Pertussis or whooping cough, known colloquially as 100-day cough, is a bacterial respiratory tract infection. Pertussis spreads when an infected person coughs, sneezes, or has a runny nose.
Reported cases of pertussis in Thailand have been relatively low. The Department of Disease Control received only 167 pertussis notifications in 2018; however, the Queen's National Institute of Child Health conducted a study on children who had been coughing for longer than seven days, excluding children with tuberculosis and asthma, about 20% had pertussis, proving that pertussis is likely significantly underdiagnosed and recognized.
The low number of confirmed pertussis is due to the subtlety of diagnoses; it needs laboratory confirmation available only at large hospitals, specimen collection requires special devices, and doctors must have an awareness and high index of suspicion for pertussis. Hence, pertussis often is still missed in Thailand.
The incubation period of pertussis is about 7-10 days, but it can take up to 20 days or more; the disease has three stages:
- Catarrhal stage: The flu-like symptoms include mild coughs, a slightly runny nose, and low-grade or no fever; unlike the flu, the coughs aggravate, but mucus production remains unchanged; the stage is highly contagious lasting 1-2 weeks.
- Paroxysmal stage: During this stage, coughs escalate; patients experience spasmodic coughing spells, and post-tussive vomiting; a bout of paroxysmal coughing spells leave hardly enough time to take a breath; mundane actions such as yawning or laughing can trigger coughing spells; some patients, particularly young children, may turn blue; this stage can last up to 8 weeks.
- Convalescent stage: Coughs become gradually less severe and eventually, this usually takes several more weeks.
Combining the three stages, infected children have coughing spells for about 112 days on average; the complications secondary to the severity and length of the cough are fractured ribs, subconjunctival hemorrhages, back pain, and urinary incontinence.
- For young children, particularly those under a year old, the symptoms can be more serious; some may have a seizure, pneumonia, encephalitis, and a short spell of apnea which can be life-threatening. If the coughs in small children are not getting better, they should come to see a doctor for diagnosis and treatment.
- For adolescents or adults who have completed the primary vaccination series and a booster dose, the symptoms are much milder or entirely asymptomatic.
Appropriate antibiotics are the treatment for pertussis; they are most effective during the first seven days after symptom onset. If there is a delay, i.e., antibiotics given after paroxysmal coughs have set in, antibiotics are of minimal help in relieving the symptoms or speeding up the recovery. Hospital admission may be necessary for young children who may need intravenous fluid from coughing so hard they cannot eat and begin vomiting or have no appetite.
The best preventive measure for pertussis is immunization. According to The Pediatric Infectious Disease Society of Thailand, 2022 guideline, Thai children should receive a primary pertussis vaccination series at ages 2, 4, and 6 months; and booster doses at age 18 months, 4-6 years, 11-12 years, and once every ten years afterward.
It takes a newborn six months to complete the primary vaccination series; because young children have more severe symptoms, women between 27-36 weeks of pregnancy should get a shot of the pertussis vaccine to generate antibodies against pertussis and pass on to the fetus.
Adults in the same household should be vaccinated to prevent them from passing pertussis to the infant.
A close-contact person at risk of developing severe pertussis or a healthy person living in the same house with a pertussis patient should receive prophylactic antibiotics to prevent the infection. As is the case of infected patients, early antibiotic treatment provides more effective prevention.
