Experimental airborne transmission of Streptococcus suis capsular type 2 in pigs.
Experimental airborne transmission of Streptococcus suis type 2 was studied in specific pathogen free piglets. Forty piglets were allotted to five groups of eight 7-week-old animals and housed in three separated units. Negative control pigs (group 1) were housed in unit A and infected batches were housed in units B (group 2) and C (groups 4). In units B and C, non-inoculated groups (groups 3 and 5, respectively), 40 cm distant from the respective inoculated group and without any physical contact between them, also took place. Six animals of groups 2 and 4 were inoculated intravenously with 2 x 10(8) colony forming units (cfu) of a mild and a high virulent S. suis strains, respectively. The remaining animals in these groups and pigs from groups 1, 3, 5 received broth medium in the same way. Differences among virulence of S. suis capsular type 2 were observed in inoculated pigs of groups 2 and 4. Pigs from group 2 became carriers, showing only mild symptoms. By contrast, animals from group 4 presented an acute form of the disease. All the indirect contact pigs in groups 3 and 5 had S. suis in palatine tonsils from day 6 after the infection and they presented clinical manifestations similar to those observed in experimentally infected pigs. Two direct contact animals were also contaminated in the upper respiratory tract but surprisingly they did not show any symptoms. Airborne transmission of S. suis in experimentally pigs was demonstrated in the present study. Indirect infections, as described in this study, are a more realistic way to infect pigs than other experimental procedures and may be used to further study the pathogenesis of the infection caused by this important pathogen.
Berthelot-Hérault
F
F
Agence Française de la Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches Avicoles et Porcines, Unité Mycoplamologie-Bactériologie, Zoopôle, B.P. 53, Les Croix, 22440 Ploufragan, France. f.herault@ploufragan.afssa.fr
Gottschalk
M
M
Labbé
A
A
Cariolet
R
R
Kobisch
M
M
D000818:Animals; D016667:Bacterial Capsules; D001831:Body Temperature; D018562:Disease Transmission, Infectious / Q000662:veterinary; D006799:Housing, Animal; D011135:Polysaccharides, Bacterial / Q000032:analysis*; D013047:Specific Pathogen-Free Organisms; D013290:Streptococcal Infections / Q000635:transmission / Q000662:veterinary*; D017011:Streptococcus suis / Q000302:isolation & purification*; D013552:Swine / Q000382:microbiology*; D013553:Swine Diseases / Q000635:transmission*
D011135:Polysaccharides, Bacterial; C028096:capsular polysaccharide, Streptococcus suis type 2