Occurrence and seasonality of Campylobacter spp. in Portuguese dairy farms

Abstract

The growing idea that natural products are better for consumption is creating behaviors that can lead to food safety problems and an increase of healthcare costs. One of the trending products is raw milk, which in some countries is sold by vending machines outside dairy farms. Campylobacteriosis is the most common gastrointestinal infection in humans in the European Union since 2005. Several outbreaks have been associated with the consumption of raw milk contaminated with Campylobacter spp. In the present study, the occurrence and seasonality of Campylobacter spp. in raw cow's milk were determined. Other samples from the dairy farm environment were also analyzed to understand the possible routes of contamination. The study was conducted from November 2020 to September 2021 in randomly selected dairy farms located in northern Portugal. One liter of milk was collected from bulk cooling tanks transported to the laboratory and analyzed within 24h. Campylobacter spp. detection and identification were performed using real-time PCR methodology and confirmation followed ISO standards. From 100 dairy farms evaluated, the occurrence of Campylobacter spp. was estimated at 4.0% in raw cow's milk samples. In the samples from the environment of the farms, only contaminated fecal samples were found, corresponding to an occurrence of 4.2%. Positivity was observed in summer months. The results of this study indicate the potential risk of campylobacteriosis after the consumption of raw milk. Consumers who seek raw milk for health reasons should be aware of the risk, especially if they belong to vulnerable groups. Moreover, it raises the question of how climate change will impact food safety, suggesting that routine surveillance for zoonotic pathogens should be implemented in dairy farms.