Water borne diseases, prevention and guidelines for safe drinking water
1. Water borne diseases, prevention
and guidelines for safe drinking
water
Made By: Navjot Kaur
Major Advisor: Dr.(Mrs.)Parampal
Sahota
2. Water borne diseases
• Disease acquired by drinking water contaminated at its source or in
the distribution system, or by direct contact with environmental and
recreational waters.
• Water-borne disease results from
- Infection with pathogenic microorganisms
- Chemical poisoning
• According to the WHO, such diseases account for an estimated 4.1%
of the total DAILY global burden of disease, and cause about 1.8
million human deaths annually.
4. Water-washed (water-hygiene) diseases
•Diseases caused by poor personal hygiene and contact with
contaminated water
Water-scarce diseases occur due to the lack of water available for washing,
bathing and cleaning.
•Hence, pathogens are transmitted from person to person or from
contaminated surfaces to a person and are spread by the faecal–oral route.
5. Water-based diseases are caused by organisms by different species of
worms that spend parts of their life-cycle in different habitats.
• They have spent one development cycle in aquatic molluscs, and another as
fully grown parasites in other.
Vector-borne diseases are caused by bites from insects that breed in water.
• Insect vectors such as mosquitoes transmit diseases such as malaria,
Chikungunya .
6. Examples and route of infection
(Water washed diseases)
(Water scare diseases)
(Water based diseases)
(Vector borne diseases)
8. Case studies
• WHO 1996. “Every year more than five million human beings die from
illnesses linked to
• Unsafe drinking water
• Unclean domestic environments
• Improper excreta disposal
• Hinrichsen, D., Robey, B., and Upadhyay, U.D. 1997. “Water-borne
diseases are "dirty-water" diseases—those caused by water that has been
contaminated by human, animal or chemical wastes.
• WHO World Health Report 1999. Statistical Annex. Totals of 2.3 million
excluding several water related diseases.
9. • Hunter et al. 2000. “Currently, about 20% of the world's population lacks
access to safe drinking water, and more than 5 million people die annually
from illnesses associated with unsafe drinking water or inadequate sanitation.
• Johannesburg Summit 2002. “More than 5 million people die each year from
diseases caused by
• Unsafe drinking water,
• Lack of sanitation,
• Insufficient water for hygiene.
• UNDP 2002. 5 million dying each year because of :
• Polluted water
• Lack of sanitation
• Waterborne diseases alone
17. Water-borne disease caused by
chemicals
• Arsenic
• Flouride
• Nitrates from fertilizers
• Carcinogenic pesticides (DDT)
• Lead (from pipes)
• Heavy Metals
• Chromium
• Nickel
• Cyanide
18. Health effects
Arsenic Cancer, vascular disease, liver disease, skin lesions,
and neurological disorders, Arsenicosis (high levels
of arsenic (GV =0.01mg/l)
Fluoride Fluorosis (Severe skeletal problems)
Cause : high levels of fluorine (GV=1.5 mg/l)
Arsenicosis
Chlorine Toxic and cause sufficient cell damage in the
human body.
Iodine Enlargement of the thyroid gland and mental
retardation.
Nitrates High levels of nitrate in water can lead to
Fluorosis
blood poisoning and eventually death.
Methaeglobinemia
Main Cause : high levels of nitrates(GV=50mg/l)
23. Escherchia coli (E.coli)
• Present in the normal microbial flora of the
gastrointestinal tract of human beings and Enteropathogenic E.coli
warm-blooded animals.
• E. coli are used as an indicator for faecal
Enteroinvasive E.coli
pollution in drinking-water surveillance.
• EHEC belongs to the serotype O157:H7 group.
• HUS (Haemolytic Uremic Syndrome) Enterotoxic E.coli
Enterohemorrhagic E.coli
Enteroaggregative E.coli
24.
25. Aeromonas hydrophila
Routes of infection-
• Ingestion of contaminated water or food
• Contact of the organism with a break in the skin.
• No person-to-person transmission has been
reported.
Virulence- enterotoxins- haemolysins.
