This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike License. Your use of this material constitutes acceptance of that license and the conditions of use of materials on this site.

Copyright 2006, The Johns Hopkins University and Jonathan M. Links. All rights reserved. Use of these materials permitted only in accordance with license rights granted. Materials provided “AS IS”; no representations or warranties provided. User assumes all responsibility for use, and all liability related thereto, and must independently review all materials for accuracy and efficacy. May contain materials owned by others. User is responsible for obtaining permissions for use from third parties as needed. Food- and Water-Borne Disease

Jonathan M. Links, PhD Johns Hopkins University Section A

Food-Borne Diseases Food-Borne Diseases: Definitions

„ Food-borne diseases − Those resulting from consumption of any solid food or milk, water, or other beverage „ Outbreak (CDC) − Two or more persons experiencing a similar illness after ingestion of a common food or beverage − Epidemiologic analysis implicates the food/beverage as the source of illness

Source: MMWR. 4 Food-Borne Outbreaks: 1988–1997

700 25000 600 20000 500 Cases 400 15000 Cases 300 10000 Outbreaks 200 5000 100 0 0

0 3 4 6 7 89 9 9 9 9 9 9 1988 1 19 1991 1992 19 19 1995 19 19

Outbreaks Cases

Source: MMWR. 5 Total Burden of Food-Borne Illness

Illnesses 76,000,000

Hospitalizations 323,000

Deaths 5,200

Source: Mead, P. S. et al. (1999). Food-related illness and death in the United States. EID, 5, 607–625. 6 Causes of Food-Borne Outbreaks, 1988–1997

60

50

40

30 Percent 20

10

0 Unknown Bact. Chem. Viral Parasitic

Source: MMWR. 7 Number of Causative Organisms

„ Number of causative organisms involved in confirmed food- borne illnesses 40

30

20

10 Number of Causative Agents Number of Causative 0 1950 1960 1970 1980 1990 2000

Source: MMWR. 8 Extent of the Problem

OCCUR?

REPORTED

Food known, agent known, causes known 9 Food Safety Issues

Microbial Contamination

Food Natural Food Additives Toxins

Environmental Pesticide Residues Contaminants 10 Selected Infectious Agents and Their Main Habitats

Microorganism Main habitat Bacillus cereus, Ubiquitous in soil and on vegetables Clostridium botulinum

Campylobacter Intestine of animals, fowl, and humans

Lower intestine of humans, warm- E. coli, Salmonella blooded animals, birds

Shigella Intestine of humans and primates

Staphylococcus aureus Common on human skin and oropharynx

Vibrio cholerae Intestine of humans

11 Selected Infectious Agents and Their Main Habitats

Microorganism Main habitat Intestine of humans, beavers, and Giardia lamblia muskrats

Intestine of humans and warm-blooded Cryptosporidium animals

Striated muscle of carnivorous and Trichinella spiralis omnivorous animals

Hepatitis A virus Intestine of humans

Norwalk virus Intestine of humans

12 The Bacterial Growth Curve

9

8 c

7 a: Lag d b: Exponential (logarithmic) 6 /ml c: Stationary 10 d: Decline

Log 5 b 4

3 a 2 048121620242832 Hours at 37oC 13 Minimal Infective Doses

„ Minimal infective doses for some pathogens and parasites

Organism Minimal dose

Salmonella spp. 104–107

Shigella spp. 101–102

Escherichia coli 106–108

Escherichia coli O157:H7 ~10

Vibrio cholerae 103

Giardia lamblia 101–102 cysts

Cryptosporidium 101 cysts

Hepatitis A virus 1–10 PFU 14 Multiplication of L. monocytogenes in Broth

„ Multiplication of L. monocytogenes in broth at low temperature 8

o 7 4 C

6

5

4

3 Bacteria per ml -20oC 2

1

0 0 1 3 612 Weeks of storage 15 Preferred Temperature Ranges for 4 Types of Bacteria

„ Relative growth rate of bacteria at different temperatures

Source: Doyle, M. P. 16 Extension of Shelf Life of Raw Foods by Cool Storage

Average useful storage life (days) Food 0oC (32oF) 22oC (72oF)

