One challenge is that early pertussis symptoms often mimic a mild respiratory infection – runny nose, sneezing, low fever, and occasional cough. After 1 to 2 weeks, the disease often enters the paroxysmal (coughing-fit) stage, which is more alarming. Typical signs include:
Intense, rapid coughing fits (paroxysms) that can last for 1 to 6 weeks or more.
A high-pitched “whoop” sound when inhaling after a bout of coughing (not everyone develops this).
Vomiting after coughing fits.
Exhaustion, fatigue, and difficulty sleeping.
In infants, the “whoop” might not appear; what is seen instead may be apnea (pauses in breathing), cyanosis (turning blue), feeding problems, or choking episodes.
In older children and adults, sometimes the only symptom is a prolonged hacking cough without the whoop.
Because the early phase is so mild, many cases go undiagnosed until the cough becomes severe.
