Methods: As part of routine respiratory disease surveillance, the preventive medicine department aboard USNS Mercy tracked all respiratory illnesses that presented to Sick Call. Viral respiratory testing was performed on patients with influenza-like illness and to further describe incidence rates of any respiratory illness. Testing included the collection of nasal and pharyngeal swabs placed in viral transport media for molecular testing using either point of care FilmArray™ technology or the Joint Biological Agent Identification and Diagnostic System (JBAIDS) platform. Respiratory cultures and rapid influenza diagnostic kits were also used when clinically indicated.
Results: 335 patients were identified with acute respiratory illnesses between 17 May and 27 September 2015. There were two significant outbreaks; the first at the start of the mission leaving San Diego, California and a second in July after anchoring in Roxas City, Philippines. Molecular testing quickly identified a circulating rhinovirus/enterovirus during the first outbreak and an influenza A H3 strain predominantly associated with the outbreak in the Philippines.
Conclusion: On board molecular diagnostic testing helped to describe two distinct outbreaks of acute respiratory viral illnesses. It enabled the preventive medicine team to implement early and effective infection control measures. Rapid detection of influenza aided in prompt treatment for those infected. This study highlights the important use of readily available diagnostic testing to help detect and control outbreaks of acute respiratory illnesses that could be potentially devastating to military ship missions.