Meat 6–10 1

Fish 2–7 1

Poultry 5–18 1

Fruits 2–180 1–29

Leafy vegetables 3–20 1–7

Root crops 90–300 7–50

17 Moisture Requirement

„ Water activity; aw

Water vapor pressure of food A = w Water vapor pressure of pure water

„ Free water in food is necessary for microbial growth „ Each microbial species has an optimum, maximum, and

minimum aw for growth „ In general, a higher aw facilitates microbial growth

18 Water Activity of Various Foods

Food aw Fresh fruit, vegetables, meat, fish >0.98 Cooked meat, bread 0.95–0.98 Cured meats, cheeses 0.91–0.95 Sausages, syrups 0.87–0.91 Rice, beans, peas 0.80–0.87 Jams, marmalades 0.75–0.80 Candies 0.65–0.75 Dried fruits 0.60–0.65 Dehydrated milk, spices 0.20–0.50

19 Lowest aw Values Permitting Growth of Microorganisms

Group of microorganisms Minimal aw value

Many bacteria 0.91

Many yeasts 0.88

Many molds 0.80

Halophilic bacteria 0.75

Osmotic yeasts 0.60

20 Oxygen-Reduction (O-R) Potential

„ O2 tension or partial pressure of O2 about a food and the O-R potential (the oxidizing and reducing power of the food) influence the types of organisms that will grow in the food „ Aerobes—Require free oxygen − Most microorganisms „ Anaerobes—Grow best in the absence of free oxygen − Clostridium spp. „ Facultative—Grow well either aerobically or anaerobically − Enterobacteriaceae family

21 pH

22 Foods Associated with Foodborne Illness

Food vehicle Microorganism

Salmonella, S. aureus, E. coli, B. cereus, T. spiralis, L. Beef and pork monocytogenes

Salmonella, Campylobacter, S. aureus, L. Poultry monocytogenes

Salmonella, Campylobacter, E. coli, L. monocytogenes, Dairy products Brucella

Eggs Salmonella, S. aureus

Dried cereal B. cereus and other Bacillus spp.

23 Foods Associated with Foodborne Illness

Food vehicle Microorganism

C. botulinum, C. perfringence, Salmonella, Shigella, B. Vegetables cereus, Norwalk virus

C. botulinum, C. perfringence, ciguatera and scombroid Fish toxins V. parahaemolyticus, V. cholerae, Hepatitis A, Norwalk Shellfish virus, neurotoxic and paralytic shellfish poisoning Chinese food B. cereus (in fried rice)

24 Some New Food Vehicles for Transmission

„ Internal content of eggs − Salmonella enteritidis „ Apple cider (low pH) − E. coli O157:H7 „ Imported raspberries − Cylospora „ Oysters − Norwalk-like virus

25 Changes in Host Susceptibility

„ Increase in diseases that cause immunosuppression − AIDS 1988–1996: 22,000 to 223,000 cases „ Increase in use of immunosuppressive agents − Number of organ transplants 1988–1996: 12,000 to 22,000 „ Aging of the population − Percentage of U.S. population >65 years old: 1950–1990: 8% to 15%

26 Host Factors and Susceptibility/Resistance to Infection

„ Personal hygiene − Sanitary conditions; number of organisms ingested „ Gastric acidity (pH ~ 3.4; acid barrier) − 99.9% of ingested coliforms killed within 30 minutes − Majority of pathogens never reach intestine − Antacids increase susceptibility and severity of gastrointestinal infections „ Intestinal motility − Fluid absorption processes − Maintaining appropriate distribution of indigenous enteric microflora − Ridding host of pathogenic microorganisms „ Specific immunity

27 Section B

Water-Borne Diseases Global Total Water and Freshwater Reserves

Total water resources Freshwater resources

Rivers, lakes, Permafrost swamps Other 0.97% 0.34% 0.97%

Groundwater Oceans Freshwater 29.9% 96.5% reserves 2.53% Glaciers and permanent snow cover 68.7%

Source: Pickering, K. T. 29 The Hydrologic Cycle

Source: Adapted by CTLT from Nadakavukaren, A. 30 Sources of Freshwater

„ Groundwater − Available at point of need at little cost − Until recently was not polluted „ Surface water − Usually requires extensive purification „ Protected runoff „ Ocean and brackish waters − Costly to desalinate

31 Water System Facts

32 Freshwater Facts

„ Body composition − Body, 65% water; blood, 83%; bones, 25% − Water loss: 1% thirst; 5% hallucinations; 15% death „ Basic requirements for safe water − Drinking: 2–3 liters/day − Minimum acceptable standard for living (WHO) X 20–50 liters/capita/day for cooking and basic hygiene

33 U.S. Water Consumption and Population Growth Rates Daily withdrawal(billiongallons) 600 600

500 500

400 400

300 300

Total population (millions) Total population 200 200

100 100 1950 1960 1970 1980 1990

Water consumption Population

Source: Gabler, R. 34 Distribution of U.S. Domestic Household Water Use

Use Gallons/capita/day Percent of total

Toilet flushing 23 40

Body washing 20 37

Drinking 3 5

Laundry 4 7

Dishwashing 4 7

Garden watering 3 5

Car washing 1 2

Total 58 100

All other* 1359

*Irrigation, livestock, commercial, industry, mining, etc.

