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

42 BACTERIOSESwere recorded in 1947, while in the period 1972–1981, the annual average was 224cases (CDC, 1982). In Denmark, where some 500 cases per year were reportedbetween 1931 and 1939, human brucellosis had disappeared by 1962 as a result ofthe eradication of the infection in animals. In Uruguay, where there is no animalreservoir of B. melitensis and where the few foci of B. suis had been eliminated(although they have recently been reintroduced through importation), the disease inhumans has almost disappeared since compulsory vaccination of calves was begunin 1964. China and Israel have been able to significantly reduce the incidence ofhuman brucellosis thanks to vaccination campaigns for sheep and goats. In the westernMediterranean area, there has also been a marked reduction of human brucellosiscases caused by B. melitensis due to vaccination of the small ruminants withthe Rev. 1 vaccine. In Spain, for example, the incidence fell from 4,683 cases in1988 to 3,041 in 1990.Occurrence in Animals: Bovine brucellosis is found worldwide, but it has beeneradicated in Finland, Norway, Sweden, Denmark, the Netherlands, Belgium,Switzerland, Germany, Austria, Hungary, the former Czechoslovakia, Rumania, andBulgaria, as well as other countries (Timm, 1982; Kasyanov and Aslanyan, 1982).Most European countries are free of bovine brucellosis (García-Carrillo and Lucero,1993). The large meat-producing countries, such as France, Great Britain, Australia,New Zealand, Canada, and the United States, among others, are free of bovine brucellosisor close to being so. Three important cattle-raising countries, Argentina,Brazil, and Mexico, still have limited control programs. A country-by-countryanalysis can be found in a monograph on bovine brucellosis (García-Carrillo andLucero, 1993). In the rest of the world, rates of infection vary greatly from one countryto another and between regions within a country. The highest prevalence is seenin dairy cattle. In many countries, including most of those Latin American countriesthat have no control programs, the data are unreliable. Nevertheless, available informationindicates that it is one of the most serious diseases in cattle in Latin Americaas well as in other developing areas. Official estimates put annual losses from bovinebrucellosis in Latin America at approximately US$ 600 million, which explains thepriority given by animal health services to control of this disease.Swine brucellosis is infrequent and occurs sporadically in most of Europe, Asia,and Oceania. In China, B. suis biovar 3 was introduced with breeding stock fromHong Kong in 1954 and spread rapidly through the southern part of the country (Luand Zhang, 1989). In many European countries, swine brucellosis shows an epidemiologicalrelationship to brucellosis caused by B. suis biovar 2 in hares (Lepuseuropaeus). With the new swine-breeding technology, swine have little access tohares and outbreaks have thus shown a marked decline. The disease has never beenpresent in Finland, Norway, Great Britain, and Canada. Many predominantlyMuslim countries and Israel are probably free of B. suis infection as a result of religiousbeliefs that have limited swine raising (Timm, 1982).In most of Latin America, swine brucellosis is enzootic and, while the availabledata have little statistical value, this region is thought to have the highest prevalencein the world. However, recent surveys of breeding operations for purebreds andhybrids in Argentina and Rio Grande do Sul (Brazil) have shown the percentage ofinfected herds to be low. The problem is possibly rooted in commercial operationswhere animals of different origins are brought together. Thus far, only B. suis bio-