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Notes Unit 15
Food and Waterborne Diseases
Structure and Function of the Digestive System
The digestive system can be divided into two principal groups of organs:
1. The Gastrointestinal Tract (GI Tract) – this consists of the mouth, throat, esophagus, stomach,
small intestine, and large intestine. The purpose of this part is to digest food, allowing food particles
to be absorbed by the body.
2. The Accessory Structures – this consists of the teeth, tongue, salivary glands, liver, gallbladder,
and pancreas. These structures function to produce secretions that go into the digestive system.
Over the average lifetime, about 25 tons of food passes through the digestive system. The undigested solids,
called feces, are eliminated through the anus. Intestinal gas, or flatus, is a mixture of nitrogen from swallowed
air and microbially produced carbon dioxide, hydrogen, and methane. On average, we produce about 0.5 to 2.0
liters of gas every day!
Normal Flora of the Digestive System
There are normal bacteria in most of the digestive system. In the mouth, each milliliter of saliva can contain
millions of bacteria. The stomach and small intestine have relatively few microorganisms because of the
hydrochloric acid produced by the stomach. However, the large intestine has enormous microbial populations,
exceeding 100 billion bacteria per gram of feces! Up to 40% of fecal mass is microbial cell material. In this
portion of the digestive system, there are mostly anaerobic bacteria such as Lactobacillus, Bacteroides, E. coli,
Enterobacter, Klebsiella, and Proteus. Most of these bacteria assist in the enzymatic breakdown of foods,
and some synthesize useful vitamins.
Intoxication vs. Infection
Food intoxication is when you ingest bacteria that produce harmful toxins. Food infection is when the
bacteria itself causes harm. Both can make you sick; however, the intoxication cannot be eliminated with
antibiobics.
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Important Diseases
1. Botulism
Causative Organism:
Type of Organism:
Types of Disease:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Clostridium botulinum
Bacteria; Gram positive rod-shaped , found in contaminated soil
3 types, but we are talking about the foodborne type of botulism
Exotoxin produced that is highly potent
With foodborne botulism, symptoms begin within 6 hours to 2 weeks (most
commonly between 12 and 36 hours) after eating food that contains the toxin.
Symptoms of botulism include double vision, blurred vision, drooping eyelids,
slurred speech, difficulty swallowing, dry mouth, and muscle weakness that
moves down the body, always affecting the shoulders first, then the upper arms,
lower arms, thighs, calves, etc. Paralysis of breathing muscles can cause a person
to stop breathing and die, unless assistance with breathing (mechanical
ventilation) is provided.
Get from eating improperly canned foods, usually home-canned ones with low
acid content.
Foodborne: eating foods that have not been canned properly.
Botulism antitoxin
2. Gas Gangrene
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Clostridium perfringens
Bacteria; Gram positive rod
Forms endospores; also produce toxins which cause tissue death.
Develops after surgery or injuries. As organisms grow, they ferment
carbohydrates in the tissue and produce gases that cause the tissue to swell.
Toxins move along nerves, kill cells, and cause necrosis. Eventually, bacteria
cause septicemia, and will kill you if not treated.
Tissue death (turns black) and foul odor - swollen.
From touching soil and from animals; also normal flora in our gut.
Antibiotics, but once tissue dies, must amputate.
3. Staphylococcal Food Poisoning
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Staphylococcus aureus
Bacteria; Gram-positive round clusters
Releases enterotoxin, which damages tissues. Can make 7 different toxins!
Toxins cannot be removed by cooking.
Staphylococcal toxins are fast acting, sometimes causing illness in as little as 30
minutes. Symptoms usually develop within one to six hours after eating
contaminated food. Patients typically experience several of the following: nausea,
vomiting, stomach cramps, and diarrhea. The illness is usually mild and most
patients recover after one to three days.
Food poisoning caused by creamy foods (things that contain milk products,
cheese, mayonnaise, custard, etc).
From foods such as custards, cream pies, and ham.
Let it run its course usually; antibiotics won’t work on toxins.
