Clinical picture compatible with pertussis, e.g. a cough illness lasting at least 2 weeks with one of the following: paroxysms of coughing, inspiratory "whoop" or post-tussive vomiting without other apparent cause.
Babies less than six months old do not cough, but they manifest dyspnea and paroxysmal asphyxia and are the most likely to die of the disease unless they receive suitable treatment.
“After four years of festering protest and a month of mounting violence, India’s oil-rich state of Assam exploded in a paroxysm of communal and religious hatred.” —Time, March 7, 1983.
Characteristics of cough should be investigated, particularly whether the cough is paroxysmal in nature, increases during the night and occurs in the absence of fever.