Download BIO 208 - Microbiology - Unit 4 - Lecture 20

BIO 208 Unit 4 – Microbes in Health and Disease
1
Unit 4 – Survey of the Role of Microbes in Health and Disease
In Lecture 20 we will talk about several aspects of microbial water quality – to aid in your
preparation, review of material from Lab 18 where it applies to lecture today.
A. Microbial Aspects of Water Quality
Clean and safe drinking water – global perspective
In the U.S. water quality is regulated by __________________________________________
Microorganisms from the intestinal system are shed with feces and can be transmitted via the
____________________________ route (E. coli and pathogens like Salmonella)
Quality Control - Water Quality Testing – Testing for likelihood of fecal contamination
Indicator Organisms – Indicator of potential fecal contamination - Ideally an indicator organism:
1. is present whenever intestinal pathogens of concern are present
2. is present only when there is real danger of intestinal pathogens being present
3. is present in greater number than the pathogens to provide a margin of safety
4. survives in the environment at least as long as the pathogens do
5. is easy to detect (such as the membrane filtration test you did in lab)
Commonly Used Indicators
1. Total coliforms – GNR that ferment lactose
Problem –
2. Fecal coliforms – a subset of coliforms that are thermotolerant
3. E. coli and enterococci (species of streptococci that are found in the intestines) – most
specific indicators of recent fecal contamination –
BIO 208 Unit 4 – Microbes in Health and Disease
2
1. Wastewater Treatment
Wastewater – comes from domestic or industrial effluents (effluent is the outpouring of water)
Domestic H2O =
Q. Why does wastewater need to be treated?
A. Because it is:
1.
2.
3.
Q. What are the goals of wastewater treatment?
A.
1.
2.
Q. What happens to domestic wastewater?
A. Wastewater treatment consists of a combination of physical and biological processes
1. Primary – physical - screen out large junk, settle  sludge + liquid
2. Secondary – microbial -  nutrient load,  organics (BOD)
Liquid – aerobic
Sludge – anaerobic
aerobic respirers (heterotrophs + chemoautotrophs)
fermenters and anaerobic respirers
Oxidation of complex organics  CO2
Fermentation of complex organics  CO2 + CH4
Liquid - disinfect with chlorine, aerate,
QC (count E. coli in water using
e.g., membrane filtration like you did in lab)
discharge to body of water.
Remaining sludge – land application as fertilizer
BIO 208 Unit 4 – Microbes in Health and Disease
2. Drinking Water Treatment
Q. What are the goals of drinking water treatment?
A.
1. decrease turbidity
2. eliminate taste and odor
3. reduce chemicals
4. remove potentially pathogenic microbes
In the US, drinking water usually comes from
Steps in a Typical Water Treatment Facility
1. Source – water from source moves to a sedimentation basin where sand and gravel are
removed. Turbidity will be decreased (clarity improves)
2. Clarify – water moves next to a clarifier where chemicals are added to create a “floc”.
Flocs
3. Filter – clarified water is filtered to remove the flocs containing organics and particles
including microorganisms.
4. Disinfect- to kill any remaining microorganisms - chlorination is most common
disinfectant of treated water, kills most microbes w/in ____________ min. (some
communities use ozone).
Problems w/ chlorination
–
residual chlorine in water
–
cysts of protozoan pathogens like Giardia and Cryptosopridium
5. Quality control (QC) – determine counts of coliform bacteria remaining in the treated
drinking water. Must be _______________________
6. Distribute –
3
BIO 208 Unit 4 – Microbes in Health and Disease
3. Protection of Great Lakes Recreational Water
The Great Lakes have more than ____________ miles of coastline
Michigan has over __________ miles of coastline
The Michigan coastline has ________ public access beaches
Q. How does fecal material gets into beach water
A.
1.
2.
3.
4.
Human source fecal contamination is
In Michigan, beach water quality is regulated by
_______________________________________.
The threshold ____________________________________________ – if thresholds are
exceeded, swim advisories may be posted or beaches closed.
4
BIO 208 Unit 4 – Microbes in Health and Disease
Lectures 21-26 will introduce you to aspects of medical microbiology – good stuff for MCAT, PA
admissions test, etc.
