Hepatitis E Acquired in San Jose, California?
ABSTRACT & COMMENTARY
Synopsis: A patient with evidence of acute hepatitis E virus infection who had not traveled outside the United States is described.
Source: Kwo PY, et al. Acute hepatitis E by a new isolate acquired in the United States. Mayo Clin Proc 1997;72: 1133-1136.
Kwo and colleagues describe the case of a 62-year-old man with symptoms of acute hepatitis with onset of symptoms two weeks after returning home from a 10-day trip to San Jose, California. He was hospitalized in San Jose three weeks later. AST peaked at almost 3000 U/L, and bilirubin later peaked at approximately 37 mg/dL. Liver biopsy revealed severe acute lobular hepatitis with marked pyknotic and ballooning degeneration of hepatocytes. The patient had complete clinical recovery with normalization of transaminase and bilirubin concentrations.
Antibody tests for hepatitis A, B, and C were negative, and HCV RNA was not detectable in blood. Although IgM antibody to hepatitis E was not detected, IgG anti-HEV was detected by three different methods. HEV RNA, confirmed by sequence analysis, was detected in serum obtained on hospital days 9 and 10 by PCR. There was no evidence of non-viral causes of hepatitis.
The patient had not traveled outside the United States for more than 10 years and had no known potential exposures. He had eaten at a Mexican restaurant and a fast-food chain restaurant prior to becoming ill; none of the food handlers at these restaurants reported foreign travel or symptoms or signs of hepatitis in the three months prior to his visit. No family members had signs or symptoms of hepatitis; six family members residing in California and the patient’s spouse were negative for anti-HEV by EIA.
COMMENT BY STAN DERESINSKI, MD, FACP
Hepatitis E is a non-enveloped RNA virus belonging to the family Calciviridae which, like hepatitis A virus, is transmittedby the fecal-oral route. Its incubation period averages 45 days, with an approximate range of 2-9 weeks. Prior to the description of this case, there had been no evidence of acquisition of hepatitis E virus infection within the United States, although one case previously described had spent just a single day in Rosarito Beach, Mexico, immediately south of the U.S. border (CDC. MMWR Morb Mortal Wkly Rep 1993;42:1-4; Reviewed in Infect Dis Alert 1993;12:86-87).
The virus recovered by Kwo and colleagues has been studied extensively and was found, by sequence analysis of its ORF-1 PCR product, to have 77.4% and 76.1% homology at the nucleotide level to Mexican and Burmese strains, respectively. The homologies of ORF-2 and ORF-3 were similar (Munoz SJ, et al. Hepatology 1992;16:76A), while the deduced amino acid sequence of the ORF-1 product is more than 90% identical to the Burmese and Mexican viral sequences, respectively. The identity predicted for the ORF-3 product is significantly less, raising the possibility that the negative IgM antibody test is the result of alteration in the relevant epitope.
In an accompanying editorial, it is pointed out that there is evidence that this strain of HEV has very high homology at the amino acid level to a strain recovered from American swine, suggesting that, in the United States, HEV infection may be a zoonosis (de Groen PC. May Clin Proc 1997;72:1197-1198).
This is only a single case, but it strongly suggests that infection with hepatitis E virus should be considered as a possible etiology of acute hepatitis in U.S. patients with no evidence of infection due to other hepatitis viruses, even in the absence of travel to known endemic areas.
Which of the following is correct?
a. Hepatitis E virus is a DNA virus.
b. Hepatitis E virus is an enveloped virus.
c. Hepatitis E virus is transmitted by the fecal-oral route.
d. The incubation period of hepatitis E virus averages 6-8 months.
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