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

4 BACTERIOSESby fistulous tracks may occur. The abdominal form usually occurs after surgery andappears as an encapsulated lesion that often becomes localized in the cecum and theappendix, where it produces hard tumors that adhere to the abdominal wall.The generalized form is infrequent and results from the erosive invasion of bloodvessels and lymphatic system, resulting in liver and brain disease.In recent years, reports of actinomycosis in the genital tract of women usingintrauterine contraceptive devices have multiplied, with the rate of infection increasingin proportion to the duration of IUD use. In one study (Valicenti et al., 1982),the infection was found in 1.6% of women in the general population of IUD usersand in 5.3% of those attending the clinics. Another study of 478 IUD users found arate of infection of 12.6% based on Papanicolaou (Pap) smears (Koebler et al.,1983). Attempts to isolate the bacteria in Pap smears rarely yield positive results.However, A. israelii is also isolated from the genital tract of women who do not useIUDs, indicating that actinomyces are part of the normal flora (Burden, 1989). In thevast majority of cases, colonization by actinomyces produces only a superficial orasymptomatic infection.Treatment consists of prolonged high doses of penicillin (weeks or months).Erythromycin, clindamycin, and tetracycline may also be used. Surgical drainage ofabscesses is important. In women with an endometrium colonized by actinomyces,removing the IUD is sometimes enough for the endometrium to return to normal.The Disease in Animals: A. bovis is the principal agent of actinomycosis inbovines and, occasionally, in other animal species. In bovines, it centers chiefly inthe maxillae where it forms a granulomatous mass with necrotic areas that developinto abscesses. These open via fistulous passages and discharge a viscous, odorless,yellow pus. The pus contains small, yellow, sulphur granules, which are rosetteshapedwhen viewed under a microscope. In some cases chewing becomes very difficult,and the animal stops eating and loses weight.The cost-benefit ratio must be measured when treating bovine and equine actinomycosis.Long-standing chronic lesions do not respond readily to treatment. If thelesions are small and circumscribed, they may be removed surgically. In other cases,curettage can be performed on the abscesses and fistulas, which are then packedwith gauze saturated with iodine tincture. Medical treatment is the same as forhuman actinomycosis, preferably using penicillin.In swine the etiologic agent localizes principally in the sow’s udder, where it givesrise to abscesses and fistulas. Its pathway of penetration is the lesion caused by theteeth of suckling pigs. This infection is attributed to Actinomyces suis, whose taxonomyis still uncertain.In dogs, the disease produces cervicofacial abscesses, empyemas accompanied bypleurisy and osteomyelitis, and, more rarely, abdominal abscesses and cutaneousgranulomas. The most common agent encountered prior to 1982 was A. viscosus(Hardie and Barsanti, 1982).Source of Infection and Mode of Transmission: The infection is endogenous.Actinomyces develop as saprophytes within and around carious teeth, in the mucinon dental enamel and in the tonsillar crypts. In studies carried out in several countries,actinomyces have been found in 40% of excised tonsils and have been isolatedin 30% to 48% of saliva samples or material from decayed teeth, as well asfrom the vaginal secretions of 10% of women using IUDs (Benenson, 1992).