Global waterborne outbreak

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Global waterborne outbreak

Water-borne diseases are any illness caused by drinking water contaminated by human or animal faeces, which contain pathogenic microorganisms.

The complete picture of water-associated diseases is complex for a number of reasons. Over the past decades, the water-related human health issues have become increasingly comprehensive, with the emergence of new water-related infection diseases and the re-emergence of ones already known.

Role of EPA / CDC

EPA and CDC coordinate surveillance and document occurrence of waterborne disease outbreaks. The surveillance system collects data on outbreaks associated with drinking water including outbreaks of infectious diseases and illness from chemical toxicity.

WHO's definition of a waterborne outbreak is when two or more persons experience a similar illness after drinking the same water from the same source and when the epidemiological evidence implicates the water as the source of the illness. Outbreaks can be caused by water contaminated with pathogens, chemicals, or toxins which can be spread through ingestion and contact with contaminated water.

Following CDC reports which are available in their website could be very useful for reference in case there is an outbreak of water related diseases:

- Boil Water Advisory procedures for the public

- Boil Water Advisory procedures for public health professionals

- Drinking Water Advisory Communication Toolbox for water utilities and public health professionals

For a complete list of natural disasters and how to prepare and respond to them, visit CDC's Natural Disasters and Severe Weather page.


A total of 1,428 outbreaks of water related diseases had been reported from 1991 to 2008. It has been reported that 49.6% of the outbreak events were caused by bacteria, 39.3% by viruses, and 11.1% by parasites.

6.5% of the outbreak events were caused by agents that could be transmitted by direct contact. 1.1% transmitted through vectors, 63.5% through environmental transmission and 28.9% by zoonotic routes.

In biology, a vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. Species of mosquito, for example, serve as vectors for the deadly disease Malaria. Zoonotic transmission transmits diseases from animals to human. The population density was shown to be a significant risk factor for reported outbreaks of all categories of water-associated infectious diseases and the probability of outbreak occurrence increased with the population density.

Common causes of outbreaks

Investigation analysis has revealed a number of common causes of outbreaks across the world. These are listed below.

- Wastewater contamination of raw water source in combination with disinfection deficiencies

- In adequate disinfection in Public water treatment

- Cross-connections

- Regrowth in the distribution system

Similar occurrences were identified from outbreaks involving groundwater, with the most common problem being source water contamination with waste water

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----------------- About Author: Nikhilesh Mukherjee worked asGlobal head of R&D water for Hindustan Unilever.Contributed to Unilever's water business from an idea to a very handsome growth from year 2000 to 2010. Known author of more than25papers. These can be viewed at