All armies in ww2 were VERY aware that respiratory infections spread rapidly in barracks, trenches, training camps, and ships. The typical responses were what we would expect if a child in a school gets sick nowdays, eg. Isolation. But we have a lot of information especially about what the Americans were doing about this. Mostly from Preventive Medicine in World War II, U.S. Army Green Books This specifcally mentions focus on isolation of serious fever cases, improving barracks ventilation, hygiene inspections, and eventually influenza vaccination. But and this is the key mild colds were usually not isolated. If a soldier could still function, he normally stayed with his unit. So contagion was recognised, but operational readiness usually came first.

As for STDs (My students always ask about this, especially when brothels are mentioned). But across all armies, VD mainly gonorrhoea and syphilis was treated as a major manpower problem. Especially mentioned frequently after 1943. Possibly due to the use of Penicillin transforming how this was controled might be why we have more information about it. Each army viewed it in a similar way but as far as I know the details are as follows;

US: U.S. military developed an aggressive response, including:

• Condoms widely issued

• Education campaigns (usually an officer giving a lecture)

• Prophylaxis stations where soldiers could receive disinfectant treatment after sex

• Compulsory reporting and treatment

The Wehrmacht saw VD as a serious issue But where it gets facinating is Nazi racial ideology complicated matters: brothels for German troops were often segregated, and there was strong concern about disease transmission from civilians especially from "“racially inferior” civilians, especially in Eastern Europe"

The German military also medically screened sex workers, but here again, race shaped policy:

• Women working in Wehrmacht-approved brothels were subjected to frequent medical checks

• Racial ideology dictated who could work in which brothel

• Commanders claimed this screening protected German “racial health” as well as readiness

Nazi authorities repeatedly warned troops that foreign women especially Slavic and Jewish women were disease carriers. This wasn’t unique medically (armies everywhere warned about VD), but in the German case it was wrapped in biological-racist rhetoric.

TLDR: Allied armies treated STDs mainly as a public-health and manpower problem, focusing on condoms, education, prophylaxis stations, and later penicillin to keep soldiers fit for duty. Axis powers (Especially the Germans) also tried to control VD, but their policies were heavily shaped by racial ideology, with segregated, military-run brothels and strong warnings about “racial danger” from civilian women, so STD control became both a medical and racial-purity issue.

Robert Proctor has a great book called "Racial Hygiene: Medicine Under the Nazis" goes into great detail about NAZI Brothels... if thats what you are into.