Source: Tchobanoglous, G. 35 Current Water Issues

„ Vulnerability of surface water to: − Drought (not replenished); i.e., lakes, reservoirs − Diversion of rivers for agricultural and urban use „ Declining groundwater levels − Failure to replenish − Compaction of aquifers − Saltwater intrusion „ Surface water pollution from nonpoint sources „ Groundwater pollution „ Increasing competition for water supplies − World’s available freshwater is not distributed evenly

36 Sources of Groundwater Contamination

Source: Adapted by CTLT from Nadakavukaren, A. 37 Surface Water Contamination

„ Point and nonpoint sources of surface water contamination

Source: Adapted by CTLT from Bucholz, R. A. 38 Classes of Water Pollutants

Oxygen-demanding wastes Plant and animal material Infectious agents Bacteria, viruses, protozoans Plant nutrients Fertilizers: nitrates, phosphates Organic chemicals Pesticides, detergents

Acids from coal mine drainage, inorganic Inorganic chemicals chemicals from steel plants

Sediment from land erosion Clay silt on stream beds Waste products from mining and Radioactive substances processing Cooling water used in steam generation of Heat from industry electricity

Source: McKinney, M. L. 39 Major Causes of Stream and River Pollution

17% Municipal sources

Nonpoint sources 9% Industrial sources 65%

6% Dredge and landfill

3% Unknown

Source: Wagner, T. 40 Water Purification

„ Goals − Provides safe source of water that meets quality objectives − Reasonable cost „ Sources − Surface water X Serves 52% of the U.S. population − Groundwater X Serves 48% of the U.S. population

Source: Patrick, R. 41 Typical Contaminants Found in Raw Water

„ Typical contaminants found in raw water that need to be removed to meet specific water quality criteria

Class Groundwater Surface water

Branches, leaves, algal mats, Bulky materials None soil particles

Microorganisms, trace Clay, silt, organic materials, Colloidal materials organic and inorganic pathogenic organisms, algae, material other microorganisms

Source: Tchobanoglous, G. 42 More Typical Contaminants Found in Raw Water

Class Groundwater Surface water

Organic compounds, Dissolved Fe, Mn, hardness ions, inorganic tannic acids, harness ions, materials salts, trace organic compounds inorganic salts

Dissolved gases Carbon dioxide, hydrogen sulfide

Immiscible liquids Oils and greases

Source: Tchobanoglous, G. 43 Simplified Flowchart of Drinking Water Treatment

DRINKING WATER SOURCE (RAW WATER)

COAGULATION, THEN FLOCCULATION Chemical treatment to form floc, which is allowed to settle from water

SEDIMENTATION

FILTRATION To remove remaining solids

DISINFECTION Chlorine to kill microorganisms

DISTRIBUTION SYSTEM 44 Water Disinfection Requirements

„ Must destroy bacteria, viruses, and amebic cysts in water within a reasonable time despite all variations in water temperature, composition, and concentration of contaminants „ Must not be toxic for humans and domestic animals, unpalatable, or otherwise objectionable

45 Water Disinfection Requirements

„ Must be reasonable in cost and safe and easy to store, transport, handle, and apply „ Residual concentration in the treated water must be easily and, preferably, automatically determinable „ Must be sufficiently persistent so that the disappearance of the residual would be a warning of contamination

46 Chlorine

Chlorine is the favored disinfectant for water supplies Chlorine kills microorganisms

Chlorine Remaining reacts with chlorine, termed ammonia and “free,” is available other to disinfect any substances new input of microorganisms

Source: ReVelle, P. 47 Inactivation Curves of Microorganisms

„ Inactivation curves of microorganisms following disinfection

100 A. Sensitive homogeneous population B. More resistant homogeneous population C. Heterogeneous population or one partially protected by aggregation Percent survival

A B C 0 Time 48 Microbial Inactivation by Chlorine

„ Microbial inactivation by chlorine (99.9% of organisms killed)

Chlorine concentration Inactivation time Ct (mg/L) (minutes) (concentration x time)

0.5 1.0 0.5

1.0 0.5 0.5

2.0 0.25 0.5

The organism, temperature and pH are the same

49 Microbial Inactivation by Chlorine: Ct Values*

Chlorine Inactivation time Microorganism Ct Conc., mg/L (minutes)