B. Medical Microbiology
1. Disease Transmission and Epidemiology – Chapter 14
These notes should be reviewed prior to the class on Disease Transmission and
Epidemiology. We will NOT go over this material in class (we are doing something very
different today), but it is essential for your understanding of what we will be covering in
class.
Disease - change from a state of health
a. Terminology related to infectious diseases
 Etiology – the cause of a disease
 Etiological agent –microorganism that causes the disease (same as pathogen)
 Pathogen – microorganism that is capable of causing disease
 Pathology – the study of disease
 Pathogenesis – the manner in which a disease develops and progresses
 Infection – invasion or colonization of the body by a pathogen
 Incubation – the time interval between infection and the first appearance of signs
and symptoms
 Symptom – A subjective indication of a disease (something you, the patient,
experiences), such as feeling hot, tired, achy, nauseous
 Sign – An objective finding, usually detected on physical examination, from a
laboratory test, or x-ray (etc.) that indicates the presence of abnormality or disease,
such as elevated body temperature (fever), increased respiration rate, elevated white
blood cell count, fluid in the lungs, etc.
Epidemiology – the study of disease in populations
a. Terminology related to epidemiology
 Endemic = disease that is constantly present in a population (e.g., measles)
 Epidemic = an unusually large number of cases (every winter we see an epidemic of
Influenza)
 Outbreak = a cluster of cases in a short time period (currently, avian influenza in
southeast Asia)
 Pandemic = an epidemic that spreads worldwide (what we fear may happen with
avian influenza)
5
BIO 208 Unit 4 – Microbes in Health and Disease
6
b. Reservoirs - where pathogens persist, a continual source of the organism that can fuel cases
i. human reservoirs of disease – the primary reservoir of most diseases of humans is the
human body itself
 symptomatic – a person exhibiting signs and symptoms of disease and is capable of
infecting others
Ex. someone with norovirus gastroenteritis (nausea, vomiting)
 asymptomatic carriers – a person that is not exhibiting signs and symptoms,
apparently healthy, but infected and infectious to others.
Ex. people infected with gonorrhea or herpes may be asymptomatic but are still
infectious
ii. nonhuman reservoirs of disease
zoonoses - diseases of animals that can be transmitted to humans
Ex. rabies, salmonellosis
iii. environmental reservoirs
soil (botulism, tetanus), water (Legionnaire's, cholera), etc
iv. hospitals and hospital personnel as reservoirs, esp. of antibiotic resistant microorganisms
c. Transmission – how pathogens are spread
i. by contact
a) direct contact – also called person-to-person contact- when 1 person physically
touches another
Ex. touching (MRSA infections), sexual contact (STIs)
b) indirect - via inanimate objects = fomites – some examples include door knobs,
telephones, computer keyboards, tv remotes, etc
Ex. cold viruses and Influenza
c) droplet transmission – in droplets coming from the respiratory system (sneezes,
coughs)
Ex. tuberculosis, Influenza, SARS
ii. by food, water, or fecal contaminated material (fecal-oral) gastrointestinal pathogens
incl. waterborne pathogens
a) ingestion
b) cross-contamination of food preparation materials
Ex. salmonellosis, shigellosis, cholera
BIO 208 Unit 4 – Microbes in Health and Disease
iii. airborne (similar to droplet transmission)
Ex. anthrax, histoplasmosis
iv. by vectors
a) mechanical - vector transfers microbes from one host to another.
Ex. housefly, fleas
b) biological - vector is required in microbe's life cycle
Ex. mosquitoes
v. nosocomial – acquired as a result of being hospitalized, from the hospital environment
or contact with hospital personnel or other patients.
Significant problem!!! 5-15% of all hospitalized patients will develop a nosocomial
infection!
