1. Viral respiratory infections
There are two types of respiratory infections: viral upper respiratory tract infections and lower respiratory tract infections. The first includes diseases such as the common cold, sinusitis, laryngitis, tonsillitis, and the flu while the latter includes diseases such as pneumonia, bronchiolitis, tuberculosis, bronchitis, and also the flu.
As the name itself indicates, viral respiratory infections are caused by different viruses and are classified accordingly. Its severity also varies greatly depending on the type of virus and the condition of the person affected.