EPIREVIEW: Pertussis in New South Wales, 1993–2005: the impact of vaccination policy on pertussis epidemiology

Abstract

Pertussis, or whooping cough, is a highly contagious disease caused by the bacteria Bordetella pertussis. The disease is characterised by paroxysmal cough, inspiratory whoop and post-tussive vomiting. 1 Pertussis is transmitted via direct contact with discharges from the respiratory tract of infected individuals (probably via droplets), and the incubation period is 9-10 days on average. 2 A secondary attack rate of 90% has been recorded in non-immune household contacts. 2 Worldwide, the incidence of pertussis has been reported to be highest in children under 5 years, except where infant vaccination programs have achieved consistently high vaccination rates. 2 In NSW, there have been several changes to the immunisation schedule affecting pertussis vaccination in recent years. From 1985, a combined whole cell diphtheria, tetanus and pertussis vaccine (DTPw) was included in the immunisation schedule at ages 2, 4 and 6 months, with a booster at 18 months. 3 In 1994, a fifth dose was introduced Methods: Surveillance data from the NSW Notifiable Diseases Database was reviewed for the period. Results: 35695 cases of pertussis were notified; annual incidence rates varied from 18.4 to 84.2 per 100000 people. The highest rates of pertussis were consistently found in infants aged 0-6 months. Rates of disease in other age groups changed markedly over the study period, with high rates currently observed in adult age groups. Conclusions: New strategies may be needed to control pertussis in infants and in adults who now comprise the largest proportion of cases.

Review of the 2008–2009 pertussis epidemic in NSW: notifications and hospitalisations

“…8 The most recent epidemic in 2005 was dominated by cases in adults whose disease was largely diagnosed by serology. 9 In this paper we review the epidemiology of pertussis cases notified in NSW since 1998.…”

NSW Annual Vaccine-Preventable Disease Report, 2009

“…In 2009, 12 578 cases of pertussis were notified in NSW compared with 8759 in 2008 and 2100 in 2007. While epidemics of pertussis occur every 3-5 years, 8,9 the number of cases notified in 2008 and 2009 far exceeded previous epidemic years (Figure 7). The number of notified cases peaked during the first quarter (5497) and declined in the last quarter of 2009 (1823).…”

Pertussis Vaccine in COPD and Asthma: An Old Acquaintance Is Back

“…The adults aged 65–74 and ≥75 years old have a higher risk of pertussis-related hospitalizations than adults aged 45–64 years, up to 4–6 times higher. 3 , 4 …”