7
BIO 208 Unit 4 – Microbes in Health and Disease
8
2. Significant or Interesting Human Diseases
Key to Understanding Infectious Diseases:
•
•
•
•
•
Microbes are as old as the planet
Humans evolved under the selective pressure of microbes
Microbes see our bodies as just another habitat
In all the vast diversity of microbial life, only the smallest fraction of microbes are
capable of causing illness
For any infection with a potential pathogen, there are a wide variety of possible
outcomes
Diseases of the Skin
General background
Main pathogens of the skin
Staphylococcus aureus
GPC, cat +
Streptococcus pyogenes
GPC, cat -
Skin diseases caused by S. pyogenes
Group A Strep (GAS)
1. impetigo
2. erysipelas – infection of dermal layer of skin
3. invasive GAS - approximately 9,000-11,500 cases in the U.S./yr resulting in 1,000-1,800 deaths.
Two most severe, least common:
a. necrotizing fasciitis (infection of muscle and fat tissue)
b. streptococcal toxic shock syndrome (a rapidly progressing infection causing low blood
pressure/shock and injury to organs such as the kidneys, liver and lungs).
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick -*Disease *Agent –
*Virulence factors (what factors does this strain have that other strains do not, that makes this
one capable of causing disease)
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
9
BIO 208 Unit 4 – Microbes in Health and Disease
Diseases of the Nervous System
General background
Nerves
Brain
The class pick -*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
10
BIO 208 Unit 4 – Microbes in Health and Disease
Diseases of the Cardiovascular or Lymphatic Systems
General background
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
11
BIO 208 Unit 4 – Microbes in Health and Disease
Diseases of the Respiratory Tract
System – upper versus lower
Main Diseases & Pathogens of Upper Respiratory Tract (URT)
Defenses of URT– very well defended - multiple defenses - chemical, immunological, and
microbial.
Nose
Rhinitis
(cold)
100% viral
Rhinovirus
Coronavirus, Adenovirus
Throat
Pharyngitis
(sore throat)
70% viral
Adenovirus
EBV, Herpes, Coxsackie
S. pyogenes, C. diphtheriae, H. influenzae
30% bacterial
Main Diseases & Pathogens of Lower Resp. Tract (LRT)
Defenses of the LRT – defenses diminish with depth into the lower respiratory system - ciliated
epithelial cells, cough reflex, alveolar macrophages
Trachea
Whooping cough
Influenza
Bronchi
Acute bronchitis
Lungs
Acute infections
Pneumonia
Respiratory Distress
Chronic infections
Tuberculosis
bacterial
viral
Bordetella pertussis
Influenza virus
50% viral
50% bacterial
Adenovirus
Mycoplasma, S. pneumoniae, H. influenzae
bacterial
viral
viral
S. pneumoniae (a.k.a pneumonococcus)
Adenovirus, Influenza virus
Hantavirus, SARS
bacterial
fungal
M. tuberculosis
Aspergillus, Histoplasma
12
BIO 208 Unit 4 – Microbes in Health and Disease
13
Example of an Acute Lower Respiratory Infection: Influenza
We will talk about:
1. seasonal flu
2. pandemic flu
*Disease - Influenza - “Flu”
*Agent - Influenza virus (Orthomyxoviridae); enveloped RNA virus
3 types infect humans (C, B, A - arranged least to most significant)
Influenza type A - Responsible for regular outbreaks, including pandemics. Influenza A viruses
also infect domestic animals (pigs, horses, chickens, ducks) and some wild birds, especially
shorebirds and waterfowl. Influenza A viruses, which cause more severe human illness, are
further categorized into subtypes on the basis of two surface antigens: hemagglutinin (H) and
neuraminidase (N). Among all Influenza viruses (human and animal) there are 14 major H
proteins and 9 major N proteins forming 144 different combinations of H+N.
* Virulence
1. kills cells of the trachea (may result in secondary bacterial infections of the respiratory system
(acute ear infections and pneumonia, both due to Streptococcus pneumonia are the most
common complications of influenza infection)
2. makes a protein that inhibits the immune system
1. Seasonal Flu
* Transmission
 via respiratory droplets released when an infected person coughs or sneezes.
 enters body thru mucous membranes of eyes, nose, mouth.
 binds to receptors on non-ciliated cells of the respiratory epithelium and then enters those
cells via receptor-mediated pinocytosis
 incubation 1-4 days, average = 2 days.
 contagious from 1 day prior to symptoms (before you know you are sick) and for another
5 days after symptoms develop.
