While there is no answer to the question of when the next pandemic will occur, one thing is certain: There’s no escaping the media’s take on it. Sweeps week did more than decide the latest “American Idol”; it brought with it a rash of movies, special reports, and updates about the threat of the avian flu. The Centers for Disease Control & Prevention (CDC) has even dedicated a portion of its site to debunking myths and concerns either in or inspired by the increased coverage.

The fears come mainly from the public’s lack of knowledge about the infamous H5N1 virus and the potential devastation it may bring with it. Clinical labs, however, do not have the luxury of being uninformed about this issue. In the event of an outbreak, they will not be passive bystanders, but active participants in the response effort. Exactly what will be expected from laboratories will depend greatly on their location and resources.

Avian Influenza A/H5 Laboratory Test Developed
Early in February, the US Food and Drug Administration (FDA) announced its approval of the Influenza A/H5 (Asian lineage) Virus Real-time RT-PCR Primer and Probe Set, designed to return preliminary results in 4 hours or less on suspected H5 influenza samples. The test is destined for the more than 140 labs in all 50 states designated as part of the CDC’s Laboratory Response Network (LRN) network.

Restricting the distribution of the test was done in part to enable the CDC to carefully monitor the performance of all real-time RT-PCR assays currently in use, a task that grows increasingly difficult as more labs acquire the test.

“The currently circulating HPAI H5 strains have been undergoing somewhat rapid mutations,” says Rosemary Humes MS, MT(ASCP)SM, director of Infectious Diseases and Preparedness for the Association of Public Health Laboratories. “The strains originally detected in Vietnam in 2004 (Clade 1 viruses) are genetically and antigenically distinct from strains that have been seen more recently (Clade 2 viruses).”

The government also believes broad distribution of testing protocols and reagents is currently inappropriate because of the extremely complicated nature of diagnostic testing for A/H5N1, compounded by the fact that existing traditional culture-based tests employed for the routine screening of seasonal influenza have serious limitations.

Specifically, it is not recommended to perform a viral culture on specimens from suspected A/H5N1 patients unless conducted under Biosafety Level 3 conditions with enhancements.

“If, in fact, this particular virus turns out to be as virulent as everybody thinks it is, it makes sense to restrict it to culturing facilities that are properly maintained and have the wherewithal to culture it safely,” says Timothy J. Cleary, PhD, professor of pathology, microbiology, and immunology at the University of Miami and director of clinical microbiology for Jackson Memorial Hospital. “The state health departments have been gearing up ever since 9/11 to develop laboratories that are Biosafety Level 3, and most of the facilities in hospitals don’t have the equivalent safety precautions.”

Another complication when screening for A/H5N1 is the fact that the commercially available rapid influenza antigen has relatively low sensitivity and a negative result does not exclude a diagnosis of influenza H5N1, and a positive test does not distinguish between seasonal and A/H5N1 viruses.

Perhaps one of the biggest reasons diagnostic testing for A/H5N1 is more demanding than what is required for the seasonal flu viruses is the scarcity of detailed studies on the pathogenesis of human infections.

“We do not have a solid knowledge of the temporal progression of the infection in people, particularly with regard to the sites of virus replication and the concentration of virus in different anatomical sites and respiratory secretions,” says Ruben Donis, PhD, chief of the Molecular Virology Branch at the Influenza Division of CDC. “The consensus is that the concentration of A/H5N1 in the upper respiratory tract, which is the most accessible for clinical diagnostic specimen collection, is orders of magnitude lower than that of seasonal flu.”

Even the Influenza A/H5 (Asian lineage) Virus Real-time RT-PCR Primer and Probe Set requires additional testing by the CDC to identify the specific H5 subtype—along with clinical and epidemiological assessment in consultation with national influenza surveillance experts—if the presence of the H5 strain is identified.

Widening the Net
Though circulation of the primer and probe is limited at this time, the current plan is to loosen the reins at some point in the future.

“FDA approval of the Influenza A/H5 (Asian lineage) Virus Real-time RT-PCR has stimulated a great deal of interest throughout the infectious disease community,” Donis says. “Many of us at CDC see this as a very positive development and are working with many partners on enhancing existing testing capabilities and facilitating the eventual future deployment of A/H5N1 testing in clinical laboratories.”

Part of that interest includes an enthusiastic response from commercial entities eager to bring equivalent assays as FDA-approved in vitro diagnostic devices to the market. The CDC and other government agencies welcome the zeal and hope it will inspire true alliances.

To that end, the CDC’s Influenza Division has initiated collaborations with several partners to develop, evaluate, and validate a panel of real-time PCR assays to not only diagnose A/H5N1 infection, but to also identify infections with type A or B seasonal influenza viruses, according to Donis.

The CDC is also working with the United States Department of Agriculture and the FDA to remove regulatory barriers that might possibly impede the rapid distribution and use of diagnostic tests and reagents in the event of a pandemic.

In the meantime, public health laboratories are working closely with the appropriate government agencies to ensure that clinical laboratories at the state and local level have the information and assistance they need when planning for pandemic influenza.

Part of such planning includes defining the roles of both the clinical and public health laboratories, as well as determining specimen requirements and testing algorithms used for routine influenza surveillance and suspected cases of H5N1 or other novel influenza viruses, according to Humes.

