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.

Respiratory health can be affected by many sources, including livestock farming in the vicinity of a residence. In Germany, reduced respiratory health of residents was linked to the presence of Confined Animal Feeding Operations, industrially managed livestock stables, near their home address. Although these studies did not focus on infectious diseases, they did indicate effects of livestock keeping on the health of nearby residents [94, 95] . In a Dutch study investigating LA-MRSA presence in a rural population, only direct animal contact was found as a risk factor [96] . When the Danish national human MRSA database was checked for a livestock-associated MecC resistance gene, this was mainly found in samples from people living in rural parts of the country and animal contact was an important risk factor. Still, the gene was also discovered in human MRSA samples from people living in rural areas, but having no livestock contact [97] . An attempt to identify risk factors for Extended-Spectrum Beta-Lactamase (ESBL) Enterobacteriaceae carriage among people living in high-and low-poultry density areas in the Netherlands showed no elevated risk between the distance of positive poultry farms from the home and ESBL carriage of residents [98] . For Q-fever, however, the link between living close to infected farms and human cases of the disease is well established [25, 26, 88] . In the Netherlands, a large outbreak occurred in recent years and an exposure-response-like relationship was found for the number of goats within 5 km of the home address and human cases [26] . In Germany, a specific flock of sheep could even be identified as the source of a human Q-fever outbreak in a village [99] . In Italy, where in some areas free-range sheep herding is still common practise, the passing of three flocks of infected sheep through a village led to an outbreak of Q-fever [100] .