noun

a disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury.

bacterial meningitis is quite a rare disease

illness,sickness,ill health,infection,ailment,malady,disorder,complaint,affliction,condition,indisposition,upset,problem,trouble,infirmity,disability,defect,abnormality,pestilence,plague,cancer,canker,blight,bug,virus,lurgy,wog,contagion