Poultry 2026, 5, 17
06 March 2026
A recent study published in the journal Poultry highlights the significant impact of drinking water quality on the stability and effectiveness of live attenuated Salmonella vaccines used in the poultry industry. Because zoonotic Salmonella remains a leading cause of global foodborne disease, the industry relies heavily on live vaccines to reduce pathogen colonization in flocks. Researchers found that several chemical and physicochemical parameters in farm water can substantially compromise vaccine stability.
The study examined a range of dissolved ions and metals commonly present in agricultural water sources. Parameters such as fluoride, nitrate, and sulfate showed negligible effects, whereas certain metals produced a pronounced, dose-dependent reduction in vaccine viability. High concentrations of aluminum (>0.5 mg/L) and iron (>1 mg/L) caused severe reductions in viable vaccine counts, particularly when the vaccine remained in the drinking system for more than four hours. Manganese proved especially detrimental: at concentrations of 4 mg/L or higher, viable vaccine organisms declined to less than 10% within four hours, irrespective of water temperature. Arsenic did not affect the vaccine at typical drinking-water concentrations, but higher levels eventually compromised stability.
Residual disinfectants in water lines were highly effective at inactivating live vaccines. Even low concentrations of free chlorine or chlorine dioxide caused substantial reductions in vaccine counts. The use of chlorine neutralizers provided strong protection against these oxidizing agents. In contrast, hydrogen peroxide rapidly inactivated the vaccine, and stabilizers offered no measurable protection against it.
The researchers emphasize that poor administration practices remain a leading cause of vaccine failure. They recommend testing water pH and mineral content prior to vaccination, as extreme pH values (below 5 or above 8) impair vaccine stability. The use of chlorine neutralizers to eliminate residual chlorine and buffer the water is also advised. In addition, water treatments, particularly hydrogen peroxide, should be discontinued sufficiently in advance of vaccination to ensure that no residues remain in the distribution lines.
The effectiveness of a vaccination program depends not only on the vaccine itself but also on the quality of the medium through which it is delivered.
