MICROBIOLOGY OF WATER AND PUBLIC HEALTH

摘要

Water, representing 70% of body weight in adults, is associated with the existence of life. Water is mainly ingested exogenously from liquids and foods, while a small percentage is generated from the oxidation of hydrogen. Been an excellent solvent, it is involved in cellular metabolism and it is also used exclusively in the manufacture of food and personal cleanliness. The microorganisms are widely dispersed in surface waters, underground waters and in wastewater environment. Water is a quick means of spreading infection in large populations. The waterborne infections manifest as gastroenteritis, hepatitis, dermatitis, conjunctivitis, and respiratory infections. The typhoid syndrome, cholera and dysentery were previously the major epidemics waterborne diseases. Due to the application of chlorination of drinking water these diseases have been eliminated from developed countries. In contrast nowdays waterborne infections are usually caused by microorganisms such as pathogenic strains of Escherichia coli, mycobacteria, Helicobacter pylori, Aeromonas hydrophila, hepatitis viruses and Cryptosporidium spp. The majority of them (eg, E. coli, A. hydrophila) belong to the intestinal flora of humans and animals and their presence is an indication of sewage pollution of water. The control of all pathogens in water is uneconomical and time consuming. Thus the assessment of the microbiological status is done by detecting microbial markers that indicate fecal contamination and the possibility of coexistence of other pathogens. The main microbiological indicators for assessing the health status of water are: 1. Total coliforms Their presence indicates infection of environmental origin. 2. Faecal coliforms Indicate faecal contamination of source water. 3. Faecal Streptococci Their presence confirms water pollution by sewage and their resistance to chlorination increases the presence of multiresistant bacteria 4. Total number of bacteria at 37 °C and 22 °C. Sudden increase in their numbers indicate contamination with environmental pathogens. In addition other bacteria like clostridia, Pseudomonas aeruginosa and bacteriophages are also used like indicators. Since access of all people to safe drinking water is a goal for the scientific community the importance of microbiological control becomes more significant for public health