775. The Burden of Arboviral Infection in the Military Health System, 2011-2019

Abstract

BackgroundTravel-related arboviral infections are important preventable, emerging infectious diseases, with an estimated annual global toll of US$950 million. We investigated the burden of arboviral infections in the military health system (MHS).MethodsKAPOS (Deployment and Travel Health: Knowledge, Attitudes, Practices, and Outcomes Study) is a multi-cohort study evaluating the burden of travel-associated diseases in the MHS. The MHS Data Repository was searched for International Classification of Diseases (ICD)-9/10 codes for arboviral infection in military beneficiaries receiving care in military treatment facilities (direct care) or civilian centers (purchased care) for fiscal years 2011-2019. Diagnostic codes were classified as Dengue, Chikungunya, Zika, or other arboviral infection. 755 outpatient charts in the direct-care system were randomly selected for diagnostic validation using Armed Forces Health Surveillance Center case definitions, and review of travel history, medical comorbidities, and pre-travel counseling.Results11,066 unique-patient ICD codes for arboviral infections were identified; 6356 (57.4%) were direct care; 4710 (42.6%) were purchased care; 889 (8.0%) were inpatient. Median age was 31 years; 5110 (46.2%) were active duty. The most frequent ICD codes for arboviral infection were Japanese encephalitis virus (JEV) (n=4483), dengue (DENV) (n=1786), yellow fever (YF) (n=230), Zika virus (ZIKV) (n=217), West Nile virus (WNV) (n=171), and chikungunya virus (CHIKV) (n=91). DENV codes were confirmed in 166/249 (66.7%) charts; CHIKV in 23/41 (56.1%), and ZIKV in 15/129 (11.6%). No cases of JEV were confirmed in 171 encounters; all codes referred to JEV vaccine administration. 173/204 (84.8%) of confirmed arboviral cases did not undergo pre-travel counseling.ConclusionArboviral infections constitute a substantial burden of preventable infections within the MHS. Dengue contributed the largest burden of arboviral infection when corrected for accuracy. Coding for ZIKV and JEV likely overestimated the burden of these diseases in the MHS. Low rates of pre-travel counseling among patients with confirmed, non-endemic arboviral infections represent an opportunity for increased emphasis on travel counseling and insect-avoidance precautions.Disclosures All Authors: No reported disclosures