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4. Salmonellosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Salmonella sp.(more than one species causes)
Bacteria; Gram negative rod
Produces endotoxins which lyses (breaks apart) cells
Most persons infected with Salmonella develop diarrhea, fever, and abdominal
cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and
most persons recover without treatment. However, in some persons the diarrhea
may be so severe that the patient needs to be hospitalized. In these patients, the
Salmonella infection may spread from the intestines to the blood stream, and then
to other body sites and can cause death unless the person is treated promptly with
antibiotics. The elderly, infants, and those with impaired immune systems are
more likely to have a severe illness.
Lives in intestines of poultry; we eat foods that are contaminated with bird feces.
Contaminated foods are often of animal origin, such as beef, poultry, milk, or
eggs, but any food, including vegetables, may become contaminated. Usually
undercooked.
Antibiotics, oral rehydration.
5. Typhoid Fever
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Salmonella typhi
Bacteria; Gram negative rod
Very virulent.
Persons with typhoid fever usually have a sustained fever as high as 103° to 104°
F (39° to 40° C). They may also feel weak, or have stomach pains, headache, or
loss of appetite. In some cases, patients have a rash of flat, rose-colored spots. The
only way to know for sure if an illness is typhoid fever is to have samples of stool
or blood tested for the presence of S. typhi .
Bloody stools.
Persons with typhoid fever carry the bacteria in their bloodstream and intestinal
tract. In addition, a small number of persons, called carriers, recover from
typhoid fever but continue to carry the bacteria. Both ill persons and carriers
shed S. typhi in their feces (stool). You can get typhoid fever if you eat food or
drink beverages that have been handled by a person who is shedding S. typhi or if
sewage contaminated with S. typhi bacteria gets into the water you use for
drinking or washing food.
Antibiotics.
6. Shigellosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Shigella sp. (more than one species)
Bacteria; Gram-negative rod
Only takes a few to make you sick; cause damage to large intestine, causing
bleeding. Enterotoxins kill cells.
Shigellosis is an infectious disease caused by a group of bacteria called Shigella.
Most who are infected with Shigella develop diarrhea, fever, and stomach cramps
starting a day or two after they are exposed to the bacterium. The diarrhea is often
bloody. Shigellosis usually resolves in 5 to 7 days. In some persons, especially
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Hallmark:
Transmission:
Treatment:
young children and the elderly, the diarrhea can be so severe that the patient needs
to be hospitalized.
Food poisoning that comes from fecal contamination; bloody diarrhea
Most Shigella infections are the result of the bacterium passing from stools or
soiled fingers of one person to the mouth of another person. This happens when
basic hygiene and handwashing habits are inadequate and can happen during
certain types of sexual activity. It is particularly likely to occur among toddlers
who are not fully toilet-trained. Family members and playmates of such children
are at high risk of becoming infected. Shigella infections may be acquired from
eating contaminated food. Contaminated food may look and smell normal. Food
may become contaminated by infected food handlers who forget to wash their
hands with soap after using the bathroom. Vegetables can become contaminated if
they are harvested from a field with sewage in it. Flies can breed in infected feces
and then contaminate food. Shigella infections can also be acquired by drinking or
swimming in contaminated water. Water may become contaminated if sewage
runs into it, or if someone with shigellosis swims in it.
Antibiotics, oral rehydration.
7. Cholera
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Vibrio cholerae
Bacteria; Gram negative curved rod
Produces an enterotoxin that results in the secretion of chlorides, bicarbonates,
and water.
Cholera is an acute, diarrheal illness. The infection is often mild or without
symptoms, but sometimes it can be severe. Approximately one in 20 infected
persons has severe disease characterized by profuse watery diarrhea, vomiting,
and leg cramps. In these persons, rapid loss of body fluids leads to dehydration
and shock. Without treatment, death can occur within hours. Grow in small
intestine and cause “rice water stools” which are stools that have lots of intestinal
mucus, epithelial cells, and bacteria in them. Sudden fluid loss can cause shock,
collapse, and often death (can lose 3-5 GALLONS of fluid a day).
Rice water stools; from eating contaminated salt water
The cholera bacterium may also live in the environment in brackish rivers and
coastal waters. Shellfish eaten raw have been a source of cholera, and a few
persons in the United States have contracted cholera after eating raw or
undercooked shellfish from the Gulf of Mexico.
Antibiotics, replacement of lost fluids.
8. E. coli O157:H7
Causative Organism: E. coli O157:H7
Type of Organism: Bacteria; Gram negative rod
Pathogenicity:
Have specialized parts that allow them to bind to certain intestinal cells. Also
produce a toxin called shiga toxin.
