Usefulness of seroconversion rates for comparing infection pressures between countries

Area of Science:

• Epidemiology
• Immunology
• Public Health

Background:

• Salmonella is a common cause of foodborne illness, but actual infection levels are unknown.
• Current surveillance systems lack sensitivity, hindering international comparisons of Salmonella burden.
• Undiagnosed and asymptomatic Salmonella infections contribute to underestimation of disease prevalence.

Purpose of the Study:

• To estimate Salmonella seroincidence, including asymptomatic infections, in three European countries.
• To compare infection rates across countries using a standardized serological method.
• To evaluate the applicability of antibody measurements for assessing national surveillance systems.

Main Methods:

• Utilized novel methods to convert Salmonella antibody measurements into seroincidence estimates.
• Applied this methodology to cross-sectional serum samples from healthy populations in Denmark, The Netherlands, and Poland.
• Developed a Bayesian approach to calculate incidence rate ratios for inter-country comparison.

Main Results:

• Denmark and The Netherlands exhibited the lowest Salmonella seroincidence (84,169 infections/1000 person-years).
• Poland showed significantly higher seroincidence (547/1000 person-years).
• A 6.3-fold higher incidence was observed in Poland compared to Denmark (95% CI 3.3-12.5).

Conclusions:

• The developed methodology accurately estimates Salmonella seroincidence, accounting for asymptomatic infections.
• Significant variations in Salmonella infection rates exist between European countries.
• This approach is valuable for evaluating surveillance systems and informing control programs for foodborne pathogens.