Hepatitis Viruses Flashcards
Which hepatitis types are waterborne?
HAV and HEV are spread via contaminated food and water, oral-faecal transmission
HEV is spread via undercooked animal meats
Which hepatitis types are bloodborne?
HBV, HCV, HDV
How does HAV spread?
Contaminated water, shellfish and seafood
Can survive outside the body for months, boiling or cooking kills the virus but freezing does not, so can spread through raw foods
How do you diagnose HAV infection?
IgM serology test
HAV symptoms?
Tiredness, muscle ache
Nausea, vomiting
Abdominal pain/discomfort, esp right upper abdomen
Loss of appetite
Mild fever
Dark urine
Jaundice (yellowish sclera)
How many serotypes does HAV have?
1, vaccine/infection results in lifelong immunity
Significant exposure to HAV?
Give vaccine within 2 weeks of exposure, consisting of 2 doses 6 months apart
HEV acute vs chronic?
Causes acute hepatitis with high mortality in pregnant women
Can become chronic in immunosuppressed patients
How many genotypes does HEV have?
4 major genotypes
1 and 2 in developing countries with poor sanitation, spreading via oral-faecal transmission or contaminated water supplies, causing frequent sporadic infection
3 and 4 are more in developed countries via zoonotic spread, often in immunosuppressed middle aged and elderly males, often causing chronic infection
What is the difference between genotype and serotype?
Genotype is sequencing of viral genome to find differences in genetic sequences for differentiation between strains
Serotype is what manifests on the surface of the virus, characterized by what antibodies are produced when inoculating animal test subjects
How does HEV spread?
Undercooked meats and shellfish, oral-faecal, contaminated water supplies, zoonotic
Relatively heat resistant and therefore can survive on lightly cooked food
HBV differences from HAV?
Has envelope with HBsAg, therefore more resistant to moderate heating, freezing, low pH and ether
HBV genome consists of partially dsDNA with a reverse transcriptase
Why can HBsAg be found in the blood with active HBV infection?
During replication HBV commonly produces excess antigens, released into the blood circulation in the form of spherical structures without DNA
These antigens can be detected via surface antigen tests to diagnose infection
Pathogenesis of HBV infection
Compared to HAV and HEV, has a long incubation period of 3-6 months. Acute disease is seen in 25% of patients, with infection in childhood more likely to lead to chronic disease
Can either resolve or develop into chronic disease, where inflammation is caused by cell-mediated lysis of the infected cells, resulting in fulminant hepatitis, primary hepatocellular carcinoma and liver cirrhosis
How is HBV spread?
Bodily secretions like blood or genital secretions, sexual, parenteral, perinatal
High risk groups:
Regions of high endemicity
Babies of infected mothers
Injecting drug users
Multiple sex partners
Hemophiliacs
Healthcare personnel performing invasive procedures
Hemodialysis patients
Blood and organ recipients
Symptoms of acute HBV infection
Fever, rash, arthritis, jaundice, dark urine, malaise, anorexia, nausea, right upper quadrant pain, itching
4 stages:
Incubation (3-6 months) –> Preicteric –> Icteric (jaundice stage) –> Convalescent (recovery) period
Serologic markers for HBV infection
HBsAg - acute infection/carrier (for testing and screening)
ALT, AST - acute infection/carrier (for testing)
Anti-HBc IgM - recent acute infection (for testing)
Anti-HBs antibody - immune (for screening)
Anti-HBc total - evidence of past infection (for screening)
HBeAg - higher infectivity
HBV DNA - higher infectivity
How to treat HBV?
Antivirals targeting the polymerase to limit disease progression: adefovir, entecavir, tenofovir
Immunization at birth, healthcare workers
Immunoglobulin prophylaxis for babies born to HBsAg positive mothers or needlestick injuries
What is HDV?
A helper virus, co-infection with HBV, can only replicate in cells also infected by HBV, making hepatitis worse and causing some fulminant hepatitis infections
How is HCV transmitted?
Infected blood, sexual intercourse, esp risk groups like injecting drug users, organ transplant recipients, hemodialysis patients, hemophiliacs
6 genotypes
Pathogenesis of HCV
Incubation period of 2-26 weeks, average of 7 weeks
Mostly asymptomatic, but high rate of progression to chronic liver disease, liver failure and liver cancer
What is HGV?
Found with coinfection with HIV, HBV, HCV, but doesnt cause hepatitis