Symptoms:
People generally become ill from E. coli O157:H7 two to eight days (average of
3-4) after being exposed to the bacteria. Often causes severe bloody diarrhea and
abdominal cramps. Sometimes the infection causes non-bloody diarrhea or no
symptoms. Usually little or no fever is present, and the illness resolves in 5 to 10
days. In some persons, particularly children under 5 years of age and the elderly,
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Hallmark:
Transmission:
Treatment:
the infection can also cause a complication called hemolytic uremic syndrome
(HUS), in which the red blood cells are destroyed and the kidneys fail. About 8%
of persons whose diarrheal illness is severe enough that they seek medical care
develop this complication. In the United States, HUS is the principal cause of
acute kidney failure in children, and most cases of HUS are caused by E. coli
O157:H7.
Get from eating undercooked ground beef.
People can become infected with E.coli O157:H7 in a variety of ways. These
bacteria live in the guts of ruminant animals, including cattle, goats, sheep, deer,
and elk. The major source for human illnesses is cattle. The ones that cause
human illness generally do not make animals sick. Other kinds of animals,
including pigs and birds, sometimes pick it up from the environment and may
spread it. Though most illness has been associated with eating undercooked,
contaminated ground beef, people have also become ill from eating contaminated
bean sprouts or fresh leafy vegetables such as lettuce and spinach. Person-toperson contact in families and child care centers is also a known mode of
transmission. In addition, infection can occur after drinking raw milk and after
swimming in or drinking sewage-contaminated water. Lives in the intestines of
healthy cattle.
Antibiotics, oral rehydration.
9. Campylobacter Gastroenteritis
Causative Organism: Campylobacter jejeuni
Type of Organism: Bacteria; Gram negative spiral shaped
Pathogenicity:
A very small number of Campylobacter organisms (fewer than 500) can cause
illness in humans. Even one drop of juice from raw chicken meat can infect a
person.
Symptoms:
Diarrhea, cramping, abdominal pain, and fever within 2 to 5 days after exposure
to the organism. The diarrhea may be bloody and can be accompanied by nausea
and vomiting. The illness typically lasts 1 week. Some persons who are infected
with Campylobacter don't have any symptoms at all. In persons with
compromised immune systems, Campylobacter occasionally spreads to the
bloodstream and causes a serious life-threatening infection.
Hallmark:
Leading cause of foodborne illness in the US. Most cases of campylobacteriosis
are associated with eating raw or undercooked poultry meat or from crosscontamination of other foods by these items.
Transmission:
The vast majority of cases occur as isolated, sporadic events, not as part of
recognized outbreaks. Associated with handling raw poultry or eating raw or
undercooked poultry meat.
Treatment:
Antibiotics.
10. Listeriosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Listeria monocytogenes
Bacteria; Gram positive rod
Can grow inside phagocytic cells, which allows it to escape detection by the
immune system.
Fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or
diarrhea. If infection spreads to the nervous system, symptoms such as headache,
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Hallmark:
Transmission:
Treatment:
stiff neck, confusion, loss of balance, or convulsions can occur. Infected pregnant
women may experience only a mild, flu-like illness; however, infections during
pregnancy can lead to miscarriage or stillbirth, premature delivery, or infection of
the newborn.
Affects pregnant women and comes from infected food.
Has recently been recognized as an important public health problem in the United
States. The disease affects primarily persons of advanced age, pregnant women,
newborns, and adults with weakened immune systems. The bacterium has been
found in a variety of raw foods, such as uncooked meats and vegetables, as well
as in processed foods that become contaminated after processing, such as soft
cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk or foods made
from unpasteurized milk may contain the bacterium. Listeria is killed by
pasteurization and cooking; however, in certain ready-to-eat foods such as hot
dogs and deli meats, contamination may occur after cooking but before
packaging.
Antibiotics
11. Viral Gastroenteritis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Different ones such as rotaviruses, noroviruses, adenoviruses, sapoviruses, and
astroviruses
Viruses
Cause inflammation of the small and large intestines.
The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. The
affected person may also have headache, fever, and abdominal cramps ("stomach
ache"). In general, the symptoms begin 1 to 2 days following infection with a
virus that causes gastroenteritis and may last for 1 to 10 days, depending on which
virus causes the illness.
