
Pneumonia is more prevalent among people living in areas with a high density of livestock farms. The risk of pneumonia is higher if people live within 2000 metres of a goat farm. Bacteria have been found in the goat stables on these farms that may offer an explanation for these pneumonia cases, since these bacteria have also been found in the surrounding area and/or in people living near the goat farms. These findings are from the third research phase in the Livestock Farming and Residential Health programme (VGO-III).
It was already known that pneumonia was more prevalent in areas with a high density of livestock farms, as shown in VGO-I and VGO-II. This has now been confirmed in VGO-III. In particular, people living in residential proximity of goat farms have an additional risk of pneumonia. The risk is highest for the people living closest to the farms.
VGO-III consisted of a range of sub-studies, in which various methods were used to explore which pathogens could be causing the pneumonia cases.
Various pathogens present in stables, in outdoor air and in people
More than thirty different types of bacteria that can cause pneumonia in humans were found in the air samples of goat farm stables. Twenty-three of these thirty types were also found in patients, local residents, goat farmers, and/or in the outdoor air around goat farms.
No direct causality
It is difficult to prove that the bacteria found in the goat stables were the direct cause of the pneumonia cases in people living in the area around goat farms. However, the 23 types of bacteria that were found may offer an explanation for the higher incidence of pneumonia. This is because they were found in the air samples taken in the stables, in the area around the stables, and/or in the people who were tested.
Manure and bedding
VGO-III investigated manure, bedding and air samples taken in the stables. The findings showed that many of the airborne bacteria in the stables came from a mixture of manure and bedding. The goats walk on this mixture, which covers the floor in the stable. This is how goats are kept at all the farms covered in the research, and nearly all goat farms in the Netherlands.
Reduce levels of airborne pathogens in goat stables
Further research is advised on whether the levels of airborne pathogens at goat farms can be lowered. The aim is to reduce exposure to airborne pathogens for local residents.
About the study
In the first two phases of the research programme (VGO-I and VGO-II), it was found that people living in the Dutch provinces of Noord-Brabant and Noord-Limburg in areas that have a high concentration of livestock farms were less likely to suffer from asthma and allergies. Conversely, pneumonia was more common in these areas, especially among people living near a goat farm. VGO-III researchers investigated whether this was also the case from 2014 to 2019. To that end, the research area was expanded temporarily to include areas in the Dutch provinces of Utrecht, Gelderland and Overijssel.
This phase also included research on the causes of these pneumonia cases. Various sub-studies looked at this topic:
- In a scientific literature review, VGO-III researchers explored which pathogens occur in goats and can cause pneumonia in humans.
- Then various sub-studies looked at which pathogens were present in patients, local residents and goat farmers.
- Researchers took various samples in the animal stables at goat farms to check for the presence of pathogens. They also took outdoor air samples at houses in the area around goat farms.
- Finally, VGO-III researchers looked at whether the pathogens found in air samples from goat stables were also found in the other sub-studies. They also investigated the possible source of the pathogens in the air samples.
The third phase of the Livestock Farming and Residential Health programme (VGO-III) is a joint initiative of the National Institute for Public Health and the Environment (RIVM), the Interfaculty Research Institute for Veterinary Medicine, Medicine and Science at Utrecht University (IRAS), Wageningen University & Research (WUR) and the Netherlands Institute for Health Services Research (Nivel).