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43 Cards in this Set

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  • Back
Who discovered Giardia?
Antoni van Leeuwenhoek. Described them as small anamacules
What is the greatest cause of food bourne non-bacterial diarrhea in the US?
What are characteristics of Giardia lamblia?
Is a Zooflagellate (have flagella)

Is single celled, has two nuclei, and has NO mitochondira (meaning it is a parasite because mitochondria are the powerhouses of the cell)

The organism is present in two states: cyst (infective stage); and Trphozoites (adult stage, inside host, not infectious)
How is Giardia trasmitted?
Consuming food or water contaminated with cysts

Putting anything that has touched a stool of an infected person or animal

Sexual transmission (homosexual men)
What are disease characteristics of Giardia?

Incubation time: 7-10d

Infective Dose: as few as 10 cysts

VERY SMELLY diarrhea, stomach cramps, bloating, gas, fatigue, weight loss. Symptoms may last up to a month. Can be contagious for MONTHS

Intestintes of infected humans/animals, waterbourne
What are prevention and treatment strategies for Giardia and Cryptosporidium?

Who is most suceptible?
Water purification via filtration boiling or chemical treatment


Treatment: Anti-protozoan drugs. Con: Have side effects because they target Eukaryotic cells (same as human). These drugs do not work for Cryptosporidium parvum.

Children, Immunocompromised, Homosexual Men, Backpackers, Swimmers
What led Cryptosporidium parvum to become noticed?
AIDS epidemic, had high fatality rate because of immunocompromised.
What are differences between Cryptosporidium and Giardia?
C. is also found in fish intestines

Illness flip flops (you think you are getting better then get worse etc)

There is no effective treatment for C.

C. is a sporozoan (not motile)Giardia is a Zooflagellate

Giardia has two nuclei, C. has one
What are characteristics of Cryptosporidium parvum?
Single celled protozoan, one nucleus, no functioning mitochondria
How is Cryptosporidium parvum transmitted?
Cosuming water or food contaminated with oocysts

Person to person in group settings

From water/resistant to chlorine (municipal water systems)
What are disease characteristics of Cryptosporidium parvum

Main reservoirs for Cryptosporidium parvum?
Incubation: 2-10d

Infectious dose: <10 oocysts

Watery diarrhea is most common symptom.

Symptoms last from 1-2 weeks. Illness flip flops from a period of feeling better to worse.

Mammals, birds, fish and reptiles
What are characteristics of Cyclospora? Where did it come from?
Protozoan parasite, member of sporozoans, cannot be grown in lab (like Cryptosporidium parvum)

Came from other countries to US. Highlighted role of international food distribution
How is Cyclospora trasmitted?
By consuming food or water contaminated with oocysts.

What are disease characteristics of Cyclosporiasis? Treatment? Reservoirs?
Incuabtion: 1week
Symptoms: Watery diarrhea, frequent and sometimes explosive bowel movements, loss of appetite, weight.

Duration: few days to months, illness relapses like Cryptosporidium parvum

Treatment: Anti-protozoan drugs

Reservoirs: Intestines of infected humans, possibly birds
What are characterisitcs of Toxoplasma gondii?

Protozoan, sporozoan, high mortality rate (50% of deaths attributed to eating contaminated meat), common
How is Toxoplasma gondii spread?
From feline to food animals to humans


From felines directly to humans
What are disease characteristics of Toxoplasma gondii? Who is especially prone to illness?
Incubation Time: 5-25d
Treatment: Anti-Protozoan drugs
Symptoms: Fever, malaise, usually not serious in healthy individuals.
Pregnant women are prone to illness, can cause serious health problems in fetus (mental retardation, blindness, and epilepsy)
What are prevention measures for Toxoplasma gondii?
Pregnant Women: Have someone else clean litter box, clean litter box daily (parasite does not become infectious until 1-5d after feces is shed, wash hands regularly, never feed cats raw meat, avoid strays, wash and cook food thoroughly
What meat is Trichinella spiralis associated with?
raw or undercooked pork (mainly), bear
What are common symptoms of Trichinella
Initial (1-2d): Diarrhea, vomiting, abdominal pain

