Bacteria

This chapter focuses on the pathogenic bacteria transmitted through water or associated with water in some manner. Bacteria are classified by their 16S ribosomal RNA characteristics into 14 kingdoms., each of which is made up of many genera, which, in turn, include many species. The human pathogens are scattered among several kingdoms. Some of the principal waterborne diseases include: cholera, gastroenteritis, salmonellosis, and typhoid fever. Cholera-caused by Vibrio cholera-is a Gram-negative, curved and flagellated rod, and is the clearest example of a waterborne disease. The most common mode of its transmission is the ingestion of contaminated water. Vibriocholerae attach to the intestinal lining and secrete an enterotoxin that causes a high rate of discharge of a watery mucus. In addition to severe diarrhoea, the symptoms include abdominal cramps, nausea, vomiting, and shock. Fluid and electrolyte loss result in death rates of up to 60% without treatment. Cholera occurs world-wide but is far more prevalent in the areas with inadequate protection of water supplies.