Waterbourne Disease Flashcards
What are the major diseases associated with waterborne illness?
- Cholera
- Bacillary dysentery
- Legionnaires’ disease
- Leptospirosis
- Enteric viruses
Why is water purification important?
It is essential for human health and helps prevent waterborne diseases.
What is the role of sanitary analysis of water?
To monitor water quality and detect potential pathogens.
Define indicator organisms in the context of water quality.
Organisms that indicate fecal pollution and the potential presence of pathogens.
What is cholera caused by?
Vibrio cholerae
What are the symptoms of cholera?
- Acute and intense diarrhea
- Severe dehydration
- Hypovolemia
- Possible death without treatment
How does cholera toxin function?
Toxin composed of two subunits A & B
•Subunit A - toxin with enzyme activity
•Subunit B - binds to intestinal receptors
- Hypersecretion of water and chloride ions
- Inhibits sodium ion absorption
What is the incubation period for cholera?
1-3 days
What is the primary treatment for cholera?
- Rehydration therapy
- Antimicrobial therapy
What is bacillary dysentery also known as?
Shigellosis
What is a key characteristic of Shigella spp.?
Gram-negative, non-motile rods
What are the four Fs associated with the transmission of bacillary dysentery?
- Food
- Fingers
- Faeces
- Flies
What symptoms are associated with legionnaires’ disease?
Pneumonia
What organism causes legionnaires’ disease?
Legionella pneumophila
What are common sources of Legionella pneumophila?
- Hot tubs
- Water tanks
- Cooling towers
- Decorative fountains
What are methods of preventing legionnaires’ disease?
- Regular disinfection
- Chemical level checks
- Daily flushing of fixtures
- Temperature control
What causes leptospirosis?
Leptospira genus
What are the symptoms of leptospirosis?
Flu-like symptoms
What are the two main types of waterborne viral diseases?
- Hepatitis A and E
- Poliomyelitis
What is the incubation period for hepatitis A and E?
2-6 weeks
What is the primary method for detecting coliforms in water?
Multiple tube fermentation method
In the multiple tube fermentation test, what does a positive result indicate?
Presence of coliform bacteria based on gas production in lactose broths
What is the significance of the Salk and Sabin vaccines?
- Salk vaccine: inactivated poliovirus vaccine for injection
- Sabin vaccine: attenuated vaccine for oral administration
What is the purpose of sanitary analysis of water?
To ensure water is safe for consumption and meets health standards
Sanitary analysis helps in identifying contamination and assessing water quality.
What is the significance of coliform count in water classification?
It indicates the level of fecal contamination in water
Different classifications of water supply are based on coliform counts.
What are the coliform count classifications for water supplies?
- Excellent: 0 coliforms/100ml
- Satisfactory: 1-3 coliforms in not more than 5% of samples
- Doubtful: 4-10 coliforms in not more than 5% of samples
- Unsatisfactory: >10 coliforms or 1 or more E. coli
These classifications help assess the potability of water.
What is the Colilert® system used for?
Detecting bacteria in water using multiple tube fermentation method
It includes inhibitors to prevent unwanted organisms and two carbon sources.
What are the two carbon sources used in the Colilert® system?
- ONPG (ortho-nitrophenolgalactopyranoside)
- MUG (4-methyl-umbelliferylglucuronide)
These substrates help in the detection of coliforms.
What molecular technique can distinguish pathogens from commensals?
16S rRNA with gene-targeted primers
This technique allows for the identification of specific bacteria in samples.
What is the detection limit for routine coliform detection in water?
1 cfu/100ml
This level of detection is crucial for ensuring water safety.
What is flow cytometry used for in water analysis?
Detecting Cryptosporidium spp.
Flow cytometry is a rapid method for identifying pathogens in water.
What are indicator organisms?
Microorganisms used to assess the microbiological quality of water
They serve as a measure of potential contamination.
True or False: E. coli is always present in excellent water supply classifications.
False
Excellent water supply classifications have 0 E. coli count.
Fill in the blank: The classification ‘Doubtful’ for water supplies is defined by a coliform count of _______.
4-10 in not more than 5% of samples
This classification indicates potential health risks.
Which two microorganisms are the main causative agents for waterborne disease?
1.Vibrio cholerae
2.Salmonella spp.
What are the cholera symptoms?
•incubation period ca. 1–3 days.
•acute and very intense diarrhoea that can exceed one litre per hour.
•Severe dehydration
What is the Cholera toxin subunits?
Toxin composed of two subunits A & B
•Subunit A - toxin with enzyme activity
•Subunit B - binds to intestinal receptors
What is the action of cholera toxin?
•Hypersecretion of water and chloride ions
•Inhibits absorption of sodium ions
Name the three treatments of cholera
- Rehydration therapy
•Replace water and salts
•Oral or intravenous - Antimicrobial therapy
•kill the pathogen
•the most efficient antibiotic is currently doxycycline - Vaccine - preventative
Name the three treatments of cholera
- Rehydration therapy
•Replace water and salts
•Oral or intravenous - Antimicrobial therapy
•kill the pathogen
•the most efficient antibiotic is currently doxycycline - Vaccine - preventative
What is the morphology of Vibrio cholerae
Small, curved-shaped Gram-negative rods, with a single polar flagellum.
•Facultative anaerobes
•Can grow at 40 °C with pH 9–10.
What are the 4 shigella species that cause disease in humans?
•Shigella sonnei (UK & USA)
•Shigella flexneri (USA)
•Shigella boydii
•Shigella dysenteriae
What is the morphology of Shigella spp.
Gram negative, non-motile, rod
What is the morphology of Shigella spp.
Gram negative, non-motile, rod
What are the four f’s and which diesease is it related to?
Food, fingers, faeces and flies.
Shigella - Bacillary dysentery
How does bacillary dysentery present itself?
Incubation 1-3 days
Facultative anaerobes, intracellular parasites
•Multiply within the villus cells of epithelium
•Severe cases result in ulcerated colon
Produce Shiga-toxin
•Heat labile toxin
•Binds to ribosomes and inhibits protein synthesis
Name the major pathogens associated with water borne illness
•Cholera - Vibrio cholerae
•Bacillary dysentery - Shigella spp.
•Legionnaires - Legionella pneumophila
. leptospirosis - Leptospira
•Enteric viruses - Hepatitis A and Hepatitis E
Name an indicator organism
Coliforms
•Facultative anaerobes
•Gram-negative
•Non spore forming
•Rod shaped
•Ferment lactose with gas formation within 48 hours at 35oC
How is river and tap water sample taken?
River water
•Sterile glass bottle inverted into current
Tap water
•Tap flamed and water run for 5 minutes
•Sodium thiosulphate is added to chlorinated water
Samples kept on ice and examined within 3 hours
How does membrane filtration work?
Sample is filtered on to membrane
•Membrane transferred to solid medium or absorbent pad
•Filter is incubated
•4 hours 30oC
•14 hours 44oC
•Filters with grid aids counting
•Differential and selective media allow identification of different organisms