* Clinical Picture
Uncomplicated influenza illness is characterized by the abrupt onset of constitutional and
respiratory signs and symptoms [Constitutional - fever, myalgia (= body aches), headache,
malaise (= overall feeling of unwell). Respiratory - nonproductive cough, sore throat, and
rhinitis].
Influenza illness typically resolves after a limited number of days for the majority of persons,
although cough and malaise can persist for >2 weeks.
The risks for complications, hospitalizations, and deaths from influenza are higher among persons
aged >65 years, young children, and persons of any age with certain underlying health conditions.
BIO 208 Unit 4 – Microbes in Health and Disease
* Treatment
 Some few, specific anti-viral drugs:
Amantadine and Rimantadine - These drugs inhibit one of the viral matrix proteins that are
used to get viral RNA into the cytoplasm of the target cell. They work against A types only
and resistance to these drugs evolves quickly.
Zanamivir (Relenza®) and Oseltamivir (Tamiflu®) - These drugs block the neuraminidase
and thus inhibit release of virus progeny from the infected cell. Spraying zanamivir into the
nose or inhaling it shortens the duration of disease symptoms by 1-3 days.
 Yearly flu vaccine (more below)
Frequency
20-50% of American population infected and 10-20% with symptomatic illness every year.
Morbidity and Mortality
In US, 114,000 hospitalizations (>57% in people under age 65) and ~40,000 deaths/year – due
to secondary bacterial infections and also primary influenza pneumonia, where the Influenza
virus infects cells of the lungs in addition to the trachea.
***Special topic of importance ***
Why is it you can get influenza multiple times? (in theory you are susceptible every year!)



Influenza virus is an RNA virus and its genome is made up of 8 RNA segments (a segmented
genome is unusual).
During replication the RNA is copied into RNA by an RNA polymerase. RNA polymerase
has no proof-reading ability; it makes mistakes (i.e., produces mutations).
These mutations cause changes in the surface proteins (the H or the N).
Point mutations = a mutation in the RNA genome caused by one wrong RNA nucleotide base
in the RNA sequence - will produce a slight, slight alteration in the surface protein.
Antibodies (specific to H and N surface proteins) that your body produced to fight previous
influenza infections do not recognize these slightly altered surface antigens very well, so
your immune response is delayed, you become ill.
This gradual change in the surface protein over time is called antigenic drift  responsible
for yearly, seasonal epidemics.
14
BIO 208 Unit 4 – Microbes in Health and Disease
There are several different types of influenza viruses circulating and different variants within
virus types, and the same type of flu virus does not necessarily circulate each year. A
person's immunity to the surface antigens reduces the likelihood of infection and severity of
disease if infection occurs. If someone was infected with the Fujian strain of Influenza A
(H3N2) that predominated last season, they are likely to have some natural immunity that
will give them protection if they are exposed to the Fujian strain or a closely related H3N2
strain again this season, but no or little immunity to an unrelated strain.
Frequent development of antigenic variants through antigenic drift is the basis for seasonal
epidemics and the reason for the usual incorporation of > 1 new strains in each year's
influenza vaccine (see table at end of lecture).
2. Pandemic Flu
When flu illness occurs worldwide is referred to as pandemic flu. Pandemic flu occurs when
the human population has no or limited immunity to an influenza virus because either the H
or N surface protein is entirely new. Pandemic strains of influenza are created by a genetic
event referred to as recombination.
Recombination - Two different Influenza strains with different H and N antigens co-infect
the exact same host cell. During packaging of viral progeny, the 2 strains will exchange an
entire segment of RNA, which will result in a tremendous change in the surface protein. This
abrupt change in surface protein is called antigenic shift responsible for pandemics.
