Diagnosis for Pertussis

The diagnosis is usually made on the clinical symptoms of pertussis. The general symptoms include:

• Cold or flu-like symptoms during the first 1-2 weeks: a runny nose, red runny eyes, a slight cough, and a temperature (usually mild)
• Bouts of coughing that become increasingly worse over the next 2-4 weeks. These episodes of coughing can be followed by the sudden effort to breathe, causing the characteristic ‘whoop’ sound of pertussis. Other symptoms during this period include coughing up thick mucus, and vomiting after the coughing attack, which is really more characteristic of pertussis that the ‘whoop’. Patients, especially infants, may turn blue, and afterwards they become very tired and may lose weight.
• The cough and whoop may last for many weeks or even months in the “classic illness”, especially if the patient simultaneously catches a cold or a throat infection

It is much harder to diagnose older children and adults suffering from mild pertussis, as the early symptoms are very similar to an ordinary cold; thus, the doctor may make the diagnosis on the basis of a characteristic history and the symptoms after several days.

The best method for diagnosis would be to take a sample from the back of the nose and culture it – that is, inoculate the sample on a growth medium so that the Bordetella pertussis bacteria responsible for whooping cough can proliferate. However, in some cases, the sample may fail to capture any of the bacteria present. Blood tests can only help if they show a high rise in pertussis antibodies, and this usually can only be seen if a blood test is taken quite early on in the course of the illness, and another blood test taken at the end of the illness. A large enough rise in antibodies must be shown in order to make the diagnosis.

- Maria Nguyen

Sources:

The Family Encyclopedia of Medicine and Health; 1996, The Book Company

http://www.pertussis.com/faq.html