Received: 1 January 2018
Accepted: 18 January 2018
LETTER TO THE EDITOR
HEV seroprevalence can significantly change after
We read with interest the paper recently published in the Journal
of Medical Virology by Baptista-González et al
prevalence of anti-HEV IgG antibodies in persons living in Mexico
City including women with a high-risk pregnancy and healthy blood
donors (BDs). The Authors reported very low overall HEV seropreva-
lence (2.34%, 10/428). They found no seropositive blood donor (out of
110 tested) and only one pregnant women with reactivity to HEV out
of 127 tested.
Data on the seroprevalence of HEV infection among pregnant
women in non-classic endemic countries (ie, areas other than Asia or
Africa) are scarce.
Therefore, every new report discussing this issue is
However, we think that the level of exposure to HEV found by
Baptista-González et al can be significantly underestimated.
A few HEV seroprevalence studies used the Euroimmun assay.
In a preliminary assessment of HEV IgG seroprevalence in Greater
Poland region (central Europe, west-central Poland) we found anti-
HEV antibodies in 2.4% (5/210) of age- and sex-matched BDs and HIV
patients with the use of the same version of the Euroimmun assay as
Baptista-González et al.
Finally, we tested 306 individuals (153 healthy BDs and 153
HIV-infected patients) aged 18-55 for the presence of anti-HEV
IgG antibodies. Two assays were used, that is, the Euroimmun
assay (Euroimmun Medizinische Labordiagnostika AG, Lübeck,
Germany) in all BDs and in 104 patients and the Wantai assay
(Wantai Biological Pharmacy Enterprise, Beijing, China) in all
study participants. All tests were performed and interpreted
according to the recommendations of both manufacturers
(borderline results were considered negative). Additionally, for
the Euroimmun assay, apart from using the original cut-off value
(OCO; results were considered positive when the quantitative
analysis found anti-HEV IgG antibodies to be ≥2.2 IU/mL) a
lowered cut-off (LCO) value (ie, 0.8 IU/mL) was also applied, as
suggested by Norder et al.
Of note, this suggestion was partially
adopted by the manufacturer for the most current quantitative
version of this assay (presently, Euroimmun recommends
interpreting results as follows: <0.8 IU/mL − negative;
0.8 IU/mL to <1.1 IU/mL − borderline; ≥1.1 IU/mL − positive).
The analyzed groups were compared with the test for proportions.
All tests were considered significant at P < 0.05. The analysis was
carried out using statistical package Statistica PL12 (StatSoft, Inc).
All BDs and patients gave their written informed consent. The
study was approved by the local Bioethics Committee. Anti-HEV kits
were funded by Poznan University of Medical Sciences (number of
funds: 502-01-02205314-04519) and Regional Blood Center in
The results of anti-HEV IgG prevalence assessment are shown in
First, these results clearly shows that HEV seroprevalence
can significantly change after re-assessment with a validated
assay (or an updated version of thesameassay).Itisawell-known
However, Baptista-González et al did not mention this
issue as a potential limitation of their study. Low sensitivity of the
older version of the Euroimmun assay in comparison to assays of
other manufacturers was also reported by Norder et al
Avellon et al.
Moreover, in previous studies from Mexico, the
presence of anti-HEV IgG antibodies was found in 0.4-40.7% of
the tested persons.
HEV seroprevalence varied depending on
age, region of Mexico, a studied population and, of course, an
assay used. It should be stressed that our knowledge on human
HEV seroprevalence in Mexico is based on studies using assays of
unknown performance (no comparative studies, no validation in
HEV RNA-positive patients).
However, a recent paper has shown that the exposure of
Mexican domestic pigs to the hepevirus in question (tested with the
Wantai assay) is very common.
Due to zoonotic spread of HEV it
supports the hypothesis that HEV infection can be significantly more
common in inhabitants of Mexico City than found by Baptista-
González et al.
Second, after matching this study participants for age and sex the
use of more sensitive assays revealed a trend toward higher HEV
seroprevalence in BDs versus HIV patients. It can be result of a weaker
humoral response in the latter group.
Third, these results suggest that exposure to HEV in west-central
Poland is unusually high. It can be due to the fact that Poland is among
10 top producers of pork in the world (www.fao.org/faostat/) and that
its consumption in this country is significant. Moreover, environmental
contamination with porcine excreta could influence the level of
exposure to HEV in the region.
It should also be mentioned that the
Wantai assay is a highly sensitive diagnostic tool. Although some false-
positive results of anti-HEV IgG testing are possible there is much
evidence that its specificity is acceptably good.
Last, it can also
be hypothesized that an undefined but locally prevalent HEV-like
J Med Virol. 2018;90:783–785. wileyonlinelibrary.com/journal/jmv © 2018 Wiley Periodicals, Inc.