Climate change and water-related infectious diseases

Background: Water-related, including waterborne, diseases remain important sources of morbidity and mortality worldwide, but particularly in developing countries. The potential for changes in disease associated with predicted anthropogenic climate changes make water-related diseases a target for prevention. Methods: We provide an overview of evidence on potential future changes in water-related disease associated with climate change. Results: A number of pathogens are likely to present risks to public health, including cholera, typhoid, dysentery, leptospirosis, diarrhoeal diseases and harmful algal blooms (HABS). The risks are greatest where the climate effects drive population movements, conflict and disruption, and where drinking water supply infrastructure is poor. The quality of evidence for water-related disease has been documented. Conclusions: We highlight the need to maintain and develop timely surveillance and rapid epidemiological responses to outbreaks and emergence of new waterborne pathogens in all countries. While the main burden of waterborne diseases is in developing countries, there needs to be both technical and financial mechanisms to ensure adequate quantities of good quality water, sewage disposal and hygiene for all. This will be essential in preventing excess morbidity and mortality in areas that will suffer from substantial changes in climate in the future

Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia

Malaria / Waterborne diseases / Disease vectors / Habitats / Disease control / Entomology / Epidemiology / Surveys / Dams / Reservoirs / Villages / Case studies / Africa / Ethiopia / Koka Reservoir / Rift Valley / Awash River Basin

Small irrigation tanks as a source of malaria mosquito vectors: a study in north-central Sri Lanka

Watersheds / Tank irrigation / Rehabilitation / Malaria / Waterborne diseases / Disease vectors / Sri Lanka / Yan Oya

The health significance of heterotrophic bacteria in drinking water

Tap water is not sterile; it contains organisms which grow in water distribution systems or inside taps and their fittings. The absence of known pathogenic bacteria is assured by the absence of the indicator organisms but concerns have been raised in the past few years that drinking water fulfilling the standards laid down in the EC Directive ECC 80/778 may still cause disease. These concerns have arisen from several sources: the fact that a cause has been identified in only half of all suspected waterborne outbreaks of disease; reports have suggested that heterotrophic bacteria possessing single pathogenic mechanisms such as haemolysin may cause disease; reports of heterotrophic organisms causing water contact diseases in hospitals. These concerns led to a reappraisal of the pathogenic potential of heteretrophic bacteria, by carrying out an extensive literature search and review commissioned by the UK Water Research Company. This research identified many papers showing an association between drinking water and heterotrophic bacteria but only very few reports of suspected waterborne disease associated with the heterotrophs. The organisms demonstrating potential to cause disease were species of Aeromonas and Yersinia, but typing of organisms identified in patients and isolated from the water revealed very few similarities. The potential of Aeromonas and Yersinia to cause waterborne disease is thought to be very low and the Communicable Disease Surveillance Centre database of laboratory infections due to these two genera of organisms was analysed to produce population-related incidences for each health region in England and Wales. Additionally a laboratory questionnaire revealed different levels of ascertainment of these two organisms in different laboratories of the Public Health Laboratory Service

Malaria in Sri Lanka: Current knowledge on transmission and control

Malaria / Disease vectors / Waterborne diseases / Environmental effects / Public health / Economic impact / Social impact / Sri Lanka

Malaria and land use: a spatial and temporal risk analysis in Southern Sri Lanka

Malaria / Waterborne diseases / Disease vectors / Land use / Water use / GIS / Statistical analysis / Risks / Mapping / Public health / Sri Lanka / Uda Walawe / Thanamalvila / Embilipitiya

Effects of climate change on the epidemiology of flood-related waterborne disease: A Systematic Literature Review

Natural disasters, such as flooding related to extreme precipitation, can lead to many adverse health effects (i.e. waterborne disease). Several outbreaks of waterborne disease have been linked to extreme precipitation, and gastrointestinal infection has been shown to increase after floods. Climate change is likely to lead to a higher frequency of waterborne disease through increases in extreme precipitation and associated flooding affecting water and sanitation infrastructure. This review sought to answer 2 research questions: 1. Has the epidemiology of waterborne disease related to floods changed over time? 2. Can this difference be related to climate change? A literature search was conducted in MEDLINE and Embase for studies reporting on the epidemiology of waterborne disease related to flooding. Studies were screened against inclusion and exclusion criteria, with a total of 52 publications included. Studies of campylobacter, dermatitis, pink eye, and schistosomiasis reported an association between floods and an increase in infection, adenovirus 40/41 and astrovirus showed a significant decrease in risk of disease related to flooding, and cryptosporidium, Giardia, cholera, Escherichia coli, leptospirosis, salmonella, shigella, hepatitis A, rotavirus, sapovirus, and dysentery had mixed evidence. Several studies reported on disease outbreaks tied to a specific flood, but the majority were from events in the past 20 years. It is difficult to draw clear conclusions regarding how waterborne disease is or is not related to floods due to the varied comparisons and outcome definitions. Additionally, most studies were of recent events precluding an analysis of any change over time. Continued research on flood-associated waterborne disease will allow for future analysis of epidemiological changes in response to alterations in climate. In the meantime, public health officials in flood-prone areas should prepare for increases in waterborne disease by educating their constituents on flood safety and implementing interventions for prevention and treatment

Malaria mosquito resistance to agricultural insecticides: risk area mapping in Thailand

Malaria / Disease vectors / Waterborne diseases / Irrigated farming / Pest control / Insecticides / Public health / Risks / Mapping / GIS / Land use / Thailand / Chiang Mai / Mae Hong Son / Tak / Kanchanaburi

Drivers Of Global Waterborne Disease Transmission Following Extreme Precipitation Events: A Systematic Review

Precipitation events such as hurricanes, typhoons, and heavy rainfall can have devastating impacts on water and sanitation infrastructure around the world and have led to large-scale waterborne outbreaks. As climate change amplifies the frequency and intensity of extreme weather events, it is also triggering an increase in waterborne disease transmission. This master’s thesis consists of a systematic review of academic literature pertaining to extreme precipitation events and the pathways by which they trigger waterborne outbreaks. A systematic review of the literature in PubMed was conducted to identify waterborne disease outbreaks associated with extreme precipitation. The initial search yielded 3,248 results for title and abstract screening, of which 173 full-text articles were subsequently retrieved and screened on inclusion criteria of extreme precipitation, waterborne disease outcomes, and importantly, discussion of mediators and mechanisms driving the association. Ultimately, 57 studies were included in the review, representing study locations in 73 countries. The waterborne diseases studied were primarily gastrointestinal illnesses and were caused by bacteria, viruses, and parasites. The most common pathogens studied included bacteria of the genera Leptospira (23%) and Shigella (11%), as well as parasites of the genus Cryptosporidium (11%). Heavy rainfall (33%) and flooding (32%) were the most common events associated with waterborne disease outbreaks. Ultimately, the most common mediators of waterborne transmission following an extreme precipitation event were (1) hydro-ecological risk factors, related to runoff from industrial, agricultural, or environmental sources (2) infrastructural risk factors, resulting from damage to or disruption of WASH (Water, Sanitation, and Hygiene) infrastructure, (3) socio-behavioral risk factors, arising from existing vulnerabilities or from changes in activities and behaviours, and (4) physical risk factors, due to contact with contaminated storm water or floodwaters. By examining and understanding these climate-related drivers of waterborne disease transmission, we can begin to envision better mitigation and prevention strategies to protect public health around the globe