Global respiratory surveillance program detects dangerous pathogens to keep armed forces healthy

The potential threat of respiratory disease outbreaks can hamper the military’s ability to carry out its mission. The mobility of military units, along with the crowded living conditions and a high-stress working environment, can increase service members’ susceptibility to illness. Frequent deployments to developing countries where pathogens can be transmitted from animals to humans can expose service members to potentially susceptible novel pathogens that can spread quickly and cause serious illness.

“Given the ever-changing nature of the flu virus, constant surveillance is necessary. The concern is that some of these changes will lead to a more transmissible and more lethal virus— a dangerous combination for our military members and the world,” said U.S. Public Health Captain Michael Cooper, who oversees the Armed Forces Health Surveillance Branch’s (AFHSB) Global Emerging Infections Surveillance section’s (GEIS) Respiratory Focus Area. “Early detection of such a situation will give public health authorities and vaccine makers’ opportunity to prepare interventions that will hopefully stem the tide of illness.”

To reduce the impact of respiratory pathogens on service members, AFHSB coordinates a global respiratory surveillance program for the military. The GEIS section funds the Department of Defense Global Respiratory Pathogen Surveillance Program at the U.S. Air Force School of Aerospace Medicine at Wright-Patterson Air Force Base in Dayton, Ohio. The program conducts year-round respiratory surveillance at 46 military installations in the U.S. and 33 sites overseas to identify influenza and other respiratory pathogens that could jeopardize the health and readiness of service members and their families.

The respiratory surveillance program offers a glimpse of AFHSB’s comprehensive work that allows the Department of Defense and the Military Health System to develop preventive and treatment programs to maintain combat readiness. The program also shares data with the Centers for Disease Control and Prevention (CDC) and World Health Organization to reduce gaps in their respective civilian respiratory surveillance efforts throughout the globe. The program also helps fulfill the Defense Department’s contributions toward the Global Health Security Agenda, a growing partnership of over 70 nations, international organizations, non-government stakeholders to help build countries’ capacity to detect and prevent infectious disease threats.

Respiratory sentinel sites submit between six and 10 respiratory specimens each week from patients who meet the case definition for influenza-like illness (i.e., present with a fever greater than 100.5°F and cough or sore throat within 72 hours of the onset of symptoms). The program has increased the number of specimens that are tested with the addition of high-throughput multiplex polymerase chain reaction systems that can detect up to 20 respiratory pathogens and co-infections. This testing panel is performed on respiratory specimens received for routine testing as well as viral culture.

Next-generation sequencing also provides whole genome sequencing in less time than previous methods to identify genetic changes in all eight gene segments of currently circulating influenza viruses. All the sequencing information is organized into phylogenetic trees that show the degree of variation and genetic grouping among the strains. These sequences are shared with the CDC and compiled into the GenBank database for use by public health researchers.

Finally, the respiratory surveillance program conducts estimated influenza vaccine effectiveness (VE) at mid-season and the end of the flu season to account for potential antigenic drift or shift. VE estimates are performed using a test-negative, case-control study design and include Department of Defense healthcare beneficiaries and select non-military subjects who seek health care in response to symptoms associated with respiratory infection. When appropriate, respiratory specimens are taken and submitted to the program for testing. "Cases" are patients who tested positive for influenza while "controls" are individuals who tested negative for influenza.

Mid-season estimates are presented at the Food and Drug Administration’s annual Vaccine and Related Biological Products Advisory Committee meeting in early spring and contribute to the determination of the influenza vaccine strain in the U.S. for the upcoming season. Additionally, VE estimates are provided to the WHO Global Influenza Vaccine Effectiveness report, which helps determine the Northern and Southern Hemispheres’ influenza vaccine strains.