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Drinking Water Contamination

AOEC Teaching Module

2007


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This educational module was produced by Michael Greenberg, MD, MPH, Arthur Frank, MD, PhD, and John Curtis, MD for The University of Texas Health Science Center at San Antonio (UTHSCSA) Environmental Medicine Education Program and South Texas Environmental Education and Research Program (STEER-San Antonio/Laredo/Harlingen,Texas)Administrative support was provided by the Association of Occupational and Environmental Clinics through funding to UTHSCSA by the Agency forToxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services.Use of this program must include acknowledgement of the authors,UTHSCSA and the funding support.For information about other educational modules contact the UTHSCSA STEER office, Mail Code 7796, 7703 Floyd Curl Drive, San Antonio,Texas 78229-3900,(210)567-7407.


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Outline MD, MPH, Arthur Frank, MD, PhD, and John Curtis, MD for

  • 2 Introductory case studies

  • Examples of specific toxicants

    • Farm chemicals

    • Perchlorate

    • Heavy Metals

    • Biologicals

  • Clinical problem solving


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Objectives MD, MPH, Arthur Frank, MD, PhD, and John Curtis, MD for

  • After completion of this module, the student will be able to:

    • Describe the importance of the water supply as it relates to epidemic illness

    • Identify issues related to water purity as related to the use of industrial and agricultural chemicals

    • Demonstrate ability to evaluate illness due to biological contamination of water


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Case Study #1 MD, MPH, Arthur Frank, MD, PhD, and John Curtis, MD for Introduction to the Problem

  • From March 23rd to April 5th, 1993 two water treatment facilities in Milwaukee reported record setting turbulence in intake water

  • April 5th the Department of Health reported an outbreak of gastrointestinal illness


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Southern Water Treatment Plant MD, MPH, Arthur Frank, MD, PhD, and John Curtis, MD for


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Maximal Turbidity of Treated Water in the Northern and Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

Mac Kenzie W et al. N Engl J Med 1994;331:161-167


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Mystery GI Illness Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • 50% of the population served by the southernmost plant and 25% of those served by the northern plant become ill

    • Over 400,000 (26% of population) estimated to be affected

  • GI illness:

    • Watery diarrhea lasting approximately 9 days

    • Low grade fever

    • Average 10 lbs. weight loss


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Investigation Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Cryptosporidium was identified in over 600 stool samples (30% of those tested)

  • No other causative organisms found in greater than 2% of samples

  • Later, Cryptosporidium was also found in ice made from water during that period


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Cryptosporidium in water Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Disease transmitted by oocysts

  • Not destroyed by chlorine or chloramine

  • Difficult to identify and not normally screened for by water treatment facilities

  • Disease is usually self-limited in immunocompetent hosts


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Illustrative Points Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Importance of evaluating air, water, and food supply in epidemic illness

  • Relevant history regarding event

  • Symptoms, evaluations of patients

  • Impact on water-quality standards

  • Impact on U.S. public health including impact on HIV/AIDS awareness


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Case Study #2 Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • In January of 2003, a resident of Hebbronville, TX contacted the Texas Department of Health concerned about elevated arsenic (As) levels in drinking water

Hebbronville Library


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Hebbronville, TX Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993


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Hebbronville Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Agency for Toxic Substances and Disease Registry (ATSDR) conducted an evaluation of local residents and water supply

  • Water supply:

    • Arsenic levels in the drinking water ranged from 43.7 to 52.1 µg/L

    • Prior to 2006, the maximum contaminant level for As was 50 µg/L

Home of the Hebbronville Longhorns


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Evaluation of Population Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • 2/3 of the 140 people sampled had urinary inorganic As concentrations > reference concentration of 10 µg/L

  • Drinkers of tap water had higher-than-reference range levels

  • Drinkers of bottled water had substantially lower levels.

Hebbronville Courthouse


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Evaluation of Population Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • According to the ATSDR 91% of the population described themselves as Hispanic

  • Typical regional diet included rice and beans cooked in water - potentially increasing arsenic consumption:

    • 8-9 µg As per serving of rice

    • 20-24 µg As per serving of beans

      (if cooked in water containing 50 µg/L)


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Actions Recommended in Hebronnville Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Those with inorganic As levels > 20 µg/g of creatinine to be retested

  • Individuals encouraged to discuss their results with a personal health care provider

  • Evaluation of other (dietary) sources of As

  • Efforts to reduce As levels in the public water system.


