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To provide a general review of food, milk, and waterborne diseases
Reporting of food and waterborne diseases began 50 years ago because of high morbidity and mortality from typhoid and infantile diarrhea. State and territorial health officials recommended that cases of enteric fever be investigated and reported.
In 1923, there appeared the first published summaries of GI illnesses due to milk.
Later, in 1938, there appeared - summaries of outbreaks due to all foods. These surveillance efforts lead to important public health measures i.e., the recording and reporting of enteric diseases transmitted through milk and water.
This was the beginning of the present reporting system. Data were collected at the local and county levels transmitted to state government and from state to the federal level. Thus all the data is received by the Center of Disease Control (CDC) where it is analyzed and summarized and published in the Morbidity and Mortality Weekly Report (MMWR) and annual summaries. These reports are made available to appropriate agencies in the country.
Food and water-borne diseases outbreaks are controlled by the identification and removal of contaminated products in circulation, improvement of food preparation and handling procedures and the identification and treatment of human carriers.
Identification of contaminated water sources and adequate treatment are important control measures following surveillance of waterborne outbreaks. In addition, thorough investigations and reporting of outbreaks are important steps to be taken in preventing future outbreaks.
The causative agents are not identified in 30-60% of foodborne outbreaks because of laboratory error or simply undetermined. In most cases, water borne agents are unknown.
Two or more persons ingesting common food resulting in a similar illness (gastrointestinal or GI) with food implicated as cause (exception - botulism or chemical poisoning). Outbreaks may be laboratory confirmed or of undetermined etiology.
Classification of Food Poisoning is based on the following incubation periods:
Data originates from consumers, practicing physicians and hospitals, food service and processing personnel. Reports are sent to the local health department for investigation; reported to State Health Department who may assist, usually provide laboratory support. Center for Disease Control(CDC) becomes involved when large or interstate outbreaks occur or when invited by the state for assistance. State data is eventually sent to CDC for analysis and distribution.
The governmental agencies responsible for food protection are:
Major reporting mechanisms are:
We only know about reported cases; outbreaks are only tip of iceberg. Quality of reporting varies widely and depends on consumer awareness, physician's interest, and the state's commitment to surveillance. Thus, inferences of incidence based on such data is not always reliable and must be critically appraised.
An example: Summarized five-year data, 1983-1987:
|
Salmonella---------------------------------- 57% of outbreaks |
7.3.6.1 Salmonella (Salmonellosis):
Approximately 1,500 serotypes. Depending on surface, can live over 1,000 days. Survive several months in frozen foods. Favor moderately acid environment.
Animals and man are susceptible to Salmonella and are prevalent in poultry, eggs, slaughter houses, animal feed (rendered). Probably, there are thousands of human cases per year.
Ingestion of organism and their fate:
- - Symptoms
- - Asymptomatic and shedding
- - Nothing
- Reason - Dose, individual, etc., (diarrhea, headache, vomiting, pain, fever.)
- Symptoms - acute GI, focal infections, septicemia.
- Onset 6-72 hours past infection (usually 18-48). Duration 1-7 days.
- Shedding continues 1-7 days.
Control of Salmonellosis:
- Limit container - adequate processing, hygiene and sanitation
- Inhibit growth - adequate holding temperatures, pH 4.5, moisture, salt
- Destroy organism - heat, irradiation, pH, gas disinfection
Important facts with references:
In l984- Antibiotic-resistant S.typhimurium involved between l68,791 to l97,58l persons (JAMA, Dec. ll, l984)In l987- Antibiotic-resistant S. newport persistent strain through hamburgers.
7.3.6.2 Staphylococcus(Staphylococcosis):
The toxin withstands drying and survives in dust Grows well in salt solution.
There are 5 antigenic types, type A mainly involved in food poisoning The following are characteristics:
- Incubation - usually 2-4 hours
- Symptoms - rapid onset, salivation, nausea, vomiting, cramps, diarrhea, possibly shock
- Duration - 1 to 3 day.
- Source - man primarily, nose: 30-50% are nasal carriers (continuous or intermittent.)
- - Also on skin, usually in feces
- - Often on wounds
- - Readily spread from person to person
- Growth in food - not too acid, relatively free of competitors. Most likely food cooked and contaminated, then inadequately refrigerated for 8+ hours
- Preference - high protein foods, such as meat, gravies, custard, sauces
- Control - rapid cooling of foods is as important as environmental hygiene
7.3.6.3 Clostridium perfringens (Clostridial infection):
- Toxin - 4 Major toxins and over 90 serotypes). Spore-former (some heat sensitive and some resistant).
