An illness has been slowly spreading throughout the inhabitants of my agrarian society, decimating villages. The first sign of infection is the excessive production of slimy yellow saliva, and since it is in excess, they have no choice other than spit it out (and risk being found out), or swallow it (a long and painful process). Those infected are tied to trees outside of inhabited regions in order to lower the spread of disease. As their illness progresses, their abdomens become bloated, until the point of eruption. Upon eruption, they die, and their bodies (particularly their slimy yellow abdominal cavity) become a hub for infection.

What is this bacteria producing that is so sickly yellow? The only thing I can think of is sulfur, yet there would be no reason for sulfur to exist in the bodies of these farmers (and I'm not looking for a reason). What compounds, in particular, are causing this, and how does it relate to a bacterial infection?

Extra Credit - How does it relate the bloating and explosion of the abdomen?

EDIT - I do not mean to find an actual illness that has these symptoms, nor do I mean for you to design one - I am asking what sort of yellow substances could be produced by a bacteria while in a host.

  • 3
    $\begingroup$ Elemental sulfur is yellow, but you're probably looking for a compound since it's biologically produced. Is there some reason you need to know what it is exactly? $\endgroup$
    – Asher
    May 13, 2017 at 1:33
  • $\begingroup$ @Asher Right - which is why I'm asking for something else, I don't quite see the bacteria producing sulfur out of no where. There isn't a reason I need to know what it is precisely (though I would like to know), but I do need to know if it's in the realm of possibility. Perhaps a "reality check" tag would be more applicable than one of the others I've put on there? $\endgroup$
    – user19838
    May 13, 2017 at 1:43
  • 3
    $\begingroup$ Are you looking for a real illness (and then you should better ask this on a byology or medical site) or something different? $\endgroup$
    – L.Dutch
    May 13, 2017 at 7:34
  • 1
    $\begingroup$ Riboflavin, also known as vitamin B₂, is yellow. Flavonoids are yellow. Carotenoids are yellow, orange or red. Bilirubin is yellow. Bile is yellow-green. Yellow sputum indicates an infection; "the more intense the yellow color, the more likely it is a bacterial infection" says Wikipedia. $\endgroup$
    – AlexP
    May 13, 2017 at 8:02
  • 1
    $\begingroup$ In-character questions can get a very mixed reception. If you want to be certain it won't be downvoted because of that, consider not writing in-character or in-story. $\endgroup$
    – user
    May 13, 2017 at 17:29

1 Answer 1


There are slime molds that have a vivid yellow color. Here is fuligo septic, the "dog vomit slime mold". Here is fulgio septicum from https://en.wikipedia.org/wiki/Slime_mold.

enter image description here

enter image description here Here is Physarum polycephalum.

The yellow is an organic molecule: a pigment that the organism makes. enter image description here

Xanthomonas is a bacterium. The prefix xanth means yellow and it was named for how yellow it is. Again the yellow is organic pigments produced by the bacterium.

enter image description here from http://www.apsnet.org/edcenter/intropp/lessons/prokaryotes/Pages/CitrusCankerPort.aspx

Xanthomonas is a plant pathogen but the related bacteria pseudomonas can make humans sick under some circumstances. Pseudomonas is a big deal for people with cystic fibrosis. Pseudomonas is known to make lots of colorful pigments. Yellow is apparently rare but has been described.

Other bacteria also make yellow pigments. from http://whitemanlabarchive.weebly.com/sonoran-desert-diversity-blog enter image description here

The yellow pigments in pseudomonas are siderophores which means they bind some inorganic molecule. "Siderophore" might be specific to iron. It is interesting that other organic molecules that bind metals (hemoglobin, chlorophyl) are also brightly colored.

In any case: your pathogen. It could be a pseudomonad. Bad pseudomonas infections can yield colored pus - usually green or blue. You can look for those images if you are interested. Pus is already usually yellowish so it would not take much help to push it to vivid yellow.

Pseudomonas also often have a strong weird smell. Pseudomonas aeruginosa is compared to grape gum. You should have your yellow pus have a strong smell too. It might be interesting for the story if it were not a bad smell. Cinnamon?

Last and best: your disease is similar to diseases caused by actinomycetes. Actinomycotic infections produce yellow lumps called sulfur granules. From https://www.studyblue.com/notes/note/n/exam-3-resp-cardio/deck/3212387 enter image description here

This is lung but the characteristic site is face and neck. Big masses can form which drain pus and these granules. The disease is called "lumpy jaw" in cattle.

The sulfur granules are not made of sulfur. The organism itself has yellow pigments, like the above mentioned and the granules are wads of organisms.

Some sort of super virulent actinomycotic infection would work for your world and would not be much of a stretch. I am sad to tell you that the sulfur granules do not at all smell like cinnamon.


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