Watery diarrhea and vomiting
Viral gastroenteritis is contagious. The viruses that cause gastroenteritis are
spread through close contact with infected persons (for example, by sharing food,
water, or eating utensils). Individuals may also become infected by eating or
drinking contaminated foods or beverages. Food may be contaminated by food
preparers or handlers who have viral gastroenteritis, especially if they do not wash
their hands regularly after using the bathroom. Shellfish may be contaminated by
sewage, and persons who eat raw or undercooked shellfish harvested from
contaminated waters may get diarrhea. Drinking water can also be contaminated
by sewage and be a source of spread of these viruses.
The most important of treating viral gastroenteritis in children and adults is to
prevent severe loss of fluids (dehydration).
12. Hepatitis A
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Hepatitis A virus
Virus
Causes acute disease of liver
Potentially none (likelihood of symptoms decreases with the person's age) If
present: yellow skin or eyes, tiredness, stomach ache, loss of appetite, or nausea
Yellow skin or eyes (jaundice)
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Transmission:
Treatment:
Most often: spread by the fecal-oral route (An object contaminated with the stool
of a person with hepatitis A is put into another person's mouth.) Less often: spread
by swallowing food or water that contains the virus.
Hepatitis A vaccine will prevent this disease; no cure.
13. Poliomyelitis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Poliovirus
Virus
Very stable; can remain infectious for long periods of time in water and food
Up to 95% of persons infected with polio will have no symptoms. About four to
eight percent of infected persons have minor symptoms such as fever, fatigue,
nausea, headache, flu-like symptoms, stiffness in the neck and back, and pain in
the limbs which often resolves completely. Fewer than one percent of polio cases
result in permanent paralysis of the limbs (usually the legs). Of those
paralyzed, 5-10% die when the paralysis strikes the respiratory muscles.
Crippling disease
Person-to-person spread by coming into contact with feces and ingesting the virus
through the mouth (usually through contaminated water).
There are two types of vaccine that can prevent polio: inactivated polio vaccine
(IPV) and oral polio vaccine (OPV). IPV has been used in the United States since
2000; however OPV is still used throughout much of the world. Polio was
officially eradicated in 1979 in the US.
14. Giardiasis
Causative Organism: Giardia lamblia
Types of Organisms: Flagellated protozoan
Pathogenicity:
Because the parasite is protected by an outer shell, it can survive outside the body
and in the environment for long periods of time.
Symptoms:
Diarrhea, gas or flatulence, greasy stools that tend to float, stomach cramps, upset
stomach or nausea. These symptoms may lead to weight loss and dehydration.
Some people with giardiasis have no symptoms at all.
Hallmark:
Get from water contaminated with animal feces; greasy stools. Nickname is
“Beaver Fever” because beavers transmit in water.
Transmission:
The Giardia parasite lives in the intestine of infected humans or animals (cats,
dogs, cattle, deer, and beavers). Millions of germs can be released in a bowel
movement from an infected human or animal. Giardia is found in soil, food,
water, or surfaces that have been contaminated with the feces from infected
humans or animals. You can get from accidentally swallowing Giardia picked up
from surfaces (such as bathroom fixtures, changing tables, diaper pails, or toys)
contaminated with feces from an infected person or animal; drinking water or
using ice made from contaminated sources (e.g., lakes, streams, shallow [less than
50 feet] or poorly monitored or maintained wells); swallowing recreational water
contaminated with Giardia. Recreational water includes water in swimming
pools, water parks, hot tubs or spas, fountains, lakes, rivers, springs, ponds, or
streams that can be contaminated with feces or sewage from humans or animals.
Treatment:
Anti-protozoan drugs.
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15. Amoebic Dysentery (Amoebiasis)
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Entamoeba histolytica
Protozoan (amoeba)
Can spread to other parts of the body, such as the lungs or brain.
On average, about one in 10 people becomes sick from the infection. The
symptoms often are quite mild and can include loose stools, stomach pain, and
stomach cramping. Amebic dysentery is a severe form of amebiasis associated
with stomach pain, bloody stools, and fever. Rarely, E. histolytica invades the
liver and forms an abscess. Even less commonly, it spreads to other parts of the
body, such as the lungs or brain.
