Notification data and criteria during a large Q-fever epidemic reassessed.

Area of Science:

• Veterinary Public Health
• Infectious Disease Epidemiology
• Clinical Microbiology

Background:

• The Netherlands experienced a significant Q-fever epidemic from 2007 to 2010, with over 4000 confirmed cases.
• Increased public awareness and healthcare provider knowledge influenced health-seeking behaviors during the epidemic.
• Laboratory diagnostic workflows and case notification criteria were modified in response to the evolving epidemic.

Purpose of the Study:

• To analyze how modifications in laboratory procedures and notification criteria affected the monitoring and interpretation of the Q-fever epidemic.
• To evaluate the impact of diagnostic workflow changes on case ascertainment and reporting.
• To compare Dutch notification criteria with international standards for acute Q-fever.

Main Methods:

• Review of articles detailing laboratory procedures and changes to notification criteria during the epidemic.
• Comparison of regional laboratory data with notifications to Public Health Services and national infectious disease registers.
• Analysis of international notification criteria for acute Q-fever.

Main Results:

• Diagnostic workflow changes included implementing ELISA IgM phase II and PCR screening.
• Serological results (IgG/IgM positive) often indicated past infections due to increasing background seroprevalence.
• IgM positivity alone became insufficient for diagnosing acute Q-fever, requiring confirmation via IgG seroconversion or PCR.

Conclusions:

• Adjustments in diagnostic criteria were necessary due to increased background seroprevalence and evolving understanding of Q-fever serology.
• Confirmation of acute Q-fever requires a combination of serological markers (IgG seroconversion) and molecular methods (PCR).
• Harmonizing Q-fever notification criteria internationally is challenging due to variations in sero-epidemiology.