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

88 BACTERIOSESThe Disease in Man: Pathogenic species of Clostridium may be found as simplecontaminants in any type of traumatic lesion. When infection occurs, the microorganismsmultiply and produce gas in the tissues. Gas gangrene is an acute and seriouscondition that produces myositis as its principal lesion. The incubation periodlasts from six hours to three days after injury. The first symptoms are increasing painaround the injured area, tachycardia, and decreased blood pressure, followed byfever, edematization, and a reddish serous exudate from the wound. The skinbecomes taut, discolored, and covered with vesicles. Crepitation is felt upon palpation.Stupor, delirium, and coma develop in the final stages of the disease. The infectionmay also begin in the uterus following an abortion or difficult labor. These casesshow septicemia, massive hemolysis, and acute nephrosis, with shock and anuria.C. perfringens type A, alone or in combination with other pathogens, caused 60%to 80% of gas gangrene cases in soldiers during the two world wars.Treatment consists primarily of debridement with extensive removal of theaffected muscle. Amputation of the limb affected by gas gangrene should be considered.Penicillin G is generally the preferred antibacterial. However, better resultshave been obtained with clindamycin, metronidazole, rifampicin, and tetracycline(Bartlett, 1990). Mortality is still very high.The Disease in Animals: C. septicum is the principal agent of clostridial woundinfection, known as “malignant edema.” C. septicum produces four toxins that causetissue damage. The incubation period lasts from a few hours to several days. This diseaseis characterized by an extensive hemorrhagic edema of the subcutaneous tissueand intermuscular connective tissue. The muscle tissue turns dark red; little or no gasis present. The infected animal exhibits fever, intoxication, and lameness. Swellingsare soft and palpation leaves depressions. The course of the disease is rapid and theanimal can die a few days after symptoms appear. Cattle are the most affected species,but sheep, horses, and swine are also susceptible. The infection is rare in fowl.C. perfringens type A is sometimes responsible for infection of traumatic woundsin calves, lambs, and goats. As in man, the infection gives rise to gas gangrene.Edema with a large amount of gas develops around the injury site, spreads rapidly,and causes death in a short time.In animals, as in man, other clostridia (e.g., C. novyi, C. sordelli, and C. histolyticum)can cause wound infection and the wound’s bacterial flora may be mixed.Treatment with high doses of penicillin or broad-spectrum antibiotics may yieldresults if administered at the onset of disease.Source of Infection and Mode of Transmission: Clostridia are widely distributedin nature, in the soil, and in the intestinal tract of man and most animals. Thesources of infection for man and animals are the soil and fecal matter. Transmissionis effected through traumatic wounds or surgical incisions. Gas gangrene can alsooccur without any wound or trauma (endogenous or spontaneous gas gangrene) inpatients weakened by malignant disease and those with ulcerative lesions in the gastrointestinalor urogenital tract or in the bile ducts (Finegold, 1977). In animals, theinfection may originate in minor wounds, such as those produced by castration, taildocking, and shearing.Role of Animals in the Epidemiology of the Disease: Wound clostridiosis is adisease common to man and animals, not a zoonosis.