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Analysis of Bordetella pertussis pertactin and pertussis toxin types from Queensland, Australia, 1999–2003

DOI: 10.1186/1471-2334-6-53

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Abstract:

Forty-six B. pertussis isolates recovered from Queensland patients between 1999 and 2003 were examined by both DNA sequencing and LightCycler? real time PCR to determine their pertactin and pertussis toxin subunit 1 genotypes.Pertactin typing showed that 38 isolates possessed the prn1 allele, 3 possessed the prn2 allele and 5 possessed the prn3 allele. All forty-six isolates possessed the pertussis toxin ptxS1A genotype. Amongst the circulating B. pertussis population in Queensland, 82.5% of the recovered clinical isolates therefore possessed the prn1/ptxS1A genotype.The results of this study compared to historical research on Queensland isolates suggest that B. pertussis pertactin and pertussis toxin variants are not becoming more prevalent in Queensland since the introduction of the acellular vaccines. Current prevalences of pertactin variants are significantly different to that described in a number of other countries with high vaccine coverage. Relative paucity of recovered isolates compared to notified infections, due primarily to non culture based pertussis diagnostics is however a confounding factor in the assessment of variant prevalence.Bordetella pertussis, the etiological agent of 'Whooping Cough' remains prevalent in Australia despite the introduction and wide spread use of pertussis vaccines as part of the childhood immunisation scheme. The Australian standard vaccination schedule for pertussis consists of acellular vaccines given in doses at 2, 4 and 6 months, followed by a fourth dose at 4 years and a booster at 15–17 years of age [1]. Prior to 1999 a local whole cell vaccine was in use beginning in the decade 1936–1945. [2]. An 'Immunise Australia' program established in 1997 has set a target of 90% coverage for pertussis vaccination [2]. In the Australian state of Queensland pertussis vaccine coverage in the 1990s moved from the high 70% to mid 80%, and then rose above the 90% target from 2001 onwards [2-4]. In spite of this high vaccine coverage, i

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