Building the Evidence Base for the Prevention of Raw Milk-Acquired Brucellosis: A Systematic Review

Abstract

Background: The scientific evidence of the health risks associated with the consumption of raw milk has been known for a long time. However, less clear is the impact of acquiring infectious diseases from raw milk consumption in the United States (US) due to incomplete reporting of cases and the complex factors associated with the sale and consumption of raw milk. Investigations of this current study focused on human brucellosis, one of the infectious diseases commonly acquired through the consumption of raw milk and milk products, and which continues to be a public health threat worldwide. Methodology: A qualitative systematic review of the sources of opinions that contribute to the increased trend of raw milk sales and consumption in the US was conducted. Results: Interestingly, opinions about the sale of raw milk and/or the benefits arising from its consumption varied by US region, with the proportion of messages supporting raw milk consumption being highest in the Northeast compared to other US regions. Several evidence gaps and factors that possibly contribute to the increased prevalence of raw milk-acquired brucellosis were identified including inadequate monitoring of the raw milk sales process and lack of approved diagnostic methods for validating the safety of raw milk for human consumption. Conclusions: The unavailability of data specifying brucellosis cases acquired from raw milk consumption have precluded the direct association between raw milk and increased brucellosis prevalence in the United States. Nevertheless, the evidence gaps identified in this study demonstrate the need for intensified surveillance of raw-milk acquired infectious diseases including human brucellosis; establishment of safety and quality control measures for the process of selling raw milk; and design of an effective strategy for the prevention of raw milk-acquired infectious diseases including brucellosis. Overall, for the first time, this study has not only shown the gaps in evidence that require future investigations, but also, variations in the perception of raw milk consumption that may impact disease acquisition in different US regions.

Keywords: brucellosis; evidence; gaps; raw milk; systematic review.

Figure 1

Theoretical framework of the factors related to the likelihood of raw-milk acquired brucellosis. An increase in raw milk sales and promotion through media advocacy could lead to increased purchase and consumption, ultimately leading to an increase of prevalence of raw milk-acquired brucellosis.

Figure 2

PRISMA flow chart of the systematic review of public opinions about raw milk consumption in the United States.

Figure 3

Accessibility of the public to the varying information sources that support or are against the consumption of raw milk.

Figure 4

Sources of information categorized based on varying reactions to the consumption of raw milk in the United States. The graph represents the percentage of messages that are against, neutral or in support of the consumption of raw milk.

Figure 5

Public opinions categorized based on varying reactions to raw milk consumption in the United States. Neutral or Supportive: The graph represents the number of publications that were indifferent about or advocated the consumption of raw milk. Media from the Northeast had the most promotion of raw milk consumption.

Figure 6

Number of confirmed cases of brucellosis in the US reported to the CDC. Outbreak of raw milk related diseases including brucellosis have been reported mostly in states that permit the sale of raw milk. Lovacore Index—A measure of the commitment of individuals to local healthy food. Legal status of the sale of raw milk in the United States.

Figure 7

An analytical framework is proposed for understanding the complex factors associated with the increased prevalence of raw milk-acquired brucellosis in the United States. The circles represent priority areas and gaps in evidence that require additional research to facilitate the establishment of the safety and quality control measures for the raw milk sales process, and also design an effective strategy for the prevention of raw milk-acquired brucellosis.