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1.  A prospective case–control and molecular epidemiological study of human cases of Shiga toxin-producing Escherichia coli in New Zealand 
BMC Infectious Diseases  2013;13:450.
Background
Shiga toxin-producing Escherichia coli (STEC) O157:H7 and related non-O157 STEC strains are enteric pathogens of public health concern worldwide, causing life-threatening diseases. Cattle are considered the principal hosts and have been shown to be a source of infection for both foodborne and environmental outbreaks in humans. The aims of this study were to investigate risk factors associated with sporadic STEC infections in humans in New Zealand and to provide epidemiological information about the source and exposure pathways.
Methods
During a national prospective case–control study from July 2011 to July 2012, any confirmed case of STEC infection notified to regional public health units, together with a random selection of controls intended to be representative of the national demography, were interviewed for risk factor evaluation. Isolates from each case were genotyped using pulsed-field gel electrophoresis (PFGE) and Shiga toxin-encoding bacteriophage insertion (SBI) typing.
Results
Questionnaire data from 113 eligible cases and 506 controls were analysed using multivariate logistic regression. Statistically significant animal and environmental risk factors for human STEC infections were identified, notably 'Cattle livestock present in meshblock’ (the smallest geographical unit) (odds ratio 1.89, 95% CI 1.04–3.42), 'Contact with animal manure’ (OR 2.09, 95% CI 1.12–3.90), and 'Contact with recreational waters’ (OR 2.95, 95% CI 1.30–6.70). No food-associated risk factors were identified as sources of STEC infection. E. coli O157:H7 caused 100/113 (88.5%) of clinical STEC infections in this study, and 97/100 isolates were available for molecular analysis. PFGE profiles of isolates revealed three distinctive clusters of genotypes, and these were strongly correlated with SBI type. The variable 'Island of residence’ (North or South Island of New Zealand) was significantly associated with PFGE genotype (p = 0.012).
Conclusions
Our findings implicate environmental and animal contact, but not food, as significant exposure pathways for sporadic STEC infections in humans in New Zealand. Risk factors associated with beef and dairy cattle suggest that ruminants are the most important sources of STEC infection. Notably, outbreaks of STEC infections are rare in New Zealand and this further suggests that food is not a significant exposure pathway.
doi:10.1186/1471-2334-13-450
PMCID: PMC3854066  PMID: 24079470
Prospective case–control study; Sporadic STEC infections; New Zealand; Risk factors; Source attribution; Cattle; Molecular epidemiology; Pathways of infection; Population attributable fractions
2.  Risk factors, microbiological findings and outcomes of necrotizing fasciitis in New Zealand: a retrospective chart review 
BMC Infectious Diseases  2012;12:348.
Background
The incidence and mortality from necrotizing fasciitis (NF) are increasing in New Zealand (NZ). Triggered by a media report that traditional Samoan tattooing was causing NF, we conducted a chart review to investigate the role of this and other predisposing and precipitating factors and to document NF microbiology, complications and interventions in NZ.
Methods
We conducted a retrospective review of 299 hospital charts of patients discharged with NF diagnosis codes in eight hospitals in NZ between 2000 and 2006. We documented and compared by ethnicity the prevalence of predisposing and precipitating conditions, bacteria isolated, complications and interventions used.
Results
Out of 299 charts, 247 fulfilled the case definition. NF was most common in elderly males. Diabetes was the most frequent co-morbid condition, followed by obesity. Nearly a quarter of patients were taking non-steroidal anti-inflammatory drugs (NSAID). Traditional Samoan tattooing was an uncommon cause. Streptococcus pyogenes and Staphylococcus aureus were the two commonly isolated bacteria. Methicillin-resistant Staphylococcus aureus was implicated in a relatively small number of cases. Shock, renal failure, coagulation abnormality and multi-organ dysfunction were common complications. More than 90% of patients underwent surgical debridement, 56% were admitted to an intensive care unit (ICU) and slightly less than half of all patients had blood product transfusion. One in six NF cases had amputations and 23.5% died.
Conclusion
This chart review found that the highest proportion of NF cases was elderly males with co-morbidities, particularly diabetes and obesity. Tattooing was an uncommon precipitating event. The role of NSAID needs further exploration. NF is a serious disease with severe complications, high case fatality and considerable use of health care resources.
doi:10.1186/1471-2334-12-348
PMCID: PMC3538518  PMID: 23234429
Bacterial infection; Ethnicity; Necrotizing fasciitis; New Zealand; Traditional Samoan tattooing
3.  Small islands and pandemic influenza: Potential benefits and limitations of travel volume reduction as a border control measure 
Background
Some island nations have explicit components of their influenza pandemic plans for providing travel warnings and restricting incoming travellers. But the potential value of such restrictions has not been quantified.
Methods
We developed a probabilistic model and used parameters from a published model (i.e., InfluSim) and travel data from Pacific Island Countries and Territories (PICTs).
Results
The results indicate that of the 17 PICTs with travel data, only six would be likely to escape a major pandemic with a viral strain of relatively low contagiousness (i.e., for R0 = 1.5) even when imposing very tight travel volume reductions of 99% throughout the course of the pandemic. For a more contagious viral strain (R0 = 2.25) only five PICTs would have a probability of over 50% to escape. The total number of travellers during the pandemic must not exceed 115 (for R0 = 3.0) or 380 (for R0 = 1.5) if a PICT aims to keep the probability of pandemic arrival below 50%.
Conclusion
These results suggest that relatively few island nations could successfully rely on intensive travel volume restrictions alone to avoid the arrival of pandemic influenza (or subsequent waves). Therefore most island nations may need to plan for multiple additional interventions (e.g., screening and quarantine) to raise the probability of remaining pandemic free or achieving substantial delay in pandemic arrival.
doi:10.1186/1471-2334-9-160
PMCID: PMC2761921  PMID: 19788751
4.  Quarantine for pandemic influenza control at the borders of small island nations 
Background
Although border quarantine is included in many influenza pandemic plans, detailed guidelines have yet to be formulated, including considerations for the optimal quarantine length. Motivated by the situation of small island nations, which will probably experience the introduction of pandemic influenza via just one airport, we examined the potential effectiveness of quarantine as a border control measure.
Methods
Analysing the detailed epidemiologic characteristics of influenza, the effectiveness of quarantine at the borders of islands was modelled as the relative reduction of the risk of releasing infectious individuals into the community, explicitly accounting for the presence of asymptomatic infected individuals. The potential benefit of adding the use of rapid diagnostic testing to the quarantine process was also considered.
Results
We predict that 95% and 99% effectiveness in preventing the release of infectious individuals into the community could be achieved with quarantine periods of longer than 4.7 and 8.6 days, respectively. If rapid diagnostic testing is combined with quarantine, the lengths of quarantine to achieve 95% and 99% effectiveness could be shortened to 2.6 and 5.7 days, respectively. Sensitivity analysis revealed that quarantine alone for 8.7 days or quarantine for 5.7 days combined with using rapid diagnostic testing could prevent secondary transmissions caused by the released infectious individuals for a plausible range of prevalence at the source country (up to 10%) and for a modest number of incoming travellers (up to 8000 individuals).
Conclusion
Quarantine at the borders of island nations could contribute substantially to preventing the arrival of pandemic influenza (or at least delaying the arrival date). For small island nations we recommend consideration of quarantine alone for 9 days or quarantine for 6 days combined with using rapid diagnostic testing (if available).
doi:10.1186/1471-2334-9-27
PMCID: PMC2670846  PMID: 19284571

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