What causes whooping cough in infants?

Whooping cough in infants is mainly caused by the following factors: 1. Low immunity: Infants' immune systems are not yet fully developed, making it easier for Bordetella pertussis to invade the respiratory tract and cause infection. 2. Droplet transmission: Bordetella pertussis can spread through respiratory droplets; when infants come into contact with these contaminated droplets, they may become infected. 3. Contact transmission: If infants come into contact with secretions from individuals with whooping cough, such as saliva or sputum, they may also contract the bacteria. 4. Malnutrition: Prolonged malnutrition can weaken an infant's immune system, thereby increasing the risk of whooping cough infection. 5. Environmental factors: Poor hygiene conditions, inadequate ventilation, and other unfavorable environmental factors in the infant's surroundings may also increase the likelihood of Bordetella pertussis infection.