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Implications Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Unclear what, if any, health effects would be expected

  • Possible parallels to areas such as Taiwan and Bangladesh that have experienced high levels of environmental arsenic


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Bangladesh Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Borders India and Burma

  • Local water wells were commonly contaminated with disease-causing microorganisms


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Bangladesh Water Supply Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • UNICEF and other international organizations promote the use of “tube wells” for safer water supply in the 1970’s and 1980’s

    • Thin tubes sunk in ground; usually < 200 meters in depth

    • Resulted in high levels of arsenic in soil leached into water, first confirmed in 1993


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Quantification of Arsenic Exposure Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • In 1980’s first reports of arsenic-related dermatologic disease

  • Analysis of water in British Geological Survey showed that >35% of wells contained

    > 50 g As/L

    • In some districts >80% of wells contained greater than 50 g As/L

    • 8% had As concentrations of

      > 300 g/L


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% of Field-tests positive for As Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993


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Chronic Arsenic Toxicity Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Approximately 125 million residents drawing from water supply

  • In some studies 30-50% of patients had skin lesions due to arsenic

    • Skin lesions typically develop after latency of 10 years


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Public Health Implications Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Other potential long-term effects of arsenic exposure:

    • Cancers, including skin, bladder, kidney and lung

    • Neurological effects

    • Hypertension, vascular disease

    • Pulmonary disease

    • Diabetes

Environmental Health Perspectives Volume 110, Number 2, February 2002


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Public Health Issues - Bangladesh Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • How to treat the millions of exposed patients?

    • Nutritional supplementation?

    • Infected hyperkeratotic lesions?

  • What about tremendous predicted expense from excess cancer morbidity/mortality?


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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Farm chemicals

  • Perchlorates

  • Solvents

  • Arsenic

  • Microbiological Agents


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Occurrence of Nitrite/Nitrate Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Naturally occurring inorganic ions

    • Enter groundwater from fertilizer use, including anhydrous ammonia

    • Releases totaled over 110 million pounds

    • Contamination from septic systems

  • Chemical characteristics lead to migration to ground water


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Exposure Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Groundwater supplies 20% of nitrate intake, but can be higher in the setting of water contamination

  • MCL for nitrates has been set at 10 ppm, and for nitrites at 1 ppm

    • US Geological survey in 1995 showed >8,000 wells had levels exceeding 10 ppm

    • 1-2% of population estimated to be exposed to excessive levels of nitrates

  • >600,000 homes draw from contaminated wells and rural wells are not routinely tested


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Health Effects Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Nitrites and nitrates cause oxidation

  • Nitrates are converted in vivo to nitrites

    • More potent oxidizers

  • Oxidation of iron in hemoglobin results in methemoglobinemia


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Methemoglobinemia Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Oxidized hemoglobin unable to carry oxygen effectively

  • Infants at risk due to:

    • Increased levels of fetal hemoglobin

    • Reduced levels of methemoglobin reductase

  • One cause of infantile cyanosis or “Blue-baby syndrome”

  • Has resulted in numerous infant deaths


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Methemoglobinemia Treatment Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Supportive care

  • Removal from exposure

  • Reducing agents such as methylene blue

  • Antioxidants such as vitamin C


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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Farm chemicals

  • Perchlorates

  • Solvents

  • Arsenic

  • Microbiological Agents


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Perchlorates Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Naturally occurring (e.g. in saltpeter deposits)

  • Magnesium, potassium, sodium, lithium, ammonium perchlorate are manufactured in large amounts

    • Uses include: solid rocket fuel, ammonium perchlorate, explosives


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Perchlorates Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Perchlorates are the primary oxidizers in solid rocket fuel

  • Perchlorates are also very stable in water


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Exposure Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • EPA reports that 40 of 1547 National Priority Sites contain perchlorates

    • Leaves soil to enter water

      • May persist for years

    • No proven method for removal from water


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Exposure Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Exposure pathways may include:

    • Drinking contaminated water

    • Also may occur through tobacco use

    • Proximity to industrial use of perchlorates


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Perchlorate Contamination Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • In 1997 perchlorates were discovered in drinking water

  • Primarily affects Western States

Environmental Science and Technology/News May 1, 1998


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Health Effects Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Perchlorates effect the thyroid

    • Interferes with the thyroid’s ability to take up iodide

    • Clinical relevance is unclear

    • Human studies generally report insufficient evidence to determine risk of carcinogenesis


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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Farm chemicals

  • Perchlorates

  • Solvents

  • Arsenic

  • Microbiological Agents


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Solvents - including MTBE Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Methyl-t-butyl-ether

    • Manufactured by reaction of methanol and isobutylene

    • Flammable liquid with disagreeable odor

    • Evaporates quickly

    • Added (like ethanol) to gasoline as an oxygenator to decrease carbon monoxide emissions.


