Herd factors associated with the seroprevalences of Actinobacillus pleuropneumoniae serovars 2, 3 and 9 in slaughter pigs from farrow-to-finish pig herds
D. Maes et al., Herd factors associated with the seroprevalences of Actinobacillus pleuropneumoniae serovars 2, 3 and 9 in slaughter pigs from farrow-to-finish pig herds, VET RES, 32(5), 2001, pp. 409-419
This cross-sectional epidemiologic study was conducted in 150 randomly sele
cted farrow-to- finish pig herds to investigate descriptive epidemiological
characteristics of infections with three different serovars of Actinobacil
lus pleuropneumoniae, and to identify risk factors for the within-herd sero
prevalences of these serovars. Different farm characteristics (n = 28) were
examined as potential risk factors for the percentage of pigs with antibod
ies against serovars 2, 3 and 9. The presence of antibodies was measured us
ing an indirect ELISA. Logistic regression analyses were used to assess the
associations between the potential risk factors and the proportion of sero
positive pigs. The median within-herd seroprevalences were 95% (range: 0-10
0%), 100% (range: 10-100%), and 35% (range: 0-100%) for serovars 2, 3, and
9, respectively. There was a positive association (P < 0.001) between each
of these serovars. The within-herd seroprevalence of serovar 2 was signific
antly higher in farms that purchased gilts from 2 origin herds (OR = 2.33;
P < 0.05) and in farms with poor biosecurity measures (OR = 4.62; P < 0.05)
. The proportion of pigs seropositive for serovar 3 was significantly highe
r when tested pigs were slaughtered in May-August and in November-December
(OR = 5.96; P < 0.001), in herds without a growing unit (OR = 2.63; P < 0.0
1), and in herds with a direct air-entry into the finishing unit (OR = 1.92
; P < 0.05). The within-herd seroprevalence of serovar 9 increased signific
antly in herds with poor biosecurity measures (OR = 1.76; P < 0.05). The st
udy documented that infections with A. pleuropneumoniae serovars 2, 3, and
9 were very common in the selected herds, and that the sero-epidemiological
characteristics and risk factors showed some variation depending on the se
rovar. The purchase policy of gilts and biosecurity measures are risk facto
rs that can be improved fairly easily on pig farms.