Catfolk are getting sick, which means Chime's friend Calsa is in danger. He has to tell Chime -

And he can't, because that would jeopardize the secret of his magic. His gut twinges.

He flops on his cot and pretends to sleep.

Dr. Montero has brought a lot of stuff, including full plastic biohazard suits and plenty of sterile supplies. They'll burn it, once they're done. He'd like to talk to the local doctors before doing anything. Due to pharmacological uncertainty, his current plan is to get saliva and skin swab samples from the sick catfolk and also from healthy catfolk and use the sequencer to detect what kinds of microbes are only present in sick catfolk saliva. If the saliva and skin swabs doesn't reveal any signs of microbes, a blood sample may be necessary, they use tiny disposable sterile needles like this. Then, maybe it's one that Exodus knows about and knows how to kill. Or maybe it's an unknown one and they'll have to figure it out. They could just use the usual set of anti-bacteria and anti-virus drugs Exodus has, or try more exotic options like a phage to hunt a particular species of bacteria or artificially produced antibodies, but he'd like to be conservative with new treatments on unknown biology. Talking to a liefling, a lot, would help with this. They can also do palliative care- Addressing the pain and monitoring for more serious issues and trying to keep everyone healthy and alive. Fluid IVs, lung lavage if they're having trouble breathing, and so on.

Nivis is undergoing a partial quarantine, itself, as well. Nobody who interacted with the aliens is sick, and everyone who interacted with them or touched things they touched or cleaned their food trays or anything like that is being made to go through checks (the same swabs and looking for unusual physiological signs), but they are being careful and double checking.

The liefling has been relieving the patients' joint inflammation.

The wroth doesn't smell anything different about the patients other than stress.

The magistrate of Orocide approves of all the precautions, but says probably everyone will get better soon and then they can reopen the town.

The saliva and skin swabs do not find any microbes only present on the sick catfolk.

Same with the blood samples.

Everyone has traces of Earth microbes on their skin, common types known to be normal on humans. The sick don't have a different amount or distribution than the healthy, except that Tolesli has more of several Ansaf microbes in his mouth, consistent with having thrown up recently.

Huh. And if he also checks for known toxic chemicals, and for radiation, and for hormone markers being markedly different between healthy and afflicted... Any luck?

When did the patients first notice symptoms? Have they done anything like taken a fall or eaten anything unusual? Any common factors among the afflicted at all? (He maintains a smooth, calm demeanor and will discuss Exodus-style medicine with doctors Shor and Mipawtn in very tentative Sotalese, in the meanwhile. He can understand liefling-lexicon better than most non-lieflings, though from a totally different angle.)

No luck.

Leslie went for a run, feeling fine, and suddenly became nauseous. As he was returning to the town, the joint pain developed rapidly. The other sick catfolk reported joint pain a few minutes later. Only some of them have had nausea, after not before, and not as badly as Leslie. 

Leslie didn't do anything unusual that Hester didn't, and Hester is still feeling fine.

One of the patients licked Hester briefly before he said to stop because of worries about alien diseases. Two of the patients are siblings who work together on experimenting with using ice as a building material; they were asleep when the party returned. One patient helped set up the ILS. There are now three more catfolk in solo quarantine just in case, and one gnomunk, all with only mild joint pain.

In general, the pain is only in a few joints, but which ones exactly varies from person to person. None of the afflicted have bio-children and only one has an adopted child... which might just be because they're younger than average.

...He also approves highly of all the caution but the symptoms are mild and don't warrant more invasive checks yet. So, time for observation.

The good Magistrate might be correct; People have been primed to think about whether they are sick, and thus report so even if it might be nothing, or something else. It's still good to be very cautious, new diseases could be very very bad, but Dr. Montero and his staff should stop poking things for now, probably.