**Question:** True regarding pertussis is all, except -

A. It is a bacterial infection caused by Bordetella pertussis
B. It primarily affects infants under the age of six months
C. It is a common infection in adults and children
D. Vaccination is the primary prevention method

**Core Concept:** Pertussis is a highly contagious respiratory illness that primarily affects infants and young children. It is caused by the bacterium Bordetella pertussis and is characterized by a series of symptoms, including paroxysmal coughing fits, whooping sound, and post-catarrhal phase with prolonged coughing. Vaccination is the primary preventive measure against pertussis.

**Why the Correct Answer is Right:**

Option A is incorrect because pertussis is caused by Bordetella pertussis, not Haemophilus influenzae, which is the bacterium associated with whooping cough. Option B is wrong because pertussis is common in infants under the age of six months, as they have not yet completed the recommended vaccination schedule, making them more susceptible to infection. Option C is incorrect because pertussis is also common in adults and children who have not received the recommended booster shots. Vaccination is the primary preventive measure against pertussis, reducing the severity and frequency of the disease in vaccinated individuals and protecting the unvaccinated population through herd immunity.

**Why Each Wrong Option is Incorrect:**

Option A (Haemophilus influenzae) is incorrect because Haemophilus influenzae is responsible for another respiratory infection, i.e., acute otitis media, not pertussis. Option B (infants aged 6 months) is wrong because pertussis affects infants of all ages, not just those aged six months. Option C (children and adults) is incorrect because pertussis can affect people of all ages, despite vaccination, making it important to maintain vaccination rates in the community.

**Core Concept:** Vaccination is crucial for preventing and controlling pertussis, as it reduces the severity and frequency of the disease in vaccinated individuals and contributes to herd immunity in the unvaccinated population.

**Why Each Wrong Option is Incorrect:**

Option A (Haemophilus influenzae) is incorrect because Haemophilus influenzae is responsible for another respiratory infection, i.e., acute otitis media, not pertussis. Option B (infants aged six months) is wrong because pertussis affects infants of all ages, not just those aged six months. Option C (children and adults) is incorrect because pertussis can affect people of all ages, making it important to maintain vaccination rates in the community to prevent the spread of the disease.

**Core Concept:** Vaccination is essential for preventing and controlling pertussis, as it reduces the severity and frequency of the disease in vaccinated individuals and contributes to herd immunity in the unvaccinated population. By maintaining high vaccination rates, we can protect infants, who are too young to be vaccinated, from contracting pertussis through herd immunity.