Have germ mechanics changed?

[Charletrom]

I was trying to make a mod (I failed) but in so doing I ended up studying germ/atmosuit interactions quite closely. I observed that dupes do not get exposed to germs pumped into the suit (eg oxygen full of slimelung/zombie spore) but they DO get exposed when equipping a suit covered in zombie spores, but not slimelung or food poisoning.

My understanding was that dupes could get infected when contaminated oxygen is pumped into the suit dock, but I was not able to replicate this. Has anyone else observed this behavior?

This thread seems to describe what I’m observing for zombie spores.

 Would be very curious if anyone can replicate these findings

[Tigin]

Note it's quite difficult to get zombie spores in the O2 tank but not on the surface of the suit in real gameplay. Nonetheless, you can see here:

 

Ellie is not currently infected.

Atmo suits with no germs but a lot of spores in the O2 itself.

Equipping it instantly and breathing instantly infects.

[Charletrom]

Hmm ok that’s quite concerning, could be a bug with another mod. I’ll do some more testing to see if I can narrow it down. I’m guessing you get the same behavior with slimelung? 

[Kderosa]

12 hours ago, Tigin said:

Equipping it instantly and breathing instantly infects.

Also, putting on a suit covered with zombie surface germs will do the trick as well.

However, if the dupe is holding his breath in a room full of C02 laden with germs, they don't.

Interacting with a cannister of O2 having zombie spores will cover the dupe's exosuit with surface germs which won't be a problem until the dupe takes off the suit at the dock.  When the dupe (or another) puts the suit back on, he will become infected.

[Charletrom]

2 hours ago, Kderosa said:

Also, putting on a suit covered with zombie surface germs will do the trick as well.

This was the surprising part for me, though a happy one! Now we just need more ways for dupes to accidentally handle debris covered in zombie spores.
 

I wonder if it’s always been this way but no one noticed until your post? 

[Tigin]

The pathway for infection for zombie spores is usually through breathing, as the only to transmit diseases through surface germs for spores is through waxed transit tubes. 

Repeatedly taking off a suit with germs on the suit but not in the oxygen doesn't result in infection after manually equipping/unequipping the suit several times. Note that if the oxygen itself is contaminated, then some of the germs within the oxygen storage will transfer onto both the duplicant and suit.

However, I believe what you were actually seeing is some germs being transferred onto the oxygen tank while unequipping at the dock via storage surface germ exchange, which caused subsequent usages of that atmos suit to cause infections.

Edited March 5 by Tigin

[Charletrom]

Ok I figured it out. After disabling all my mods and performing a fresh install, I realized that I was not loading the atmosuits up with enough zombie spores to trigger the exposure warning. Using sandbox tools I filled a room with oxygen with 1 million zombie spores per tile. I was pumping the oxygen from there into the suit dock. I had set the mass per tile of oxygen too high, so that the spores/kg O2 was actually quite low. Once I fixed this issue I was able to replicate Tigin's findings.

Thanks very much @Tigin and @Kderosa for your help. I thought I was going crazy =)

 

[Charletrom]

In case anyone cares, I thought I should clarify to avoid spreading false information.

Upon further testing (and looking at the relevant code) it appears that there are two mechanics at play here. 1) transference of germs to internal atmosuit tanks when the suit is placed into an atmosuit dock. This is the same mechanic that causes germs to appear on the surface of storage bins when debris is deposited. In this case it applies not only to the surface of the dock, but to the internal atmosuit tanks as well. 2) low exposure threshold of zombie spores (1 germ for zombie spores vs 100 for slimelung).

In theory, a dupe CAN become infected by slimelung when using a contaminated suit, but in practice this will never happen. I would guess that the required number of germs in the tank needs to be something like 75,000 for slimelung, which is not possible without sandbox tools. For zombie spores you only need 750 germs, which is clearly possible based on Kderosa’s post. However, vanishingly few players will ever actually encounter this mechanic due to the rarity of debris contaminated by zombie spores.

Note that the disease difficulty settings do not matter here. They only affect the chance for an exposed dupe to acquire a disease and have no effect on exposure thresholds.

Edited March 6 by Charletrom

[Kderosa]

39 minutes ago, Charletrom said:

For zombie spores you only need 750 germs, which is clearly possible based on Kderosa’s post. However, vanishingly few players will ever actually encounter this mechanic due to the rarity of debris contaminated by zombie spores.

I've only ever run into the issue when a dupe has come into contact with a gas canister that is full of a gas containing millions of zombie spores, making it difficult to dispose of such infected gasses. 

If the gas is CO2 you can have slicksters consume the gas, you can pump the gas into the void of space, or you can take your chances releasing the spores into the atmosphere where they will eventually dissipate if not in CO2 (I believe).