I am a new hire at a software company in North America. I recently noticed that my direct manager coughs up a lot and keep coughing for 1-2 minutes straight. 

When I inquired couple of colleagues , they also seemed worried but don't know what to do. They informed me that he has this condition for more than 4 years and they don't know about the exact disease. 

I sit in close proximity to him and am very worried that his disease might a contagious one. The company is a small company with about 50 employees and we don't have a formal HR department. 

What can I do in this situation ?