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Reassessing a large-scale syphilis epidemic using an estimated infection date
Christina M Schumacher1, Kyle T Bernstein, Jonathan M Zenilman
1Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
Sexually Transmitted Diseases
|October 29, 2005
Summary
Using estimated infection dates, not report dates, provides a more accurate picture of syphilis epidemics. This helps avoid lag-time bias and improves disease control measures for public health.
Area of Science:
- Epidemiology
- Public Health
- Infectious Disease Dynamics
Background:
- Accurate syphilis case ascertainment is crucial for effective disease control.
- Epidemic curves commonly use report dates, which can introduce lag-time bias.
Purpose of the Study:
- To reassess a large syphilis epidemic by utilizing an imputed infection date.
- To evaluate the impact of using estimated infection dates versus report dates on epidemic curve analysis.
Main Methods:
- Comparison of two epidemic curve types: one based on report date and another on estimated infection date.
- Utilized the 1993-2003 Baltimore syphilis epidemic as a case study.
- Conducted a sensitivity analysis varying stage-specific incubation periods.
Main Results:
- Report date curves inaccurately reflected infection curves during epidemic growth periods.
- Peaks in report curves did not align with infection curve peaks by the expected lag time during hyperendemic periods.
- Reporting data tended to underestimate infections during growth and overestimate during hyperendemic periods, irrespective of incubation period assumptions.
Conclusions:
- Lag-time bias is a significant concern when relying solely on report dates for syphilis epidemic analysis.
- Health departments should consider incorporating estimated infection dates for more precise epidemic assessment and control strategies.