Program of vaccination and antibiotic treatment to control polyserositis caused by Haemophilus parasuis under field conditions

Abstract

The present study investigated the effects of vaccinating sows and piglets or piglets alone against Haemophilus parasuis on the prevalence of H. parasuis in nasal swabs, on the humoral and cellular immune responses, and on the production parameters of piglets at 3 Korean farms with a clinical history of polyserositis caused by H. parasuis. Piglets born to vaccinated or non-vaccinated sows were subdivided into 3 groups: vaccinated sows and vaccinated pigs (VS-VP), non-vaccinated sows and vaccinated pigs (NVS-VP), and non-vaccinated sows and non-vaccinated pigs (NVS-NVP). The proportion of piglets with positive nasal swabs was significantly lower (P < 0.05) in the vaccinated animals (VS-VP and NVS-VP groups) than in the non-vaccinated animals (NVS-NVP group) at 35 and 60 d of age at the 3 farms. The overall growth performance (from 7 to 60 d of age) of the vaccinated piglets was significantly better (P < 0.05) than that of the non-vaccinated piglets at the 3 farms. Piglets in the VS-VP group had significantly higher levels (P < 0.05) of H. parasuis-specific IgG antibodies, lymphocyte proliferation, and interferon-γ-secreting cells than piglets in the NVS-VP and NVS-NVP groups on days 1, 7, 21, 35, and 60 after birth at the 3 farms.

Figure 1

Mean titer of serum IgG antibody against Haemophilus parasuis, determined by enzyme-linked immunosorbent assay, in the group of vaccinated sows and vaccinated piglets (VS-VP group; ), the group of non-vaccinated sows and vaccinated piglets (NVS-VP group; ○), and the group of non-vaccinated sows and non-vaccinated piglets (NVS-NVP group; ) at 3 farms in Korea. Variation is standard deviation. Significant differences are indicated by the symbols (P < 0.001^†) and (P < 0.05*).

Figure 2

Mean differential H. parasuis-specific lymphocyte stimulation index per million peripheral blood mononuclear cells (PBMCs) per milliliter in the group of vaccinated sows and vaccinated piglets (VS-VP group;▦), the group of non-vaccinated sows and vaccinated piglets (NVS-VP group; □), and the group of non-vaccinated sows and non-vaccinated piglets (NVS-NVP group; ▥). Variation is standard deviation. Significant differences are indicated by the symbols (P < 0.001^†) and (P < 0.05*).

Figure 3

Mean relative proportion of CD4⁺CD8⁺ double-positive T-lymphocytes per million PBMCs/mL for the in the group of vaccinated sows and vaccinated piglets (VS-VP group; ), the group of non-vaccinated sows and vaccinated piglets (NVS-VP group; ○), and the group of non-vaccinated sows and non-vaccinated piglets (NVS-NVP group; ); and mean number of H. parasuis-specific interferon-γ-secreting cells (IFN-γ-SCs) per million PBMCs/mL in the the group of vaccinated sows and vaccinated piglets (VS-VP group; ▦), the group of non-vaccinated sows and vaccinated piglets (NVS-VP group; □), and the group of non-vaccinated sows and non-vaccinated piglets (NVS-NVP groups; ▥). Variation is standard deviation. Significant differences are indicated by the symbols (P < 0.001^†) and (P < 0.05*).