Epidemiology of Pertussis among Young Pakistani Infants: A Community-Based Prospective Surveillance Study

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Clin Infect Dis. 2016 Dec 1;63(suppl 4):S148-S153.

Epidemiology of Pertussis among Young Pakistani Infants: A Community-Based Prospective Surveillance Study

Omer SB^1,2,3,4, Kazi AM⁵, Bednarczyk RA^2,4, Allen KE¹, Quinn CP⁶, Aziz F⁵, Sial K⁵, Phadke VK⁷, Tondella ML⁶, Williams MM⁶, Orenstein WA^4,7, Ali SA⁵.

¹Department of Global Health.
²Department of Epidemiology.
³Department of Pediatrics.
⁴Department of Emory Vaccine Center, Emory University, Atlanta, Georgia.
⁵Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan.
⁶Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention.
⁷Division of Infectious Diseases, Emory University, Atlanta, Georgia.

Abstract below; full text is at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5106628/

BACKGROUND:

Pertussis remains a cause of morbidity and mortality among young infants. There are limited data on the pertussis disease burden in this age group from low- and lower-middle-income countries, including in South Asia.

METHODS:

We conducted an active community-based surveillance study from February 2015 to April 2016 among 2 cohorts of young infants in 4 low-income settlements in Karachi, Pakistan. Infants were enrolled either at birth (closed cohort) or at ages up to 10 weeks (open cohort) and followed until 18 weeks of age. Nasopharyngeal swab specimens were obtained from infants who met a standardized syndromic case definition and tested for Bordetella pertussis using real-time polymerase chain reaction. We determined the incidence of pertussis using a protocol-defined case definition, as well as the US Centers for Disease Control and Prevention (CDC) definitions for confirmed and probable pertussis.

RESULTS:

Of 2021 infants enrolled into the study, 8 infants met the protocol-defined pertussis case definition, for an incidence of 3.96 (95% confidence interval [CI], 1.84-7.50) cases per 1000 infants. Seven of the pertussis cases met the CDC pertussis case definition (5 confirmed, 2 probable), for incidences of CDC-defined confirmed pertussis of 2.47 (95% CI, .90-5.48) cases per 1000 infants, and probable pertussis of 0.99 (95% CI, .17-3.27) cases per 1000 infants. Three of the pertussis cases were severe according to the Modified Preziosi Scale score.

CONCLUSIONS:

In one of the first prospective surveillance studies of infant pertussis in a developing country, we identified a moderate burden of pertussis disease in early infancy in Pakistan.