Other people nearby can then breathe in the germs. Touching a tissue or sharing a cup used by someone with pertussis can also spread the disease. The first symptoms appear about 7 to 10 days after a person is exposed. People with pertussis can spread the disease starting 2 weeks before until 3 weeks after the cough starts, or until they have finished 5 days of the 14-day antibiotic treatment. In this state, pertussis is most common among people 10-20 years old, who have lost the protection they got from childhood vaccines.
Infants are the next group most likely to get the disease, but anyone can catch it.
Pertussis can be hard to diagnose in very young infants, teens and adults because their symptoms often look like a cold, followed by a nagging cough that lasts for weeks or months. It can be, especially for infants. Pertussis can also cause death, especially in very young infants, but this is rare. In older children, teens and adults, the disease is milder but may last for weeks or months. A doctor may think a patient has pertussis because of the symptoms, but a sample of mucus must be taken from the back of the nose for testing.