A newly published study in Agricultural Economics has provided the first in-depth analysis of the economic impact of Salmonella Dublin (SDB) infections on dairy farms—revealing that even mild infections in cows can significantly hurt farm productivity and profitability.
What Is Salmonella Dublin?
Salmonella Dublin is a contagious strain of Salmonella found primarily in cattle. While it often shows no symptoms in cows, it poses a serious threat to human health—causing severe illness and even death in some cases. It’s also difficult to treat because of antibiotic resistance.
Despite its risks, farmers are often unaware of infections in their herds because cows can carry the bacteria without showing signs of illness. This has made it challenging to encourage widespread adoption of control measures.
What the Study Found
The research, which examined data from nearly every dairy farm in Denmark, used milk samples to detect levels of SDB antibodies. These samples, measured by “Optical Density Counts” (ODC), were used to track infections and compare them to key economic indicators on each farm.
Key findings include:
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Milk Production Losses: Even low levels of SDB infection were linked to noticeable drops in milk yield. Farms with the highest ODC levels produced up to 21 litres less milk per cow per month, compared to uninfected herds.
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Calf Mortality Increases: Infections were associated with significantly higher death rates in calves. In heavily infected herds, mortality increased by up to 17 calves per 1,000 births.
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Higher Costs: Infected herds faced rising costs for veterinary care, medications, and labor related to biosecurity—while feed and energy costs remained largely unchanged.
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Long-Term Economic Risk: The costs added up, even in herds where cows showed no outward signs of illness. This silent impact makes SDB economically damaging over time.
Why This Matters
This research provides strong evidence that undetected or ignored infections carry real financial consequences. Farms that don’t actively monitor or manage SDB may be losing money through reduced production and higher calf losses without even realizing it.
Looking Ahead
The authors suggest that stronger incentives and more support are needed to help farmers take action against SDB—especially since controlling the disease not only protects human health but also improves farm performance. Regular testing, better biosecurity, and coordinated efforts to reduce transmission could offer both health and economic benefits.
The study underscores a simple message: Preventing invisible infections can protect both public health and farm profitability.
