viral hepatitis Flashcards
how do viruses enter the liver to cause hepatitis (3)
- hepatitis viruses enter the bloodstream through the hepatic artery or portal vein
- hepatitis viruses infect the hepatocytes
- as the hepatitis viruses spread, the viral infection/immune response may cause damage to the liver such as scarring (cirrhosis) -> raise in ALT
what is the blood supply to the liver
75% hepatic portal vein, 25% hepatic arteries
Which pathogen is the main cause of viral hepatitis in the UK? (3)
- EBV - in the young
- Adenovirus - in immunosuppressed
- Hepatitis E (HEV) - can get from pigs
what is hepatitis
Acute or chronic parenchymal liver damage
what is the main symptom of hepatitis
jaundice [usually detectable when bilirubin >50];
Can be asymptomatic or Can develop symptoms later on in course of dx, e.g., Hep C infection
what blood abnormalitiy is associated w viral hepatitis
raised ALT
Histological features of parenchymal damage of hepatitis (3)
- Hepatocytes show degenerative changes (swelling, cytoplasmic granualtion,
vacuolation) - Hepatocytes undergo necrosis (become shrunken, eosinophilic councilman bodies)
- Necrosis maximal in zone 3 (adjacent to central vein).
causes of hepatitis
- viral infections
- Bacterial infections
- Drugs
- Alcohol
- Poisons
- Other (pregnancy, Wilson’s dx, circulatory insufficiency).
exmples of viral infections that can cause hepatitis
- EBV
- CMV
- HSV - usually immunocompromised
- VZV
- Yellow fever
- Viral haemorrhagic fevers
- Rubella
- Mumps
- Coxsackie B
- Adenovirus
- HIV
examples of bacterial infections that can cause viral hepatitis (4)
- Leprospira
- Coxiella
- Brucella
- Borrelia
what is the duration of disease of hep C
symptomless for decades but all the while slowly destroying the liver
what percentage of all acute hepatitis cases does HCV acount for
20%
what is the most common blood borne infection in the uk
HCV
what is the main presenting symptoms of HCV (if symptomatic)
jaundice
how to the majority of HCV pts present
with liver disease of liver cancer which develops many years later
what type of hepatitis increases the risk of liver cancer
Hep C
what are the risk factors for Hep C infection
- Transfusion abroad
- IV drug use
- Needle-stick injury if donor infected
- Including tattoos
- Haemodialysis (rare)
- Sexual / household exposure
- Multiple sexual partners
- Birth to HCV-infected mother
investigations for hep C (4)
- HCV antibody (anti-HCV) ->Takes 12 weeks after infection for antibody to appear so useful in chronic disease
- HCV RNA-> Used in acute infection and monitoring response to antiviral therapy
- HCV-antigen -> Also used in acute infection - less sensitive but easier to carry out
- ALT -> rises acutely
what are some chronic hep C manifestations (hepatic -3, extra hepatic -3)
Hepatic manifestations include:
1. Chronic persistent hepatitis
2. Cirrhosis
3. Hepatocellular carcinoma
Extrahepatic manifestations include:
2. Mixed essential cryoglobulinaemia
3. Glomerulonephritis
4. Sporadic porphyria cutanea tarda
how to prevent Hep C infections (5)
- Screening blood and its products and organs
- Infection control practices
- Occupational exposure - prevention and management of infected healthcare worker
- checking of sexual partners
- Mother-to-baby transmission
what are the 7 major genotypes distributed across the world of hep C
G1 + G2 - worldwide (G1 commonest in UK).
G3 - Southeast Asia.
G4 - Egypt, Africa, Middle East.
G5 - South Africa.
G6 + 7 - Far East.
