Canoeist Pathogenic Illness Guide
The Risk to Canoeists from Pathogenic Microorganisms in River Water
SIMON ROBERT DAWSON
Nottingham Trent University 1996
A thesis submitted in partial fulfilment of the requirements of the Nottingham Trent University for the degree of Master of Science in Integrated Environmental Control.
In recent years the risk to canoeists of gastrointestinal and other illnesses from river water used for recreation has caused increasing concern. Disease causing pathogens consist primarily of bacteria and viruses found in sewage and other waste streams discharged into rivers. Other, potentially fatal, diseases can be caused by toxins from blue green algae and by leptospirosis.
Widespread epidemiological research, mainly of sea bathing but including some canoeing studies, shows that bathing/canoeing is a risk factor for gastroenteritis and other skin, eye, ear and respiratory tract infections. Such infections are mild and short term. No serious illnesses were found.
It has proved difficult to find indicators (normally faecal bacteria) whose presence can be measured to allow estimations of the amount of sewage pollution in a water-course or beach, and hence index the infectious risk. Some water quality standards have been implemented, but their epidemiological basis is weak. Where standards do exist, bathing/canoeing in water which meets the standards approximately doubles the normal, everyday risk of gastrointestinal or other symptoms.
Pathogenic microorganisms in water come from sewage effluent, storm water run-off from urban and rural areas, and many other diffuse sources. Disinfection of sewage effluent is an option, but storm water control is more difficult. Some natural disinfection takes place in rivers due to the Ultra Violet component of sunlight.
The risk to canoeists is low in the summer, higher in the winter. Storm water run-off increases the risk dramatically, especially in the summer after a long dry spell.
There are no current water quality standards for UK recreational inland watercourses, but the development of Statutory Water Quality Obectives will provide a means of putting regulation of recreational water quality onto a statutory basis.
Nottingham City Council, whose sponsorship (as my employer) gave me both the time and the facilities to work on this report.
Dr Keith Neal of the University of Nottingham Medical School, and the staff of the National Watersports Centre, Holme Pierrepont, who by allowing me to join the team carrying out the Risk Assessment, gave me an invaluable insight into epidemiological and microbiological research.