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Flashcards in hepatitis virus Deck (81)
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what are the most common hepatitis viruses

- hep b
-hep a
- hep c
- hep d (delta agent)
- hep e


what is the biology of the hep a virus

- spherical non enveloped virus of 27nm
- single stranded RNA genome
- exceptional stability


what is the basic form of a virus

- protein coat with either DNA or RNA
- can only grow in cells, not in an agar plate


what is the transmission and epidemiology of hep A

- mainly transmitted through focal-oral route (can also be blood borne)
- person-person, food borne and water borne
- commonly follows food poisoning from sea food
- in developed countries, 20-50% of adult's have antibody
- in developing countries >90% have antibody


what are the clinical features of hep A

- incubation period is 2-7 weeks
- many subclinical infection s
- illness usually brief and self limiting
- mortality <0.2% = very rarely die from it
- no chronic disease


what is the diagnosis of hep A

- demonstration og HAV antigen in faeces
- serology - detection of IgM and anti-HAV


what is serology

take blood from individual and look for antibodies


what is the immunisation of hep A

- passive or active
- passive = give preformed antibodies (short term)
- active = give antigen and body makes antibodies
- human normal immunoglobulin = short term protection (4 months) - passive
- vaccine = formaldehyde inactivated, prepared from the GBM of HM 175 strain of HAV, single dose will give antibody for a year, then booster does at 6-12 month gives 10 years immunity, active


is hep a preventable

yes - it is an eminently preventable disease


how many people are affected with hep b worldwide

350 million globally


what age is hep b most prominent

70% of new cases are in 15-39 y/o


how much more infectious is hep b than HIV

more than 100x more infectious
- only take a tiny amount go blood from an infected individual to cause you infection


is there a curative treatment

no, but new antivirals suppress the viral load
- been big strides in recent years in suppressing the viral load


what is the viral load

- nor of virus particles in 1 ml of blood
- lower load = better


what genome does hep b have

- DNA virus
- partially double stranded DNA virus


what family of viruses does hep b come from

- hepadnavirus
- family of DNA viruses with a unique life cycle involving an RNA intermediate ad use of a viral polymerase with reverse transcriptase activity
- cause liver damage
- hep B is best known virus from family


what is the intact part of the hep b virus

- dane particle
- viral code and genome in the centre


how many subtypes of hep b exist



what is the structure of hep b

- has hep b surface antigen (HBs Ag)
- has dna polymerase
- has dna in centre
- has hep b core antigen
- has protein kinase


what forms the protein coat of the hep b virus

hep b surface antigen
- forms excessive amounts of this


what is the concept of the vaccine

- produce antibodies against the coating to protect you


where is the highest prevalence of hep b

Africa mainly and Asia
- have >8% people have it here


where has an intermediate prevalence of hep b

russia, india, top of Africa
- 2-7% of population


where has low prevalence of hep b

uk, america, australia, netherlands
- <2% of population


in 2018 what were the lab reports of hep b in England

- 381 acute or probable cases
- incidence = 0.68/100,000
- highest incidence was in London = 64.7%
- many people do not know they have it or that they carry the virus


how is hep b transmitted

- 3 main routes
- blood borne, sexual or perinatal


what are examples of people wit higher risk of hep b

- iv drug users
- sexually active people
- children of immigrants from disease-endemic areas
- infants born to infected mothers (perinatal)
- healthcare workers
- haemo-dialysis patients


what is perinatal spread of hep b

- mother can transmit to infant
- important in pairs of the world where hep b is endemic
- if you are infected as a child you are more likely to be a carrier = have it for many years and will infect others


what is the epidemiology of hep b in non-endemic areas (UK)

- 80% inapparent disease, 20% acute hepatitis
- 95% recovery, 5% chronicity (most are adults)
- can lead to cirrhosis and liver cancer


what is the epidemiology of hep b in endemic areas (Asia)

- mostly inapparent disease
- 5-20% recovers, 80-95% chronicity (most are infants)
- can lead to cirrhosis and liver cancer