Human–livestock contacts and their relationship to transmission of zoonotic pathogens, a systematic review of literature

Klous, Gijs; Huss, Anke; Heederik, Dick J.J.; Coutinho, Roel A.

Zoonotic infectious diseasesdiseases transmitted from vertebrate animals to humansaccount for an estimated 60% of all human infectious diseases [1] . The rise of zoonotic diseases in humans began after the introduction of agriculture and the domestication of animals when humans started living in large numbers together, in close contact with other vertebrate animals [2, 3] . Nowadays, livestock associated infectious diseases are still a major threat to human health, as recently illustrated by the outbreak of pig origin H1N1 influenza A pandemic in 2009 or the emergence of camel-origin Middle-East Respiratory Syndrome Coronavirus [4] [5] [6] . The occurrence of a zoonotic disease may lead to large economic losses in the agricultural sector [7] [8] [9] [10] [11] [12] [13] [14] . When it comes to recent emerging infectious diseases, zoonoses again account for the majority of the newly introduced infectious diseases to the human population. Although zoonoses with a wildlife origin dominate among emerging pathogens, livestock associated zoonotic diseases occur mainly in densely human populated areas in the world [15] and can therefore have a considerable public health impact. In developing countries humans often live close to their livestock [16] [17] [18] ; in developed countries there are mainly occupational contacts with large numbers of live [19] , ill [20] or dead animals [21] [22] [23] [24] , but there are also reports of micro-organism transmissions via the environment [25, 26] or after brief contact [27, 28] .