Microbes present in the contaminated water cause various infectious diseases. Some of the water borne diseases are cholera, typhoid, infectious hepatitis, poliomyelitis, diarrhoea, etc. The most common waterborne diseases and their causative microbial agents are given below.
Cholera is an epidemic disease and in the earlier days many people died due to this.
It is caused by Vibrio cholerae mostly due to contaminated food and water. Acute diarrhoea with watery stool, vomiting, nausea and dehydration are the symptoms of this disease.
This disease is common in children of age group 1-15 years. Nearly 2.5 million people suffer from typhoid disease every year. This is caused by the bacteria Salmonella typhi. Food and water contaminated by the faeces of infected person causes this disease. Infected persons show symptoms of fever, weakness and vomiting.
Table 8.5 gives more information about water borne diseases caused by bacteria.
It is caused by polio virus and spreads from person to person. This virus gets into the blood and enters into the brain or spinal cord and affects the central nervous system. Muscles get paralysed and result in difficulty in walking.
It is caused by Hepatitis A virus (HAV). It is transmitted through contaminated water and food and through oral route. It causes inflammation of liver resulting in jaundice (Yellow fever).
Acute diarrhoea is commonly caused by infection of intestine. It is caused by Rotavirus and results in sudden onset of frequent stools, three or more in a day. It is transmitted through contaminated water and food. Increased fluidity and the volume of bowel movements result in excessive loss of fluid and electrolytes from the intestine.
Symptoms of these diseases and preventive measure are given in Table 8.6.