• Significant proportion of the A. hydrophila isolated from water (chlorinated and
unchlorinated supplies) contained genes responsible for enterotoxigenic or
cytotoxic activity.
• The clinical isolates tested produced more enterotoxins at 37°C than at 28°C.
Treatment- Maintaining chlorine at or above 0.2 mg/L should provide adequate
control of A. hydrophila in the water.
• Use of carbon dioxide and monochloramine.
26. Legionella
• Legionella spp. Can cause two types of disease: (a) Legionnaires’ disease (type of
pneumonia)
(b) Pontiac fever
(milder, flu like form)
• Symptoms- Non-specific signs such as anorexia, malaise, headache, and rapidly
rising fever, cough, abdominal pain and diarrhoea.
• Legionella is chlorine tolerant.
• Treatment- Temperature below
20 °C or over 50 ºC
• Use of biocides
• ultraviolet (UV) irradiation
• Filtration
27. Campylobacter
• Zoonotic, enteritic disease
• Pathogenic important strains- C. jejuni
C.coli
• Symptoms- Diarrhea, abdominal cramps, fever, malaise, vomiting.
Sometimes arthritis can occur.
• Rare complications include seizure due to high fever or neurological
disorders such as Guillain-Barre syndrome or meningitis.
• Therefore, raw milk, undercooked poultry and beef are significant
sources of infection.
• Transmitted via the faecal–oral route.
• Treatment- sensitive to chlorine and inactivated by disinfection
during drinking-water purification
29. Multiple tube fermentation
• The method consists of inoculating a series of tubes with appropriate
decimal dilutions of the water sample.
• The results of the MTF technique are expressed in terms of the most
probable number (MPN) of microorganisms present.
31. Membrane filter technique
This method consists of filtering a water sample on a sterile filter
with a 0.45-mm pore size which retains bacteria, incubating this filter
on a selective medium and enumerating typical colonies on the filter.
Coliform bacteria forms-
• Red colonies with a metallic sheen on an Endo-type medium
containing lactose
• Yellow-orange colonies on Tergitol-TTC media.
• Other media used- MacConkey agar and the Teepol medium
To enumerate FC, filters be incubated on an enriched lactose
medium (m-FC) at a temperature of 44.5°C for 24 h.
33. Enzymatic methods
• The enzymes β-D galactosidase and β-D-glucuronidase are used for
the detection and enumeration of total coliforms and Escherichia
coli, respectively.
• Many chromogenic and fluorogenic substrates exist for the specific
detection of these enzymatic activities.
• β-D-glucuronidase - positive reactions were observed in 94–96% of
the E. coli isolates tested.
• Higher proportion of β-D-glucuronidase- negative E. coli (a median of
15% from E. coli isolated from human fecal samples).
• β-D-glucuronidase activity is less common in other
Enterobacteriaceae genus, such as Shigella (44 to 58%), Salmonella
(20 to 29%) and Yersinia strains and in Flavobacteria.
• β-D-galactosidase, catalyzes the breakdown of lactose into galactose
and glucose and has been used mostly for enumerating the coliform
group within the Enterobacteriaceae family.
35. Immunological method
Based on the specific recognition between antibodies and antigens
and the high affinity that is characteristic of this recognition reaction.
Two types of antibodies can be produced: polyclonal and monoclonal
antibodies
The properties of the antigen–antibody complex can be used:
• To perform an immunocapture of cells or
• Antigens by enzyme-linked immunosorbent assay (IMS or ELISA), or
• To detect targeted cells by immunofluorescence
• Assay (IFA) or immuno-enzyme assay (IEA).
36. Polymerase Chain Reaction
(PCR)
• Process includes an in vitro cycling replication after a DNA
extraction step. Amplification is performed on the nucleic
acid
• Content obtained by a cellular lysis followed by a chemical
extraction. These extraction steps can be performed on
bacterial cells retained on a membrane filter.
• The PCR amplification process involves: (i) a DNA
denaturation from double- to single-stranded DNA, (ii)
annealing primers to the single-stranded DNA at a specific
hybridization temperature, and (iii) primer extension by a
DNA Taq polymerase.
