Michael G Baker's research while affiliated with University of Auckland and other places

Publications (364)

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Background Group A streptococcal (GAS) infections can trigger an immune-mediated response resulting in acute rheumatic fever (ARF). The role of social and environmental risk factors for GAS pharyngitis and skin infections are not well understood. This study aimed to identify factors associated with GAS pharyngitis and skin infections, and to determ...
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The 2021 Global Health Security (GHS) Index Report was published on 8 December 2021. With an average country score of 38.9 out of a possible 100 points, global scores are essentially unchanged from 2019. Despite experience with the COVID-19 pandemic, no country is adequately prepared for future biological threats. No country scored above 75.9 and t...
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Background Legionellosis is a collective term used for disease caused by Legionella species which result in community and hospital acquired pneumonia worldwide. The aim of this analysis was to describe the epidemiology of legionellosis hospitalisations in Aotearoa New Zealand (NZ) over a 21-year period and quantify the health care costs. Method Th...
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Background Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are rare in high-income countries; however, in Aotearoa New Zealand ARF and RHD disproportionately affect Indigenous Māori and Pacific Peoples. This narrative review explores the evidence regarding non-surgical management of patients with clinically significant valve disease o...
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Background Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) remain an inequitable cause of avoidable suffering and early death in many countries, including among Indigenous Māori and Pacific populations in New Zealand. There is a lack of robust evidence on interventions to prevent ARF. This study aimed to identify modifiable risk facto...
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Objectives In August 2016, Campylobacter spp contaminated an untreated reticulated water supply resulting in a large-scale gastroenteritis outbreak affecting an estimated 8320 people. We aimed to determine the incidence of probable reactive arthritis (ReA) cases in individuals with culture-confirmed campylobacteriosis (CC), self-reported probable c...
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Public health risks associated with the intensification of dairy farming are an emerging concern. Dairy cattle are a reservoir for a number of pathogens that can cause human illness. This study examined the spatial distribution of dairy cattle density and explored temporal patterns of human campylobacteriosis and cryptosporidiosis notifications in...
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Taumata Arowai, the new independent water services regulator, recently consulted publicly on the drinking water rules for water suppliers. We use a case study on nitrate and official information requests to demonstrate the current weaknesses in the drinking water monitoring and reporting systems and why the reforms proposed by Taumata Arowai seem u...
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Alves DE, Mamelund S-E, Dimka J, et al. Indigenous peoples and pandemics. Scandinavian Journal of Public Health. May 2022. doi:10.1177/14034948221087095
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Objective: In 2020, we developed a public health decision-support model for mitigating the spread of SARS-CoV-2 infections in Australia and New Zealand. Having demonstrated its capacity to describe disease progression patterns during both countries' first waves of infections, we describe its utilisation in Victoria in underpinning the State Govern...
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Legionnaires’ disease (LD) (Legionella) is a common cause of community-acquired pneumonia (CAP) in those requiring hospitalization. Geographical variation in the importance of Legionella species as an aetiologic agent of CAP is poorly understood. We performed a systematic review and meta-analysis of population-based observational studies that repor...
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Background Group A Streptococcus (GAS) causes superficial pharyngitis and skin infections as well as serious autoimmune sequelae such as acute rheumatic fever (ARF) and subsequent rheumatic heart disease. ARF pathogenesis remains poorly understood. Immune priming by repeated GAS infections is thought to trigger ARF, and there is growing evidence fo...
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Hotel-based Managed Isolation and Quarantine (MIQ) is a key public health intervention in Aotearoa New Zealand's (NZ) COVID-19 border control strategy for returning citizens and permanent residents. We aimed to investigate the experience of transiting through MIQ in NZ, to inform future refinements of this type of system. A qualitative thematic ana...
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Objective: There is growing epidemiological evidence linking nitrate contamination to adverse health outcomes. Health concerns may drive consumers towards bottled water, however, nitrate levels in bottled water are not readily available. Methods: We tested water samples from the 10 most popular brands using a TriOS OPUS UV optical nitrate sensor. R...
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Aim: In August 2016, a large waterborne campylobacteriosis outbreak occurred in Havelock North, New Zealand. This analysis describes the clinical complications of cases admitted to hospital as a result of acute infection, identifies risk factors for hospitalisation and compares deaths between hospitalised and non-hospitalised cases. Hospital admis...
