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Labs struggle with influx of diagnostic specimens from potential influenza A (H1N1) cases

Influenza AH1N1 case counts have steadily increased since the first reports in early April, sending droves of fearful citizens in affected areas to seek reassurance in pediatric offices, and creating substantial chaos in virology labs as health officials clamor to characterize incoming specimens.

“As of last night we had about 1,000 specimens that still needed to be logged in,” Gail Demmler-Harrison, MD, professor of pediatrics at Baylor College of Medicine and director of the diagnostic virology department at Texas Children’s Hospital, both in Houston, said at a special swine influenza session held today at the Pediatric Academic Societies Annual Meeting in Baltimore. “Typically wet get between 30 to 50 samples a day, maybe 100 during the peak influenza season. Last week had about 300 in a two-hour period.”

As the number of states with confirmed cases climbed to 36 today, more health care personnel in labs across the country may experience influxes similar to those at Texas Children’s Hospital.

“The real challenge will be meeting the massive surge in the volume of samples, and to make sure that labs have the reagents and personnel to handle this testing so we can get results back to pediatricians and schools,” Demmler-Harrison said.

She and other infectious disease specialists at the meeting shared several strategies for health care providers to keep in mind while managing the outbreak. Although the CDC’s interim guidance is broadly inclusive, efforts should prioritize care for individuals who are severely ill or immunocompromised. A tiered system for incoming patients at sites experiencing high patient volumes may be useful for triage and infection control in emergency centers.

Additionally, physicians should remember basic clinical presentations when determining if a patient has flu-like symptoms. James D. Cherry, MD, professor and chief in the department of infectious diseases and microbiology at the University of California and Mattel Children’s Hospital, both in Los Angeles, reminded the audience that although fever likely indicates influenza, an abundance of nasal symptoms usually means that influenza is not the culprit.

Using other departments within a hospital may also be beneficial.

“Our emergency department colleagues were very helpful in offsetting some of the rapid testing to the point-of-care venue in the emergency center, and helped keep the hospital virology lab from drowning,” Demmler-Harrison said.

The Texas Children’s Hospital Emergency Center created a mobile pediatric emergency response team (MPERT), a triage system based on Hurricane Katrina contingency plans that converted a hospital parking lot into an emergency center where patients were triaged, issued color-coded arm bands and then assigned specific areas for assessment and treatment based on their illness severity. MPERT was complete with a child-friendly waiting area, stations for patient assessment, point-of-care testing for influenza and hand washing. Rapid influenza tests were performed on-site, and physicians wrote and filled antiviral prescriptions immediately as positive results were available and provided pediatric patients and their families with educational materials about the influenza outbreak.

Members of the Texas Children's Hospital mobile pediatric response team transformed a hospital parking garage into a patient reception area in response to the state's H1N1 swine influenza outbreak.

After triage, patient's were assigned to stations like these for assessment.

Hospital staff performed rapid influenza diagnostic tests at point-of-care testing stations.

All photos courtesy of Paul E. Sirbaugh, DO, Andrea Cruz, MD and Coby Allen, MD

In the meantime, infectious disease specialists continue to emphasize the fluidity of current influenza outbreak. “As this pandemic evolves, there is a lot that we do not know,” said Pablo J. Sanchez, MD, professor of pediatrics at the University of Texas Southwestern Medical Center, Dallas, and Infectious Diseases in Children Editorial Board member.

“Things are changing very quickly,” Stephen C. Redd, MD, influenza team leader at the CDC, told meeting attendees via conference call. “As the situation changes, so will our response and the guidance we provide to the public.”

Currently, the CDC recommends that health care providers obtain specimens from any person with acute-febrile respiratory illness who fit the following profile:

• Symptom onset within seven days of close contact with a confirmed case of swine-origin influenza A virus.
• Symptom onset within seven days of travel to a community with a confirmed case of swine-origin influenza A.
• Resides in a community in which one or more cases of swine-origin influenza A have been confirmed.

Physicians should perform real-time rapid-test polymerase chain reaction assays or viral culture for strain characterization at onsite labs or send specimens to local hospital references, health departments or the CDC for confirmatory testing.

Although susceptibility to swine influenza A (H1N1) seems to be widespread, officials remain unsure about the degree of severity but think that the virus may be milder than initially suspected, according to Redd.

Cherry predicted that the number of cases will die down during the upcoming summer months, but that the strain will return next fall with the start of the flu season. He said that bacterial co-infections with pathogens such as MRSA may significantly affect morbidity and mortality. – by Nicole Blazek

For more information:

• Pediatric Academic Societies Annual Meeting; Baltimore; May 2-5, 2009.