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

ZOONOTIC TUBERCULOSIS 291ent in wild animals, particularly the opossum (Trichosurus vulpecula). Cutaneouslesions were observed in 58% of the cats, with a pyogranulomatous reaction andcoagulative necrosis. These lesions had not been described earlier in other geographicareas, where the prevalence of tuberculosis among cats was 2% to 13%before successful control and eradication programs were implemented. Presumablythe cats acquired the infection when feeding on tuberculous wild animals (De Lisleet al., 1990). Several cases of reinfection of cattle herds by tuberculous cats havebeen described.WILD, CAPTIVE, AND DOMESTIC ANIMALS: Animals living in the wild, far from manand domestic animals, generally do not contract tuberculosis. On the other hand,captive animals in zoos, on pelt farms, in laboratories, and in family homes may beexposed to infection. Monkeys are susceptible to M. tuberculosis as well as M.africanum and M. bovis. Almost 70% of the isolations from these animals are strainsof the human bacillus, some are M. africanum, and the rest are M. bovis. The diseaseis contracted via the respiratory or digestive route. The infection can be propagatedfrom monkey to monkey and constitutes a grave problem for colonies kept inscientific institutions and zoos. These animals can retransmit the infection to man.It is not unusual to find tuberculous pet monkeys that may have been infected beforetheir acquisition or through contact with a family member. In France, infection dueto M. africanum has been described in three chimpanzees and a Cercopithexus monkey.Three of these animals belonged to a scientific center and one of the chimpanzeesbelonged to a zoo. Since M. africanum has properties intermediate betweenthose of M. bovis and M. tuberculosis, it is possible that infection by M. africanumwas not described earlier in nonhuman primates because the species type of strainsisolated previously was misidentified. It still has not been determined whether theinfection was transmitted to the primates by man or acquired in their natural foresthabitat (Thorel, 1980).Tuberculosis is a problem in cervids, particularly now that deer farming hasbecome popular in several countries. Tuberculosis in deer is caused primarily by M.bovis. This presents the possibility of retransmission of the infection to cattle incountries that are practically free of bovine tuberculosis. It is also a potential risk forpeople who are in contact with these animals. M. bovis has been found in free-roamingdeer, probably living near cattle operations in Canada, the US (Hawaii), GreatBritain, Ireland, and Switzerland. Deer most exposed to the disease are captive animalsin zoos or deer on farms.The first report on infection in farmed deer comes from New Zealand, in a regionwhere the disease exists in cattle and opossum (Trichosurus vulpecula). An outbreakof bovine tuberculosis was recorded on farms in England that imported red deer(Cervus elaphus) from an eastern European country. Upon necropsy of 106 deer, 26were found to be infected and 19 had visible lesions. The tuberculin test had 61.3%specificity and 80% sensitivity (Stuart et al. 1988). In a case of this type, the testwould be used primarily to determine whether or not tuberculosis exists on a farm.An eradication program has been established in New Zealand based on the tuberculintest and slaughter of reactors, but the high percentage of false negatives hamperssuccess.In South Australia, an outbreak was reported in 1986 in three herds of anotherdeer species (Dama dama). Upon necropsy, 47 of 51 animals were found to have