Preprint
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Key messages Risk assessment for children has been a polarising issue during the Covid-19 pandemic. Governments around the world are preparing to ‘open up’ before risks to children are fully quantified, with unknown implications for their long-term health. Applying the Precautionary Principle to child health requires decision makers to 1) take prev...
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Introduction Acute rheumatic fever (ARF) is usually considered a consequence of group A streptococcus (GAS) pharyngitis, with GAS skin infections not considered a major trigger. The aim was to quantify the risk of ARF following a GAS-positive skin or throat swab. Methods This retrospective analysis used pre-existing administrative data. Throat and...
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New Zealand responded to the COVID-19 pandemic with a combination of border restrictions and an Alert Level (AL) system that included strict stay-at-home orders. These interventions were successful in containing an outbreak and ultimately eliminating community transmission of COVID-19 in June 2020. The timing of interventions is crucial to their su...
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There is increasing evidence that elimination strategies have resulted in better outcomes for public health, the economy, and civil liberties than have mitigation strategies throughout the first year of the COVID-19 pandemic. With vaccines that offer high protection against severe forms of COVID-19, and increasing vaccination coverage, policy maker...
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Background Epidemiological evidence in multiple jurisdictions has shown an association between nitrate exposure in drinking water and an increased risk of colorectal cancer (CRC). Objective We aimed to review the extent of nitrate contamination in New Zealand drinking water and estimate the health and financial burden of nitrate-attributable CRC....
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Objectives Rates of acute rheumatic fever, a sequelae of group A Streptococcal (GAS) infection, remain unacceptably high in Indigenous Māori and Pacific children in New Zealand. This prospective study aimed to describe GAS antibody titres in healthy children (5-14 years) by ethnicity, and to determine how paired titres vary with GAS culture positiv...
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Background: COVID-19 elimination measures, including border closures have been applied in New Zealand. We have modelled the potential effect of vaccination programmes for opening borders. Methods: We used a deterministic age-stratified Susceptible, Exposed, Infectious, Recovered (SEIR) model. We minimised spread by varying the age-stratified vaccin...
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The Climate Change Commission's draft report and recommendations provide a pathway towards achieving the New Zealand Government's commitment to net zero emissions by 2050. However, the Commission has not adequately considered the health co-benefits of climate change mitigation. In this viewpoint, we assess how the Commission has considered health c...
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Objectives To identify COVID-19 quarantine system failures in Australia and New Zealand. Design, setting, participants Observational epidemiological study of travellers in managed quarantine in Australia and New Zealand, to 15 June 2021. Main outcome measures Number of quarantine system failures, and failure with respect to numbers of travellers...
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Background: As with many Indigenous populations internationally, Māori in New Zealand suffer health inequity. We aimed to assess the rate of fall injuries at home with and without home modifications in houses with Māori occupants. Methods: We did a single-blind randomised controlled trial in the Wellington and Taranaki regions of New Zealand and...
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New Zealand has a strategy of eliminating SARS-CoV-2 that has resulted in a low incidence of reported coronavirus-19 disease (COVID-19). The aim of this study was to describe the spread of SARS-CoV-2 in New Zealand via a nationwide serosurvey of blood donors. Samples ( n = 9806) were collected over a month-long period (3 December 2020–6 January 202...
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In response to the COVID-19 pandemic, Aotearoa New Zealand adopted a clear 'elimination strategy', which has (up to June 2021) been very successful in both health and economic terms compared to other OECD countries. Nevertheless, the pandemic response has still been a very major shock to the New Zealand health system. This issue of the New Zealand...
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Aim: This research explores the experience of low-income New Zealanders during the COVID-19 pandemic lockdown and their advice to the Government about addressing future pandemics. New Zealand had a rapid and effective lockdown that meant the virtual elimination of community transmission. Method: Twenty-seven semi-structured interviews were under...
Preprint
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Background: In response to the COVID-19 pandemic, some countries in the Asia-Pacific Region used very intensive control measures, and one of these, New Zealand (NZ), adopted a clear elimination strategy. We therefore aimed to compare key health and economic outcomes of NZ relative to OECD countries as of mid-June 2021. Methods: This analysis compar...
