An almost ubiquitous feature of space Airlocks is the "Environmental Monitoring System", as described here . Since the aliens on board died, we should assume that their Environmental Monitoring System was completely insufficient for detecting the virus in question, and thus, unfit for future use. It obviously needs to be replaced. It is probably safe to assume that the airlock doors are sufficient at compartmentalizing the atmosphere, but those too should be tested. But, in the meantime, if we have some spare EMS equipment on the ship we came in on, we can start setting them up in a temporary fashion, determine which parts of the ship are contaminated, and use the parts that are not more freely, without suits, and even set up a base of operations in the parts of the ship that can be verified as clean zones. However, this requires our Doctor to pass on some basic identifying characteristics of this virus, so we can plug that data into the tiny database the EMS panels use. And when I say basic, I do mean basic; you don't have to understand what a virus does to a living thing to be able to identify it, in much the same way you don't have to understand the systems of a mystery starship on your sensors in order to identify it again; you just have to find a combination of things about it that are unique. The size and shape of the outer coating (which can be rather polyhedral) can be easily detected with the Traveller equivalent of a mass-produced scanning electron microscope; if these two things are sufficiently unique and consistent, the virus can be identified by those characteristics alone. The chemical composition of the outer coating (which proteins it's made of), and whether its genetics is composed of DNA or RNA or both, are also simple chemical litmus-type testable characteristics that would make such a system effective but affordably "low tech". This is all without getting into detailed genetic stuff, like whether the genes are a double or single helix, whether there are multiple "chromosomes", the size of its genome, basic chromatography, and the composition and variation of its actual genetic sequences. Of course, the virus itself may simply not be easily identified, or may be genetically diverse enough to have different specimens look differently from one another. On the other hand, if the virus is genuinely radically different from other viruses, it should be easy to identify on the basis that it's completely unique; but that would make it a spectacular scientific discovery as opposed to a mundane one, meaning the virus itself is the mission , on account of its value to science, and also that the ship itself is unfit for its intended mission, having a radical, poorly understood, and potentially disasterous disease on board... and that we would need to get a new ship, that doesn't have that problem. :P
