Answer: Legionella infection.
Step-by-step explanation:
Legionnaires disease doesn't spread from one person to another person. They spread by the help of mist such as air conditioning units in large buildings.
The adults who are greater than the age of 50 and have addiction of tobacco is more prone to this disease because they have weaker immunity.
The common symptoms of this disease is also same like common flu, fever, chills , diarrhea, headache et cetera.