Water borne diseases, prevention and guidelines for safe drinking water
Water borne diseases, prevention and guidelines for safe drinking waterMade By: Navjot KaurMajor Advisor: Dr.(Mrs.)ParampalSahota
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.
Classification of waterborne diseases Vector borne diseases
Water-washed (water-hygiene) diseases•Diseases caused by poor personal hygiene and contact withcontaminated waterWater-scarce diseases occur due to the lack of water available for washing,bathing and cleaning.•Hence, pathogens are transmitted from person to person or fromcontaminated surfaces to a person and are spread by the faecal–oral route.
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 .
Examples and route of infection(Water washed diseases)(Water scare diseases) (Water based diseases) (Vector borne diseases)
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.
• Hunter et al. 2000. “Currently, about 20% of the worlds 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
Water-borne disease caused by chemicals• Arsenic• Flouride• Nitrates from fertilizers• Carcinogenic pesticides (DDT)• Lead (from pipes)• Heavy Metals• Chromium• Nickel• Cyanide
Health effectsArsenic 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) ArsenicosisChlorine 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)
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
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.
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
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
Detection, identification and quantification of microorganisms Classical methods• Multiple Tube Fermentation• Membrane filter technique• Enzymatic methods using enzymes β-D galactosidase and β-D glucuronidase. Molecular method• Immunological• Polymerase chain reaction (PCR)• In-situ hybridization (ISH) techniques
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.
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.
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.
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).
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.
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
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.
Conventional Method for Water Sequence of stages : Treatment1. Screening2. Aeration3. pH correction4. Coagulation and flocculation5. Sedimentation6. Pre-chlorination and dechlorination7. Filtration8. Disinfection9. pH adjustment
Initial Stages1. Screening - removal of coarse floating objects - weeds2. Aeration - dissolving oxygen into the water – removes smell and taste – promotes helpful bacteria growth – precipitates nuisance metals like iron and manganese.
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.
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.
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-
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 – Ozonation9. pH adjustment - So that treated water leaves the plant in the desired range of 6.5 to 8.5 pH units.
Chlorine as disinfectantChlorine gas hydrolyses completely to form hypochlorous acid(HOCl): Cl2 + H2O HOCl + H+ + Cl–Chlorine Water Hypochlorous acidThe hypochlorous acid dissociates into hydrogen ions (H+) andhypochlorite ions in the reversible reaction: HOCl H+ + OCl– Hypochlorous acid Hypochlorite ions
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)
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).
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.
Emergency treatment of drinking- water at the point of use
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.