Hepatitis Viruses Flashcards
What is hepatitis
Inflammation of the liver without pinpointing a specific cause
What disorders may a patient present with when they have hepatitis
- Have a liver injury caused by a toxin
- Have liver damage caused by interruption of the organ’s normal blood supply
- Be experiencing an attack by his or her own immune system through an autoimmune disorder
- Have experienced trauma to the abdomen in the area of the liver
- Viral or bacterial infection of the liver
What do the hepatitis viruses do in acute infectious fevers
They infect the Kuppfer cells of the reticuloendothelial system, so avoiding liver damage
What are the characteristics of hepatitis carriers
- Evolve from acute infections that are mild and anicteric
- May be asymptomatic but detectable by blood testing
- Are frequently the source of infection for others
- Suffer long term sequelae of persistent infection
What types of hepatitis are common to form hepatitis carriers
Hepatitis C and B
What kind of virus is hepatitis A and how is it spread most frequently
- Enterovirus
- Fecal oral contamination - shellfish, children, group homes, water food
- Oral anal sexual activity contamination
What are the clinical features of Hepatitis A
Jaundice - chances increase as you get older
What complications are associated with hepatitis A
Fulminant hepatitis
Cholestatic hepatitis
Relapsing hepatitis
How serious is hepatitis A
Tests show 40% of urban americans have had Hep A but only 5% recall being sick
Hep A can cause prolonged illness but usually only short term and doesn’t cause chronic liver disease
Describe the pathogenesis of hepatitis A
- Virus replicates primarily in the hepatocytes
- Passes through the bile duct into the intestine where it is shed in large quantities
- Damage to liver function results in raised liver enzymes
- Jaundice lasts ~ 1 month, no carrier state, no tendency to chronicity or malignancy
What passive protection methods for Hep A are there
Human normal immunoglobulin - 3-6 months coverage, post exposure prophylaxis for health care workers
How is Hep A managed
- Vaccine - formalin inactivated vaccine prepared from HAV grown in human diploid cells
- Very high hygiene standards required
What is the incubation period for Hepatitis A
15-50 days
How does Hep B contamination occur
Skin/mucus membrane contamination with blood or serous fluid, most likely transmission is through blood - low concs of virus in saliva, semen and vaginal fluid
What is the incubation period for Hepatitis B
48-180 days
What are the complications hepatitis B
Chronic hepatitis
Cirrhosis
Liver cancer
How does replication occur for hepatitis B
- RNA intermediate and use of reverse transcriptase
- High mutation rates, however small genome prevents a large degree of genetic variability
What are the clinical features of hepatitis
Jaundice
Acute case-fatality rate - 0.5-1%
Chronic Infection
Premature mortality from chronic liver disease - 15-25%
What are the modes of transmission of Hep B
- Parenteral - transfer in blood
- Sexual - via genital fluids, sex workers and homosexuals
- Perinatal - at/during birth
What chronic hep B diseases are there from bad to the worst
- chronic persistent hepatitis asymptomatic
- chronic active hepatitis - symptomatic exacerbations of hepatitis
- Cirrhosis of Liver
- Hepatocellular carcinoma
What in the blood indicates the patient’s blood is infective for others
Presence of HBeAg and Dane Particles
NB the core antigen is not detectable
What antigens are serological markers of Hepatitis B
HBsAg: present in acute and chronic infections
HBeAg: present in acute and chronic infections (indicates infectivity when present)
What enzyme is present in acute and chronic Hep B infections
Viral DNA polymerase
What antibodies are serological markers for Hepatitis B
- Anti-HBs indicate recovery, present in convalescence
- Anti-HBe indicates little or no infectivity
- Anti-HBc indicates recent infection if present in IgM form
AY BAWS CAN I HABE DE NOTE PLZ
Only after a few years of life can symptomatic infection of Hep B occur but chronic infection is less and less likely with age
What methods of control are there for Hep B
- Block person to person transmission - safer sex
- Large scale immunisation
