Paediatrics (RCH) - Theses
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ItemEarly life oral exposures as risk factors for food allergy and the impact of infant feeding guidelines( 2021)Food allergy is a severe immune reaction affecting around 10% of infants. The recent rise in food allergy is a growing public health concern. Susceptibility to food allergy is affected by environmental exposures that affect infant gut immunity, including oral food and microbial exposures. Changes in infant feeding guidelines recommending introduction of allergenic foods in the first year were the first public health measure introduced specifically to prevent food allergy. I aimed to evaluate their impact on timing of allergenic food introduction and prevalence of food allergy, as well as investigating oral microbial exposure as a potential food allergy risk factor. The effect of 2016 updates to infant feeding guidelines on food allergy was evaluated using two large population-based cross-sectional studies (n=5,300 and n=1,933) that recruited 12-month-old infants in Melbourne, Australia 10-years apart (2007-2011 and 2018-2019) to study allergenic food introduction and peanut allergy. Microbial exposure was investigated in relation to food allergy using data from a cohort study (n=1,072) based in south-east Australia which measured pacifier cleaning methods in the first year of life. Data were analyzed using multivariable logistic regression models and direct standardization. Regression models were adjusted for known food allergy risk factors, depending on the exposure. An overview of systematic reviews searched systematic reviews in four databases to examine age of complementary feeding in relation to other health outcomes. These studies are the first report that peanut introduction by 12 months of age (inclusive) in the population increased (88% in 2018-2019 vs 28% in 2007-2011) following the implementation of 2016 infant feeding guidelines. Despite this massive shift, peanut allergy prevalence did not decrease as much as expected (3.1% to 2.6%). However, the increase in peanut introduction seems to have halted the rise of peanut allergy in one-year-old infants. The systematic review found 27 reviews on age of complementary or allergenic food introduction on multiple outcomes. There was no evidence of a detrimental effect on other health outcomes of the recommended introduction of solids and allergenic foods starting around 6 months of age, though solids introduced earlier than 4 months could increase the risk of overweight. Furthermore, sanitization of infant pacifier with antiseptics at 6 months of age increased the risk of food allergy at age one, possibly an effect of the chemicals on oral or gut microbiome. An increase in early introduction following 2016 guideline changes has halted the overall rise in peanut allergy. Nevertheless, peanut allergy is still high in Melbourne, thus additional prevention strategies are required. Reassuringly, other health outcomes are not risked by the recommended age of allergenic food introduction. The findings on cleaning pacifiers with antiseptics suggests that suggests microbial exposure can protect against food allergy. This warrants further interventional studies to determine if microbial exposures could prevent food allergy. Moreover, early life risk factors, prior to food introduction, need to be explored further.
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ItemImproving the diagnosis of scabies in low-resource settings( 2020)Scabies is a parasitic disease and a global health problem that predominantly affects disadvantaged communities in low-resource settings. Scabies significantly impacts the health and quality of life of those with the disease. To accurately assess the global burden of disease and to compare data across regions, standardised diagnosis with consistent disease definitions is necessary. In low-resource settings, diagnosis by clinical assessment is the principal diagnostic method. In the absence of available experts, non-expert health workers are likely to play critical roles in diagnosis, including for prevalence mapping. Currently, standardised processes for clinical diagnosis for scabies do not exist. This thesis explores the diagnosis of scabies in low-resource settings and the role and utility of non-expert health workers in the diagnosis of scabies. Chapter 3 describes the evaluation of non-expert health workers in the diagnosis of scabies and impetigo using clinical criteria. The diagnosis of four briefly-trained nurses was compared to the consensus diagnosis of two experienced doctors. The sensitivity of the nurses’ diagnosis compared to the reference standard was 55.3% for scabies with a specificity of 89.9% Sensitivity for moderate to severe scabies was 93.5% with a specificity of 74%. The accuracy of diagnosis by non-expert health workers is promising and may be acceptable for scabies and impetigo disease mapping in low-resource settings. Chapter 4 describes the development and evaluation of a training protocol for the diagnosis of scabies and impetigo for non-expert health workers. The aim of this study was to measure the change in knowledge and confidence of the participants and explore their experience and perceptions of the training. Training was evaluated using a case-based test, a questionnaire and semi-structured interviews. The overall results of the case-based test were 90% for scabies and 75.5% for impetigo. The mean score for both self-reported knowledge and confidence increased from 2.5 to 4.5 following training and scores increased for all nurses (mean difference 2, 95%CI 1.1-2.9, P=0.005). The study showed that training local health staff in scabies diagnosis was enjoyable for participants and led to improvements in self-reported knowledge and confidence. Chapter 5 investigates the prevalence of scabies and impetigo using a cross-sectional study in a primary school in Gizo in the Solomon Islands. Using the International Alliance for the Control of Scabies (IACS) diagnostic criteria the classified the diagnosis of scabies. The prevalence of scabies was 54.3% and prevalence of impetigo was 32.1%. 63.5% of those with impetigo had scabies, corresponding to a population attributable risk of 11.8%. The study highlighted the extremely high burden of these diseases supporting the need for interventions for scabies in this community. Chapter 6 evaluates the methods of data collection, analysis and display for describing in detail the distribution of scabies lesions in a pilot study. The study used a novel technique of representation of dermatological lesions in the form of a choropleth map. The study found that the methods used were feasible for a larger population and would describe valuable detailed information on specific lesion location in scabies. The study will provide information on lesions at specific body sites to determine if simplified examinations are appropriate for prevalence surveys. The public health control of scabies requires identification of high-prevalence communities to target interventions, as well as methods to monitor the effectiveness of interventions. Such programs would be dependent on accurate and standardised diagnosis for population mapping. This thesis suggests methods to improve the diagnosis of scabies in low-resource settings. Modifications to training and diagnostic methods are likely to improve diagnostic accuracy. Improvements to scabies diagnosis will contribute to efficient collection methods and reliability of prevalence data.