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Potential Exposure Pathways Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Possible ingestion of MTBE in water

    • Concentration dependant

  • Dermal exposure while showering or swimming

    • Medically important systemic absorption is unlikely


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MTBE - possible health effects Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Any adverse effects are expected to be a function of exposure and dose

  • Vapor exposure (at high concentration for prolonged periods) may have mild but reversible effects

  • Ingestion

    • Potential cancer risk is unproven

      • Not classified by the IARC

      • Only weak evidence of carcinogenicity in some animal studies


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Water Purity Standards Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • EPA recommends < 4 mg MTBE/Liter

  • State-specific limits exist

  • Taste/odor threshold is 20-40 ppb


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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Farm chemicals

  • Perchlorates

  • Solvents

  • Arsenic/Heavy Metals

  • Microbiological Agents


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Heavy Metal Occurrence Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Mostly natural

    • Mineral deposits

    • Natural soil constituents

  • Increased levels may exist at some industrial sites


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Potential Exposure Pathways Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Contaminated water supply

  • Food grown in contaminated soil or with contaminated water


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Potential Health Effects - Arsenic Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Acute

    • Possible GI illness, neuropathy

    • Uncommon from environmental exposure

    • Intentional exposures

      • Suicidal

      • Homicidal

  • Chronic

    • Dermatologic, vascular and malignant disease

    • Environmental exposure

      • Bangladesh


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Treatment for Arsenic/Metals Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • For chronic exposure the treatment is REMOVAL FROM EXPOSURE

  • For acute exposure, consultation with a Poison Control Center or medical toxicologist is advisable

    • Chelation may be considered in some extreme cases


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TOXICOLOGICAL AND ENVIRONMENTAL SPECIFICS Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Farm chemicals

  • Perchlorates

  • Solvents

  • Arsenic

  • Microbiological Agents


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Microbiological Water Contamination Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Several broad categories, including:

    • Bacterial

    • Protozoa

    • Viruses


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Bacterial Contamination Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Traveller’s diarrhea

    • Up to 50% of international travelers may be afflicted depending on region

      • Approximately 10 million people

    • High-risk areas

      • Latin/Central America

      • Africa

      • Middle-East

      • Asia


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Traveller’s Diarrhea Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Caused by infectious agents

    • Primarily Escherichia coli

      • Produces enterotoxins

    • Watery diarrhea lasting several days

E.coli 0157:H7


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Traveller’s Diarrhea Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Prevention:

    • Avoidance of local waters and ice

    • Bottled water for consumption

    • Daily bismuth (e.g.Pepto-Bismol) preparations

    • Avoidance of strong antacids (PPIs)

    • Possibly prophylactic antibiotics for select patients


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Treatment Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Usually self-limited

  • Only symptomatic treatment usually required

  • Antibiotics (sulfa drugs, quinolones) may slightly reduce duration of illness


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Dysentery Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Enteroinvasive disease caused by any of several organisms

    • Salmonella, Shigella, Campylobacter

  • Bloody mucoid diarrhea with fever, fecal leukocytes

  • Antibiotic treatment recommended

Salmonella infantis


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Protozoan Infections Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993


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Protozoal Infections Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Common cause of endemic diarrheal illness

  • Typically spread through fecal-oral transmission

  • Common types include

    • Cryptosporidium

    • Giardia


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Cryptosporidium parvum Southern Water-Treatment Plants of the Milwaukee Water Works from March 1 through April 28, 1993

  • Worldwide presence in water supply

    • Not effectively killed by chemical purification methods

  • Prevention through

    • Boiling of drinking water

    • Water filtration with 1 micron pores


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Life Cycle of Cryptosporidium and Infection of Host Epithelial Cells

Chen X et al. N Engl J Med 2002;346:1723-1731


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Cryptosporidium - Health Effects Epithelial Cells

  • Watery diarrhea lasting 1-2 weeks in normal hosts

  • May result in dehydration, weight-loss

  • Usually self-limited, but may be severe in immunocompromised hosts

    • Treatment includes anti-retrovirals for those with HIV

    • Possible role for nitrazoxanide


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Giardia Lamblia Epithelial Cells

  • Very common parasitic disease

  • More common in warmer climates

  • Prevention is similar to measures for cryptosporidium

    • Boiling of water

    • Filtration

      • Reverse osmosis

      • 1 micron pores


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Viral Diseases Epithelial Cells

