Focus into the nose of pig farmers

There are approximately 600 communicable diseases between humans and animals. Knowing in detail the close links between the health of pigs and that of breeders is necessary to meet public health challenges but also in order to conceive sustainable and economic development of the pig industry.

In terms of respiratory and general health, it is also necessary to accumulate knowledge on the exposure of farmers to microbes present in the air. This is why the team of Professor Caroline Duchaine, an expert in the study of bioaerosols (biological content in the air, sucha as microbes for example), has been collaborating for many years with hog farmers in Quebec to characterize bioaerosols in barns as well as the exposure of pigs and breeders to them.

This Laval University team compared the microbial content of the ambient air of hog barns or wastewater treatment plants (used here as a control environment) with that of the nasopharyngeal flora of non-smoking adults, having not consumed antibiotics recently. The upper respiratory tract consists of the nose, mouth and throat and includes the nasopharyngeal area. The flora (microbes) of it is easily removed with a swab (a long cotton swab). The human subjects in this study included: pig breeders, workers at wastewater treatment plants in Quebec, and university students who had never been exposed to an agricultural environment.

Treatment plant air is heavily loaded with bioaerosols, as is the air in pen houses. However, the microbial diversity of ambient air in barns and in the upper respiratory tract of hog producers is much richer (i.e. more diverse) than that of workers in wastewater treatment plants. In addition, the microbial flora in the air of barns is very similar to that of the nasopharynx of breeders, which is not the case between the air in stations and the upper respiratory tract of their workers. Professional and residential exposure in hog barns thus seems to modify in the more or less long term the microbial flora of the upper respiratory tract of pig producers. Sampling the microbial flora of the nasopharynx could be an excellent substitute for monitoring farmers' exposure to air microbes. The size of the particles (dust) present in the air could influence the colonization of the respiratory tracts. Therefore explaining the absence of correlation of microbial diversity in wastewater treatment plants (less dust) and that positive between microbial diversity of nasopharynx of pig breeders and bioaerosols. The hypothesis is to be verified by studying other environments rich in dust (composting factories, peat bagging factories).

Highlights for the risk to the health of breeders with regard to their professional exposure. By comparing pork producers to students (urban population in general), the researchers show that farmers are more exposed to certain risks. In particular, the flora of the nasopharynx of breeders contains various bacteria possibly pathogenic to humans (Staphyloccus aureus resistant to methicillin, Clostridium difficile, Listeria) and genes for resistance to antibiotics of importance in human health (cephalosporin, colistin) and zinc resistance genes.

In this study, the general health of the participants was not analyzed. It is therefore impossible to deduce that the breeders are sicker or healthier. The hygienic hypothesis that microbial exposure at a young age (child raised on a farm) can help reduce the development of certain diseases in adulthood (allergies) was also not evaluated. The results reveal, however, that sampling the microbial flora of the nasopharynx is a simple and inexpensive way to: 1) study and monitor the exposure of farmers to air microbes, 2) to test the hygienist hypothesis and above all 3) identify and monitor risk markers for farmers' health.

Source: Bioaerosols Play a Major Role in the Nasopharyngeal Microbiota Content in Agricultural Environment. Hamza Mbareche, Marc Veillette, Jonathan Pilote, Valérie Létourneau and Caroline Duchaine. Int. J. Environ. Res. Public Health 2019, 16, 1375; doi:10.3390/ijerph16081375. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518280/