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We investigated outcomes for patients born after 1983 and hospitalized with initial acute rheumatic fever (ARF) in New Zealand during 1989-2012. We linked ARF progression outcome data (recurrent hospitalization for ARF, hospitalization for rheumatic heart disease [RHD], and death from circulatory causes) for 1989-2015. Retrospective analysis identi...
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Background Acute rheumatic fever (ARF) is a serious sequela of Group A Streptococcus (GAS) infection associated with significant global mortality. Pathogenesis remains poorly understood, with the current prevailing hypothesis based on molecular mimicry and the notion that antibodies generated in response to GAS infection cross-react with cardiac pr...
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Acute rheumatic fever (ARF) and its sequela rheumatic heart disease (RHD) remain significant causes of morbidity and mortality. In New Zealand, ARF almost exclusively affects Indigenous Māori and Pacific children. This narrative review aims to present secondary interventions to improve early and accurate diagnosis of ARF and RHD, in order to minimi...
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Acute rheumatic fever (ARF) is a serious post-infectious immune sequelae of Group A streptococcus (GAS). Pathogenesis remains poorly understood, including the events associated with collagen autoantibody generation. GAS express streptococcal collagen-like proteins (Scl) that contain a collagenous domain resembling human collagen. Here, the relation...
Preprint
Aim: Given the availability of both public health and social measures (PHSMs) and safe and highly-effective vaccines against covid-19, we aimed to assess the feasibility of covid-19 eradication, relative to the benchmarks of smallpox and polio (albeit only 2 of 3 polio serotypes eradicated to date).Methods: Our scoring system was partly based on pr...
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We aimed to estimate the risk of COVID-19 outbreaks associated with air travel to a COVID-19-free country [New Zealand (NZ)]. A stochastic version of the SEIR model CovidSIM v1.1, designed specifically for COVID-19 was utilised. We first considered historical data for Australia before it eliminated COVID-19 (equivalent to an outbreak generating 74...
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Real-time genomic sequencing has played a major role in tracking the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), contributing greatly to disease mitigation strategies. In August 2020, after having eliminated the virus, New Zealand experienced a second outbreak. During that outbreak, New Zealand used genomic sequen...
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A large-scale SARS-CoV-2 serosurvey of New Zealand blood donors (n=9806) was conducted at the end of 2020. Seroprevalence, after adjusting for test sensitivity and specificity, was very low (0.1%). This finding is consistent with limited community transmission and provides robust evidence to support New Zealand's successful elimination strategy for...
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The failure to mount an antibody response following viral infection or seroconversion failure is a largely underappreciated and poorly understood phenomenon. Here, we identified immunologic markers associated with robust antibody responses after influenza virus infection in two independent human cohorts, SHIVERS and FLU09, based in Auckland, New Ze...
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Objective: To assess the burden of disease related to unsafe and substandard housing conditions in New Zealand from 2010 to 2017. Methods: We focused on substandard housing conditions most relevant for New Zealand homes: crowding, cold, damp or mould, and injury hazards linked to falls. We estimated the population attributable fraction using exi...
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Background/aims Over the last decade and following international trends, cases of mosquito-borne arboviral infections, notably dengue fever, chikungunya and Zika, have increased among travellers arriving in New Zealand, but no locally acquired cases have been identified. Imported cases are characterised and examined to identify trends and features...
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Rheumatic heart disease (RHD) is a large, preventable, global public health burden. In New Zealand (NZ), acute rheumatic fever (ARF) and RHD rates are highest for Māori and Pacific children. This structured review explores the evidence for primary prevention interventions to diagnose and effectively treat group A Streptococcus (GAS) pharyngitis and...
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Public health lessons from one pandemic become the planning assumptions for the next one. Aotearoa New Zealand’s 2017 pandemic plan was derived from past experience of influenza. When Covid-19 emerged as a major global health threat, it took time for the realisation to crystallise that this infection was so different from influenza that it required...
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Background Group A Streptococcus (GAS) can trigger an immune-mediated response resulting in acute rheumatic fever (ARF). Historically, ARF has been considered a consequence of preceding GAS pharyngitis, but increasing evidence suggests that GAS skin infections may be a driver. Data on the primary care burden of GAS skin infection are limited. This...
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Rheumatic fever is a serious post-infectious sequela of Group A Streptococcus (GAS). Prior GAS exposures were mapped in sera using a large panel of M-type specific peptides. Rheumatic fever patients had serological evidence of significantly more GAS exposures than matched controls suggesting immune priming by repeat infections contributes to pathog...