15
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
16
BIO 208 Unit 4 – Microbes in Health and Disease
For Your Information – additional information on Influenza virus and Influenza disease
How Influenza viruses are named:
Ex. Influenza A/Singapore/6/86/H1N1:
TYPE
of influenza
TOWN
where first
isolated
A
SINGAPORE
NUMBER
YEAR
of isolates
of isolation
isolated
6
TYPE
of H and N
86
(H1N1)
Composition of the Trivalent (= 3 flu strains) Vaccine Last 10 years
Season
H1N1
H3N2
Type B
02–03
A/New Caledonia/20/99
A/Moscow/10/99
B/Hong Kong/330/01
03–04
A/New Caledonia/20/99
A/Moscow/10/99
B/Hong Kong/330/01
04–05
A/New Caledonia/20/99
A/Fujian/411/02
B/Shanghai/36/02
05–06
A/New Caledonia/20/99
A/California/7/04
B/Jiangsu/10/03
06-07
A/New Caledonia/20/99
A/Wisconsin//6705
B/Malaysia/2506/04
Influenza A/New Caledonia/99 was discovered and characterized by former CMU student Luke Daum,
who now owns his own company called Longhorn Vaccines and Diagnostics. He is an international
expert on Influenza.
07-08
A/Solomon Islands/3/26
A/Wisconsin/67/05
B/Malaysia/2506/04
08-09
A/Brisbane/59/07
A/Brisbane/10/07
B/Florida/4/06
09-10
A/Brisbane/59/07
A/Brisbane/10/07
B/Brisbane/60/08
10-11
A/California/7/09
A/Perth/16/09
B/Brisbane/60/08
A/California/7/2009 (H1N1) is the pandemic strain that the media called “swine flu”
11-12
A/California/7/09
A/Perth/16/09
B/Brisbane/60/08
The World Health Organization began in February to hold meetings to determine the
composition of the 2012-2013 vaccine.
17
BIO 208 Unit 4 – Microbes in Health and Disease
18
Recent flu pandemics
Year
1580
1874
1889-90
1900
1918-20
1933
1940
1957-58
1968-69
1976-77
2009
HN type
(H3N8)
(H2N2)
(H3N8)
(H1N1)
Strain
?
?
?
?
?
(H2N2)
(H3N2)
(H1N1)
(H1N1)
A/Singapore/57
A/Aichi/68
A/New Jersey/76
A/California/09
Name of pandemic
first Influenza pandemic of recorded history
Asiatic (Russian) Flu pandemic
”Spanish” Flu pandemic
Influenza viruses were finally discovered
US military began the first Influenza vaccinations
"Asian" Flu pandemic
"Hong Kong" Flu pandemic
"Swine" Flu – turned out to be a false scare
3,900 deaths in U.S. in 1st 6 months.
Since 1977, Influenza A (H1N1) and Influenza A (H3N2) viruses have been in global cocirculation. In 2002, Influenza A (H1N2) viruses that probably emerged after genetic
recombination between (H3N2) and (H1N1), viruses began circulating widely, causing an
increase in morbidity and mortality, but not a true pandemic.
Avian Influenza (= Bird Flu)
Bird flu is caused by avian influenza viruses. These flu viruses occur naturally among birds.
Wild birds worldwide carry the viruses in their intestines, and among birds the virus is
transmitted in the feces, but avian influenza is usually not fatal to wild birds. However, it is very
contagious among birds and can make some domesticated birds (chickens, ducks, and turkeys)
very sick and kill them.
The risk from bird flu is generally low to most people because the viruses occur mainly among
birds and do not usually infect humans. However, during an outbreak of bird flu among poultry
(domesticated chicken, ducks, turkeys), there is a possible risk to people who have contact with
infected birds or surfaces that have been contaminated with excretions from infected birds.
Several cases of human infection with bird flu viruses have occurred since 1997, the most recent
outbreak began in 2003. In October 2003, an epidemic of influenza in chickens began sweeping
through several countries in the Pacific Rim (Vietnam, Thailand, Japan, China, South Korea,
Cambodia). The virus is H5N1. The H5 molecule is common among bird influenza viruses but
has not been seen on flu viruses that cause human epidemics. As a glance at the tables above will
show, humans have had long experience with infections and vaccines by both H1 and H3 flu
viruses. But the human population has absolutely no immunity against any H5 viruses.
