Section VII. HEPATITIS NON-A, NON-B
7-28. VIRUS STRUCTURE
The exact structure and classification of the virus attributable for hepatitis non-B (NANB)
is unknown at this time. It is believed there are two or more viruses involved due to
recurrent episodes of hepatitis which have not been related to the other types of
hepatitis (HAV, HBV, or delta). The identification and classification of this infectious
agent is the focus of intense research.
7-29. MODE OF TRANSMISSION
a. Hepatitis non-A, non-B is believed to be capable of both parenteral and
enteric transmission. However, there is strong evidence that the parenteral route is
predominant since hepatitis NANB accounts for 80-90 percent of all post-transfusion hepatitis
cases in the United States (US) and is a major source of hepatitis among dialysis patients.
Proposed nomenclature for blood-borne hepatitis NANB is hepatitis C (HCV).
b. Enteric (epidemic) NANB has been responsible for several large,
well-documented waterborne outbreaks of hepatitis. Most cases have been reported in
developing countries or among travelers who have recently returned from areas in
which the disease is known to be endemic. Proposed nomenclature for enteric hepatitis
NANB is hepatitis E (HEV).
7-30. NON-B IMMUNOLOGICAL ASSAYS
a. No hepatitis non-A, non-B immunological markers have been positively
identified at this time. However, promising research has provided for a possible
immunological assay in the near future.
b. Presently a diagnosis of NANB is made through clinical symptoms, patient
history, elevated liver enzymes, and the exclusion of the other types of hepatitis through