Denise Murphy

The Changing Epidemiology of Invasive Pneumococcal Disease in Aboriginal and Non-Aboriginal Western Australians from 1997 through 2007 and Emergence of Nonvaccine Serotypes

BACKGROUND. In 2001, Australia introduced a unique 7-valent pneumococcal conjugate vaccine (7vPCV) 2-, 4-, and 6-month schedule with a 23-valent pneumococcal polysaccharide vaccine (23vPPV) booster for Aboriginal children, and in 2005, 7vPCV alone in a 2-, 4-, and 6-month schedule for non-Aboriginal children. Aboriginal adults are offered 23vPPV but coverage is poor. We investigated trends in invasive pneumococcal disease (IPD) in Western Australia (WA). METHODS. Enhanced IPD surveillance has been ongoing since 1996. We calculated IPD incidence rates for Aboriginal and non-Aboriginal Australians before and after introduction of 7vPCV. RESULTS. A total of 1792 cases occurred during the period 1997-2007; the IPD incidence rate was 47 cases per 100,000 population per year among Aboriginal people and 7 cases per 100,000 population per year in non-Aboriginal people. After introduction of 7vPCV, IPD rates among Aboriginal children decreased by 46% for those <2 years of age and by 40% for those 2-4 years of age; rates decreased by 64% and 51% in equivalent age groups for non-Aboriginal children. IPD rates decreased by >30% in non-Aboriginal people 50 years of age but increased among Aboriginal adults (eg, from 59.1 to 109.6 cases per 100,000 population per year among those 30-49 years of age). Although IPD due to 7vPCV serotypes decreased in all age groups, IPD incidence due to non-7vPCV serotypes increased, and it almost doubled among Aboriginal adults 30-49 years of age (from 48.3 to 97.0 cases per 100,000 population per year). Among non-Aboriginal children, 37% of IPD is now due to serotype 19A. CONCLUSIONS. IPD incidence rates have decreased markedly among children and non-Aboriginal adults with a 3-dose infant 7vPCV schedule. However, IPD due to non-7vPCV serotypes has increased and is of particular concern among young Aboriginal adults, for whom an intensive 23vPPV campaign is needed. An immunization register covering all age groups should be established.

The initial coverage and impact of the pneumococcal and influenza vaccination program for at-risk Indigenous adults in Far North Queensland

Objectives: To describe the initial coverage and impact of a pneumococcal and influenza vaccination program for at‐risk Indigenous adults in Far North Queensland that formally commenced in 1996.

Age-Specific Cluster of Cases of Serotype 1 Streptococcus pneumoniae Carriage in Remote Indigenous Communities in Australia

ABSTRACT Seven-valent pneumococcal conjugate vaccination commenced in 2001 for Australian indigenous infants. Pneumococcal carriage surveillance detected substantial replacement with nonvaccine serotypes and a cluster of serotype 1 carriage. Our aim was to review Streptococcus pneumoniae serotype 1 carriage and invasive pneumococcal disease (IPD) data for this population and to analyze serotype 1 isolates. Carriage data were collected between 1992 and 2004 in the Darwin region, one of the five regions in the Northern Territory. Carriage data were also collected in 2003 and 2005 from four regions in the Northern Territory. Twenty-six cases of serotype 1 IPD were reported from 1994 to 2007 in the Northern Territory. Forty-four isolates were analyzed by BOX typing and 11 by multilocus sequence typing. In the Darwin region, 26 children were reported carrying serotype 1 (ST227) in 2002 but not during later surveillance. Scattered cases of serotype 1 carriage were noted in two other regions. Cocolonization of serotype 1 with other pneumococcal serotypes was common (34% serotype 1-positive swabs). In conclusion, pneumococcal carriage studies detected intermittent serotype 1 carriage and an ST227 cluster in children in indigenous communities in the Northern Territory of Australia. There was no apparent increase in serotype 1 IPD during this time. The rate of serotype 1 cocolonization with other pneumococcal serotypes suggests that carriage of this serotype may be underestimated.

Multilocus genetic analysis reveals that the Australian strains of Vibrio cholerae O1 are similar to the pre-seventh pandemic strains of the El Tor biotype

Episodes of cholera stemming from indigenous Vibrio cholerae strains in Australia are mainly associated with environmental sources. In the present study, 10 V. cholerae O1 strains of Australian origin were characterized. All of the strains were serogroup O1 and their conventional phenotypic traits categorized them as belonging to the El Tor biotype. Genetic screening of 12 genomic regions that are associated with virulence in V. cholerae showed variable results. Analysis of the ctxAB gene showed that the Australian environmental reservoir contains both toxigenic and non-toxigenic V. cholerae strains. DNA sequencing revealed that all of the toxigenic V. cholerae strains examined were of ctxB genotype 2. Whole genome PFGE analysis revealed that the environmental toxigenic V. cholerae O1 strains were more diverse than the non-toxigenic environmental O1 strains, and the absence of genes that make up the Vibrio seventh pandemic island-I and -II in all of the strains indicates their pre-seventh pandemic ancestry.