Bloody diarrhea from unsanitary conditions.
In the United States, amebiasis is most often found in immigrants from
developing countries. It also is found in people who have traveled to developing
countries and in people who live in institutions that have poor sanitary conditions.
Men who have sex with men can become infected and can get sick from the
infection, but they often do not have symptoms.
Anti-parasite drugs.
16. Cryptosporidium
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Cryptosporidium sp.
Protozoan
The parasite is protected by an outer shell that allows it to survive outside the
body for long periods of time and makes it very resistant to chlorine-based
disinfectants.
Symptoms of cryptosporidiosis generally begin 2 to 10 days (average 7 days) after
becoming infected with the parasite. In persons with healthy immune systems,
symptoms usually last about 1 to 2 weeks. The most common symptom of
cryptosporidiosis is watery diarrhea. Other symptoms include: stomach cramps or
pain, dehydration, nausea, vomiting, fever, weight loss. Some people with Crypto
will have no symptoms at all.
During the past 2 decades, Crypto has become recognized as one of the most
common causes of waterborne disease (recreational water and drinking water) in
humans in the United States.
Crypto lives in the intestine of infected humans or animals. An infected person or
animal sheds Cryptosporidium parasites in the stool. Millions of parasites can be
released in a bowel movement from an infected human or animal.
Anti-parasite drugs
17. Toxoplasmosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Toxoplasma gondii
Protozoan
However, pregnant women and individuals who have compromised immune
systems should be cautious; for them, a Toxoplasma infection could cause serious
health problems.
Mild symptoms that clear up for most people. However, in pregnant women, can
cause congenital infection of the fetus, resulting in a stillborn baby. Can cause
loss of immune function in host, neurological impairment, and can damage vision.
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Hallmark:
Transmission:
Treatment:
Pregnant women who come in contact with cat feces
Eating undercooked, contaminated meat (especially pork, lamb, and venison);
accidental ingestion of undercooked, contaminated meat after handling it an not
washing hands thoroughly (Toxoplasma cannot be absorbed through intact skin);
eating food that was contaminated by knives, utensils, cutting boards and other
foods that have had contact with raw, contaminated meat; drinking water
contaminated with Toxoplasma gondi; accidentally swallowing the parasite
through contact with cat feces that contain Toxoplasma.
Anti-parasite drugs.
18. Trichinellosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Trichinella spiralis
parasitic helminth
Can burrow into your muscles and cause pain
Abdominal symptoms can occur 1-2 days after infection. Further symptoms
usually start 2-8 weeks after eating contaminated meat. Symptoms may range
from very mild to severe and relate to the number of infectious worms consumed
in meat. Often, mild cases of trichinellosis are never specifically diagnosed and
are assumed to be the flu or other common illnesses. Nausea, diarrhea, vomiting,
fatigue, fever, and abdominal discomfort are the first symptoms of trichinellosis.
Headaches, fevers, chills, cough, eye swelling, aching joints and muscle pains,
itchy skin, diarrhea, or constipation follow the first symptoms. If the infection is
heavy, patients may experience difficulty coordinating movements, and have
heart and breathing problems. In severe cases, death can occur. For mild to
moderate infections, most symptoms subside within a few months. Fatigue,
weakness, and diarrhea may last for months.
Eating raw or undercooked pork.
When a human or animal eats meat that contains infective Trichinella cysts, the
acid in the stomach dissolves the hard covering of the cyst and releases the
worms. The worms pass into the small intestine and, in 1-2 days, become mature.
After mating, adult females lay eggs. Eggs develop into immature worms, travel
through the arteries, and are transported to muscles. Within the muscles, the
worms curl into a ball and encyst (become enclosed in a capsule). Infection occurs
when these encysted worms are consumed in meat.
Anti-helminth medicine
19. Draculculiasis (Guinea Worm Disease)
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Dracunculus medinensis
parasitic helminth
Emerges from skin; painful
Infected persons do not usually have symptoms until about one year after they
become infected. A few days to hours before the worm emerges, the person may
develop a fever, swelling, and pain in the area. More than 90% of the worms
appear on the legs and feet, but may occur anywhere on the body.
