Abstract:
BACKGROUND : In low- and middle-income countries, including South Africa, the epidemiology of pertussis
in relation to immunization, nutritional, and HIV status is poorly described. This article reports on risk
factors in South African children hospitalized with pertussis.
METHODS : A prospective, hospital-based, sentinel surveillance programme for pertussis was conducted in
Gauteng Province, South Africa. Hospitalized children ( 10 years) meeting the surveillance criteria for
clinically suspected pertussis were screened and enrolled. Nasopharyngeal specimens were collected for
real-time multiplex PCR and culture of Bordetella species.
RESULTS : Bordetella pertussis was detected in 6.2% (61/992) of children. Pertussis was significantly more
prevalent in infants younger than 3 months (9.8%; 38/392) and in young children between the ages of 5
and 9 years (12%; 4/34) (p = 0.0013). Of the 61 confirmed pertussis cases, 17 were too young for
vaccination. Of the remaining 44 infants, vaccination DTP1 was administered in 73% (32/44) of pertussisconfirmed
patients who were eligible, DTP2 in 50% (16/32), DTP3 in 54% (14/26), and DTP4 in 56% (5/9) of
vaccine-eligible cases at 18 months of age. B. pertussis infection was less likely in children immunized at
least once (5%, 32/692) than in unvaccinated children (10%, 24/230) (p = 0.0001). HIV exposure and
infection status were determined in 978 (99%) patients: 69% (678/978) were HIV-unexposed and
uninfected and 31% (300/978) were HIV-exposed. Of these HIV-exposed patients, 218 (22%) were proven
HIV-exposed and uninfected and 82 patients were HIV-infected (8.4%, 82/978). HIV prevalence was
similar in pertussis-positive (6%, 5/82) and pertussis-negative (6%, 55/896) children (p = 0.90). B. pertussis
infection was unrelated to poor nutritional status.
CONCLUSIONS : In South Africa, B. pertussis poses a greater risk to infants who are too young for the
first
vaccine dose, those who are not vaccinated in a timely manner, and those who do not receive all three
primary doses. HIV infection and HIV exposure were not associated with pertussis infection.
