There is growing evidence that asthma symptoms can be aggravated or events triggered by exposure to indoor nitrogen dioxide (NO₂) emitted from unflued gas heating.The impact of NO₂on the respiratory health of children with asthma was explored as a secondary analysis of a randomised community trial, involving 409 households during the winter period in 2006 (June to September).Geometric mean indoor NO₂levels were 11.4 μg·m⁻³, while outdoor NO₂levels were 7.4 μg·m⁻³. Higher indoor NO₂levels (per logged unit increase) were associated with greater daily reports of lower (mean ratio 14, 95% CI 1.12–1.16) and upper respiratory tract symptoms (mean ratio 1.03, 95% CI 1.00–1.05), more frequent cough and wheeze, and more frequent reliever use during the day, but had no effect on preventer use. Higher indoor NO₂levels (per logged unit increase) were associated with a decrease in morning (-17.25 mL, 95% CI -27.63– -6.68) and evening (-13.21, 95% CI -26.03– -0.38) forced expiratory volume in 1 s readings. Outdoor NO₂was not associated with respiratory tract symptoms, asthma symptoms, medication use or lung function measurements.These findings indicate that reducing NO₂exposure indoors is important in improving the respiratory health of children with asthma.

We found inequalities in the prevalence of acute rheumatic fever (ARF) and rheumatic heart disease, which disproportionately affect Māori and Pacific Peoples in New Zealand, particularly those living in high socioeconomic deprivation.

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 skin swab data (1 866 981 swabs) from the Auckland region, New Zealand and antibiotic dispensing data were used (2010–2017). Incident ARF cases were identified using hospitalisation data (2010–2018). The risk ratio (RR) of ARF following swab collection was estimated across selected features and timeframes. Antibiotic dispensing data were linked to investigate whether this altered ARF risk following GAS detection. Results ARF risk increased following GAS detection in a throat or skin swab. Māori and Pacific Peoples had the highest ARF risk 8–90 days following a GAS-positive throat or skin swab, compared with a GAS-negative swab. During this period, the RR for Māori and Pacific Peoples following a GAS-positive throat swab was 4.8 (95% CI 3.6 to 6.4) and following a GAS-positive skin swab, the RR was 5.1 (95% CI 1.8 to 15.0). Antibiotic dispensing was not associated with a reduction in ARF risk following GAS detection in a throat swab (antibiotics not dispensed (RR: 4.1, 95% CI 2.7 to 6.2), antibiotics dispensed (RR: 4.3, 95% CI 2.5 to 7.4) or in a skin swab (antibiotics not dispensed (RR: 3.5, 95% CI 0.9 to 13.9), antibiotics dispensed (RR: 2.0, 95% CI 0.3 to 12.1). Conclusions A GAS-positive throat or skin swab is strongly associated with subsequent ARF, particularly for Māori and Pacific Peoples. This study provides the first population-level evidence that GAS skin infection can trigger ARF.

In preparation for the future arrival of a group A Streptococcus (GAS) vaccine, this study estimated the economic and health burdens of GAS diseases in New Zealand (NZ). The annual incidence of GAS diseases was based on extrapolation of the average number of primary healthcare episodes managed each year in general practices (2014-2016) and on the average number of hospitalizations occurring each year (2005-2014). Disease incidence was multiplied by the average cost of diagnosing and managing an episode of disease at each level of care to estimate the annual economic burden. GAS affected 1.5% of the population each year, resulting in an economic burden of 29.2 million NZ dollars (2015 prices) and inflicting a health burden of 2373 disability-adjusted life years (DALYs). Children <5 years of age were the most likely age group to present for GAS-related healthcare. Presentations for superficial throat and skin infections (predominantly pharyngitis and impetigo) were more common than other GAS diseases. Cellulitis contributed the most to the total economic and health burdens. Invasive and immune-mediated diseases disproportionately contributed to the total economic and health burdens relative to their frequency of occurrence. Preventing GAS diseases would have substantial economic and health benefits in NZ and globally.

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 determine if these are the same as those for ARF. A case-control study, including 733 children aged 5-14 years, was undertaken between March 2018 and October 2019 in Auckland, New Zealand. Healthy controls (n = 190) and symptomatic cases including GAS pharyngitis (n = 210), GAS seronegative carriers (n = 182), and GAS skin infections (n = 151) were recruited. Trained interviewers administered a comprehensive, pre-tested, face-to-face questionnaire. Multivariable analysis identified strong associations between barriers to accessing primary healthcare and having GAS pharyngitis (adjusted OR 3·3; 95% CI 1·8-6·0), GAS carriage (aOR 2·9; 95% CI 1·5-6·0) or a GAS skin infection (aOR 3·5; 95% CI 1·6-7·6). Children who had GAS skin infections were more likely than all other groups to report living in a crowded home (aOR 1·9; 95% CI 1·0-3·4), have Māori or Pacific grandparents (aOR 3·0; 95% CI 1·2-7·6), a family history of ARF (aOR 2·2; 95% CI 1·1-4·3), or having a previous diagnosis of eczema (aOR 3·9; 95% CI 2·2-6·9). Reducing barriers to accessing primary healthcare (including financial restrictions, the inability to book an appointment, lack of transport, and lack of childcare for other children) to treat GAS pharyngitis and skin infections could potentially reduce these infections and lead to a reduction in their sequelae, including ARF. These strategies should be co-designed and culturally appropriate for the communities being served and carefully evaluated. This work was supported by the Health Research Council of New Zealand (HRC), award number 16/005.