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Markers for Ongoing or Previous Hepatitis E Virus Infection Are as Common in Wild Ungulates as in Humans in Sweden

View Article: PubMed Central - PubMed

ABSTRACT

Hepatitis E virus (HEV) is a human pathogen with zoonotic spread, infecting both domestic and wild animals. About 17% of the Swedish population is immune to HEV, but few cases are reported annually, indicating that most infections are subclinical. However, clinical hepatitis E may also be overlooked. For identified cases, the source of infection is mostly unknown. In order to identify whether HEV may be spread from wild game, the prevalence of markers for past and/or ongoing infection was investigated in sera and stool samples collected from 260 hunted Swedish wild ungulates. HEV markers were found in 43 (17%) of the animals. The most commonly infected animal was moose (Alces alces) with 19 out of 69 animals (28%) showing HEV markers, followed by wild boar (Sus scrofa) with 21 out of 139 animals (15%), roe deer (Capreolus capreolus) with 2 out of 30 animals, red deer (Cervus elaphus) with 1 out of 15 animals, and fallow deer (Dama dama) 0 out of 7 animals. Partial open reading frame 1 (ORF1) of the viral genomes from the animals were sequenced and compared with those from 14 endemic human cases. Phylogenetic analysis revealed that three humans were infected with HEV strains similar to those from wild boar. These results indicate that wild animals may be a source of transmission to humans and could be an unrecognized public health concern.

No MeSH data available.


Related in: MedlinePlus

Unweight pair-group method using arithmetic averages (UPGMA) phylogenetic tree formed by 335 nucleotides of partial open reading frame 1 (ORF1) of 361 HEV sequences representing HEV3, HEV4, and moose HEV from this study and obtained from GenBank. The genotypes of the strains are indicated on the branches of the tree. The branch formed by HEV moose strains is indicated. A branch within the 3II clade [37] is enlarged. Accession number or strain designation of the strains in this study together with origin and host of the strains are given at the nodes. The three clades formed by strains from endemic human cases and strains from Swedish wild boar are boxed. Strains from humans infected in Sweden are colored blue, strains from Swedish pigs are colored red, and strains from Swedish wild boar are colored green.
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viruses-08-00259-f001: Unweight pair-group method using arithmetic averages (UPGMA) phylogenetic tree formed by 335 nucleotides of partial open reading frame 1 (ORF1) of 361 HEV sequences representing HEV3, HEV4, and moose HEV from this study and obtained from GenBank. The genotypes of the strains are indicated on the branches of the tree. The branch formed by HEV moose strains is indicated. A branch within the 3II clade [37] is enlarged. Accession number or strain designation of the strains in this study together with origin and host of the strains are given at the nodes. The three clades formed by strains from endemic human cases and strains from Swedish wild boar are boxed. Strains from humans infected in Sweden are colored blue, strains from Swedish pigs are colored red, and strains from Swedish wild boar are colored green.

Mentions: Strains from six wild boars could be amplified and sequenced in the ORF1 region. Phylogenetic analyses showed that all wild boar HEV strains and the 14 strains from human endemic cases were of genotype 3 and were found in the clade previously designated 3II in the phylogenetic tree based on HEV3 strains (Figure 1) [37]. Wild boar strains from animals killed by the same hunter team were similar to each other, although no geographical clades formed by the strains were apparent. Three humans were infected by strains similar to wild boar HEV strains. The strain isolated from one patient from the province of Södermanland, who often consumed wild game meat, was identical to a strain from a wild boar from the province of Blekinge in Southern Sweden. This strain was also similar to a wild boar HEV strain from Närke in Central Sweden (Figure 1). A hunter from the province of Värmland was infected by a strain related to a wild boar from the same province, and a female was infected by a strain similar to a wild boar strain from Småland (Figure 1). HEV strains from wild boar from the provinces of Halland and Blekinge formed one clade. The wild boar strains from Västergötland were distantly related to strains from Swedish pigs in Närke (Figure 1).