38. In situ hybridization techniques
• ISH uses oligonucleotide probes to detect
complementary nucleic acids sequences.
• This method exploits the ability of nucleic acids to
anneal to one another in a very specific
complementary way to form hybrids.
• The target sequence should be short (15 to 30 bases)
and have at least two to three different nucleotides
with homologous sequences of closely related
organisms
39. Treatment Of Drinking Water
• Water treatment describes those industrial-scale processes
used to make water more acceptable for a desired end-use.
• These can include use for drinking water, industry, medical
and many other uses.
• Objective -To remove existing contaminants in the water, or
reduce the concentration of such contaminants so the water
becomes fit for its desired end-use.
40. Conventional Method for Water
Sequence of stages :
Treatment
1. Screening
2. Aeration
3. pH correction
4. Coagulation and flocculation
5. Sedimentation
6. Pre-chlorination and
dechlorination
7. Filtration
8. Disinfection
9. pH adjustment
41. Initial Stages
1. Screening - removal of
coarse floating objects
- weeds
2. Aeration - dissolving oxygen
into the water
– removes smell and taste
– promotes helpful bacteria growth
– precipitates nuisance metals like
iron and manganese.
42. 3. pH correction - Preparing for coagulation and to help
precipitate metals.
4.Coagulation and flocculation –
- add coagulating agent (aluminumsulfate or iron sulfate)
- causes agglomeration (clumping) and sedimentation of solid
particles
- these solid particles are called floc or sludge.
43. 5.Sedimentation –
- Floc settles out and is scraped and vacumed off the bottom of
large sedimentation tanks.
- Clarified water drains out of the top of these tanks in a giant
decanting process.
6. Pre-chlorination and dechlorination - Mostly to kill algae
that would otherwise grow and clog the water filters.
44. 7.Filtration
-Rapid-sand filters force water through a 0.45-1m layer of sand and
work faster, needing a smaller area. But they need frequent back-
washing
-Slow-sand filters require a much larger area but reduce
bacteriological and viral levels to better due to the Schmutzdecke
(biofilm) layer. The top 1 inch of biofilm must be periodically scraped
off and the filter occasionally back-
46. 8.Disinfection - Water completely free of suspended
sediment is treated with a powerful oxidizing agent usually.
– Chlorine- Dosage- 5 mg per litre.
– Chloramine (chlorine then ammonia)
– Sodium hypochlorite solution (5%)
– Ultraviolet radiations
– Ozonation
9. pH adjustment - So that treated water leaves the plant
in the desired range of 6.5 to 8.5 pH units.
47. Chlorine as disinfectant
Chlorine gas hydrolyses completely to form hypochlorous acid
(HOCl):
Cl2 + H2O HOCl + H+ + Cl–
Chlorine Water Hypochlorous
acid
The hypochlorous acid dissociates into hydrogen ions (H+) and
hypochlorite ions in the reversible reaction:
HOCl H+ + OCl–
Hypochlorous acid Hypochlorite ions
48. Ozonation
• Effective against bacteria and viruses,
organic matter compared to
chlorination.
• Eliminates bad taste and odour.
Ultraviolet radiations
• High germicidal properties.
• Disinfects water containing viruses,
Giardia lamblia and cryptospotium
cysts.
• Lacks residual disinfection,
secondary disinfectants(chlorine or
ozone)
50. Possible Additional Steps
• Heavy metal removal: Oxygenation
Coagulation
Ion exchange in filters to
remove them
• Activated carbon filters are required where soluble
organic constituents are present because many will pass
straight through standard plants, e.g. pesticides, phenols
and MTBE (Methyl tertiary butyl ether).
51. Water softening (Ion Exchange)
• Removal hardness ions
calcium and magnesium
and replacing them with
non hardness ions,
typically sodium supplied
by dissolved NaCl salt or
brine.
53. Public Education For safe drinking
water
• Provide an overview of drinking water sources,
monitoring, regulation, treatment, and health
considerations
• Discuss origins of water supply problems-natural
and human induced
• Ways of intervening in water
supply problems—such as
monitoring, education
and remediation.
