Which of these hepatitis viruses can be prevented by vaccination?
Answer: C
Correct answer: Hepatitis A and B
Effective vaccines exist for both, and a combined preparation is available. Vaccinating against B also protects against D. There is no vaccine for hepatitis C, whose variability has defeated the attempt so far, and the hepatitis E vaccine is licensed only in a few countries.
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Dark urine and pale stools in hepatitis reflect
Answer: D
Conjugated bilirubin that cannot reach the gut spills into the urine and darkens it, while its absence from the stool removes the normal colour. The pair of signs points to the liver rather than to the kidney or the gut.
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Hepatitis B is an occupational risk for health care workers chiefly through
Answer: A
Correct answer: needlestick injury
Hepatitis B is transmitted by percutaneous exposure to blood, and a needlestick from an infected patient carries a substantial risk - historically as high as 30 per cent from an e-antigen-positive source, which is far greater than for hepatitis C or HIV. Vaccination of health care workers is the reason the occupational risk is now small.
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Instruments contaminated with blood must be
Answer: B
Hepatitis B survives on surfaces for at least a week and is transmitted very efficiently by inoculation, so nothing short of sterilization is adequate for an instrument that will penetrate tissue. Cleaning alone leaves infectious virus behind.
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A blood donor found to carry hepatitis B surface antigen is
Answer: C
Correct answer: permanently deferred from donating
Surface antigen indicates active infection, so the blood is infectious and the donor is deferred permanently. The finding is also a clinical result: the donor is informed, investigated and referred for assessment, since many are unaware they are infected.
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The letters A to E in the hepatitis viruses denote
Answer: D
Each letter marks a separate, unrelated virus identified as the causes of hepatitis were teased apart. They differ in family, genome, transmission and outcome, so the alphabet records history rather than any biological ordering.
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Which hepatitis virus has the longest average incubation period?
Answer: A
Correct answer: Hepatitis B
Hepatitis B incubates for 60 to 90 days on average and may take up to six months, against about a month for A and E. The long interval means the source of an infection is often impossible to trace, and it is why exposure and illness may seem unconnected.
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Chronic infection is a feature of
Answer: B
Correct answer: hepatitis B, C and D
The blood-borne viruses can persist; the enterically transmitted ones cannot, except in the immunosuppressed, where chronic hepatitis E has been described. The division is the same one that separates their routes of transmission, and it is why A and E cause outbreaks while B, C and D cause chronic disease.
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Handwashing after using the toilet is most relevant to preventing
Answer: C
Correct answer: hepatitis A
Hepatitis A is shed in the faeces and transmitted by the faecal-oral route, so handwashing after using the toilet and before handling food interrupts it directly. The blood-borne viruses are unaffected, and hepatitis E is the other virus for which the measure applies.
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The hepatitis B vaccine cannot cause infection because it contains
Answer: D
A single recombinant protein has no genome, so there is nothing to replicate and no possibility of infection even in an immunocompromised recipient. That is a further advantage over inactivated whole virus preparations.
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