The Big Picture
The intense focus on influenza H5N1 is understandable when taking its history into account. During late 2003 and early 2004, outbreaks of the virus killed more than 100 million birds in eight countries throughout Asia. Although the virus was believed to be contained as of March 2004, there were new influenza H5N1 outbreaks among Asian avian populations; and by mid-2005, infection in wild birds in Europe were being reported.

According to statistics of laboratory-confirmed cases maintained by the World Health Organization1 (WHO) through May 2006, a total of 208 human cases had been reported—115 of which were fatal. This year alone, 64 human cases were reported. Of these, 39 resulted in death.

But while the H5N1 is garnering the bulk of public attention, the Association of Public Health Laboratories encourages labs to monitor for other viruses that also have the potential to generate outbreaks.

“As other avian influenza viruses have been implicated in human disease—including HPAI H7N7, and LPAI H9N2, H7N2, H7N3—it is essential that current influenza surveillance programs provide for rapid detection of any novel strain.” Humes says. “Therefore, testing for H5 only is not recommended. It is important that we continue planning for a pandemic, not just the spread of H5N1.”

Humes notes that in addition to the Influenza A/H5 (Asian lineage) Virus Real-time RT-PCR Primer and Probe kit, designated public health laboratories have a battery of real-time RT-PCR assays to detect Influenza A and B viruses and subtype H1, H3, H5, and H7 strains.

A Waiting Game
Without much doubt, detection of H5N1—or any novel influenza strains—in the United States will result in an extensive public health response.

Predictions may abound, but no one knows when the next influenza pandemic will cease to be hypothetical and launch a new reality. Clinical labs across the country should take their lead from government organizations and public health laboratories, and work to be as prepared as possible.

“We have developed and implemented mechanisms to handle patients as they come into the hospital so that they’re isolated, as well as created procedures to culture and get specimens over to our regional health facility quickly so a definite diagnosis can be made,” Cleary says. “That plan includes having the proper history forms available, culture material available, and well-established lines of communication.”

Those lines of communication should extend beyond the walls of the clinical lab. A pandemic would put strain on many departments in a health care facility, and each department should know what is expected of it.

“A lot of people don’t even talk to the staff within their own hospital, so you need to make sure that you are in close contact with the director of the emergency room and also infection control, because they will be handling people as they come in,” Cleary says. “In the laboratory, one thing I need to guarantee is that the material is available in the ED for obtaining specimens.”

Using Available Resources
Just as important as communicating within a facility is for labs to familiarize themselves with state plans, as well as current PHL testing requirements, including effective methods for specimen collection and management, and packing and shipping procedures. It is also important for labs to become involved in their institutional, community, and regional pandemic exercises.

“They should also develop or review their strategies and mechanisms for communication with clients—to relay pandemic-status updates, specimen collection and testing guidance, and provide updates on changes in their testing priorities, availability, etc,” Humes says.

Clinical labs can help themselves by making the most of available partnerships with their state public heatlh laboratories, along with the appropriate local, regional, and federal agencies. These groups will be able to provide recommendations for isolation and quarantine, release of medical therapies from the strategic national stockpile, and, if necessary, can assist in ramping diagnostic testing and vaccine production, according to Humes.

Established communications channels will be increasingly vital as an epidemic evolves. Depending on the course of the outbreak, it may be necessary for labs to shift to a different set of duties and responsibilities.

“One thing we have learned in all of the emerging disease responses over the past few years is that part of planning is to ‘be prepared for things to change’—be ready to meet the unique requirements of the disease and its human and animal impact,” Humes says. “It should be noted that once a pandemic is under way, the need for laboratory confirmation of clinical diagnoses may decrease as the virus becomes widespread, and the role of hospital and independent labs may vary depending on their existing capacity and expertise to perform real-time RT PCR or other relevant tests.”

In the event of an outbreak, clinical labs will be called on not only to provide tests for other respiratory pathogens, but to conduct diagnostic services in support of patient-management needs.

“From a public health perspective, the critical elements are going to be the accuracy of the tests being performed, along with the epidemiological data on the patient from which it was collected,” Donis says. “Of course, that rapid test-turnaround time and prompt communication of the test results to the physician and public health authorities are also critical in these circumstances.”

A Developing Game Plan
According to the CDC, the specific role of the regional labs is continuously being re-assessed and is evolving at all levels of government.

“We want to be as inclusive as possible, because this is the only avenue for meeting our national needs to better handle our annual seasonal influenza demands, as well as those early-warning and laboratory testing surge capacity requirements anticipated during the onset of a pandemic influenza outbreak,” Donis says. “It is clear that the importance of robust differential A/H5N1 versus seasonal influenza diagnostics has now reached center stage; the momentum is being felt, and we are very excited with the positive impact this will have on public health.”

1. Cumulative Number of Confirmed Human Cases of Avian Influenza A/(H5N1) Reported to WHO, Updated 12 May 2006. Available at: http: //www.who.int/csr/disease/avian_influenza/country/cases_table_2006_05_12/en/index.html. Accessed June 20, 2006.

Dana Hinesly is a contributing writer for Clinical Lab Products.