of the skin microbiome is influenced by diet, host genetics, environment, and other factors (sun exposure, hygeine, etc.).

1. http://journals.plos.org/plosone/article?id=10.1371/journal....


This company is working on an acne treatment based on bacteria: http://www.nakedbiome.com


This is super fascinating, thanks for the link.

The next time I go on a nature walk I am going to soak myself in a bathtub full of bleach first, I'll be invisible.


Very interesting

I am a person who mosquitoes love to bite but I don't have any disease (that I know off). My wife can lay next to me and not get a single bite while I am fighting them off left and right. I wonder what else can contribute to this difference.


Mosquitoes are attracted to co2. You are probably just bigger than your wife, exhaling more co2.


That reasoning never quite made sense to me because if that was a or the major reason, why do I have the signs of unwanted mosquito encounters mostly on or my feet and ankles?

If that theory indeed is true I think CO2 is just a rough guide to find the approximate location (within meters) of something alive with blood. I think once close other guidance systems might take over.

My above opinion isn't worth much, but the CO2 hypothesis seems pretty limited to me?


Mosquitos who feed on humans have developed behavior to bite around the feet because they are less likely to get smacked. https://www.npr.org/sections/goatsandsoda/2016/02/22/4655948...


Of course, that's an obvious conclusion - OPs point though was about CO2, which is unlikely to be what guides those vicious beasts to ones feet.


They detect CO2 and odors:

"Both Aedes aegypti and Anopheles gambiae mosquitoes — which transmitdengue and malaria respectively — were much less attracted to the scented beads after being exposed to the chemical. These results showed that the receptor responsible for detecting carbon dioxide also detects skin odorants."

https://www.nih.gov/news-events/nih-research-matters/how-mos...

And thermal features:

http://www.caltech.edu/news/mosquitoes-use-smell-see-their-h...


So, this might be a long shot, but I might hazard a guess that in hot, humid weather, with stagnant air, the dynamics of where exhaled exhaust goes, changes.

In the cold, dry air of winter your breath vents upward, but getting near sunny 90 degree weather, during summer time, it might descend and pool at the feet of gatherings of people at barbecues.

Carbon dioxide in ambient, matched temperature mixtures tends to be dense, and sinks toward the floor in many conditions (similarly true for carbon monoxide), but local conditions obviously vary, and odor travels differently than entire air masses. If mosquitos are already out, they probably travel along the odor gradient, toward the most concentrated area of scent.


You assume waaayyyy too much stability for a body of air. The air around you is moving constantly. Every bit of movement and every tiny heat source causes movement.

The problem is people don't see "air", but there are ways to visualize it (e.g. Schlieren photography). Or just watch smoke.


The mosquitos love my feet, even when I'm laid. Your theory does not match my anecdotal data.


CO2 is 44g/mol vs 29g/mol for air so perhaps it’s higher density causes more concentration close to your ankles.


Feet have more odour I guess. :)


Mosquitoes are generally attracted to Co2 but when it comes to differences between humans it's genetic. There are a few genes that influence it. See more in the veratasium [1] video below.

[1] https://veritasium.com/education/why-are-mosquitoes-attracte...


My husband is virtually immune to mosquitoes, while they find me irresistible. I'm smaller than he is and have a much lower base metabolism.


"I don't need to breath out no CO2. Just less than you."


I am 6'3" and 300 lbs. Mosquitoes pretty much ignore me.


See the reply by tomkinstinch. It is likely that the combination of gases produced by your skin's microbiome are more attractive to mosquitoes than that of your wife's.

This seems more probable than increased amounts of CO2 floating around your feet and ankles, especially if you are laying next to you wife where the aggregate CO2 from both of you breathing will be distributed fairly evenly between you.

A quote from tomkinistinch's linked article: "...washing the feet with a bactericidal soap significantly alters the selection of biting sites...".

I wish we were at a point technologically where it would be simple(and cheap) for a person to detect and catalog things like VOCs that skin bacteria produce, or quantities of bacteria on the skin to determine how they correlate with something like mosquito attraction.

It would be pretty great to be able to say definitively that x bacteria concentrations on your skin are attracting mosquitoes to you, rather than simply conceding "mosquitoes love to bite me".


Diet and bite sensitivity. I get a few tiny ones that I usually don't notice, a relative gets many huge swellings that need medical attention.

I believe different attractors are weighted more strongly in different types of mosquitoes too. Some prefer co2, some heat, other detect compounds in sweat or exhaled gases, like the aldehydes from bananas!


Are you o negative?


"Extended Phenotype" much?

> The Extended Phenotype is a 1982 book by Richard Dawkins, in which the author introduced a biological concept of the same name. The main idea is that phenotype should not be limited to biological processes such as protein biosynthesis or tissue growth, but extended to include all effects that a gene has on its environment, inside or outside the body of the individual organism.

----

Totally unrelated mosquito story: A friend of mine told me about a time he was laying down resting on a hot day with a fan blowing over him to keep mosquitoes away. He watched a mozzy land in the lee of his body and walk towards him.


Mosquitos love me, but when I know I'll go to a place with a lot of them, I start taking B12 vitamin. It was a tip a friend of mine gave me, and it usually works. I don't know why and never read anything about it.


Interesting. I started taking B12 supplements this winter. I usually get swarmed by mosquitoes in the summer. It will be interesting to see if my experience changes this season.


Sorry to be that guy, but this is probably not true.

the notion that ingesting certain products like B vitamins (or garlic, for that matter) might repel mosquitoes is common, but unfounded. Based on scientific studies I was able to dig up, B vitamins are not effective mosquito repellants, and vitamin B12, specifically, is not well-studied.

What scientists know more about is another B vitamin - B1 - also known as thiamine. As part of a larger survey of effective mosquito repellants, a 2002 study in the New England Journal of Medicine reported that, "No ingested compound, including garlic and thiamine (vitamin B1), has been found to be capable of repelling biting arthropods." -- http://thechart.blogs.cnn.com/2010/07/21/can-vitamin-b12-pre...


I wonder whether some of these folk remedies might affect the response to bites, i.e. modulating the immune system response and inflamation...

My wife always claims to be a mosquito magnet, but I have thought about it in various situations like camping and touring the tropics. I am not sure if she is getting harassed more than me, or if she just reacts more strongly to all the bites. Some of my bites are very mild, and I could believe that there might be more that I don't even notice.


I wonder if there are biochemical pathways in, let's say, Neisseria gonorrhoeae that are actually handy to have in a night on the prowl...


I wonder if this is something dogs could be trained to detect.

I used to live near a creek where there were lots of mosquitoes, and when my roommates and I could go from the car to the house on a bad day, most of us would get bitten 0-1 times, and one would get bitten 3+




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