Brucellosis as a world problem

Abstract

Brucellosis is one of the most widespread and economically the most ravaging of zoonoses. The occurrence of the acute, often incapacitating infection in man caused by Brucella melitensis usually coincides with occurrence of the infection in sheep and goats. Well-known foci of this infection have been identified in the Mediterranean basin, Central Asia and Latin America. Recent investigations in parts of Africa and India have shown that the infection is much more widespread than was previously suspected and that more foci remain to be discovered by the application of laboratory methods in epidemiological investigations. Bovine infection has a wider distribution and is more important than infection of sheep and goats as far as economic losses are concerned. Although the infection has been reduced by control measures to a low level of incidence in some countries of Europe and North America, its incidence in other parts of the world has actually increased because of emphasis on increased animal production and aggregation under poor hygienic conditions. This is particularly the case with dairy production units which have developed around rapidly growing urban centres in many developing countries. Although human infection with B. abortus may be mild, it can cause troublesome and intractable illness. The economic ravages of bovine brucellosis are tremendous and the losses in Latin America and the USA alone have been estimated by their respective governments to be 700 million dollars annually. The world figure must be truly staggering. Swine brucellosis is largely a problem of the Americas although a few foci have recently been discovered in other parts of the world, notably in Europe and Southern Asia. In the Americas, swine infection is second only to bovine brucellosis in its economic importance. A large number of human cases of B. suis infection are detected every year in the endemic areas. Other forms of brucellosis, e.g. B. canis in dogs and B. suis, biotype 4 in reindeer, have a limited distribution and are responsible for only sporadic human infections. B. ovis of sheep is more widespread but is generally confined to sheep. Annexes 1 and 2 show the reported incidence of brucellosis in man and animals. However, the officially reported data are generally incomplete and the actual incidence must in most cases be much higher than is shown in these tables. FAO and WHO have been assisting countries in which brucellosis is endemic by organizing control measures, providing training and reference materials, and by focusing coordinated research on problems which arise in these programmes. Some of the highlights of this work are outlined in the following paragraphs.