Further Symptoms (2-8w): MUSCLE PAIN, fever nausea
How does Trichinella persist in the host>?
Penetrates into small intestine tissue and then migrates to burrow in muscle tissue where it becomes infective.
What disease brought mycotoxins to the forefront?
Turkey X disease where millions of turkeys were killed in England. Linked to peanut feed that was heavily contaminated.
What are the six most important mycotoxins, in regards to foodbourne disease?
Aflatoxins, Deoxynivalenol (vomitoxin), Zearalenone, Funonisins, T-2 Toxin, Ochratoxin A
What are characteristics of Aflatoxins
most potent natural carninogen, produced by some aspergillis (a. flavus , a. nominus) species, most prevalent in SE US, important varieties are B1 B2 G1 & G2, M1 in milk,

found in corn, grains, nuts, oilseeds
How do aflatoxins cause cancer?
Metabolized in the liver, digestion creates reactive intermediaries. Intermediaries bind to DNA and cause disruption of transcription and abnormal cell proliferation, leading to cancer
How was vomitoxin named?
Scientists noted that swine refused to eat certain moldy corn. When tricked into eating it, the pigs vomited.
What are characteristics of vomitoxin or Deoxynivalenol?
Physical: Purple or pink color

Source: Fusarium genus (esp culmorum & graminearium); corn, wheat, oats, barley

Location: Common in Midwest
What type of problems does the mycotoxin Zearalenon cause? What genus does it originate from? Species?
Toxin that causes reproductive problems

Fusarium genus, graminearium and culmorum species
What disease does Fumonisins cause? From what genus of mold do they originate? What foods are they found in?
Caise espophaegal cancer (adverse affect on brain, liver lungs, kidneys, pancreas, etc)

Caused by Fusarium

Found in corn, grain, beans, rice
What disease does T-2 toxin cause? From what genus of mold do they originate? What foods are they found in?
T-2 inhibits protein synthesis and is also associated with lesions of the intestinal tract & espophagus

Originate from Fusarium thichothecenes

Found in corn, wheat, rye, barley and oats
What disease does Ochratoxin A cause? From what genus of mold do they originate? What foods are they found in?
Cause kidney failure, cancer, and are immunosuppressive

Produced by aspergillus and penicillium

Found in coffee(mostly), cereals, bread and wine
Norovirus has several distinct characteristics, what are they?
Most common foodbourne infection (viral), Single stranded (non enveloped) RNA virus, Causes explosive vomiting because of unique ability to replicate in stomach

Vomiting expels millions of viruses, so is very infectious

Can become airbourne

Internalizes in mucosal cells and replicates, kills the cells, and are expelled to continue the cycle
What are the top two leading causes of childhood diarrhea?
Astrovirus (2) and Rotavirus (1)
What are characteristics of Astrovirus?
PHYSICAL: Small round, star shaped, Single Stranded RNA

MOST AFFECTED: Children, Elderly and Animals (broad specificity)

OCCURENCE: Widespread, all over the world

DURATION: 2-3 Days

INCUBATION: 3-4 days
What are symptoms of Astrovirus gastroenteritis? How is it infectious?
Copious, watery diarrhea. The Astrovirus is thought to replicate in the small intestinal tissue.
What are characteristics of Rotavirus?
PHYSICAL: Wheel like appearance, 100nm

MOST AFFECTED: Children, less problematic for adults if built immunity

DURATION: 3-8 Days

What makes Rotavirus so deadly to children?
Length of disease and nature of diarrhea end up in massive water loss. Dehydration is primary reason for death.
What are symptoms of Rotavirus?
Very watery diarrhea (look like yogurt mixed with water), vomiting, fever
How can Rotavirus be treated and prevented?
TREATMENT: Intravenus fluid, Oral rehydration therapy

PREVENTION: Attenuated (live, but inactivated) vaccine (Rotateq) available. Has five different strains that it protects against.
How important is Hepatitis A in foodbourne disease? How is it contracted?
Not very important, only comprises ~5% of cases. Transmitted in foods by feces of infected food handlers.
What is one distinguishing characteristic about Hep A infection that is different from all other viral foodbourne infections?
Infection in children is mild and provides immunity.

If adult gets disease, symptoms are far worse.
What is one inherent flaw to the ELISA test?
False (+) are fairly common.. ~10%. Reason is because of cross reactivity of aB. However, false (-) are very rare..~1%
What are characteristics of Hep A? Prevention?
INCUBATION: 15-50 days

SYMPTOMS: Sudden onset of fever, fatugue, DARK URINE & JAUNDICE


PREVENTION: HAV Inactivated Vaccine