What ways can Hep B transmit in the clinical setting
Due to:
- Breakdown in sterilisation
- Breakdown in infection control
- Care with bodily fluids and PPE
What emergency treatment is there for Hep B viruses
- With potential exposure seeing GP asap
- Dose of Hep B vaccine + 2 boosters
- Hep B immunoglobulin - antibodies that can offer immediate but short term protection while the vaccine takes effect
What treatment is there for short term (acute) Hep B
- Doesn’t usually need specific treatment, except sometimes to relieve symptoms
What treatment is there for long term (chronic) Hep B
Focused on keeping the virus under control:
- Peginterferon - if liver is working well 1st treatment option
- Antiviral medicines e.g. Entecavir, tenofovir
Describe the successful response to treatment using entecavir
Results in disappearance of HBsAg, HBV-DNA and seroconversion to HBeAg
What is cool about entecavir
Most powerful antiviral known, similar to adefovir
What kind of drug is tenofovir
- NRTI - nucleoside reverse transcriptase inhibitor antiretroviral medicine
- Treatment usually for several years
What is the contamination route of Hep D
Skin/mucus membrane contamination with blood or serous fluid, most likely transmission is through blood - low concs of virus in saliva, semen and vaginal fluid
Whats unique about Hep D
Infection is seen with Hepatitis B
What is the incubation period of hepatitis D
14-56 days
What are the symptoms of Hepatitis D
Usually asymptomatic
What antigen is found on the surface of Hepatitis D
HBsAg
What are the clinical features of confection with Hepatitis D
- Severe acute disease
- Low risk of chronic infection
What are the clinical features of superinfection with Hep D
- Usually develop chronic HDV infection
- High risk of severe chronic liver disease
- May present as an acute hepatitis
What is the difference between coinfection and superinfection with HBV and HDV
Coinfection - When a person becomes infected with both HBV and HDV simultaneously
Superinfection - when a person who is already chronically infected with HBV acquires HDV
What prevention methods are there to avoid HBV/HDV coinfection
Pre or postexposure prophylaxis to prevent HBV infection
What prevention methods are there to avoid HBV/HDV superinfection
education to reduce risk behaviours among persons with chronic HBV infection
How does Hep C contamination occur
Skin/mucus membrane exposure with blood or serum
What is the incubation period for Hep C
21-140 dats
How common is chronic hepatitis in people who get Hep C
70-90%
What are some complications of Hep C
Number 1 cause of cirrhosis and liver cancer
AY BAWS CAN I HABE DE NOTE PLZ
usually severe signs and symptoms of hep C
What risk factors are associated with Hep C transmission
- Transfusion or transplant from infected donor
- Injecting drug use
- Haemodialysis
- Accidental injuries with needles/sharps
- getting a tattoo or body piercing with unsterilised tools
- Sexual/household exposure to anti-HCV positive contact
- Multiple sex partners
- Birth to HCV-infected mother
What immunity does the body develop for Hep C
none
What clinical features are there in Hep C patients
- Clinical illness (jaundice)
- Chronic hepatitis
- Persistent infection (85-100%)
What control methods are there for Hep C
Vaccine - under development but difficult due to multiple serotypes
General measures - screening of blood donors and blood products, needle exchange schemes
What drugs and combinations are used to treat Hep C
- Simeprevir - protease inhibitor
- Sofosbuvir - polymerase inhibitor
- Daclatasvir
- Combo of ledipasvir and sofosbuvir
- Combo of sofosbuvir and velpatasvir
How is hepatitis E transmitted
Contaminated water = fecal oral route
What is the incubation period for Hep E
15-64 days
What is the clinical features of HEV
Similar to HAV but:
- Longer incubation time
- Infection is generally acquired in adolescence or adult hood rather than infancy
- In women infected in the late stages of pregnancy the mortality rate is about 20%
What prevention and control methods are there for travellers to HEV-endemic regions
- Avoid drinking water of unknown purity, uncooked shellfish and uncooked fruit/veg not peeled or prepared by traveller
- IG prepared from donors in west and endemic regions aren’t so effective
