Pathogen Lecture Powerpoint (1)

Chapter 7: Pathogens in the Water Supply

Page 1: Introduction to Pathogens in Water Supply

• Focuses on various pathogens affecting water supplies.

Page 2: Pathogen Overview Study Guide

• Sources of Pathogens in Natural Waters:

  • Agricultural runoff

  • Sewage discharge

  • Industrial waste

  • Wildlife feces

  • Natural occurrences (e.g., flooding)

• Steps in Infection:

  • Contact/exposure

  • Pathogen entry

  • Sufficient dosage to overcome defenses

• Indicator Organism Characteristics:

  • High numbers in human intestines

  • Present during enteric pathogen presence

  • Survives longer than hardiest enteric pathogen

  • No reproduction in contaminated water

• E. coli Monitoring:

  • Done by Georgia Adopt A Stream to assess contamination levels.

• Weather Influences:

  • Weather impacts coliform bacteria levels in water.

• Cholera Epidemics:

  • London 1854: caused by contaminated water from Broad Street pump.

  • Haiti 2010: linked to UN camps post-earthquake with poor sanitation.

Page 3: Classification of Pathogens

• Types of Water-Borne Diseases:

  • Viruses: Cause diseases like hepatitis.

  • Protozoans: Include pathogens like Giardia.

  • Bacteria: E.g., E. coli, Vibrio cholera.

  • Helminths: Intestinal worms (e.g., Schistosoma).

Page 4: Pathogen Entry into Water Supply

• Entry Methods:

  • Land runoff from agriculture and urban areas.

  • Sewage releases from households and industries.

  • Malfunctioning wastewater systems.

  • Poorly treated water or infrastructure.

Page 5: Steps in Infection

• Infection Process:

  • Exposure to pathogens.

  • Entry into the body through skin or ingestion.

  • Sufficient pathogen load to bypass immune defenses.

Page 6: Vibrio cholera

• Pathogen Type: Bacterium

• Disease: Cholera

• Symptoms: Severe diarrhea, dehydration, and death if untreated.

• Transmission: Via contaminated feces and water.

• Prevention/Treatment: Safe water access and fluids for rehydration.

Page 7: The Birth of Epidemiology

• John Snow’s Contribution:

  • Identified Broad Street pump as cholera infection source in London 1854.

  • Removal of the pump handle ceased the epidemic, showcasing waterborne transmission.

Page 8: Cholera Epidemic in Haiti

• Post-earthquake in 2010, UN camps caused water resources contamination.

• Strain traced back to Nepal; Haitians had no immunity, exacerbating spread.

• Lack of clean water infrastructure facilitated rapid disease transmission.

Page 9: Tests for Pathogens

• Testing procedures cover pathogen identification in water samples.

Page 10: Indicator Organisms

• Ideal Characteristics:

  • Applicable for all water types.

  • High presence in human intestines.

  • Survives longer than pathogens.

  • No reproduction in contaminated habitats.

  • Sensitivity and specificity in testing.

Page 11: Coliform Bacteria

• Types of Coliforms:

  • Found naturally in soil and faeces.

  • Fecal Coliforms: Specific to human and warm-blooded animals (E. coli).

Page 12: Monitoring E. coli

• Why Monitor:

  • E. coli serves as an indicator of fecal contamination.

  • Sources include wildlife, livestock, urban runoff, and sewage systems.

Page 13: Weather and Seasonal Influences

• Influence of Rain:

  • Increased bacterial counts after heavy rains.

  • Seasonal temperature impacts E. coli survival rates (higher in summer).

Page 14: Bacterial Monitoring

• Processes Involved:

  • Sample collection and plating to enumerate E. coli colonies.

  • Assesses water health risks due to contamination.

Page 15: Reading Results of Tests

• Counting E. coli Colonies:

  • Units of measurement: CFU/100 ml.

  • Criteria for counting: color and gas bubbles.