- Anaerobe- but some can be grow in the presence of oxygen.
- Contaminated food-usually high protein,i.e., meat, poultry, stews, gravies.Invariably held at inadequate temperatures - thus related to food service industry.
- Symptoms - nausea, vomiting, gas, diarrhea, rarely fever.
- Incubation - average 8-12 hours.
- Duration - usually 12 hours or less.
Organisms common in intestinal, contents of men and animals, in sewage and soil. Incrimination-culture organisms from food, feces. (91 serotypes - rare to find same type in large percentage except in an outbreak).
Control - inhibit growth
Organisms are extremely common in red meat, poultry. Sanitation and hygiene may help chance of problem, but no way to keep organism out of foods. Thus adequate heating before serving minimizing size amounts and should be cooked and cooled, rapidly. Some spores can survive lower cooling temperatures.
Millions of organisms are necessary to cause illness, so the presence of organism is not enough. Multiplication of the organism is necessary for food poisoning.
7.3.6.4 Escherichia coli (Coli bacillosis):
0l57:H7 is the most dangerous food poisoning organism and is potentially fatal. This strain of E. coli causes hemorrhagic colitis and hemolytic syndrome. It has been found in ground beef from dairy cows or calves in Northern United States and Canada. An outbreak in l985 in a Canadian Nursing Home affected 55 of l69 residents and l8 of 37 staff members ; hemolytic uremic syndrome developed in l2 (ll of whom died) while overall l9 or 35% of the affected residents died ( New England J Med., Dec. l0, l987).
7.3.6.5 Campylobacter jejuni (Campylobacteriosis):
This is an important emerging zoonotic disease which is characterized by an enterocolitis of variable severity. The causative agent, Campylobacter jejuni has been recognized as a significant cause of enteritis in humans and a wide range of animals. This organism is found in nearly 3/4 of turkeys vs 38.2% of chicken carcasses.
7.3.6.6 Shigella sonnei (Shigellosis):
This microbe causes diarrhea in man and animals. In Texas, an outbreak of shigellosis in humans was caused by contaminated shredded lettuce probably the result of an infected food handler.
7.3.6.7 Yersinia enterocolitica (Yersiniosis):
Yersinia is an emerging world-wide enteric pathogen associated with a wide spectrum of clinical and immunologic manifestations resulting in acute gastroenteritis. It has been isolated from a variety of mammals-serotypes O:3 and O:9-grows well in cold climates. Symptoms:self-limited enterocolitis to potentially fatal systemic infection; postinfection manifestations include erythema nodosum ,and reactive arthritis. Diarrhea, low grade fever, abdominal pain, nausea, vomiting, and inflammation of bowel.
7.3.6.8 Vibrio vulnificus (Vibriosis):
This organism is an opportunistic pathogen in individuals having compromised immune system or medical disorders- through raw shellfish including shrimp and crabs.
7.3.6.9 Clostridium botulinum (Botulism):
The neurotoxicity of this organism affects the central nervous system.
7.3.6.10 Listeria monocytogenes (Listeriosis):
In l985 contaminated cheese caused 85 deaths. The organism may be present in 30% of raw, ready-to-eat meat products, l5-20% in ground beef, and l5-80% in retail poultry ( JAMA, March 3, l989). Listeriosis is a rare but potentially fatal disease. Most vulnerable are those with weakened immune systems-infants, pregnant women, the elderly, and the chronically ill. Listeriosis is usually manifested as meningitis or meningoencephalitis; affects tissues around the brain or spine, or septicemia. Listeriosis can cause spontaneous abortions and stillbirths. The first report (Siddique: Can J Microbial l5:955-957, l968) indicated that the hemolysin elaborated by Listeria monocytogenes had cytotoxic activity. This concept is being used as a potential means of measuring the invasiveness of Listeria isolates--as one of the diagnostic methods for Listeria monocytogenes in foods.
Scombroid fish egg, tuna, mackerel and swordfish have a high concentration of histamine which are responsible for the acute syndrome with dizziness, headache, diarrhea, burning sensation in mouth, tachycardia, pruritis, and asthma-like signs. FDA has established histamine limits 50 mg/ l00 g as hazardous.
Paralytic shellfish poison toxins - resulted in 22 deaths and l76 illnesses in Guatemala- " red tide bloom" identified as Pyrodinium bahamese isolated from clams.
Unpleasant odors and tastes are produced by "putrefactive" organisms, i.e., those which digest proteins and produce H2S , rendering them completely unpalatable. Canned oysters may become covered with a layer of red yeast, in which case they are considered "spoiled" although unchanged in odor, taste, and safety.