E. coli 0.1 0.4 0.04

Poliovirus 1.0 1.7 1.7

E. histolytica cysts 5.0 18 90

G. lamblia cysts 5.5 100 250

Cryptosporidium >250

*99.9% kill; Temp. - 5oC; pH = 6.0

Source: Bitton, G. 50 The Shortcomings of Chlorine

„ Chlorine does not kill protozoan cysts and some resistant viruses

Raw sewage

Treated sewage

RiversRive andrs & streams streams

ReservoirsReservo andirs & lakes lakes

Pristine surface water

Drinking water

0 20406080100 Percent of samples positive for oocysts Source: McFeters, G. A. 51 Chlorine Reaction Products

„ Chlorination has the potential of reacting with some organic compounds present in the water supply to create trihalomethanes (THM; chloroform) „ Surface water supplies, high in dissolved natural organic material (humics), are especially vulnerable to THM formation

52 Chlorine Reaction Products

„ When free chlorine is the disinfectant, THM levels are generally higher in communities using rivers and streams as their source of drinking water than in communities using wells „ THMs are potentially carcinogenic

53 Activities Permitted for Various Coliform Levels

„ Activities permitted for various levels of coliform bacteria in water

Coliform level per Activity permitted 100 ml of water

1 coliform or fewer Water safe for drinking

State must be notified and corrective 4 coliforms or more measures taken

2,300 coliforms or fewer Swimming is allowed

10,000 coliforms or fewer Boating is allowed

54 Section C

Wastewater Wastewater Components of Concern

Wastewater components of concern

Nutrients Pathogens BOD* (N and P)

Suspended Toxic solids chemicals

*Biological oxygen demand (oxygen-demanding substances)

56 Some Primary Constituents of Municipal Sewage

Constituents Potential sources Effects in water

Oxygen-demanding Organic material Consumes dissolved O substances (human feces) 2

Pathogens Human waste Cause disease

Nutrients Detergents Algal nutrients

Toxic chemicals Industrial waste Toxicity

Interferes with Suspended solids Silt disinfection

57 Enteric Organisms in U.S. Surface Water and Sewage

„ Estimated levels of enteric organisms in U.S. sewage and polluted surface water—concentration per 100 ml

Polluted stream Organism Raw sewage water

Coliforms 109 105

Enteric viruses 102 1–10

Giardia 10 0.1–1

Cryptosporidium 10–103 0.1–102

Source: Pepper, I. L. 58 Biological Oxygen Demand (BOD5)

„ Organic decomposition requires oxygen „ BOD is defined as the amount of oxygen used by organisms in a body of water to carry out decomposition „ The amount of oxygen utilized by microorganisms to oxidize

organic compounds in the dark at 20ºC in 5 days (BOD5) „ CH2O + O2 H2O + CO2 bacteria

59 Biological Oxygen Demand (BOD5)

„ When bacteria act upon organic matter in sewage, large amounts of dissolved oxygen are rapidly used up; this can result in fish kills and drastic alterations of the aquatic environment „ BOD is an indication of how much putrecible organic material is present in the water, with low BOD indicating good water quality, and high BOD reflecting polluted conditions

60 BOD5 of Selected Waters

Water source BOD5 (mg/L) Domestic sewage Raw 300 Treated 10 Textile dying 600 Dairy wastewater 900 Tannery wastewater 1,270 Slaughterhouse wastewater 2,000 Rubber factory 3,300 Distillery vinasse 30,000 Swine lagoon 800 Open feedlot runoff 1,000 Raw swine manure 50,000 61 Why Are Nitrates and Phosphates Pollutants?

„ Eutrophication − Premature aging of an aquatic system − Excessive nutrient level and subsequent excessive growth of algae eventually fills up a lake and transforms it into a marsh or a bog „ Source − Domestic sewage and animal sewage, fertilizer runoff, detergent (P) „ Effect on dinoflaggelates (Pfiesteria) − Fishkills

62 Simplified Flowchart of Wastewater Treatment Wastewater Primary Pretreatment Grit Physical methods to remove solid materials

Sedimentation Suspended solids allowed to settle Primary Secondary sludge BIOLOGICAL TREATMENT Uses microorganisms to digest soluble substances

Secondary SEDIMENTATION sludge Tertiary SPECIALIZED TREATMENT Removes phosphorus and nitrogen

DISINFECTION

DISCHARGE OF EFFLUENTS TO RECEIVING STREAM 63 Municipal Sewage Treatment

„ The aim of sewage treatment is to improve the quality of wastewater to the point that it can be discharged into a waterway without seriously disrupting the aquatic environment or causing human health problems in the form of waterborne disease

