Which of the following statements regarding human viral hepatitis are correct?
a. The primary mode of transmission of types A and E is fecal-oral.b. Infections with type D can occur without type B coinfection.c. Type E hepatitis is often a zoonosis.d. Vaccines are currently available in the US for only types A, B, and C.e. Chronic types B and C infection may result in cirrhosis and hepatocellular carcinoma.
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Answers: A, C, and E
a. The primary mode of transmission of types A and E is fecal-oral.
c. Type E hepatitis is often a zoonosis.
e. Chronic types B and C infection may result in cirrhosis and hepatocellular carcinoma.
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Until the 1970s, it was recognized that there were 2 types of human hepatitis:
One type had roughly a 4-week incubation period; it could be transmitted by contaminated water and by person-to-person within a household. It was referred to as infectious hepatitis and became known as hepatitis A, for which a vaccine is available. We now know that hepatitis E is transmitted in a similar way.1 In general, neither hepatitis A nor hepatitis E causes chronic hepatitis, but either may cause fulminant viral hepatitis-especially type E in pregnant women.2
A second type had about a 100-day incubation period; it was transmitted by blood and blood products. The original disease was called serum hepatitis; later, it was referred to as type B and non-A, non-B hepatitis. The term “serum hepatitis” was derived from the recognized association with human immune serum, which was used as a preventative or therapeutic agent beginning in the 1930s.3 Eventually, non-A, non-B blood-associated hepatitis was linked to the hepatitis C virus-a flavivirus related to yellow fever, which can also cause hepatitis in man.
Types B and C can cause chronic infection, which can lead to cirrhosis and liver cancer. A vaccine to protect against type B has been available in the US since 1982 and was the first “cancer vaccine.” No vaccine is currently available for type C, although treatment options are increasing and vaccine research continues.4,5The hepatitis D, or delta hepatitis, virus is a very small, defective virus that requires hepatitis B infection either previously present or coinfective to replicate.6 It uses the hepatitis B surface antigen (HBsAg) as its coat. Essentially, it cannot replicate without type B virus in humans.Although types B and D can infect certain primates, most of these viruses have essentially only human reservoirs-except for type E. It is now clear that certain genotypes of hepatitis E are zoonotic infections. In the western world, most human cases of type E are related to pigs.7References1. Naik SR, Aggarwal R, Salunke PN, Mehrotra NN. A large waterborne viral hepatitis E epidemic in Kanpur, India. Bull World Health Organ. 1992;70:597-604.2. Borkakoti J, Hazam RK, Mohammad A, et al. Does high viral load of hepatitis E virus influence the severity and prognosis of acute liver failure during pregnancy? J Med Virol. 2013;85:620-626.3. Propert SA. Hepatitis after prophylactic serum. Br Med J. 1938;2:677-678.4. Liang TJ, Ghany MG. Current and future therapies for hepatitis C virus infection. N Engl J Med. 2013;368:1907-1917.5. Liang TJ. Current progress in development of hepatitis C virus vaccines. Nat Med. 2013;19:869-878.6. Farci P, Niro GA. Clinical features of hepatitis D. Semin Liver Dis. 2012;32:228-236.7. Christou L, Kosmidou M. Hepatitis E virus in the Western world-a pork-related zoonosis. Clin Microbiol Infect. 2013;19:600-604.
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