Could be someone was harboring some kind of cold virus and due to the stress of the environment—it had turned colder 4 days prior—the virus reemerged and became infectious. Another idea that's not mentioned in the article, but that might be possible, is that there was some dust that contained enough of some respiratory virus to be infectious, and due to the recent cold or just by chance, someone was digging through some supplies and breathed it in. Usually viruses degrade rapidly in the environment, since they have no metabolism to speak of to correct damage; I wonder, though, if enough could survive in a cold environment with limited or no sunlight, especially if it was in a storage area that had low relative humidity.
Critical part of the conclusion for those not wanting to skim the article:
> Virus might have persisted in the respiratory tract of one or more men at the Base. If such were the case it would be necessary to postulate a triggering mechanism to precipitate symptoms, and it is interesting to note that symptoms occurred 4 days after a precipitous fall in outside temperature, and during one of the coldest months of the year, which Hope-Simpson (1958) and Lidwell, Morgan & Williams (1965) have correlated with increased incidence of respiratory disease. There is disagreement about whether the viruses which cause common colds can be carried by adults, and how important this is in epidemiology. The pattern of virus infection revealed by long-term studies, such as the virus watch programme (Elveback et al. 1966), is of a series of short infections with different viruses, and in the case of influenza virus disappearance of the current strain when a new serotype appears. On the other hand, adenoviruses may be shed by children for periods of months and recove"ed from the tonsils in a high proportion of cases, without evidence of acute respiratory infection, and non-respiratory viruses such as those of the herpes group often persist for the lifetime of a man. Furthermore, observations in animals have shown that pigs can carry swine influenza and transmit infection to other pigs 3 months later (Blaskovic et al. 1970), turkeys may carry and shed influenza virus A after apparent recovery (Robinson, Easterday & Tumova, 1972), and cattle which have recovered from foot and mouth disease still reproduce virus in the pharynx, and can initiate epidemics on contact with non-immune cattle (Graves et al. 1971).
> There are thus precedents in both children and animals for persistence of respiratory viruses, but in adults the laboratory evidence for carriage and reactivation of common cold viruses is weak. It may be that such evidence can only be found in rather unusual conditions of isolation and stress, such as occur in Antarctica. It is likely to be a rare phenomenon, but it might well be important in explaining the persistence of the large number of rhinovirus serotypes which make an appearance in many areas when the temperature falls.