The Epidemiology of Diseases Transmitted by Water
Received Date: Oct 26, 2017 / Accepted Date: Dec 30, 2017 / Published Date: Jan 08, 2018
Keywords: Waterborne diseases; Outbreak; Pathogens; Vaccinations
The diseases that are transmitted through contaminated water are known as waterborne diseases. Water contaminated by faecal matter is the commonest mode of transmission of the offending microorganisms to man. Some of the important waterborne diseases/ pathogens are Cholera, Shigellosis, and Enterotoxigenic E. coli, Vibrio parahaemolyticus, Salmonella, Giardia lamblia and Cryptosporidium. Entamoeba histolytica, Enterohaemorrhagic E. coli, and Enteroinvasive E. coli cause bloody diarrhoea (dysentery).
A severe cholera outbreak occurred in London in 1854. John Snow, a physician, was in charge of the investigation of the outbreak. He observed that the people of the area, who drank water from a hand pump situated at the corner of the broad street, were mostly affected in contrast to those who did not drink water from the hand pump. This study for the first time demonstrated that cholera is transmitted by water. Further, when the mouth of the pump was sealed, transmission completely stopped and cases came down sharply [1,2].
Sanitation and safe water are two pillars for prevention of waterborne diseases. Their implementations are most likely to cut down the transmission of pathogens to a reasonable level. To implement these measures will require long term activities and allocation of large funds and considerable time. Handwashing will further reinforce the strategy of reduction of waterborne diseases .
To boost up the individual immunity, it is required to use vaccines. An injectible cholera vaccine was available. The vaccine was highly reactogenic and provided protection in only 40-50% of vaccinated individuals (two shots at two weeks interval) for 4-6 months only. Of late two Oral cholera vaccines were developed, but they are no longer used much except for travellers’ going to cholera endemic areas. Recently, a heat-killed Oral Cholera Vaccine has been developed that gives protection in upto 66% of the vaccinated people for 5 year . This vaccine is available in the market. Hepatitis A vaccines are available and confer immunity. Ty21 and Vi-lipopolysaccharide typhoid vaccines are available and used for vaccination against typhoid .
Handwashing is a simple method that stops transmission of pathogens. Although it is simple, it is difficult to adhere to by illiterate people. Improvement of personal hygiene helps in dispelling pathogenic organisms from the body. Chlorination of water kills the pathogens and water becomes safe. Hepatitis A and E vaccines are useful and effective. Breast feeding up to 2 years of age is recommended for protection against diarrhoea. Boiling of water before drinking is good, but cost of fuel is prohibitive. Besides sanitation and safe water, a number of other methods will be useful in controlling waterborne diseases. These methods are adjunct to sanitation and safe water including oral cholera vaccination .
Improvement of personal hygiene helps in dispelling pathogenic organisms from the body. Trimming of nails prevents carrying germs through contaminated fingers.
Chlorination of water kills the pathogens and water becomes safe. During epidemic of diarrhoeal diseases or hepatitis, super chlorination at source is recommended that prevents growth of microorganisms. However, it must be ensured that at the user end there is sufficient chlorination.
Hepatitis A and E, typhoid and oral cholera vaccines are useful. Breast feeding up to 2 years of age is recommended for protection against diarrhoea. Boiling of water before drinking is good, but cost of fuel is prohibitive.
At one time in the past, on the presumption that killing the V. cholerae will stop transmission, but this approach was found to be wrong and there in a limit to use tetracycline for a reasonable period. The appearance of drug resistance was also feared and chemoprophylaxis is no longer recommended.
It is therefore evident that besides sanitation and safe water, a number of other methods will be useful in controlling waterborne diseases. These methods are adjunct to sanitation and safe water. Vaccination will be particularly useful .
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Citation: Bhattacharya SK (2018) The Epidemiology of Diseases Transmitted by Water. J Biomed Pharm Sci 1: 103.
Copyright: © 2018 Bhattacharya SK. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.