Questions: What is incorrect about pertussis? Multiple Choice The paroxysmal stage is characterized by persistent coughing. The number of cases is steadily decreasing since 1976. It can cause severe, life-threatening complications in babies. A virulence factor of B. pertussis is toxins that destroy cilia cells is produced. The source of infection is direct contact with inhaled droplets.

The answer is the second one: The number of cases is steadily decreasing since 1976.

Explanation for each option:

1. The paroxysmal stage is characterized by persistent coughing.

   • This is correct. The paroxysmal stage of pertussis (whooping cough) is indeed characterized by severe and persistent coughing fits.

2. The number of cases is steadily decreasing since 1976.

   • This is incorrect. While there was a significant decrease in pertussis cases following the introduction of the vaccine, there have been periodic increases in cases in recent years due to factors such as waning immunity and reduced vaccination rates.

3. It can cause severe, life-threatening complications in babies.

   • This is correct. Pertussis can be particularly dangerous for infants, leading to severe complications such as pneumonia, seizures, and even death.

4. A virulence factor of B. pertussis is toxins that destroy cilia cells is produced.

   • This is correct. Bordetella pertussis produces several toxins, including pertussis toxin, which can damage the cilia in the respiratory tract, impairing their function and contributing to the symptoms of the disease.

5. The source of infection is direct contact with inhaled droplets.

   • This is correct. Pertussis is transmitted through respiratory droplets when an infected person coughs or sneezes, making direct contact with these droplets a common source of infection.

Summary: The incorrect statement about pertussis is that the number of cases is steadily decreasing since 1976.