Epidemiology of Streptococcus suis serotype 5 infection in a pig herd with and without clinical disease.
The aim of this study was to describe the transmission and the kinetics of the infection caused by Streptococcus suis serotype 5 in a multisite farrow-to-finish pig herd. Most sows carried S. suis serotype 5 in their vaginal tract, but not in their nasal cavities, as demonstrated by immunomagnetic separation (IMS) technique. Their offspring became infected during farrowing, confirming vertical transmission. During the first 4 weeks of life, a low number of piglets were carriers of S. suis serotype 5 in their nasal cavities. However, when clinical signs appeared, the carrier rate significantly increased, suggesting that isolation from nasal cavities is a better indication of active transmission than of a carrier state. Clinical cases were present in animals between 4 and 8 weeks of age, when maternal antibodies were at their lowest level. Up to six different genotypes of the same serotype could be identified by random amplified polymorphic DNA; however, a single clone was responsible for all clinical cases studied. This clone could only be isolated from a single sow, indicating that its prevalence in breeding animals was low. Interestingly, 1 year later, clinical disease associated with S. suis serotype 5 spontaneously disappeared. At that time, the genotype responsible for the clinical signs was not detected in the herd and the levels of antibodies in sows and maternal antibodies in piglets were not higher than those of the previous year.
Cloutier
G
G
Groupe de Recherche sur les Maladies Infectieuses du Porc, Département de pathologie et microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, St-Hyacinthe, Que., Canada J2S 7C6.
D'Allaire
S
S
Martinez
G
G
Surprenant
C
C
Lacouture
S
S
Gottschalk
M
M
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D002170:Canada / Q000453:epidemiology; D002353:Carrier State / Q000662:veterinary; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D018189:Immunomagnetic Separation / Q000662:veterinary; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary; D009296:Nasal Cavity / Q000382:microbiology; D011247:Pregnancy; D019105:Random Amplified Polymorphic DNA Technique / Q000662:veterinary; D016036:Seroepidemiologic Studies; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D017011:Streptococcus suis / Q000235:genetics / Q000302:isolation & purification*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D014621:Vagina / Q000382:microbiology
D000907:Antibodies, Bacterial; D004269:DNA, Bacterial