Children's Health

A doctor considers the following when making a preliminary diagnosis of whooping cough (pertussis):

• Symptoms. A doctor may suspect whooping cough when a person has recently had cold symptoms and a dry, hacking cough that progresses to bursts of uncontrollable, often violent coughing that may make it temporarily impossible to breathe. Fever, sore throat, and wheezing are usually absent or very mild with whooping cough. When present, these symptoms can help a doctor distinguish between whooping cough and other conditions with similar symptoms, such as a cold or bronchitis.
• Immunization status. An important consideration when making a preliminary diagnosis of whooping cough (pertussis) is whether a person's immunizations against pertussis are up to date.
• Community outbreaks. Whooping cough may be suspected when other cases of whooping cough have recently been reported within the local community.

To diagnose whooping cough, doctors may test mucus from the nasopharynx region, which is where nasal passages meet the back of the throat. To collect a mucus sample, doctors may pass a swab or suction tube deep into the back of the nose. The sample can be tested by culture. It is the most accurate method, but it takes 10 to 14 days to get the results. Polymerase chain reaction (PCR) is often used along with culture to get test results within several days. PCR detects the genetic material (DNA) of whooping cough bacteria.

The doctor may do more than one test to find out if you or your child has whooping cough. Treatment will usually start right away if your doctor strongly suspects whooping cough as a cause of the symptoms.

Other tests may be done to rule out other problems, to monitor the person's condition, or to find out whether complications have developed.

• A complete blood count or other blood tests may be done to help rule out other diseases.
• Chest X-rays may be done, especially in infants. Although X-ray images often appear normal in whooping cough, they may be needed to rule out other possible causes of symptoms or to find out whether complications, such as pneumonia, have developed.
• A pulse oximeter may be used to check the blood oxygen levels, which helps a doctor monitor how well the lungs are working and decide what treatments to use.