  • Multiple viral pathogens

    • Rotaviruses

    • Hepatitis A

    • Enteroviruses

  • Most common epidemic (not endemic) diarrheal illnesses

  • No specific treatment


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Norwalk Virus Epithelial Cells

  • Common cause of epidemic diarrheal illness

  • Responsible for recent outbreaks on cruise ships


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Prevention Epithelial Cells

  • Hygiene

    • Reduce fecal-oral transmission

    • Hand-washing

    • Sanitization of surfaces

  • Vaccination

    • Effective for hepatitis A prevention


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Reported Cases of Hepatitis A, United States Epithelial Cells

1995: Vaccine Licensed

1996: ACIP recommendations

1999 ACIP recommendations

Source: NNDSS, CDC


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States with Hepatitis A Rates Epithelial Cells> 10/100,000 1987-97

Rate > 20/100,000

Rate 10-20/100,000

Rate < 10/100,000


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Number of years that Reported Incidence of Epithelial Cells

Hepatitis A Exceeded 10 Cases per 100,000,

by County, 1987-1997


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Rate per 100,000 Epithelial Cells

> = 20

10 - 19

5 - 9

0 - 4

Hepatitis A Incidence, United States

1987-97 average incidence

2002 incidence


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Approach to the Evaluation and Management of Infectious Diarrhea

Thielman N and Guerrant R. N Engl J Med 2004;350:38-47


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Water as a Terrorist Target Diarrhea

  • Watersheds and reservoirs contain a centralized depot of an essential resource for large numbers of people

  • Often inadequately protected

  • Impossible to monitor for all possible pathogens at all times


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Prevention of Water Terrorism Diarrhea

  • Certain chemical properties of water are monitored continuously

  • Very large volume of water

    • Would require very large amounts of toxins to reach harmful levels

    • Attractive terrorism agents would have to be extraordinarily potent to be effective (such as botulinum toxin)


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Clinical Problem Solving Diarrhea

  • 40 patients present over a 2-3 day period with GI illness

    • Watery diarrhea

    • Crampy abdominal pain

    • No fever/vomiting

  • No occupational, social, or family connection between most patients


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Key Physician Actions Diarrhea

  • Recognize cluster of illnesses

  • Try to find shared exposure

    • Attendance at a gathering

      • Family/workplace picnic etc.

    • Eating at same restaurant or similar unusual foods

    • Face-to-face contact (same school, workplace)


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Observations Diarrhea

  • Some hospitals receive many more patients than others

  • Most patients come from same geographic area

  • No particular meals, restaurants, or workplaces occur with greater than expected frequency


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Investigation Diarrhea

  • Comparing geographical distribution of patients to water distribution plans reveals that areas affected all receive water from same reservoir and treatment plant.


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Role of Community Physician Diarrhea

  • Physicians are on the “front-line”

  • They are the interface between the public and the public health agencies

  • Therefore, physicians must treat not only individual patients, but be vigilant to protect and treat their entire community


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Key Physician Actions Diarrhea

  • Recognition of illness cluster

  • Recognition of probable environmental illness

  • Development of rational evaluation and treatment options

  • Reporting responsibilities

    • Contact the CDC and local public health officials


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Treatment and Disposition of Patients Diarrhea

  • Evaluate and resuscitate as necessary

    • Identify and treat dehydration

    • Check stool for blood and/or fecal leukocytes to screen for enteroinvasive disease (dysentery)

    • Symptomatic treatment

  • Obtain stool cultures, send stool for evaluation for ova and parasites


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References Diarrhea

  • http://www.atsdr.cdc.gov/hac/pha/hebbronville/hae_p1.html#sum

  • Agency for Toxic Substances and Disease Registry. 2001. Case studies in environmental medicine: taking an exposure history. Atlanta: US Department of Health and Human Services


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References Diarrhea

  • American Academy of Pediatrics. 1970. Policy statement. Infant methemoglobinemia: the role of dietary nitrate. Pediatrics 46(3):475-8


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References Diarrhea

  • U.S. EPA. Integrated Risk Information System: Perchlorate and Perchlorate Salts. 2/18/2005

  • U.S. EPA. Assessment Guidance for Perchlorate. January 26, 2006

  • Chen X.-M. et al. Current Concepts: Cryptosporidiosis. N Engl J Med 2002; 346:1723-1731, May 30, 2002.

  • Thielman NM, Guerrant RL. Acute Infectious Diarrhea. N Engl J Med 2004; 350:38-47, Jan 1, 2004


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