Seroprevalence and molecular characteristics of hepatitis E virus in household-raised pig population in the Philippines

Abstract

BackgroundHepatitis E virus (HEV) infection is a significant public health concern in Asia, and swine is an important source of sporadic HEV infection in human. However, no epidemiological data are available regarding HEV infection among the swine or human population in the Philippines. To assess the HEV infection status among pigs in rural areas, we investigated the molecular characteristics and seroprevalence of HEV among household-raised pigs in San Jose, Tarlac Province, the Philippines.ResultSerum and rectal swab samples were collected from 299 pigs aged 2–24 months from 155 households in four barangays (villages) between July 2010 and June 2011. Enzyme-linked immunosorbent assay (ELISA) revealed that 50.3% [95% confidence interval (CI) 44.5–56.2%] and 22.9% (95% CI 18.2–28.1%) of pigs tested positive for anti-HEV IgG and IgM, respectively. HEV RNA was detected in the feces of 22 pigs (7.4%, 95% CI 4.7–10.9%). A total of 103 households (66.5%, 95% CI 58.4–73.8%) had at least one pig that tested positive for anti-HEV IgG or IgM or HEV RNA. The prevalence of anti-HEV IgG and IgM in breeding pig (8–24 months) were higher than that in growing pigs (2–4 months) (p < 0.0001 and p = 0.008, respectively). HEV RNA was more frequently detected in 2–4-month-old pigs (9.2%, 95% CI 5.4–14.6%) than in ≥5-month-old pigs (4.8%, 95% CI 1.1–8.5%) without statistical significance (p = 0.142). HEV RNA showed 0–27.6% nucleotide difference at the partial ORF2 gene among the detected viruses, and a majority of them belonged to subtype 3a (20/22, 90.9%).ConclusionWe found a high prevalence of HEV antibodies in the household-raised pig population in rural areas of the Philippines, which indicates the potential risk of HEV infection among local residents. Only genotype 3 of HEV was observed, and genetically diverse strains of HEV were found to be circulating in pigs in this study.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0322-z) contains supplementary material, which is available to authorized users.

Seroepidemiology and molecular characterization of hepatitis E virus infection in swine and occupationally exposed workers in Punjab, India

“…Results of this study showing an overall seroprevalence of 65.0% in pigs were consistent with previous findings in mixed age group swine populations reported from western India and China where the anti‐HEV IgG seropositivity was 54% and 50.3%, respectively (Arankalle et al., ; Liu et al., ), although a high seropositivity of 96.50% was reported from adult pigs in Lucknow, India (Shukla et al., ). Several other studies have reported the seropositivity for anti‐HEV IgG in pigs in the range of 6.1%–7.2% from Belgium, 31.0% to 65.0% from France, 49.8% from Germany, 68.0% from the Netherlands and 87.0% from northern Italy (Kim et al., ; Van Hoecke et al., ).…”

Seroepidemiology of hepatitis E virus infection in pigs in Durango State, Mexico

“…Therefore, this study was aimed to determine the prevalence and correlates of HEV infection in the In an international context, the overall seroprevalence of HEV infection found in pigs in Durango is higher than the 9.9% and 29% seroprevalences found in farm pigs in Thailand 10 and Scotland, 11 respectively. The seroprevalence found in our study is comparable with intermedium (46.9-66.4%) seroprevalences in pigs reported in Germany, 12 Italy, 13 Philippines, 14 Switzerland, 15 and China. 16 In contrast, the seroprevalence found in our studied pigs is lower than those (71.2-90%) reported in pigs in Madagascar, 6 Netherlands, 17 Belgium, 18 France, 19 Burkina Faso, 20 and Norway.…”

“…For instance, a relatively low (9.9‐29%) seroprevalence of HEV infection in pigs has been reported in Thailand and Scotland . Whereas, intermedium (46.9‐66.4%) seroprevalences of HEV infection have been reported in pigs in Germany, Italy, Philippines, Switzerland, and China . In contrast, high (71.2‐90%) seroprevalences of HEV infection have been found in pigs in Madagascar, Netherlands, Belgium, France, Burkina Faso, and Norway …”

Patterns of mutation within an emerging endemic lineage of HEV‐3a

“…Globally, HEV-3a appears to be a well-travelled lineage, with sequences found in farmed pigs in Canada, China, Columbia, France, Indonesia, Japan, South Korea, and Philippines. [28][29][30][31][32][33][34][35] It was also recently identified in German wild boars 36 and was the causative agent of an autochthonous human infection in Europe. 37 It should be noted that nonporcine transmission modes are possible and cannot be ruled out completely.…”

“…All of the National University Hospital (NUH, Singapore) sequences in this study fall within subtype 3a on the phylogenetic tree. Globally, HEV‐3a appears to be a well‐travelled lineage, with sequences found in farmed pigs in Canada, China, Columbia, France, Indonesia, Japan, South Korea, and Philippines . It was also recently identified in German wild boars and was the causative agent of an autochthonous human infection in Europe .…”