Farmers know a lot about the microscopic elements affecting the health of their dairy herds and crops.
As researchers at the Marshfield Clinic Research Institute in Marshfield, Wisconsin, we are taking a fresh look at agricultural microbiomes (the clusters of bacteria, fungi and viruses that live together) in different farm environments. This work will further define the array of farm micro-organisms and explore both the negative and positive impacts on health.
Nasal and gut micro-organisms in dairy workers
Allergies and disease that challenge the human immune system have been linked to a lack of exposure to biodiversity in a person’s environment. In a previous study, we hypothesized healthy dairy farmers and workers have more variety and richness of bacteria in their mouths and noses than healthy non-farmers, e.g., office workers living in nearby suburban settings.
We also hypothesized this increased diversity and richness is due to exposure to a greater biodiversity in the dairy environment.
We swabbed the noses and mouths of both groups, comparing the kinds and amounts of micro-organisms between them. The nasal samples from dairy workers showed high diversity, with hundreds of unique kinds of micro-organisms that reflected environmental/occupational exposures.
Dairy workers tended to harbor up to two times greater exclusive kinds of bacteria in their noses and mouths than did non-farmers. Additionally, the nasal environment of the dairy workers had a low amount of illness-causing bacteria. This suggests people with a rich and diverse community of micro-organisms in their noses and mouths have reduced chances of being infected with illness-causing viruses or pathogens.
Future studies will analyze what micro-organisms living in and on the bodies of livestock could offer humans protection from acute and chronic diseases. For example, a lot could be learned by comparing the micro-organisms in the guts of dairy cows and dairy workers, comparing the biological samples of each group.
The micro-organisms in the human digestive system have major connections to our health. Similar to the nasal passages, it is possible environmental factors from dairy farms provide gut bacteria that promote health. A key ingredient in this environment is likely the shared bacteria between animals and humans. While zoonotic diseases have been more thoroughly researched, the “good” bugs have received less scientific attention.
Wisconsin infant study
The Wisconsin Infant Study Cohort (WISC) study seeks to follow nearly 200 farm kids and 200 non-farm kids as their immune and respiratory system develop, from in utero until 4 to 7 years old. Researchers believe farm environments – specifically those with large livestock, like dairies – and farm lifestyles may provide an individual with greater immune strength and decrease their likelihood of developing allergies and asthma.
To investigate, this research team is collecting and comparing samples and health data. Samples range from mucus, cord blood, skin swabs, dust from homes and barns, and blood draws. Health data being collected includes occupational exposures, documented infections, allergic reactions and respiratory difficulties.
Combined, the samples and health data drive new research questions about what may promote health or be hazardous in a child’s environment.
For example, one way to test for exposures to micro-organisms in homes and barns is through the use of electrostatic dust collectors. These cloth pads or petri dishes are set up in common rooms of the homes and in barns. In preliminary analysis, these tests showed babies growing up in farm homes are exposed to a greater number and greater richness of microbes. For the most part, it is thought these are “good bacteria.”
In terms of the health data, preliminary data analysis reveals farm kids are associated with health benefits. Kids with early farm exposure appear to be less likely to develop viral illnesses, especially colds, in early life. The early results show babies on farms are also less likely to develop atopic dermatitis or eczema.
These are itchy patches of skin rashes that can be the first sign of allergies and are often a precursor to asthma. As more children reach 2 years old, we will also be able to test for environmental factors associated with health benefits in children who grow up in non-farm homes.
The WISC study is now entering a five-year renewal. More families will be recruited to participate, and those already involved will have the option to continue. The team will also be recruiting 50 Amish children in the coming years.
The WISC study is supported by a grant from the National Institutes of Health, in collaboration with the University of Wisconsin Asthma and Allergic Diseases Clinical Research Center. Visit Marshfield Clinic Research Institute or email Bendixsen.
As technology improves and becomes more readily available, researchers will be able to further explore and describe the diversity of agricultural microbiomes. These studies will point to ways to prevent agricultural illnesses as well as how the farm environment can be health-promoting.
ILLUSTRATION: Illustration by Philip Warren.
Sanjay Shukla, Ph.D., is a microbiologist and senior research scientist at the Center for Human Genetics. His agricultural nasal and gut microbiome studies are supported by the Centers for Disease Control – National Institute for Occupational Safety and Health. The department is housed at the Marshfield Clinic Research Institute in Marshfield, Wisconsin.
