Waterborne Diseases: Impact on Health and Guidelines for Microbial Quality

Question 1

What are the health costs of waterborne diseases?

Answer 1

1. The treatment of waterborne diseases costs in terms of the consumption of medical resources
2. Accommodating the household needs of the affected person incurs direct costs
3. Travelling to and fro health services incurs transportation costs
4. The individual affected incurs lost economic opportunities
5. The quality-of-life reduction associated with pain and suffering entails a social cost
6. The wider economic cost in terms of the impact on the GNP due to reduction in productivity and allocation of limited resources to health care.

Question 2

Example of the health costs of water borne diseases associated with the cholera epidemic, Peru 1991

Answer 2

Loss of $1 trillion USD in first 10 weeks from reduced exports and tourism. This is over 3 times the amount the country invested in water supply and sanitation during the 1980s.
Effective prevention options available that would cost the average family 0.25 - $2 / year

Question 3

Exposure to pathogenic microbes occurs via four routes..

Answer 3

1. water-borne
2. water-based
3. water related
4. excreta related

Question 4

Explain Waterborne diseases:

Answer 4

Due to water contaminated by human or animal excreta or urine containing pathogenic bacteria or viruses.

Transmitted via hands, food, eating utensils, flies, contaminated soil, and personal contact with infected people.

Personal hygiene and safe sanitation facilities are more important than the quality of water (assuming not directly contaminated)

Question 5

Explain water-based diseases

Answer 5

Due to water and soil contaminated by human faeces containing parasitic intestinal nematodes.

Transmitted by intermediate organisms living in water and soil.

Prevention: Avoid contact with water and soil containing intermediate organisms

Question 6

Explain water-related diseases

Answer 6

Caused by micro-organisms with life-cycles associated with insects that live or breed in water.

Transmitted via insect vectors

Prevention: Control of breeding habitats is of prime importance

Question 7

Explain excreta-related diseases

Answer 7

Caused by direct or indirect contact with pathogens and/or vectors that breed in excreta.

Transmitted via contaminated pillows and clothes, eye-seeking flies, lice that live in excreta

Prevention: proper disposal of human wastes

Question 8

The function of the World Health Organisation (WHO) is to:

Answer 8

propose regulations and make recommendations with respect to international health matters.

Question 9

Role of the The World Health Organisation Guidelines:

Answer 9

1. Allow governments to make risk management decisions related to public health protection and environmental preservation
2. Guidelines are not absolute, instead they provide a common background on which to base national or regional standards
3. Guidelines have an advisory nature (national standards may differ appreciably from guideline values)

Question 10

Role of the World Health Organisation Standards:

Answer 10

1. Adapted to a country’s national priorities, they are guidelines fixed by law
2. Standards consider economic constraints, technical capabilities, as well as the social, cultural and political situation
3. Standards consider the quanitity and quality of available water
4. Standards are.enforced by adopting an “acceptable risk” approach

Question 11

A Water Quality Index (WQI) measures:

Answer 11

the quality of a drinking water source through an aggregate score

Question 12

Three groups of parameters form a 10 parameter index, WQI

Answer 12

1. Physical (temperature, conductivity, suspended solids)
2. Chemical (pH, ammonia, nitrate, dissolved oxygen)
3. Organic/ microbiological (Faecal coliforms, BOD and COD)

Question 13

Practical solutions to avoid waterborne diseases

Answer 13

1. remove latrines from immediate vicinity of wells
2. disinfect the latrines with quicklime
3. add bleach to drinking and kitchen water
4. increase water pH by adding oyster/clam shells
5. prevent wandering domestic animals from the well vicinity by fencing