Lecture 11: Gastroenteritis & Hepatitis Flashcards by Anaili Abreu

How would you define diarrhea clinically?

-3 off more loose or liquid stools per day
-lasting less than 14 days

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Warning signs of bacterial GI infection?
What happens when warning signs of bacterial infection are absent?

-high fever
-blood/mucus in stool
-severe abdominal pain
- >6 stools/24h

When the warning signs of bacterial infection are absent, then you should suspect a viral cause

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Rotavirus diarrheal disease
-caused by
-capsid
-genome
-envelope

-caused by Rotavirus A,B,C
-capsid: triple layer Icosahedral
-genome: dsRNA
-naked

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Rotavirus characterized in a colorized EM

Show characteristics of “spoked-wheel”- like appearance

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What virus is responsible for 50% of all acute gastroenteritis in developing and developed countries?

-rotavirus
**adenoviruses can cause gastroenteritis as well but not as common at rotaviruses*

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What virus is the most common cause of severe diarrhea among unvaccinated children <5yoa?

Rotavirus
=human infantile gastroenteritis

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Rotavirus transmission

Predominantly spread via FECAL-ORAL route
-large amounts of virus released in feces even in asymptomatic patients
-stable in the environment (obviiiiiiii))
why ?
B/c its naked and tripled capsuled

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Rotavirus clinical presentations

-vomiting and watery diarrhea for 3-8 days
-fever and abdominal pain occur frequently
-dehydration in infants (undernourished)

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Rotavirus pathogenesis

Infects epithelial cells of the VILLI of the SI
-lytic infection of the intestinal epithelium
-loosening of the tight junctions of intestines
-effects of the viral enterotoxin

causing loss of electrolytes and prevents reabsorption of water = diarrhea

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Diagnosing Rotavirus

-direct ELISA by feces or rectal swabs
-latex agglutination test for rotavirus
-LFA: immunochromatographic
-RT-PCR

Genome: dsRNA
Capsid: triple
Naked

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Treatment for Rotavirus

No anti-viral
-replace lost fluids and electrolytes

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Prevention of rotavirus

2 live, oral Vaccines !!!!
-Rotarix = given at 2 & 4 months
-RotaTeq = given at 2, 4 and 6 months

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Norovirus diarrheal disease
Caused by
Capsid
Genome
Envelope

Caused by:
-genus = norovirus
-species = Norwalk virus

Icosahedral
(+) ssRNA
Naked

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What virus is globally most important non-bacterial cause of acute gastroenteritis for all ages?

NOROVIRUS

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Norovirus is often associated with outbreaks regarding?

Outbreaks on cruise ships and ingestion of raw or improperly steamed shellfish

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Most common cause of viral GI diarrhea in the US

NOROVIRUS

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Norovirus transmission?
What about re-infections?

fecal-oral (contaminated food or water)
-person-to-person
-contact w/ contaminated fomites (obviiii)

Reinfections are common
-many different strains
-no life long immunity

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Norovirus clinical presentations

-nausea
-acute onset non-bloody diarrhea
-some abdominal cramping
-sore throat
-vomiting = in children
-low fever, chills, muscle aches

-self-limiting (1-2 days)
-viral shedding occurs up to 2-3 weeks after symptom resolution (can be asymptomatic while still shedding)

Norovirus diagnosis

Clincial diagnosis
-detection of viral RNA w/ RT-PCR in food, water, stool samples
-LFA- immunochromatographic = poor sensitivity

Norovirus treatment

Oral rehydration
-patients greatest risk comes from illness-associated dehydration

Hepatitis symptoms

-HYPERBILIRUBINEMIA
causes jaundice of the skin which is especially apparent in the eyes
-fatigue
-anorexia
-nausea
-vomiting
-dark urine
-clay colored stool

-hepatitis trends in the U.S
-most common
-chronic hepatitis
-hepatocellular carcinoma
-rarely lead to liver failure

-HAV, HBV, HCV causes 90% of the acute cases of hepatitis in the U.S.
-HAV is the most common
-chronic hepatitis can be caused by HBV HCV
but HCV most common
-HBV&raquo_space;> HCV both are causally linked to hepatocellular carcinoma
-acute infection with with HAV HBV HCV rarely lead to liver failure

Hepatitis A virus
-from what genus & family
-capsid
-genome
-envelope

-picornavirus, enterovirus 72 (hepatovirus)
-Icosahedral
-(+) ssRNA
-naked

HAV transmission

-fecal-oral route
-person-to-person
-contaminated food or water
-sexual contact

HAV referred to as

Infectious hepatitis

Which hepatitis is not associated with hepatic cancer or liver failure?

HAV

Which hepatitis does not cause chronic infection?

HAV

HAV diagnosis

-ELISA = IgM -RT-PCR

Hepatitis B -capsid -genome and shape -envelope

Capsid: Double shelled Genome: ss/dsDNA, circular Enveloped

HBV transmission

-parental (needle sticks) route -mucosal (sexual) exposure to HBV+ body fluids (saliva, semen, blood)

Which hepatitis is the primary cause of Hepatocellular carcinoma?

HBV

HBV diagnosis

ELISA (for acute and chronic infection) PCR usually not used for initial diagnosis b/c it cannot discriminate b/w acute and chronic infections HBV Genome: ss/ds DNA circular Enveloped

HBV treatment Chronic and acute ? Do they completely cure the infection?

Acute infections: Supportive care only Chronic infections: PEG-IFN-alpha + and NRTI Drugs do not provide a complete cure for HBV Instead Drugs slow down/stop the virus from replication **”Sustained repression”** Significantly decreasing the risk of liver damage Virus titers will rebound if treatment is discontinued.

What do the drugs for chronic Hep B do?

**Drugs do not provide a complete cure for chronic Hepatitis B** drugs slow down/stop the virus from replicating -“Sustained repression” -Significantly decreasing the risk of liver damage -Virus titers will rebound if treatment is discontinued

HBV prevention

vaccines -vaccines can be use for PrEP or PEP -single-antigen recombination vaccines —— RECOMBIVAX HB = available for all ages —— Engerix-B = available for all ages —— HEPLISAV-B

Hepatitis C -capsid -genome -envelope

-Icosahedral -(+) ssRNA, linear -enveloped

Most common chronic blood borne infection in the U.S is what virus?

HCV

Chances of adults developing chronic hepatitis is with which strain?

HCV (50%) HBV (5%)

When do patients of HCV have an increased risk of developing hepatocellular carcinoma

With patients with HCV + cirrhosis

HCV transmission

Occurs via Parenteral or mucosal exposure to blood: -shared needles -infant born to infected mother -100% RE-INFECTION

HCV diagnosis

-ELISA or immunochromatographic LFA: for serology -RT-PCR: To confirm serology

Treatment for HCV

Treatment for HCV is generally a combination of anti-virals NOT VACCINE

Which virus survives freezing and heating to 140 degrees Fahrenheit?

NOROVIRUS

HAV treatment & prevention

-GamaSTAN S/D **Pre-exposure Prophylaxis (PrEP)** **Post-Exposure Prophylaxis (PEP)** -children routinely vaccinated

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Lecture 11: Gastroenteritis & Hepatitis Flashcards

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