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

CORYNEBACTERIOSIS 101Two different pathological conditions have been found in horses. One is ulcerativelymphangitis, with metacarpal and metatarsophalangeal abscesses that containa thick, greenish pus and at times leave an ulceration that is slow to heal. The otherconsists of large and painful abscesses on the chest and in the inguinal and abdominalregions. It may also affect camels, deer, mules, and bovines.C. pseudotuberculosis has two serotypes. Serotype 1 predominates in sheep andgoats, and serotype 2 in buffalo and cows. It produces an exotoxin, phospholipaseD, which gives the bacteria much of its virulence by increasing vascular permeability.The other virulence factors are a thermostable pyogenous factor that attractsleukocytes and a surface lipid that is toxic to leukocytes.C. renale is the most frequent agent in the group that causes pyelonephritis. It isalso responsible for many cases of cystitis and ureteritis, particularly in cows. Thisbacteria produces diphtherial inflammation of the bladder, ureters, kidneys, andpelvis. It can be found in healthy cows in herds with sick animals. C. renale alsoaffects horses and sheep sporadically. C. pilosum is not very virulent and is onlyoccasionally the agent of pyelonephritis. C. cystitidis causes severe hemorrhagiccystitis, followed by pyelonephritis. C. bovis is usually a commensal in the udderand is only sometimes the primary agent of mastitis.C. ulcerans is a commensal in bovines and horses. It has been isolated frommilk and is presumed to occasionally cause mastitis in cows (Lipsky et al., 1982).An outbreak of gangrenous dermatitis caused by C. ulcerans occurred inRichardson ground squirrels (Spermophilus richardsonii) captured within the citylimits of Calgary (Canada). Between two and five months after capture, 63 (18%)of the animals fell ill with symptoms of dermatitis and cellulitis. Some of the 350squirrels captured died, probably due to toxemia and/or septicemia, and had lesionsfrom acute necrotic dermatitis over a large part of their bodies. Pharyngitis wasfound in 4 of the 10 that were examined (Olson et al., 1988). The infection isassumed to have spread through bites, in a manner similar to that described inmonkeys (May, 1972).Most infections due to C. kutscheri in rodents are subclinical. Clinical cases shownasal and ocular secretion, as well as dyspnea, arthritis, and cutaneous abscesses thatform gray nodules some 15 mm in diameter. Upon autopsy, abscesses are found inthe liver, kidneys, lungs, and lymph nodes. Diagnosis can be performed through cultureand isolation of the etiologic agent or serology (ELISA, complement fixation,agglutination). Treatment with penicillin can prevent the appearance of clinicalsymptoms in animals in an affected colony, but does not eliminate carrier status(Fraser et al., 1991).C. diphtheriae is an exclusively human pathogen. However, in an outbreak thatoccurred in a colony of 300 guinea pigs in Nigeria, 60 died with pneumonia lesions,endometritis, and slight intestinal congestion. C. diphtheriae was considered thecause of death, since it was isolated from the lungs and heart blood. The source ofinfection could not be determined (Okewole et al., 1990).Treatment with high doses of penicillin is effective if begun early in the course ofthe disease.Source of Infection and Mode of Transmission: The corynebacteria describedhere are considered zoonotic, with the exception of C. diphtheriae, for which thereservoir is man and transmission is from human to human.