The milk delivered to consumers contains comparatively few organisms. The bacteria commonly found in milk may be classified according to changes they cause when growing in milk at room temperature or above.
7.3.11.1 Acid-forming Bacteria:
Portion of lactose is converted into lactic acid. S. lactis causes souring in milk. S. lactis is used as starter culture. Cultures used as starters in preparing certain milk product are usually Lactobacillus acidophilus or Lactobacillus bulgaris.
7.3.11.2 Gas-forming bacteria:
Escherichia coli and Aerobacter aerogenes are the most common in this category. Milk produced under the best conditions may be expected to contain less than 100 coli-aerogenes organisms per ml of milk.
7.3.11.3 Peptonizing bacteria:
These bacteria digest and liquefy the protein in milk (casein especially) and give a fecal odor and bitter taste. Bacillus subtilis and Streptococcus liquefaciens cause curdling of milk. These bacteria secrete a rennet-like enzyme which coagulates the casein. Later, acid is developed and finally protein decomposition takes place. Peptonizing bacteria in milk usually indicate poor sanitary conditions in milk production.
7.3.11.4 Ropy Milk:
Alcaligenes viscosus, Streptococcus cremoris, Escherchia coli, aerogenes group, micrococcus species and Lactobacillus bulgaricus cause ropiness. Ropiness is most common in milk held at about 55 F and is caused by the synthesis of capsular material (mucins and galactans) of bacteria. Pasteurization effectively controls the ropy condition. Keeping milk below 50 F before pasteurization helps to control this condition.
7.3.11.5 Sweet Curdled milk:
Streptococcus liquefaciens, and certain spore formers cause this condition. Extracellular enzymes like rennet causes casein to form small specks of curd. This reaction occurs before an appreciable amount of acid is produced and is known as sweet curdling. This has a rare-bitter flavor.
After proper pasteurization about 1% bacteria still survive. These bacteria may be thermoduric or thermophilic. Thermoduric are spore-formers such as Bacillus subtilis and thermophilic such as Streptococcus thermophilus.
Coliform organisms are usually present in freshly drawn raw milk in numbers of less than 100 per ml. These organism can grow at 50 F and high count indicates unsatisfactory production methods.
Their presence means that proper steps should be taken to locate and eliminate all sources of contamination.
Keep in mind that waterborne diseases may be caused by agents other than viruses, but for purposes of the present discussion, we are talking exclusively about viruses. Over 100 types of human enteric viruses including polio, hepatitis, enteroviruses may be transmitted through water. There is no conclusive evidence that enteric viruses can be recirculated through treatment. It is believed that drinking water contains viruses.
7.4.1 Viral sources
Human, animal feces, dead animals, various water sources and plants. For example:
Toilets, food processing, streets, farms, parks, sewage run-off->underground water estuaries and lakes etc. Modes of transmission of human enteric viruses: run-off, toilets, hands, insects, droplets.
7.4.2 Water Treatment:
Hepatitis and polio viruses are about 10,000 times more resistant. The 3 immunological types of polio and the coxsackie viruses differ greatly in susceptibility to chlorine; further, clumped virus is harder to kill.
No retrievable virus found after this process.
Two (2) or more persons experience illness after water consumption with epidemiologic evidence implicating the water as cause.
There are exceptions, for example, a case of chemical poisoning is considered an outbreak. Only contaminated drinking water should be included in statistics.
Outbreaks should first be reported to State Health Department and then to the Centers for Disease Control (CDC). The Environmental Protection Agency (EPA) works with state water supply agencies to get information on additional outbreaks.
Investigation - CDC and EPA together can also act as consultants in these investigations. The reported outbreaks are only a small portion of those actually occurring. Data indicate that there is a seasonal likelihood of outbreaks with similar etiology and a common water system deficiency.
There were 22 waterborne outbreaks in 1986, 15 in 1987 and 13 in 1988, affecting 25,846 persons. During the two-year period, 1989-1990, there were 26 outbreaks with 4,288 persons becoming ill. The 1986-1987-1988 outbreak classification involve the following etiologic agents:
Cryptosporidium 13,000 cases Norwalk virus 5,474 cases Acute GI illness (etiology unknown) 2,975 cases
Campylobacter 250 cases
Chemical 103 cases
Other 72 cases
Salmonella 70 cases
Total 25,846 cases
Protozoa of small intestine. Found worldwide.
Chronic diarrhea, cramps, bloating, weight loss. No invasion of intestinal wall. Symptoms usually 1 week.
Carrier Rate - 1-20%
Reservoir - man, possibly animals.Asymptomatics or carriers are important in transmission.
