Serological and molecular studies on subclinical hepatitis E virus infection using periodic serum samples obtained from healthy individuals

Abstract

Subclinical hepatitis E virus (HEV) infection among healthy individuals was studied serologically and molecularly. Serum samples collected at screening between March and April 2004 (or just before retirement) from 266 medical staff members (35 males, 231 females) who had been working for 8.8 +/- 8.5 (mean +/- standard deviation, range, 0.3-35.1) years in a city hospital in Japan and serum samples that had been collected from these staff members at the start of employment were tested for IgA, IgM, and IgG antibodies to HEV (anti-HEV) by in-house enzyme-linked immunosorbent assays. Overall, six subjects (2.3%) tested positive for anti-HEV IgG at the screening; among them, four subjects (1.5%) had already been positive for anti-HEV IgG at the start of employment and two subjects (0.8%) seroconverted after initiation of employment. Periodic serum samples that had been collected from the two seroconverted subjects were tested for HEV antibodies and HEV RNA. The two subjects became positive for anti-HEV IgG in 1978 or 2003, respectively, with no discernible elevation in alanine aminotransferase (ALT) level, and continued to be seropositive up through the screening date. Although anti-HEV IgM was not detectable in the two subjects, one was infected transiently with Japan-indigenous HEV strain of genotype 3 and the other was positive transiently for anti-HEV IgA. The present study indicates that even an individual with subclinical HEV infection had evidence of transient viremia in the absence of ALT elevation and that anti-HEV IgA detection may be useful for serological diagnosis of recent subclinical HEV infection.

High Hepatitis E Virus Seroprevalence in Forestry Workers and in Wild Boars in France

“…Recent reports that indicate that the virus is detected in 4 to 6% of pig livers in the Netherlands, France, and Germany (1, 37, 48) support the role of undercooked pig products as a source of zoonotic HEV infection in humans. In addition, the higher frequency of detection of anti-HEV antibodies in swine veterinarians and pig farm workers (4,10,18,26) supports the existence of zoonotic infection from domestic swine and is in agreement with the existence of asymptomatic and subclinical hepatitis E in industrial countries (30,32,47) in proportions higher than those observed in areas where HEV is endemic (2).The aims of the study reported here were to evaluate different anti-HEV tests for their ability to detect HEV antibodies in order to establish the prevalence of anti-HEV in wild boar in France and determine whether forestry workers are at a higher risk of HEV infection. …”

“…Four major HEV genotypes belonging to a single serotype have been identified (11). Genotype 1 is detected in most cases of human HEV disease (waterborne epidemics and sporadic cases), genotype 2 is rare and has been found in several epidemics in Mexico and central Africa, and genotypes 3 and 4 are detected in swine and in autochthonous HEV infections in industrial countries (5,19,20,30,34,39,45,49).HEV is a significant fecally and orally transmitted human pathogen of worldwide distribution, causing self-limited disease with mortality rates of 1 to 3% in the general population and up to 20 to 25% in pregnant women. In developing countries, HEV outbreaks have been attributed to feces-contaminated water supplies.…”

Hepatitis E Virus

“…In recent years, increasing numbers of HEV infections with a subclinical course have been reported, in particular in blood donors [50,51]. As markers of infection, elevated transaminase levels may occur.…”

“…About 10 years ago, Japan reported HEV RNA-positive blood donations from healthy donors for the first time [50]. Retrospective studies of donations with elevated transaminases (study period 1991-2006) revealed an invariant incidence of HEV infection in Japanese blood donors [175].…”

Hepatitis E Virus

“…In addition to the serious liver failure which is observed in particular in pregnant women in their third trimester, encephalopathies and disseminated intravascular consumptive coagulation disorders can occur. In the past few years, there have been an increasing number of reports about HEV infections with sub-clinical course [15,16]. Increased levels of transaminases may act as infection markers.…”