hep C mgx (3)
- Protease inhibitors
- NS5A inhibitors
- NS5B inhibitors
what does the HDV virus require to be present in the body in order to complete its life cycle within human hepatocytes
HBV
routes of transfer for HBV and HDV (3)
- percutaneously through contact with infectious blood
- sexually through contact with infectious blood
- vertically
what is HDV a coinfection with
HBV
HDV coinfection vs superinfection
coinfection:
1. infection with both HBV and HDV in HBV-susceptible individuals
2. presentation resembles classic acute hepatitis B
3. usually self-limiting
superinfetion:
1. infection w HDV of a pt w chronic HBV infection
2. presents as severe acute hepatitis or exacerbation of chronic hep B
3. majority progress to chornic disease w severre morbidity and complications such as cirrhosis, clinical decompensation and HCC
why can HDV only be found as a co-infection with HBV
HDV uses HVsAg as an envelope in replication
what is the most severe form of viral hepatitis in human
HDV
what is the incubation period for HDV
2wks - 6 months
2 complications of HDV
cirrhosis; hepatocellular carcinoma
investigations for HDV
- anti-HDV IgG (in all HBsAg +ve pts)
- anti-HDV IgM (shows disease activity)
- HDV RNA quantitative
- HDV genotypes
- HBsAg quantification
- liver biopsy (staging of liver disease)
HDV mgx
- PegIFN
- nucleoside/nucleotide analogues (NAs) therapy e.g. entecavir
- experimental treatments
what organisms do the 5 genotypes of HEV affect
1 + 2 - humans
3 + 4 - humans and swine
5 - avian
how is HEV transmitted
blood in faeces
hep E presentation (6)
- Mild fever
- Jaundice
- Reduced appetite
- N&V
- Abdo pain
- Hepatomegaly
investigations for HEV
- anti-HEV IgM - acute phase
- anti-HEV IgG
- PCR virus load
how long after infection do symptoms tend to present
6 weeks
prevention measures for HEV (3)
- Avoid drinking water (and drinks with ice) of unknown purity
- Avoid uncooked shellfish and uncooked fruit / vegetables not peeled or prepared by
traveller - In UK - avoid eating inaequately cooked pork meat
apart from tobacco what is the most important carcinogen
HBV
HBV transmission (4)
- Sexual: Sex worker and men who have sex with men
- Parenteral: PWID, health workers are at increased risk
- Perinatal: Antenatal women chronically infected with HBV
- Transfusion: Screening and viral inactivation have eliminated this in Europe
HBV presentation
Many asymptomatic.
Can be jaundiced, tired, abdo pain, N&V.
If severe, can lead to liver failure → death.
acute hep B mgx
usually self limiting
what are the 5 major phases of chronic Hep B
- HBeAg +ve chronic HBV infection
- HBeAg +ve chronic hepatitis B
- HBeAg -ve chronic HBV infection
- HBeAg -ve chronic hepatitis B
- HBeAg -ve phase
serological tests for HBV (7)
- HBsAg - general marker of infection
- anti-Hbs - used to document recovery and/or immunity
- anti-HBc IgM - acute infection marker
- anti-HBc - current or past infection
- HBeAg - active replication of virus and marks high infectivity
- Anti-HBe - coincides with significant reduction in replication
- HBV-DNA
Hep B prophylaxis (2)
- pre exposure - vaccine
- post exposure - accelerated active immunisation, together with HBIg (for some)
when should HBV pts be treated
when they enter the immune elimination phase and develop active hepatitis (ALT elevation, biopsy evidence of chronic hepatitis and fibrosis)
hep B mgx (3)
- immunomodulators - IF alfa-2b, pegylated IF alfa-2a;
- nucleoside analogues - lamivudine, telbivudine etc.
- nucleotide analogue - adefovir, tenofovir
what is the mgx for contacts of acute HPV infection
Test contact for surface antigen.
If not detected, give vaccine and immunoglobulin
mgx for babies with mothers of acute HBV
Baby will get vaccine and immunoglobulin immediately in different arms, Then at 1 year, another jab
Then normal immunisation programme.
what does hep A NEVER result in
chronic liver disease
what is hep A
an acute, self-limiting infection of the liver
what is a complication of hep A
fulminant hepatitis - severe liver function impairment, which causes hepatic coma and the decrease in synthesizing capacity of liver
HAV trasmission routes (5)
- close personal contact (househols, sexual, child day care)
- poor hygeine (e.g. in homeless)
- drug use (poor hygiene)
- contaminated food/water
- blood exposure (rare)
hep A presentation (6)
- Jaundice
- N&V
- Dark urine
- Abdo pain
- Fever
- Loss of appetite
HAV incubation period
2-4 wks
HAV detection (3)
- Acute infx → diagnosed by detection of IgM anti-HAV by Elisa
- Genome or antigen detection in stool may be used
- To detect immunity to HAV (i.e. prior infection) → +ve total anti-HAV in serum
hep A prevention measures (4)
- good hygiene
- pre exposure active immunisation vaccine (travellers, staff and residents of homes, lab staff, pts who exhibit risky behaviours)
- post exposure - vaccine and immunoglobulin HNIG (withing 14 days of onset)
- contact tracing - testing, vaccination and immunoglobulin (just Igs if young no vaccine)
which hepatitis strands result in chronic liver disease
HCV; HBV