Chlorine in standard concentrations probable is not effective in killing organisms. The infection can be treated with available drugs.
Transmission - fecal contamination of water. Reported after eating washed fruits, vegetables.
There are 4 Species - Shigella sonnei is most important.
Primarily affects large intestine--diarrhea, fever, often vomiting, cramps. In most outbreaks there are mild cases, asymptomatics. Reservoir - man, some primate colonies. Transmission - fecal, oral. Incubation - less than 4 days (1-7 days). Shedding - usually 4 weeks or less. Carriers may shed for one year + chronic problem in institutions. Disease more severe in kids. 39 cases in 1974 from swimming in Mississippi. Recent cruise ship outbreaks. Chemical agents - fluoride and phenol are effective against this organism.
The virus has never been isolated so incrimination circumstantial. Uncommon waterborne disease agent. Incubation - 15-50 days (average 1 month). Duration - 1-2 weeks to several months. Transmission - person to person (usually fecal, oral).
May be epidemic or endemic -- more often in countries with poor sanitation, water treatment. India -- large epidemics due to polluted surface water and inadequate treatment plants.
Cross connections (Note: Holy Cross episode). Important to monitor water pressures and locate cross connections.
Surface water communities tend to have higher hepatitis rates than groundwater communities (1 study).
Note: The prevention of food-borne diseases is shown in the following progressive form as shown in Figure 1:
Raw foods
|
Cleaned in potable Water
|
Handled carefully
|
Refrigerated
|
Processed
|
Preserved by heating, by addition of spices, salts, sugars, chemical preservatives, or by dehydration or freezing. Also by refrigeration
|
Prepared for service Heated to 40°F or
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Refrigerated to 40°F
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Served
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Leftovers: refrigerated to 40°F or frozen
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When prepared serve at once
Laboratory, clinical,
and/or
epidemiologic criteria
for
Clinical Syndrome
confirmation
BACTERIAL
1. Bacillus
cereus Vomiting toxin: a) isolation of >105
organisms per
a) incubation period 1-6
hrs. gram in epidemiologically incriminated
food
b) vomiting, some
cases with diarrhea
OR
Diarrheal toxin: b)
isolation of organism from stools
a) incubation
period 6-24 hrs. of ill Persons and not in stools
of
b) diarrhea, abdominal
cramps, controls
some cases with
vomiting
______________________________________________________________________________
2. Brucella a)
incubation period several
a) 4-fold
increase in titer
days to several months
OR
b) positive blood
culture
b) clinical syndrome
compatible with brucellosis
______________________________________________________________________________
3. Campylobacter
a) incubation
period 2-10 days, Isolation of organisms from
stool/
jejuni usually
4-7 blood of ill individuals
b) gastrointestinal
syndrome--abdominal pain, often severe;
bloody diarrhea
common
______________________________________________________________________________
4. Clostridium a)
incubation 2 hours-8 days, a) detection of botulinal toxin
in
botulinum usually
12-48 hours human sera, feces, or food
OR
b) clinical syndrome
compati- b) isolation of C. botulinum
organism
ble with botulism (see CDC
from stools
Botulism
Manual)
OR
c) clinical syndrome in
persons
known to have consumed same
food
as other individuals
with
laboratory-proven
cases
______________________________________________________________________________
5.
Clostridium
a) incubation
period 9-15 hrs. a) organisms of same serotype
in
perfringens
epidemiologically incriminated food
b) lower intestinal
syndrome-- and stool of ill individuals.
majority of cases with
diarrhea OR
but little vomiting
or fever
b) isolation of
organisms with same
serotype in stool of
most ill individuals and not in stool of
controls
OR
c)
