viral infections I Flashcards
what is hepatitis and what are the three main clinical presentations?
Inflammation of the liver
- acute
- chronic
- fulminant
what are some lab tests that are elevated with hepatitis
bilirubin, AST (aspartate aminotransferase), ALT (alanine amino transferase)
symptoms of acute viral hepatitis
- jaundice- skin and eyes (b/c increased bilirubin)
- dark urine
- acholic stool- grey or white stool due to reduction of bile secretion
- prodrome- 1-2 wks before jaundice-vomiting, headache. myalgia, fatigue, pharyngitis and mild fever
why do we get elevated levels of bilirubin in the blood when there is hepatitis
rbc’s heme break down to bilirubin and liver makes bilirubin more water soluble to be excreted in the urine but if the liver is not working, there is no place for the bilirubin to go
acute viral hepatitis biochemistry
> 3 mg/dL bilirubin, commonly 5-20
bilirubin in urine
enzymes hi- ALT, AST =USUALLY HIGHER THAN THAT OF OTHER HEPATITIS CAUSES (MAYBE UP TO 1000)
chronic viral hepatitis
- hepatitis what does not resolve in 6 mo.
- predispose to hepatocellular carcinoma and cirrhosis- immune system recognize antigen in liver and kill it leading to damage and then liver regenerates over and over to cause cirrhosis- the over-generation of the cells can lead to hepatocellular carcinoma (3-5%)
- can take up to 15-40 yrs -often asymptomatic
fulminant viral hepatitis
- rapid, sever, hep
- massive hepatic necrosis and ENCEPHALOPATHY that leads to confusion, disorientation and coma
- edema- cerebral, brainstem compression, GI bleeds, sepsis and organ failure
what are the 5 types of hepatitis and how are they transmitted? are they results of chronic infection
A, E = fecal/oral- no chronic infection
B, C, D = body fluids- yes chronic infection
hepatitis A symptoms
-jaundice, diarrhea, vomiting, liver inflammation that usually resolves in 2 months
what virus causes hep A
incubation
-picornavirus (ssRNA) via oral/fecal
incubation time- 28 days
DOES NOT CAUSE CHRONIC HEP AND VERY RARELY CAUSES FULMINANT HEP
diagnosis and prevention of Hep a
- diagnosis -acute infection- Igm antibodies against HAV (hep a virus)
- anti- HAV IgG for past infection
- prevention
- vaccines since 1995- 2 dose schedule
- vaccine is also used as post-exposure prophylaxis
hepatitis B virus- what does it look like under the microscope
- has tubes and spheres that are incomplete and non-infectious particles but show that there is an active infection
- dane particles that are complete virons- infectious
what is hep B virus caused by? what are some characteristics and parts of the virus?
-hepatDNAvirus
-has partially dsDNA genome
-has reverse transcription in a part of the life cycle
-parts: HBsAG (hep B surface antigens) = surface antigen of dane particles and tubes and spheres
HBcAG (core)-not soluble but we are able to test for antibodies to it
HBe Ag- DNA that is water soluble so can find and test in blood
how do you diagnose Hep B
- look at viral antigens and HBV antibodies
- HBsAg- is a sign of ACTIVE INFECTION- both chronic and acute
what does the serology look like in an ACUTE Hep B viral infection
- Igm antiHBc up at first and then tapers as IgG anti-HBc increases
- HBs Ag is obviously high at first and then as the virus clears AntiHBs rises
- HBeAg rises at start of infection and then anti-Hbe come in and replaces it
what does the serology look like in an CHRONIC Hep B viral infection
- as pt is infected the HBsAg rises and stays up to a plateau
- AntiHBc rises and also stays up to a plateau
- IgM anti HBc increases and then plummets because not clearing the virus
- anti HBs antibody not made
- HBeAg also stays up for chronic and replicating infections and we see antiHbe antibodies when HBe is present but not replicating***
if someone is vaccinated against Hep B virus , what would you expect to see? where do you also have this finding?
- positive HBs antibody
- also see positive HBs antibody with someone previously infected
how do you distinguish between a patient who is acutely infected with Hep B virus and one that has a chronic infection
-acute has presence of IgM
how is hep B virus transmitted? what’s important to note about age of infection and risk of chronic infection?
- bodily fluids-sexual, needle stick, at birth
- half of adults are asymptomatic- acute hep B often milder than acute hep A
- the older you are, the less likely you are to develop a chronic infection
treatment for Hep B virus?
- none for acute infections
- chronic- lamivudine- reverse transcriptase inhibitor, famcylovir/adefovir dipivoxil- nucleoside inhibitor, interferon- alpha
prevention of Hep B virus?
- vaccine made up of purified HbsAg protein and give IM at 3 doses
- children born from moms that have unknown or known HBV infection are given HBsAG vaccine and HBIG 12 hrs post birth
Hepatitis C virus
what family?
kind of virus?
transmission?
- flavivirus family
- enveloped
- ssRNA
- blood borne and bodily fluids (IV drug users!!! -45% of IV drug users between ages of 18 and 45 infected)- sexual is rare
diagnosis of Hep C virus
- expected chronic infection
- screening test- antibody-based test for anti-HCV antibodies
- confirm via nucleic acid test for viral genome
disease outcomes for HAV or HBV
- chronic infection- 70%
- acute only- 15%
- rapid progression to cirrhosis- 15%