Clinical Picture - Symptoms of avian influenza in humans have ranged from typical human
influenza-like symptoms (fever, cough, sore throat, and muscle aches), to eye infections,
pneumonia, severe respiratory diseases (such as acute respiratory distress syndrome), and other
severe and life-threatening complications.
Mortality - currently 63%.
BIO 208 Unit 4 – Microbes in Health and Disease
Sexually Transmitted Infections (STI = STD = VD)
MMWR
TABLE II. Provisional cases of selected notifiable diseases, United States.
2011
Reporting Area
Population
Hepatitis B
Syphilis
Gonorrhea
Chlamydia
Michigan
10,071,822
80
243
12,207
47,003
U. S.
312,856,000
2,399
12,325
291,262
1,272,762
What all STIs have in common:
 Transmission – direct mucosal contact with infected individual
 Asymptomatic
 Can be acquired multiple times
 Having one makes it much more likely you will have/get others
 Can cause infertility and other permanent complications
Prevention –
 Abstinence – the only guarantee
 Monogamy
 Latex condoms
 Regular screening – all sexually active women should be screened for STIs every 6 months!
19
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
20
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
21
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention –
22
BIO 208 Unit 4 – Microbes in Health and Disease
Infectious Disease of the Gastrointestinal (GI) Tract
Digestive system overview
CDC estimates that each year ~ 1 in 6 Americans (or 48 million people) gets sick, 128,000 are
hospitalized, and 3,000 die of food borne diseases.
Focus Syndrome - Gastroenteritis = inflammation of stomach & intestines - extremely common –
symptoms include primarily diarrhea; sometimes nausea, vomiting, crampy abdominal pain –
caused by a diverse assortment of bacterial, viral, and protozoan pathogens.
General mechanisms by which microbes cause disease in the GI:
A. Produce toxins
B. Adhere to and damage intestinal microvilli
C. Invade intestinal epithelial cells
A. Diseases due to toxin production:
1. Toxin production only (no colonization of intestines) = Bacterial Food Poisoning
 bacteria need not enter the body
 they secrete toxins into the food that you ingest
 these toxins aren’t destroyed by heating
Example organisms that cause food poisoning
Bacillus cereus, Clostridium botulinum (6 cases in 2010), Clostridium perfringens,
Staphylococcus aureus.
Toxin contaminated foods do not look, smell, or taste bad!
23
BIO 208 Unit 4 – Microbes in Health and Disease
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
Prevention of food borne disease at end of lecture.
24
BIO 208 Unit 4 – Microbes in Health and Disease
2. Colonization of intestines followed by toxin production – Vibrio cholerae
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
25
BIO 208 Unit 4 – Microbes in Health and Disease
B. Disease due to microbes that adhere to, enter, and damage intestinal microvilli –
Shigella, E. coli O157:H7, Campylobacter, Rotavirus and Norwalk virus (of cruise ship fame),
Entamoeba histolytica.
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
26
BIO 208 Unit 4 – Microbes in Health and Disease
C. Disease due to microbes that adhere to and then invade across intestinal epithelial cells;
may spread to deeper tissues – Salmonella, Hepatitis A, Reovirus, Enterovirus.
The class pick –
*Disease *Agent –
*Virulence factors -
*Transmission –
*Clinical picture –
Treatment –
Frequency –
Mortality –
27
BIO 208 Unit 4 – Microbes in Health and Disease
Prevention and Control of Food borne Illness
Careful food production, handling of raw products, preparation of finished foods
Near Future Industry Advances
1. Chlorinating drinking water sources for food animals
2. Sanitary slaughter and meat processing
3. Irradiation of raw products
At home
1. Wash hands (w/ soap, 20 sec)
2. Thaw in refrigerator or microwave
3. Don't cross-contaminate cooked w/raw
4. Wash fruits & veggies - even pre-washed
5. Wash knives
6. Wash countertops, cutting boards, etc. in dilute bleach
7. Clean sponges daily
8. Separate towels
9. Pay attention to "use-by" dates
10. Don't buy "bad" cans
11. Immediately refrigerate leftovers - shallow (less than 2") - less than 40ºF
28