Applied epidemiology in communicable diseases and environmental health, Victoria, 2015 – 2016

Abstract

The Health Protection Branch within the Victorian Government Department of Health and Human Services has a role to reduce the incidence of preventable disease in Victoria by protecting the community against hazards resulting from, or associated with, communicable disease, food, water, or the environment. During 2015 and 2016, I completed a field placement with the branch, with a specific emphasis on environmental health and communicable disease. In this time, I both led and assisted with several public health investigations, and participated in general response and reporting activities to expand my breadth of knowledge in field epidemiology. In doing so, I fulfilled the requirements of the Master of Philosophy in Applied Epidemiology (MAE). The skills I have gained are demonstrated in this thesis. Although Victoria has no major documented industrial source of lead air pollution, the existence of legacy sources means lead remains an environmental hazard with the potential to adversely impact human health. My evaluation of the system for surveillance of elevated blood lead levels in Victoria is the first since this became a mandatorily notifiable condition in Victoria on 1 January 2010. I made a number of recommendations to simplify investigation, and recording, of a case’s lead exposure, and highlighted the need to increase capacity for surveillance reporting and strategies to enable the sustainability of the system. The outcomes of this evaluation are already informing surveillance activities for this condition. This evaluation was supported by my analysis of the data for notifications of elevated blood lead levels greater than 10 micrograms per decilitre received in 2010–2015. This represents the first complete analysis of the data from this surveillance system. I found that while high-risk occupations remain the principal lead exposure source for notified cases, non-occupational lead exposure represents a small, but important, proportion of the incidence of elevated blood lead levels in Victoria. Specifically, my analysis highlighted that lead exposure was exacerbated by poor personal lead hygiene practices in hobby activities (including recreational gun shooting and home renovation), but also emphasised the continued dangers of lead exposure associated with imported alternative medicine use. I also investigated two communicable disease outbreaks. I designed and conducted a case-control study to investigate the cause of an increase in notifications of cryptosporidiosis in the North and West Metropolitan region of Victoria in March–April 2015. This epidemiological study showed that recreational water facilities, including water parks, present risks for bathers to become infected with Cryptosporidium spp. I also conducted a cohort study to investigate an outbreak of gastrointestinal illness among guests who attended a canape-style wedding reception. Molecular testing and epidemiological diagnostic criteria identified the causal pathogen as norovirus. Although the specific vehicle of infection was unclear, this study suggested person-to food-to person transmission of norovirus was the likely cause of the outbreak of gastroenteritis in this wedding cohort. In this thesis, I present my experience and capabilities gained during the MAE program, and demonstrate my contribution to protecting the public health of Victorians. The public health impact of this work is also described. Show more