Page 16: Calculating Results

• Example Calculation:

  • Average colonies in plates converted to CFU/100 ml for assessment.

Page 17: EPA Recommended E. coli Levels

• E. coli Levels for Recreational Waters:

  • Swimming <235 CFU/100 ml

  • Moderate swimming <298 CFU/100 ml

  • Higher levels increase health risks.

Page 18: Fecal vs. E. coli levels

• E. coli Percentage:

  • Approx. 60% of fecal coliforms are E. coli.

  • Sample analysis relates E. coli levels to fecal contamination.

Page 19: Action Levels for Monitoring

• Thresholds:

  • 1000 CFU/100 ml requires continuous monitoring and investigations by health agencies.

Page 20: Pathogen ID Learning Outcomes

• Exam Preparation:

  • Focus on infection pathways and symptoms of various pathogens, e.g., likely pathogens in water exposure cases.

Page 21: Vibrio cholera Recap

• (Repeat of Page 6 content)

Page 22: Giardia

• Pathogen Type: Protozoan

• Disease: Giardiasis

• Symptoms: Range from diarrhea to abdominal pain.

• Sources: Mostly in mountainous areas; water contaminated by beavers.

• Treatment: Filtration or boiling water to eliminate cysts.

Page 23: Naegleria fowleri

• Pathogen Type: Protozoan

• Disease: Amebic meningoencephalitis.

• Symptoms: Severe inflammation and high fatality rate.

• Transmission: Entry through the nose from contaminated water.

Page 24: Cryptosporidium

• Pathogen Type: Protozoan

• Disease: Gastroenteritis.

• Symptoms: Watery diarrhea.

• Transmission: Resistant oocysts in contaminated water or via person-to-person.

Page 25: Leptospira

• Pathogen Type: Bacteria

• Disease: Leptospirosis.

• Symptoms: Acute infections affecting kidneys and CNS.

• Transmission: Via water contaminated by rodent urine.

Page 26: Legionella

• Pathogen Type: Bacterium

• Disease: Legionnaire's disease & Pontiac Fever.

• Transmission: Inhalation of contaminated water droplets.

Page 27: E. coli O157:H7

• Pathogen Type: Bacterium

• Disease: Severe illness from shiga toxins.

• Prevention: Hygiene and boiling contaminated water.

Page 28: Shigella

• Pathogen Type: Bacterium

• Symptoms: Diarrhea and abdominal cramps.

• Transmission: Ingesting contaminated recreational water.

Page 29: Schistosoma

• Pathogen Type: Helminth (worm)

• Disease: Schistosomiasis.

• Symptoms: Skin rashes, chronic cases linked to fatigue and abdominal pain.

Page 30: Ascaris lumbricoides

• Pathogen Type: Helminth (worm)

• Disease: Ascariasis.

• Symptoms: Range from none to intestinal blockage.

• Transmission: Eggs from infected feces contaminating soil.

Page 31: Drinking Water Treatment: Learning Outcomes

• Trace the water treatment process and identify treatment functions.

• Explain flocculation process and disinfecting methods.

• Understand water purity issues leading to boil alerts.

Page 32: Drinking Water Treatment Overview

Page 33: Water Fluoridation

• Purpose: To reduce dental cavities.

• Georgia adopts fluoridation widely.

• Recognized as a major public health achievement.

Page 34: Corrosion Control Chemicals

• Functionality:

  • Chemicals like phosphoric acid prevent lead leaching into water.

  • Forms a protective coating inside plumbing.

Coagulation: Coagulation is a crucial process in water treatment that involves the aggregation of small particles into larger clumps or flocs, which can then be removed from the water. This process typically uses chemicals called coagulants (like aluminum sulfate) that promote the formation of floc by neutralizing the charge on particles, helping them to bond together. Coagulation is often followed by sedimentation, where the floc is allowed to settle out of the water, ensuring cleaner water before further treatment steps such as filtration and disinfection.