The course of hepatitis E virus infection in pigs after contact-infection and intravenous inoculation

Abstract

<p>Abstract</p> <p>Background</p> <p>Worldwide, hepatitis E virus (HEV) genotype 3 is observed in pigs and transmission to humans is implied. To be able to estimate public health risks from <it>e.g</it>. contact with pigs or consumption of pork products, the transmission routes and dynamics of infection should be identified. Hence, the course of HEV-infection in naturally infected pigs should be studied.</p> <p>Results</p> <p>To resemble natural transmission, 24 HEV-susceptible pigs were infected either by one-to-one exposure to intravenously inoculated pigs (C1-pigs; n = 10), by one-to-one exposure to contact-infected pigs (C2-pigs: n = 7; C3-pigs: n = 5) or due to an unknown non-intravenous infection route (one C2-pig and one C3-pig). The course of HEV-infection for contact-infected pigs was characterized by: faecal HEV RNA excretion that started at day 7 (95% confidence interval: 5–10) postexposure and lasted 23 (19–28) days; viremia that started after 13 (8–17) days of faecal HEV RNA excretion and lasted 11 (8–13) days; antibody development that was detected after 13 (10–16) days of faecal HEV RNA excretion. The time until onset of faecal HEV RNA excretion and onset of viremia was significantly shorter for <it>iv</it>-pigs compared to contact-infected pigs, whereas the duration of faecal HEV RNA excretion was significantly longer. At 28 days postinfection HEV RNA was detected less frequently in organs of contact-infected pigs compared to <it>iv</it>-pigs. For contact-infected pigs, HEV RNA was detected in 20 of 39 muscle samples that were proxies for pork at retail and in 4 of 7 urine samples.</p> <p>Conclusion</p> <p>The course of infection differed between infection routes, suggesting that contact-infection could be a better model for natural transmission than <it>iv </it>inoculation. Urine and meat were identified as possible HEV-sources for pig-to-pig and pig-to-human HEV transmission.</p

Detection of hepatitis E virus genome in pig livers in Antioquia, Colombia

“…However, some extrahepatic areas of HEV replication have also been reported, such as in the small intestine and the colon, which may be involved in human exposure to the virus. Bouwknegt et al (2009) reported the presence of HEV RNA in the viscera 28 days after infection in over 50% of animal samples infected experimentally. The meat samples evaluated in this study were often destined for commercial ends, primarily for the production of sausages or processed meats (Williams et al, 2001).…”

Scientific Opinion on an update on the present knowledge on the occurrence and control of foodborne viruses

“…Presence of infectious HEV could not be confirmed for Dutch commercial porcine livers (Bouwknegt et al, 2007), whereas those obtained in the USA contained infectious HEV (Feagins et al, 2007). Twenty of 39 muscle samples from pigs of an HEV infection experiment, which may serve as proxies for pork meat at retail, contained HEV RNA (Bouwknegt et al, 2009).…”

“…Some risk profiles, the first part of a RA, have been reported on FBV, such as a risk profile of Norwalk-like virus in molluscs (raw) in New Zealand (Greening et al, 2003) 17 , on foodborne NoV infections 18 and for HEV (Bouwknegt et al, 2009). Due to data limitations, it was concluded at an international meeting of experts that undertaking a full quantitative risk assessment for FBV may be premature (FAO/WHO meeting report 19 ).…”

“…The option to prevent HEV introduction into pig farms and thereby reduce the proportion of HEV infected pigs at the time of slaughter is hampered so far by the limited knowledge about the distinct transmission pathways of HEV in pigs (Bouwknegt et al, 2009;Kasorndorkbua et al, 2004).…”

“…Many commercially available kits exist for the isolation of RNA from tissue samples. The isolated RNA is thereafter analysed by PCR; several protocols for conventional Preiss et al, 2006;Schlauder et al, 1999) or real-time RT-PCR (Bouwknegt et al, 2009;Gyarmati et al, 2007;Jothikumar et al, 2006) for the detection of HEV genotypes 1 to 4 in humans and animals have been published.…”