Markers for Ongoing or Previous Hepatitis E Virus Infection Are as Common in Wild Ungulates as in Humans in Sweden
Unweight pair-group method using arithmetic averages (UPGMA) phylogenetic tree formed by 335 nucleotides of partial open reading frame 1 (ORF1) of 361 HEV sequences representing HEV3, HEV4, and moose HEV from this study and obtained from GenBank. The genotypes of the strains are indicated on the branches of the tree. The branch formed by HEV moose strains is indicated. A branch within the 3II clade [37] is enlarged. Accession number or strain designation of the strains in this study together with origin and host of the strains are given at the nodes. The three clades formed by strains from endemic human cases and strains from Swedish wild boar are boxed. Strains from humans infected in Sweden are colored blue, strains from Swedish pigs are colored red, and strains from Swedish wild boar are colored green.
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Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035973&req=5

viruses-08-00259-f001: Unweight pair-group method using arithmetic averages (UPGMA) phylogenetic tree formed by 335 nucleotides of partial open reading frame 1 (ORF1) of 361 HEV sequences representing HEV3, HEV4, and moose HEV from this study and obtained from GenBank. The genotypes of the strains are indicated on the branches of the tree. The branch formed by HEV moose strains is indicated. A branch within the 3II clade [37] is enlarged. Accession number or strain designation of the strains in this study together with origin and host of the strains are given at the nodes. The three clades formed by strains from endemic human cases and strains from Swedish wild boar are boxed. Strains from humans infected in Sweden are colored blue, strains from Swedish pigs are colored red, and strains from Swedish wild boar are colored green.
Mentions: Strains from six wild boars could be amplified and sequenced in the ORF1 region. Phylogenetic analyses showed that all wild boar HEV strains and the 14 strains from human endemic cases were of genotype 3 and were found in the clade previously designated 3II in the phylogenetic tree based on HEV3 strains (Figure 1) [37]. Wild boar strains from animals killed by the same hunter team were similar to each other, although no geographical clades formed by the strains were apparent. Three humans were infected by strains similar to wild boar HEV strains. The strain isolated from one patient from the province of Södermanland, who often consumed wild game meat, was identical to a strain from a wild boar from the province of Blekinge in Southern Sweden. This strain was also similar to a wild boar HEV strain from Närke in Central Sweden (Figure 1). A hunter from the province of Värmland was infected by a strain related to a wild boar from the same province, and a female was infected by a strain similar to a wild boar strain from Småland (Figure 1). HEV strains from wild boar from the provinces of Halland and Blekinge formed one clade. The wild boar strains from Västergötland were distantly related to strains from Swedish pigs in Närke (Figure 1).

View Article: PubMed Central - PubMed

ABSTRACT

Hepatitis E virus (HEV) is a human pathogen with zoonotic spread, infecting both domestic and wild animals. About 17% of the Swedish population is immune to HEV, but few cases are reported annually, indicating that most infections are subclinical. However, clinical hepatitis E may also be overlooked. For identified cases, the source of infection is mostly unknown. In order to identify whether HEV may be spread from wild game, the prevalence of markers for past and/or ongoing infection was investigated in sera and stool samples collected from 260 hunted Swedish wild ungulates. HEV markers were found in 43 (17%) of the animals. The most commonly infected animal was moose (Alces alces) with 19 out of 69 animals (28%) showing HEV markers, followed by wild boar (Sus scrofa) with 21 out of 139 animals (15%), roe deer (Capreolus capreolus) with 2 out of 30 animals, red deer (Cervus elaphus) with 1 out of 15 animals, and fallow deer (Dama dama) 0 out of 7 animals. Partial open reading frame 1 (ORF1) of the viral genomes from the animals were sequenced and compared with those from 14 endemic human cases. Phylogenetic analysis revealed that three humans were infected with HEV strains similar to those from wild boar. These results indicate that wild animals may be a source of transmission to humans and could be an unrecognized public health concern.

No MeSH data available.


Related in: MedlinePlus