- Just how serious is it, Doctor?
- Extremely serious. It starts with a slight fever, dryness of the throat.

10 seconds sound clip from the Airplane (1980) movie soundboard.

You can hear this line at 00:41:29 in the Blu-ray version of the movie.

Quote context

[...]

- It's nothing to be alarmed about. We'll be back to you very quickly.

- Dr. Rumack, Mr. Hammen ate fish, and Randy said there are five more cases, and they all had fish, too.

- And the copilot had fish. What did the navigator have?

- He had fish.

- All right. Now we know what we're up against.

- Every passenger on this plane who had fish for dinner will become violently ill in the next half-hour.

- Just how serious is it, Doctor?

- Extremely serious. It starts with a slight fever, dryness of the throat.

- As the virus penetrates the red blood cells, the victim becomes dizzy, begins to experience an itching, a rash.

- From there, the poison goes to work on the central nervous system, causing severe muscle spasms, followed by the inevitable drooling.

- At this point, the entire digestive system collapses, accompanied by uncontrollable flatulence...

- Until finally the poor bastard is reduced to a quivering, wasted piece of jelly.

[...]