zoonoses and communicable diseases common to ... - PAHO/WHO

260 BACTERIOSESmonia, and arthritis. Less frequently, it causes endocarditis, polyserositis, encephalitis,and abscesses. Although the rate of infection in a herd can be high, it does notusually affect more than 5% (Clifton-Hadley, 1984). Of 663 strains isolated from sickswine in Canada, 21% belonged to type 2 (the most frequently occurring type in allcountries), followed by types 1/2 (which has capsular antigens from 1 and 2) and 3,with 12% each. Types 20 and 26 were the only types not found (Higgins andGottschalk, 1992). In Denmark, types 2 and 7 represented 75% of the isolates. Type7 was isolated more frequently than in other countries, usually in suckling pigsyounger than 3 weeks. Experimental inoculation with S. suis type 7 in suckling pigsunder 7 days old caused severe disease (Boetner et al., 1987). In Australia, type 1 hascaused septicemia, meningitis, and polyarthritis in suckling pigs (Cook et al., 1988).In weaned piglets from various regions of Australia, type 2 is predominant (Ossowiczet al., 1989), although types 3, 4, and 9 have also been isolated and there are indicationsthat they can produce the same disease picture. In another study in New SouthWales and Victoria (Australia), type 9 was predominant (Gogolewski et al., 1990).In cattle, sheep, and goats, strains of types 5 and 2 were isolated from purulentlesions in the lungs and from other extramammary sites (Hommez et al., 1988).Most isolates of S. suis type 2 are sensitive to penicillin.S. agalactiae (S. mastitidis), in Lancefield’s group B, is the principal agent ofchronic catarrhal mastitis in dairy cows. S. dysgalactiae (group C) and S. uberis(group E) cause sporadic cases of acute mastitis in bovines. S. pyogenes, a humanpathogen, can infect the cow’s udder, producing mastitis and leading to epidemicoutbreaks in man.Horse strangles, caused by S. equi (group C), is an acute disease of horses characterizedby inflammation of the pharyngeal and nasal mucosa, with a mucopurulentsecretion and abscesses of the regional lymph nodes.S. equisimilis (group C) infects different tissues in several animal species. GroupC streptococci that are adapted to animals and classified as S. zooepidemicus producecervicitis and metritis in mares and often cause abortions. They also cause septicemiain colts. They are pathogenic for bovines, swine, and other animals, in whichthey produce various septicemic processes.S. zooepidemicus (group C) is an opportunistic pathogen in many animal species.It is a commensal on the skin, the mucosa of the upper respiratory tract, and in thetonsils of many animal species. In horses, it is the common agent of wound infectionsand is a secondary disease agent after a viral infection in the upper respiratorytract of colts and young animals. It is also the agent of other infections in horses(Timoney et al., 1988). In cows, S. zooepidemicus can cause acute mastitis when itenters a wound in the teat. A fatal case of septicemia was described in a chicken(Timoney et al., 1988).Streptococci belonging to other groups cause abscesses and different diseaseprocesses in several animal species. The many diseases caused by streptococci areclinically differentiated by the agent’s portal of entry and the tissue it affects.Source of Infection and Mode of Transmission: The reservoir of S. pyogenes isman. Transmission of this respiratory disease agent (septic sore throat, scarlet fever)results from direct contact between an infected person, whether patient or carrier,and another susceptible person. The disease is most frequent among children from5 to 15 years old, but also occurs at other ages.