Are there any episodes, in any of all the released Star Trek series, whose main plot is about an infection/contagion/disease or any other medical hazard affecting a large share of a starship crew or a planet population (so, not about a single sick character), and about how the crew/population try to deal with it, from a medical point of view but also with its crisis management aspects?

I'm interested in episodes where the medical aspect is the main theme, or at least one of the main plots that is explored with considerable detail, not just where there is a background reference, i.e. "We were on course to planet Random III to assist with their contagion while we encountered the energy-life-form-of-the-week".

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    Define "infection/contagion/disease"? I can think of at least three TOS episodes that might qualify.
    – Zeiss Ikon
    Commented Mar 10, 2020 at 16:49
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    good grief - there's like at least one per season for most of the series :)
    – NKCampbell
    Commented Mar 10, 2020 at 17:16
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    As to Star Trek TNG, off the top of my head I can think of Genesis, Naked Now, and Unnatural Selection. Though honestly I think Babylon 5 did it better in the episode Confessions and Lamentations. Way more realistic depiction of an epidemic than any of the Star Trek episodes I've personally seen.
    – Kai
    Commented Mar 10, 2020 at 17:27
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    I feel I should point out that there is actually an episode of TNG called “Contagion”. It’s not actually about the themes you asked about though.
    – Darren
    Commented Mar 11, 2020 at 13:35
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    'episodes of Star Trek that deal with X' are finite lists and on topic. Take a look at the 'related' for the 'mental health' question; all of those are 'lists'. Just because you're tired of thinking about corvid-19 doesn't make it off topic.
    – Mazura
    Commented Mar 12, 2020 at 5:02

5 Answers 5


The most obvious is the TOS episode The Naked Time

In the episode, a strange, intoxicating infection, which lowers the crew's inhibitions, spreads throughout the Enterprise. As the madness spreads, the entire ship is endangered.


Which was referenced in the TNG episode The Naked Now

In this episode, the Enterprise encounters a research ship where all personnel are found dead. The Enterprise crew quickly become infected with the same affliction, one that is similar to that suffered by the crew of James T. Kirk's USS Enterprise decades before.


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    What about "Miri" or "The Omega Glory"? And that's just TOS...
    – DavidW
    Commented Mar 10, 2020 at 17:30
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    And "City on the Edge of Forever" and "Operation: Annihilate!" (parasites are a form of disease, right?). And this is just three seasons of TOS...
    – Zeiss Ikon
    Commented Mar 10, 2020 at 17:31
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    don't forget "This Side of Paradise" for TOS season 1
    – NKCampbell
    Commented Mar 10, 2020 at 17:32
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    TOS season 2 - The Deadly Years. The Immunity Syndronme and Trouble with Tribbles could be honorable mentions
    – NKCampbell
    Commented Mar 10, 2020 at 17:33
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    TOS S3 - For the World is Hollow and The Cloud Minders could be honorable mentions
    – NKCampbell
    Commented Mar 10, 2020 at 17:38

The Star Trek Enterprise episodes Affliction (4x15) and Divergence (4x16) might fit what you're looking for. In the episode, Dr. Phlox is...persuaded to help the Klingon's deal with a virus that's threatening the entire Klingon species.

As an aside, the best example of the sci-fi medical crises story I know of is the Babylon 5 episode Confessions and Lamentations

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    Well, I downvoted because it's a stubby 'single example' answer to an obvious list question. I can''t speak to why others downvoted it.
    – Valorum
    Commented Mar 10, 2020 at 21:16
  • same as @Valorum - one example for a question asking for a list of examples isn't a quality answer - as well as the unnecessary reference to Bablyon 5 :)
    – NKCampbell
    Commented Mar 11, 2020 at 17:48
  • I don't think the question specified a minimum number of examples, or a minimum popularity in the specific series of Star Trek. "unnecessary reference to Bablyon 5" would be an understandable complaint if only Babylon 5 was mentioned, but it doesn't take away from the answer.
    – komodosp
    Commented Mar 12, 2020 at 9:08
  • The Babylon 5 reference is clearly marked as an aside... which means it doesn't need to be included and should be deleted. Stack Exchange is not a conversation forum.
    – T.J.L.
    Commented Mar 12, 2020 at 18:25

The Deep Space Nine episode The Quickening (4x24) deals with an illness called "the blight" on a planet in the Gamma Quadrant. The entire episode focuses on the medical situation and Dr Bashir spends a significant amount of time on the planet, trying to find a cure.

  • 1
    This is probably the best one of you are looking for something serious, and where the whole point is the disease impacting a culture
    – Andrey
    Commented Mar 13, 2020 at 19:07
  • Also a DS9 Episode where a Bajoran virus planted in the replicator gives everyone Aphasia. Commented Mar 20, 2020 at 17:07

Star Trek The Next Generation episode Unnatural Selection has a mysterious illness that destroys 1 vessel, and causes a research station to enter quarantine.


Do biological weapons count? Then there is DS9 episode 5 Babel
A natural Klingon disease is the main issue of Voyager episode 160 Prophecy

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