Dynamic of Hepatitis E Virus (HEV) Shedding in Pigs

Abstract

Genotype 3 of hepatitis E virus (HEV-3) is the most common in Europe in both humans and pigs. HEV-3 strains are zoonotic, and foodborne cases associated with consumption of raw and undercooked pork products, mainly liver sausages, have been described. HEV-3 circulates largely in European pig farms, maybe due to its long persistence in the environment. Animals get infected around 3-4 months of age; shortly after, the infection starts to decline up to the age of slaughtering (8-9 months of age in Italy). With the purpose to understand the duration in farmed pigs of the shedding of the virus and its quantity, HEV-RNA detection was performed by Real-time RT-PCR from feces collected individually from two groups of 23 pigs. Sampling was conducted for 4 months shortly before slaughtering age. At 4-months-old, all animals were shedding HEV-3 to high load around 10⁵ genome copies per gram (GC/g). Prevalence was higher in growers than in fatteners, with most of the pigs still positive around 166 days of age. Beyond some difference among individual pigs, the amount of HEV in feces decreased with the age of animals. The longest fattening period should ensure a lower risk of HEV shedder animals at slaughter, reducing the risk of food contamination.

Keywords: HEV; fatteners; fecal shedding; foodborne; pigs; risk; slaughterhouse; swine.

Figure 1

Scheme summary of HEV-RNA detection for each batch over the study period. Animals lost during the study are indicated in white (lost at follow-up because died or lost the ear-tag).

Figure 2

Kaplan–Meier survival curves for animals of the two batches. Censored animals are pigs remained HEV-RNA positives for the entire study period and animals of the batch A that lost the ear-tag or died (n = 4, lost at follow-up).

Figure 3

Amount of HEV-RNA expressed as log₁₀ genome copies (GC) per gram of feces shed by each animal during the whole survey. Single values of GC for each pig are indicated by circle. The red colored points and line are referred to batch A, the blue to batch B.