Clinical and epidemiologic characteristics of an outbreak of novel H1N1 (swine origin) influenza A virus among United States military beneficiaries.

BACKGROUND: A novel swine-origin influenza A (H1N1) virus was identified in March 2009 and subsequently caused worldwide outbreaks. The San Diego region was an early focal point of the emerging pandemic. We describe the clinical and epidemiologic characteristics of this novel strain in a military population to assist in future outbreak prevention and control efforts. METHODS: We performed an epidemiologic evaluation of novel H1N1 virus infections diagnosed in San Diego County among 96,258 local US military beneficiaries. The structured military medical system afforded the ability to obtain precise epidemiologic information on the impact on H1N1 virus infection in a population. The novel H1N1 virus was confirmed using real-time reverse transcriptase polymerase chain reaction (rRT-PCR). RESULTS: From 21 April through 8 May 2009, 761 patients presented with influenza-like illness and underwent rRT-PCR testing. Of these patients, 97 had confirmed novel H1N1 virus infection, with an incidence rate of 101 cases per 100,000 persons. The median age of H1N1 patients with H1N1 virus infection was 21 years (interquartile range, 15-25 years). Fever was a universal symptom in patients with H1N1 virus infection; other symptoms included cough (present in 96% of patients), myalgia or arthralgia (57%), and sore throat (51%). Sixty-eight (70%) of our patients had an identifiable epidemiologic link to another confirmed patient. The largest cluster of cases of H1N1 virus infection occurred on a Navy ship and involved 32 (8%) of 402 crew members; the secondary attack rate was 6%-14%. The rapid influenza testing that was used during this outbreak had a sensitivity of 51% and specificity of 98%, compared with rRT-PCR. Only 1 patient was hospitalized, and there were no deaths. CONCLUSIONS: A novel H1N1 influenza A virus caused a significant outbreak among military beneficiaries in San Diego County, including a significant cluster of cases onboard a Navy ship. The outbreak described here primarily affected adolescents and young adults and resulted in a febrile illness without sequelae.

Gastroenteritis in US Marines during Operation Iraqi Freedom.

BACKGROUND: Approximately 83,000 US Marines participated in the opening phase of Operation Iraqi Freedom in Spring 2003. A Navy Preventive Medicine laboratory was set up in Ad Diwaniyah, Iraq, to provide clinical diagnostic support for Marine medical units during a period of repositioning in south-central Iraq. METHODS: Specimen collection boxes were sent to >30 primary care medical stations handling 500-900 personnel each. The laboratory had capability to detect many different disease agents, especially those causing febrile illness. Diarrheal stool diagnostic evaluation included plating and biochemical identification, antigen serologic testing, fluorescent antibody antigen detection, disk diffusion antimicrobial susceptibility testing, enzyme immunoassay, and reverse-transcriptase polymerase chain reaction for norovirus (NV). Confirmation and sequencing work for NV was done at Cincinnati Children's Hospital Medical Center (Ohio). RESULTS: By far the most common reason for infectious disease sick call visits was gastrointestinal illness; no other symptoms had equivalent impact. An enteropathogen was detected in 57 (44%) of 129 stool samples, with NV detected in 30 stool samples (23%) obtained from 14 different battalion or similar-sized units; next in frequency were Shigella flexneri and Shigella sonnei, which were isolated from 26 stool samples (20%) obtained from 15 units. Sequencing the NV RNA polymerase gene demonstrated that NV strains represented 7 genetic clusters, including 2 strains from genogroup I and 5 from genogroup II. Ciprofloxacin was effective in vitro against most bacterial agents, but neither doxycyline (which was taken daily as the antimalarial prophylaxis dose) nor trimethoprim-sulfamethoxazole were effective. CONCLUSIONS: Multiple strains of Shigella species and NV predominated, probably because they do not require a large inoculum to cause infection. Otherwise, personnel remained free of infectious illness during this phase of the conflict, because other infectious agents were rare or absent.

Disease and nonbattle injury patterns: afloat data from the U.S. Fifth Fleet (2000-2001).

Disease and nonbattle injury (DNBI) patterns were analyzed for reports from the Commander Fifth Fleet for 2000-2001 covering 217,972 person-weeks. The overall DNBI rate was 4.38 visits per 100 person-weeks with the largest subcategory being "other medical/surgical" conditions (1.36 visits/100 person-weeks and over 30% of the initial patient visits). This was followed by dermatological (0.89 visits/100 person-weeks) and respiratory conditions (0.65 visits/100 person-weeks). Collapsing total injuries would have created the third largest incidence category. The mean DNBI rate for cruisers/destroyers/ frigates (4.23 visits/100 person-weeks; SD, 2.64 visits) was not significantly different from aircraft carriers (4.76 visits/100 person-weeks; SD, 1.60, t(df = 207) = -0.91, p = 0.363) but was statistically different from supply ships (8.93 visits/100 person-weeks; SD, 2.44, t(df = 191) = -6.23, p = 0.000) and amphibious support ships (8.07 visits/100 person-weeks; SD, 3.99, t(df = 190) = -4.72, p = 0.000). These results are compared with historical data from land-based units, and the limitations in shipboard DNBI reporting are discussed.

A multivariate analysis of factors associated with differential disease and nonbattle injury and morbidity aboard ships of the U.S. Naval 5th Fleet during peacetime deployment.

Disease nonbattle injury (DNBI) surveillance is a critical component of U.S. military force health protection and has been aggressively implemented by the U.S. Central Command. This study presents a multivariate analysis of factors associated with DNBI incidence rates as well as a description of morbidity measures associated with DNBI from U.S. Navy ships deployed to the Middle East from October 2000 through September 2001. Weekly DNBI reports (N = 331) from a total of 44 individual units representing six different classes of U.S. Navy ships were included in the analysis. There were statistically significant differences in summary and categorical DNBI rates associated with ship class, season, and presence of female sailors embarked. The top three DNBI categories associated with the most lost workdays because of sick in quarters and hospitalization were other medical/surgical (36%), infectious gastrointestinal (23%), and all types of nonbattle injury combined (17%).