64 Municipal Sewage Treatment

„ With few exceptions, water purification and wastewater treatment processes are alike in concept and in kind − They differ only in the amount of pollutants they must remove and in the degree of purification they must accomplish

65 Municipal Sewage Treatment: Primary Treatment

„ Primary treatment consists of simply holding sewage in a large tank to permit the removal of solids by sedimentation − Before entering the settling tank, the sewage is commonly sent through a chamber or collector to remove sand, grit, and small rocks that would otherwise damage pumps or other equipment in the treatment plant

66 Municipal Sewage Treatment: Secondary Treatment

„ Whereas primary treatment is based upon physical and mechanical methods of removing suspended solids from wastewater, secondary treatment depends on biological processes—similar to naturally occurring decomposition, but greatly accelerated—to digest organic waste

67 Municipal Sewage Treatment: Tertiary Treatment

„ Tertiary treatment, if done, removes nutrients such as nitrogen and phosphorus

68 Municipal Sewage Treatment: Disinfection

„ Disinfection: Since most waterborne diseases are caused by pathogenic bacteria, viruses, or protozoans present in human excrement, one of the primary purposes of sewage treatment is to kill such organisms before they can infect new victims

69 Municipal Sewage Treatment: Disinfection

„ Disinfection: Primary and secondary treatment leave a substantial number of live organisms still remaining in the wastewater − Therefore, it has been standard procedure for many years to disinfect treated effluent by adding chlorine prior to discharge in order to eliminate any remaining disease- causing organisms

70 Municipal Sewage Treatment: Chlorination

„ More recently, the policy of chlorinating all sewage treatment plant discharges has met with increasing resistance and today more than half of all states no longer require chlorination of wastewater

71 Municipal Sewage Treatment: Chlorination

„ There are several reasons for this change in accepted practice − Chlorine is effective in killing bacteria but less so in relation to protozoans and viruses − Chloramines are formed which may be toxic to aquatic life − Chlorine treatment is expensive

72 Removal of Contaminants by Sewage Treatment ses and Viru protozoans Dissolved organics Nitrogen Sewage solids Pathogenic bacteria Phosphorus

Primary treatment

Secondary treatment

Tertiary treatment

Disinfection

Still Source: ReVelle, P. detectable 73 Waterborne Outbreaks (U.S.)

40

30

20

10 Average annual number of Average annual waterborne disease outbreaks waterborne disease

1938– 1941– 1946– 1951– 1956– 1961– 1966– 1971– 1976– 1980– 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985

Source: Gabler, R. 74 Outbreaks by Public Water System Deficiencies

„ Percentage distribution of waterborne disease outbreaks caused by deficiencies in public water systems

Distribution network problems 21% Miscellaneous 9%

Contaminated untreated surface water Inadequate 8% or interrupted treatment 27%

Contaminated untreated groundwater 35% Source: Bitton, G. 75 Agents Associated with Cases of Waterborne Diseases

„ Etiologic agents associated with cases of waterborne diseases

Bacterial 10% Acute gastro- Giardia intestinal illness of 11% unknown origin (AGI) 43%

Viral AGI 15%

Cryptosporidium

Source: Pepper, I. L. 20% 76 Classification of Water-Related Illnesses

„ Classification of water-related illnesses associated with microorganisms

Class Cause Examples Pathogens that originate in fecal Cholerae, giardiasis, Waterborne material and are transmitted by salmomellosis, poliomyelitis, (fecal-oral) ingestion typhoid, E. coli

Pathogens that originate in feces Infectious eye and skin diseases, and are transmitted through Watershed louse-borne typhus and contact because of inadequate relapsing fever sanitation or hygiene

Organisms that originate in water or spend part of their life cycle in Schistosomiasis, dracunculiasis Water-based water and come in direct contact (helminths) with humans in water Microorganisms with life cycles Malaria, yellow fever, dengue Water-related insect vector associated with insects that live or fever, filariasis breed in water

77 Key Points

„ The hydrological cycle controls the availability of freshwater, which is diminishing „ Groundwater and surface water are polluted by both point and nonpoint sources „ Water purification is used to provide potable water; chlorine is the favored disinfectant „ Wastewater treatment must address pathogens, suspended solids, toxins, nitrogen and phosphorus, and BOD

78 Key Points

„ Microbial contamination represents the greatest food hazards „ The extent and magnitude of foodborne disease outbreaks are largely underestimated „ Microbial growth in food depends on nutrient availability, moisture content, redox potential, temperature, and pH „ Host susceptibility factors are an important determinant in foodborne diseases „ Food preservation is used to prolong shelf life

79