Meningitis
From Tardis Wiki, the free Doctor Who reference
Meningitis was a potentially fatal disease.
In an alternative timeline in which penicillin had never been discovered, new strains of meningitis and pneumonia ravaged Earth in 1956. (BFA: The Sirens of Time)
In Peri's dream on YT45, her son Kyle was diagnosed with meningitis. (BFA: The Mind's Eye)