>105 organisms per gram in
epidemiologically
incriminated food
provided specimen
properly handled
______________________________________________________________________________
6. Escherichia a)
incubation period 6-36 hrs. a) demonstration of organisms
of
coli same serotype
in epidemiologically
b) gastrointestinal
syndrome-- incriminated food and stool of ill
majority of cases with
diarrhea individuals and not in stool of
controls
OR
b) isolation from stool of
most ill
individuals, organisms of
the same
serotype which have been
shown to
be enterotoxigenic or
invasive by
laboratory
techniques
______________________________________________________________________________
7. Salmonella a)
incubation period 6-48 hrs. a) isolation of
Salmonella organism
from epidemiologically
implicated food
b) gastrointestinal
syndrome-- OR
majority of cases with
diarrhea b) isolation of Salmonella
organism
from stools of ill
individuals
______________________________________________________________________________8.
Shigella a) incubation period 12-50 hours a)
isolation of Shigella organism
from epidemiologically
implicated food
b) gastrointestinal
syndrome-- OR
majority of cases with
diarrhea b) isolation of Shigella organism
from stools of ill
individuals
______________________________________________________________________________9.
Staphylococcus a) incubation period 30 min.- a)
detection of enterotoxin in
aureus 8 hours
(usually 2-4 hrs.) epidemiologically implicated
food
OR
b) gastrointestinal
syndrome-- b) organisms with same phage type in
majority of cases with
vomiting stools or vomitus of ill individuals; isolation
from epidemiologically implicated food and/or skin or nose
of food handler is supportive evidence
OR
c) isolation of
>105 organisms per
gram in epidemiologically
implicated food
______________________________________________________________________________
10. Streptococcus a)
incubation period 1-4 days a) isolation of organisms with
same
Group A M and T type from
implicated food
b) febrile URI syndrome
OR
b) isolation of organisms
with same
M and T type from throats
of ill individuals
______________________________________________________________________________
11. Vibrio cholerae
01 a) incubation period 1-5 days a) isolation of toxigenic
V. cholerae 01 from epidemiologically
incriminated food
b) gastrointestinal
syndrome-- OR
majority of cases with
diarrhea b) isolation of organisms from
and without fever stools
or vomitus of ill individuals
OR
c) significant rise in
vibriocidal,
bacterial agglutinating
or anti-
toxin antibodies in
acute and early
convalescent sera, or
significant
fall in vibriocidal
antibodies in
early and late
convalescent sera in
persons not recently
immunized
Laboratory, clinical,
and/or
epidemiologic criteria
for Vibrio
cholerae
a) incubation period up to
3
a) isolation of non-01
V. cholerae
Non-01 days of same
serotype from stools of ill
b) gastrointestinal
syndrome-- persons; isolation from
epidemio-
majority of cases with
logically implicated food is supportive evidence
diarrhea
______________________________________________________________________________
12.
Vibrio a) incubation period 4-30 hrs.
a) isolation of
>105 organisms
parahaemolyticus
from epidemiologically implicated
b) gastrointestinal
syndrome-- food (usually seafood)
majority of cases
with diarrhea OR
b) isolation of
Kanagawa-positive
organisms from stool
of ill individuals
______________________________________________________________________________
13. Others clinical data
appraised in laboratory data appraised in individual
individual circumstances circumstances
______________________________________________________________________________
CHEMICAL
1. Heavy metals a)
incubation period 5 min. to demonstration of high
concentration
8 hrs. (usually less
than 1 hr.) of metallic ion in
epidemiologically
Antimony incriminated
food or beverage
Cadmium b) clinical
syndrome compatible
Copper with heavy metal
poisoning--
Iron usually
gastrointestinal syndrome
Tin and often metallic
taste
______________________________________________________________________________
2.
Ichthyosarcotoxin
Ciguatoxin a) incubation
period 1-48 hrs. a) demonstration of ciguatoxin
in (usually
2-8 hrs.) epidemiologically incriminated
fish OR
b) usually gastrointestinal
b) clinical syndrome in person(s)
symptoms followed by
neurologic who have eaten a type of fish
pre- manifestations,
including pares- viously associated with
ciguatera
thesia of lips, tongue,
throat fish poisoning (e.g., snapper,or extremities, and
reversal of grouper)
hot and cold
sensation
______________________________________________________________________________
Puffer fish a) incubation
period 10 min.
a) demonstration of
tetrodotoxin in
(tetrodotoxin) to 3 hrs.
(usually 10-45 min.) fish
OR
b) paresthesia of lips,
tongue, b) puffer fish epidemiologically
face or extremities
often follow- incriminateded by numbness, loss of
proprio-
ception or a "floating"
sensation
________________________________________________________________________
Scombrotoxin a) incubation
period 1 min. to
a) demonstration of
elevated hista-3 hours (usually less than 1 mine levels in
epidemiologically
hour) incriminated
fish
OR
b) flushing, headache, b)
clinical syndrome in person(s)
dizziness, burning of
mouth and known to have eaten a fish of
order
throat, upper and lower
gastro- Scombrodei or type of fish
previous-
intestinal symptoms,
urticaria ly associated with scombroid poison-and
generalized pruritus ing (e.g., mahi-mahi)
______________________________________________________________________________
3. Monosodium a) incubation
period 3 min. to history of large amounts (usuallyglutamate
2 hours (usually less than 1 hour) >1.5 grams) of
MSG having been added
to epidemiologically
incriminated foodb) burning sensations in
chest,
neck, abdomen or
extremities,
sensations of lightness
and pressure
over face, or a heavy
feeling in the
chest_
