Clinical Application Cases of Porcine Epidemic Diarrhea Vaccine Immunization in Pig Farms

The outbreak of African swine fever has severely disrupted the domestic swine‑raising balance, driving hog prices to persistently high levels. Consequently, pig farms have become more eager to resume and expand production, leading to a growing pool of three‑way crossbred replacement gilts. This situation poses a significant risk of diarrhea in farrowing units, as primiparous sows, having not been exposed to diarrheal pathogens, exhibit markedly insufficient IgA antibody levels, thereby substantially increasing the likelihood of such outbreaks. In this case study, laboratory techniques were employed to assess IgA antibody levels in the sow population, evaluating the safety and efficacy of a bivalent live vaccine against transmissible gastroenteritis and porcine epidemic diarrhea—comprising the SD/L and LW/L strains (hereafter referred to as the “Gastroenteritis–Diarrhea Bivalent Vaccine”)—under real‑world production conditions.

Disease Situation at the Case Pig Farm

This pig farm previously experienced a severe outbreak of diarrhea in the farrowing unit, resulting in substantial losses. Affected neonatal piglets exhibited vomiting and watery diarrhea, with dehydration leading to death within the first three days of life. Mortality among piglets under five days old approached 100%, while morbidity in piglets older than one week exceeded 50%. The disease persisted for about a week, causing heavy economic losses. Currently, the farm remains stable, with no further outbreaks of diarrhea (the farm has never administered vaccines against diarrhea). Given the recent introduction of a large number of first-parity sows—accounting for over 60% of the herd—and the lack of an assessment of the current risk of diarrheal disease or the efficacy of vaccination, an immunization trial was conducted.

Test materials

vaccine

The bivalent live vaccine against porcine transmissible gastroenteritis and porcine epidemic diarrhea (SD/L strain + LW/L strain) and the bivalent inactivated vaccine against porcine transmissible gastroenteritis and porcine epidemic diarrhea (SD/L strain + LW/L strain) are supplied by Luoyang Huizhong Biotechnology Co., Ltd.

Testing material

The porcine epidemic diarrhea IgA-ELISA antibody detection kit is provided by a mutually accredited third-party laboratory and supported by technical expertise.

Experimental Protocol

Sow blood samples were sent to a third-party laboratory for IgA antibody testing to assess the risk of diarrhea. The tested pig herd was then vaccinated with Huizhong Bio’s Huibuning (a live bivalent vaccine against gastric and intestinal diseases) and Huibu’an (an inactivated bivalent vaccine against gastric and intestinal diseases). Three weeks after vaccination, blood was collected for IgA antibody analysis, thereby confirming, based on antibody titers, that Huizhong Bio’s Huibuning and Huibu’an—administered as a live‑plus‑inactivated vaccination regimen—provide comprehensive control of diarrhea in pig farms.

The test results for sow samples that were not vaccinated with Huizhong Bio’s “live + inactivated” vaccination regimen are as follows:

The test results indicate that the IgA antibody positivity rate in the samples submitted from this pig farm is 13.33%. This low positivity rate makes it difficult to provide adequate maternal antibodies to the piglets and fails to ensure their protection against outbreaks of epidemic diarrhea and transmissible gastroenteritis. Consequently, should farrowing‑house diarrhea occur at this farm, the resulting losses would be substantial.

The test results for sow samples submitted following the “live + inactivated” vaccination regimen from Yimui Huizhong Biotechnology are as follows:

Following the “live + inactivated” vaccination regimen developed by Immun惠Zhong Biotechnology, the IgA antibody positivity rate in sow samples reached 93.33%, significantly higher than the pre‑vaccination baseline, thereby providing robust maternal antibody protection for piglets in the farrowing unit.