Cough as a manifestation of an atypical respiratory tract infection

When should we suspect that an apparent postinfectious cough is rather a manifestation of an atypical respiratory tract infection?

Imran Satia: In patients who have cough with other symptoms, such as fever, or constitutional symptoms, such as lethargy, weight loss, malaise, I would be more worried that they may have an atypical infection, be it bacterial or mycobacterial. In this situation the history is very important. The duration of cough, travel history, drug history, the nature of the phlegm which is produced will give me more of an idea of whether or not this is an atypical infection; particularly the ethnic origin. In patients who are from an endemic area where tuberculosis (TB) is a manifestation, a common occurrence, I would be worried that a cough which lasts more than 6 weeks and is not improving may be a manifestation of TB.

If a patient who has been on immunosuppressant medications has now developed a cough, there is a possibility that this could be a reactivation of TB, could be drug-induced; if they have had chemotherapy or radiotherapy, it could be radiation-induced or drug-induced as well. In these situations taking a global history is very important to ensure that other possibilities are also evaluated.