Which of the hepatitis viruses has no vaccine available?
Answer: C
The diversity and mutability of hepatitis C have so far defeated vaccine development, so prevention rests on avoiding blood exposure and on treatment. Vaccines exist for A and B, and B vaccination also prevents D, which cannot infect without it.
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Modern treatment of hepatitis C with direct-acting antivirals cures
Answer: D
An oral course of eight to twelve weeks clears the virus in the great majority, transforming a disease once managed with poorly tolerated interferon. Cure is possible because the virus, unlike HIV or hepatitis B, does not persist in a stable integrated or archived form.
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Hepatitis C testing begins with an antibody test and, if reactive, proceeds to
Answer: A
Antibody persists after the virus has been cleared, so a reactive antibody result cannot distinguish current from past infection; detecting viral RNA is what establishes that infection is present. That reflex to nucleic acid testing is now standard.
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Hepatitis D virus is described as defective because it
Answer: B
The delta agent encodes its own antigen and a small circular RNA genome but no envelope protein, so it can only be packaged and transmitted using the surface antigen of hepatitis B. Without that helper it cannot complete a cycle.
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Infection with hepatitis D can occur only in a person who
Answer: C
Because it borrows the hepatitis B surface antigen, the delta agent needs either simultaneous infection with hepatitis B or an existing chronic hepatitis B infection. Someone immune to hepatitis B is therefore also protected against D.
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Simultaneous infection with hepatitis B and hepatitis D is called
Answer: D
Coinfection means both viruses arrive together, usually giving a severe acute illness that nonetheless often resolves. Superinfection is delta arriving in someone already chronically infected with hepatitis B, and it carries a much worse prognosis.
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Hepatitis D superinfection of a chronic hepatitis B carrier typically
Answer: A
Delta added to established hepatitis B produces more severe and more rapidly progressive liver disease than hepatitis B alone. That is why the delta agent is looked for in a carrier whose condition deteriorates unexpectedly.
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Vaccination against hepatitis B also prevents hepatitis D because it
Answer: B
Correct answer: denies the delta agent the helper it needs
The delta agent is defective and cannot make its own envelope, so it borrows the hepatitis B surface antigen and can infect only someone who has hepatitis B. Prevent the B infection and there is nothing for delta to coinfect - so the vaccine protects against a virus it contains no part of.
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Large epidemics of hepatitis E usually follow contamination of
Answer: C
Faecal contamination of a piped or well water supply is the classic setting, and outbreaks in regions with poor sanitation can involve many thousands of people. Undercooked meat from infected animals is an additional route in industrialised countries.
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Hepatitis E is particularly dangerous in
Answer: D
Mortality in pregnancy, especially in the third trimester, is far higher than in the general population, reaching a substantial percentage in some outbreaks. The reason is not fully understood but the association is consistent.
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