Enhancing Influenza surveillance with provider collaboration in Houston, Texas; 2007-2008

Structured influenza surveillance is instrumental in estimating the extent and magnitude of influenza morbidity and mortality as well as providing the capacity for early detection and treatment. In December 2007, Houston Department of Health and Human Services (HDHHS) implemented a sentinel provider-based culture surveillance system in addition to its existing passive and syndromic monitoring systems.

Thirty (30) providers were randomly selected from the community-based clinical settings using the probability proportional sampling (PPS) method. Providers were trained to conduct rapid flu tests in their clinics and to collect nasopharyngeal swabs for shell-vial rapid culture and real time polymerase chain reaction (RT-PCR) for typing and sub-typing in the HDHHS laboratory. Results are reported to the providers within 24 - 48 hours.

In 2007-2008, Influenza A (66.9%) was the most common type detected with Influenza A/H3 being the most prevalent (89.4%) subtype. Influenza A was more prevalent (80.4%) in January. However, the distribution pattern reversed, and in February Influenza B became more prevalent (56.9%). Based on patient interviews, 35.3% of those who tested positive for either flu A or B were vaccinated against flu. Approximately 3% of those vaccinated and who tested culture positive were infected with both influenza A and B.

HDHHS was able to monitor, detect and respond to ILI and circulating strains of influenza in the community. Timely reporting of results assisted the providers in better management of patients.