Preprint
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Aim: With increasing global use of hotel-based quarantine as part of COVID-19 border control efforts, we aimed to assess its risk of failure. Methods: We searched official websites in both Australia and New Zealand (NZ) to identify outbreaks and border control failures associated with hotel quarantine (searches conducted up to 12 February 2021). We...
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Physical distancing (also commonly known as social distancing) is an important non-pharmaceutical strategy to minimise the risk of transmission of SARS-CoV-2 virus. A range of restrictions to promote physical distancing form a key part of the Aotearoa New Zealand (NZ) all-of-government response to the global COVID-19 pandemic. The effectiveness of...
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Stringent nonpharmaceutical interventions (NPIs) such as lockdowns and border closures are not currently recommended for pandemic influenza control. New Zealand used these NPIs to eliminate coronavirus disease 2019 during its first wave. Using multiple surveillance systems, we observed a parallel and unprecedented reduction of influenza and other r...
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Aim: We aimed to estimate the risk of COVID-19 outbreaks in a COVID-19-free destination country (New Zealand) associated with shore leave by merchant ship crews who were infected prior to their departure or on their ship. Methods: We used a stochastic version of the SEIR model CovidSIM v1.1 designed specifically for COVID-19. It was populated wi...
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Background Very little high quality evidence exists on the causal relationship between income poverty and childhood health. We provide a comprehensive overview of the association between household income poverty and hospitalisations for children. Methods We used New Zealand’s Integrated Data Infrastructure (IDI) to link income poverty data from th...
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Objectives The aims of this study are to describe area deprivation levels and changes that occur during residential moves involving New Zealand children from birth to their fourth birthday, and to assess whether these changes vary by ethnicity. Design Longitudinal administrative data. Setting Children born in New Zealand from 2004 to 2018. Parti...
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We describe trends in acute rheumatic fever (ARF), rheumatic heart disease (RHD), and RHD deaths among population groups in New Zealand. We analyzed initial primary ARF and RHD hospitalizations during 2000–2018 and RHD mortality rates during 2000–2016. We found elevated rates of initial ARF hospitalizations for persons of Māori (adjusted rate ratio...
Preprint
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Background: Excess winter mortality (EWM) has been attributed to both seasonal cold exposure, and to infectious disease. In 2020, New Zealand's border management and lockdown measures successfully eliminated community transmission of SARS-CoV-2, and also largely eliminated influenza and many other respiratory viruses. This study investigates the co...
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Between August and November 2020, Aotearoa New Zealand experienced eight known failures of the COVID-19 border control system. Multiple introductions of this highly transmissible virus into New Zealand’s almost completely susceptible population present a high risk of uncontrollable spread, threatening New Zealand’s elimination strategy. In this edi...
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New Zealand, a geographically remote Pacific island with easily sealable borders, implemented a nationwide ‘lockdown’ of all non-essential services to curb the spread of COVID-19. Here, we generate 649 SARS-CoV-2 genome sequences from infected patients in New Zealand with samples collected during the ‘first wave’, representing 56% of all confirmed...
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Introduction High residential mobility has been shown to have a negative impact on young children, with long-term consequences for their physical and mental health, and social outcomes. Understanding the broad trends in moves and differentiating between moves to neighbourhoods which are likely to have ‘positive’ or ‘negative’ consequences is an imp...
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Background Six thousand children are hospitalized each year in New Zealand with housing sensitive conditions, and 86.2% of these children are rehospitalized during childhood. The Healthy Homes Initiative, set up by the Ministry of Health, and implemented in Wellington through Well Homes, carries out housing assessments and delivers a range of housi...
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Objectives In preparation for the future arrival of a GAS vaccine, this study estimated the economic and health burdens of GAS diseases in New Zealand (NZ). Methods The annual incidence of GAS diseases were based on extrapolation of the average number of primary healthcare episodes managed each year in general practices (2014-16) and on the averag...
Preprint
Full-text available
Stringent nonpharmaceutical interventions (NPIs) such as lockdowns and border closures are not currently recommended for pandemic influenza control. New Zealand used these NPIs to eliminate coronavirus disease 2019 during its first wave. Using multiple surveillance systems, we observed a parallel and unprecedented reduction of influenza and other r...