Abstract
Burden of disease analyses can quantify the relative impact of different exposures on population health outcomes. Gastroenteritis where the causative pathogen was not determined and respiratory illness resulting from exposure to opportunistic pathogens transmitted by water aerosols have not always been considered in waterborne burden of disease estimates. We estimated the disease burden attributable to nine enteric pathogens, unspecified pathogens leading to gastroenteritis, and three opportunistic pathogens leading primarily to respiratory illness, in Ontario, Canada (population ~14 million). Employing a burden of disease framework, we attributed a fraction of annual (year 2016) emergency department (ED) visits, hospitalisations and deaths to waterborne transmission. Attributable fractions were developed from the literature and clinical input, and unattributed disease counts were obtained using administrative data. Our Monte Carlo simulation reflected uncertainty in the inputs. The estimated mean annual attributable rates for waterborne diseases were (per 100 000 population): 69 ED visits, 12 hospitalisations and 0.52 deaths. The corresponding 5th-95th percentile estimates were (per 100 000 population): 13-158 ED visits, 5-22 hospitalisations and 0.29-0.83 deaths. The burden of disease due to unspecified pathogens dominated these rates: 99% for ED visits, 63% for hospitalisations and 40% for deaths. However, when a causative pathogen was specified, the majority of hospitalisations (83%) and deaths (97%) resulted from exposure to the opportunistic pathogens Legionella spp., non-tuberculous mycobacteria and Pseudomonas spp. The waterborne disease burden in Ontario indicates the importance of gastroenteritis not traced back to a particular pathogen and of opportunistic pathogens transmitted primarily through contact with water aerosols.
Highlights
Gastrointestinal (GI) illness from exposure to pathogens in water can result from factors such as weather events, the failure of water treatment or distribution systems, and human error [1]
For unspecified pathogen GI illness, we developed an attributable fraction by fitting a distribution to the mean estimates of the proportion of GI illness attributable to waterborne pathogens in Canada that were published in the last 10 years [8, 9, 35,36,37]
We presented estimates where the mean attributable rate was at least 0.01 for deaths, 0.1 for hospitalisations or 0.1 for emergency department (ED) visits
Summary
Gastrointestinal (GI) illness from exposure to pathogens in water can result from factors such as weather events, the failure of water treatment or distribution systems, and human error [1]. There is growing concern about pathogens that are naturally occurring in water and can be transmitted by inhalation of aerosols [10,11,12,13,14] Such pathogens include Legionella spp. and Pseudomonas spp., which are naturally occurring in water and not correlated with faecal indicators often used to assess water quality [15]. These two pathogens along with non-tuberculous mycobacteria (NTM) were collectively associated with 91% of deaths from diseases transmitted by water in the USA [16]
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