Hepatitis E surveillance in Sweden involves the notification and reporting of suspected and confirmed hepatitis E cases to the national surveillance database SmiNet hosted by the Public Health Agency of Sweden. Clinicians and diagnostic laboratories report clinical and laboratory data on notified cases, including demographic, epidemiological, and diagnostic testing information. The County Medical Officer is responsible for contact tracing notified cases to identify potential transmission routes. Between 1997-2015, 173 hepatitis E cases were notified in Sweden, with most being travel-related and acquired through food or water. Studies show hepatitis E virus RNA has been detected in pigs, wild boars, and moose in Sweden, with genetic sequencing linking some human strains to those found in local animals.

1. Hepatitis E surveillance in Sweden
Lena Sundqvist
ECDC, Stockholm
9-10 December 2015

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National surveillance
Case definition
Suspected case: Clinical illness compatible with the diagnosis and an
epidemiological link
Confirmed case: A laboratory-confirmed case
Laboratory criteria for diagnosis (at least one of the following conditions):
• detection of hepatitis E virusspecific antibody-respons in serum indicating current
infection
• detection of hepatitis E virus RNA in serum or faeces
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• A legally notifiable disease in Sweden since 1993.

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Notification
• Suspected and laboratory confirmed cases are reported by clinicians
and the diagnostic laboratory to a national surveillance database,
SmiNet, hosted by the Public Health Agency of Sweden.
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SmiNet
Clinician Laboratory

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Data collected in SmiNet
Clinical notification
Demographic and epidemiological data
 Unique patient number, age, sex
 Date and responsible county for notification
 Type of infection, onset of disease, related cases
 Country of infection, travel history, source of infection
 Occupation
 Specific instructions and recommendations
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Laboratory notification
 Sample material: serum, faeces
 Date of sampling
 Diagnostic method: antibody-detection
nucleic acid-detection
antigen-detection
 Results: anti-HEV IgM
anti-HEV IgG/IgM
HEV-RNA
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Contact tracing
• 21 counties
• The County Medical Officer is responsible for
contacting notified cases of hepatitis E to collect
additional information on possible routes of
transmission.
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Laboratory diagnostics
Department of clinical Microbiology at Sahlgrenska University Hospital,
Gothenburg.
Diagnostic methods
 ELISA (IgM/IgG)
 RT-PCR
Molecular typing
 Sequencing is routinely performed on all confirmed positive samples
HEV test on blood samples is only performed if requested by the
reffering clinician.
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0
0.1
0.2
0.3
0.4
0
5
10
15
20
25
30
Numberofcases
Notified cases of hepatitis E in Sweden
1997-1 dec 2015 (n=173)
Travel-related cases Domestic cases Incidence
Data available in SmiNet since 1997
Incidence(inc/100000)

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0
10
20
30
40
50
60
70
80
90
Female Male
Proportionofcases(%)
Travel-related cases Domestic cases

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0
5
10
15
20
25
30
35
0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-90
Proportionofcases(%)
Age group
Travel-related cases Domestic cases

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0
10
20
30
40
50
60
Food Food/water Water Unknown
Numberofcases
Travel-related cases Domestic cases

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Studies on hepatitis E in Sweden
Humans
 The seroprevalence of anti-HEV antibodies in the general population is
6-9% and in pig farmers 13%. (Sylvan et al, Olsen et al)
 HEV RNA has been detected in 57% of anti-HEV-positive samples
(22% were from patients with detectable anti-HEV IgG only) (Widén et al)
 HEV RNA has been detected in 1:8000 plasma donations. (Baylis et al)
 The first case of chronic hepatitis E infection in a heart transplant
recipient in Sweden has been identified. (Waldenström et al)
 13% of Swedish lungtransplant recipients had anti-HEV IgG one year
after lung transplantation. HEV RNA could not be detected. (Magnusson et al)
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Animals
 HEV could be detected in 30% of the pigs from 22 pig farms
and in 8% of the wild boars from nine counties. (Widén et al)
Genotype 3 strains from pigs and wild boars show
close relatedness between strains from piglets from the
same farm and from wild boars from the same county.
Genotype 3 strains from humans show relatedness with
strains from pigs and wild boars from the same county.
 30% of Swedish moose have markers of active
and past infection and 15% are positive for HEV RNA.
The HEV genome is 35-60% identical to existing HEVs
belonging to the genotype 1-6 group. (Lin et al)

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Environment
 Sewage samples were investigated for the presence of different
pathogenic viruses as a method to detect upcoming outbreaks and to
provide an early warning. (Hellmér et al)
HEV was detected at a constant low concentration in sewage samples
indicating that HEV circulated in the population during the study period.

15. Thank you for your attention!