Lecture 11: Gastroenteritis & Hepatitis Flashcards
How would you define diarrhea clinically?
-3 off more loose or liquid stools per day
-lasting less than 14 days
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
Rotavirus diarrheal disease
-caused by
-capsid
-genome
-envelope
-caused by Rotavirus A,B,C
-capsid: triple layer Icosahedral
-genome: dsRNA
-naked
Rotavirus characterized in a colorized EM
Show characteristics of “spoked-wheel”- like appearance
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*
What virus is the most common cause of severe diarrhea among unvaccinated children <5yoa?
Rotavirus
=human infantile gastroenteritis
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
Rotavirus clinical presentations
-vomiting and watery diarrhea for 3-8 days
-fever and abdominal pain occur frequently
-dehydration in infants (undernourished)
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
Diagnosing Rotavirus
-direct ELISA by feces or rectal swabs
-latex agglutination test for rotavirus
-LFA: immunochromatographic
-RT-PCR
Genome: dsRNA
Capsid: triple
Naked
Treatment for Rotavirus
No anti-viral
-replace lost fluids and electrolytes
Prevention of rotavirus
2 live, oral Vaccines !!!!
-Rotarix = given at 2 & 4 months
-RotaTeq = given at 2, 4 and 6 months
Norovirus diarrheal disease
Caused by
Capsid
Genome
Envelope
Caused by:
-genus = norovirus
-species = Norwalk virus
Icosahedral
(+) ssRNA
Naked
What virus is globally most important non-bacterial cause of acute gastroenteritis for all ages?
NOROVIRUS
Norovirus is often associated with outbreaks regarding?
Outbreaks on cruise ships and ingestion of raw or improperly steamed shellfish
Most common cause of viral GI diarrhea in the US
NOROVIRUS
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
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»_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