People, in remote, rural communities who are most commonly affected by Guinea
worm disease (GWD) frequently do not have access to medical care. Emergence
of the adult female worm can be very painful, slow, and disabling. Frequently, the
skin lesions caused by the worm develop secondary bacterial infections, which
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Hallmark:
Transmission:
Treatment:
exacerbate the pain, and extend the period of incapacitation to weeks or months.
Sometimes permanent disability results if joints are infected and become locked.
Slowly emerges from skin; must be wound around a stick until totally free.
Persons become infected by drinking water containing the water fleas harboring
the Guinea worm larvae. Once ingested, the stomach acid digests the water fleas,
but not the Guinea worm larvae. These larvae find their way to the small intestine,
where they penetrate the wall of the intestine and pass into the body cavity.
During the next 10-14 months, the female Guinea worm larvae grow into full size
adults, 60-100 centimeters (2-3 feet) long and as wide as a cooked spaghetti
noodle. These adult female worms then migrate and emerge from the skin
anywhere on the body, but usually on the lower limbs. A blister develops on the
skin at the site where the worm will emerge. This blister causes a very painful
burning sensation and it ruptures within 24-72 hours. Immersion of the affected
limb into water helps relieve the pain but it also triggers the Guinea worm to
release a milky white liquid containing millions of immature larvae into the water,
thus contaminating the water supply and starting the cycle over again. For several
days after it has emerged from the ulcer, the female Guinea worm is capable of
releasing more larvae whenever it comes in contact with water.
There is no drug to treat Guinea worm disease (GWD) and no vaccine to prevent
infection. Once the worm emerges from the wound, it can only be pulled out a
few centimeters each day and wrapped around a piece of gauze or small stick.
Sometimes the worm can be pulled out completely within a few days, but this
process usually takes weeks or months. Analgesics, such as aspirin or ibuprofen,
can help reduce swelling; antibiotic ointment can help prevent bacterial
infections. The worm can also be surgically removed by a trained doctor in a
medical facility before an ulcer forms.
20. Tapeworms
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Taenia sp.
parasitic helminth
The head of the tapeworm contains hooks with which it attaches itself to the walls
of the intestines.
Some of the signs of human tapeworm infection are: constipation; diarrhea;
discomfort in the abdomen; and segments of tapeworm in the feces or clothes.
Individual proglottids shed in feces. For humans who have tapeworm infection,
the parasite is the most dangerous when it is at the embryo stage, because an
insidious infection called cysticercosis can develop in the brain.
The embryos of the tapeworm are ingested either by direct contact with infected
feces, or by drinking contaminated water, or by eating the flesh of animals
infected with tapeworm.
Anti-helminth medicine.
21. Variant Creutzfeldt-Jakob Disease (vCJD)
Causative Organism:
Type of Organism:
Pathogenicity:
Prion
Not alive – is a piece of infectious protein
100% fatality rate
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Symptoms:
Transmission:
Treatment:
Early in the illness, patients usually experience psychiatric symptoms, which most
commonly take the form of depression or, less often, a schizophrenia-like
psychosis. Unusual sensory symptoms, such as "stickiness" of the skin, have been
experienced by half of the cases early in the illness. Neurological signs, including
unsteadiness, difficulty walking and involuntary movements, develop as the
illness progresses and, by the time of death, patients become completely immobile
and mute. Upon autopsy, the brain is riddled with spongy holes. Death usually
occurs within one year.
From eating infected nervous tissue from a cow (brain and spinal cord). Usually,
this is found in ground beef which contains many different parts of the cow. Note:
cooking the meat does NOT get rid of the prion. It cannot be destroyed.
None.
22. Toxoplasmosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Toxoplasma gondii
Protozoan
Loss of immune system function
Mild symptoms that clear up for most people. However, in pregnant women, can
cause congenital infection of the fetus, resulting in a stillborn baby. Can cause
loss of immune function in host, neurological impairment, and can damage vision.
Pregnant women who come in contact with cat feces
Accidentally swallowing cat feces from a Toxoplasma-infected cat that is
shedding the organism in its feces. This might happen if you were to accidentally
touch your hands to your mouth after gardening, cleaning a cat's litter box, or
touching anything that has come into contact with cat feces. Eating contaminated
raw or partly cooked meat, especially pork, lamb, or venison; by touching your
hands to your mouth after handling undercooked meat.
Anti-parasite drugs.
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