Surveillance networks such as GeoSentinel and TropNetEurop conduct global infectious disease surveillance using travel and tropical medicine clinics, which contribute clinical information during or after travel. These networks have published data characterizing the spectrum of disease associated with travel to specific regions of the world and among specific groups of travelers, informing post-travel patient evaluation and pre-travel health advice.
Military forces constitute an international traveler population that presents unique opportunities for global infectious disease surveillance. Health data collected during or after military deployment may become part of the patient's longitudinal medical record, enabling assessments of predeployment health status and vaccinations on deployment-related risks. In some countries, there is near-complete capture of military medical encounters as military personnel receive care almost exclusively in a military or national health system. This could reduce bias compared to surveillance systems dependent on referrals to specialty clinics, which could miss patients seen only in primary care clinics. Another advantage is that incidence rates can be calculated with more precision as often the size of the population (ie, the denominator) and duration of risk are known.
In this issue of the Journal of Travel Medicine, de Laval and colleagues provide a global snapshot of dengue using epidemiological surveillance in deployed French Armed Forces personnel. As part of an established surveillance program, military physicians complete case report forms for patients with dengue symptoms and send them to the Institute of Tropical Medicine at the Army Health Service in Marseille, France. Blood specimens are analyzed in local civilian laboratories or at the National Arbovirus Reference Center at the Institute of Tropical Medicine. This program is an important model for dengue surveillance and, more broadly, for global infectious disease surveillance.
For dengue, large data gaps exist, especially in Africa, where mosquito species prevalence and dengue virus serotypes appear to be changing. De Laval and colleagues demonstrate that surveillance of military populations with appropriate clinical evaluation and laboratory analysis could help fill these gaps. Their surveillance program identified a change in the predominant circulating dengue virus serotype in the French West Indies, which could increase epidemic risk.
The French Armed Forces previously demonstrated that real-time military syndromic surveillance can provide early detection of dengue fever outbreaks. The surveillance system captures remote, field-based events through reporting across a variety of platforms, including handheld and satellite communication tools. If such a syndromic surveillance system could also integrate systematic sample collection and analysis, as in the surveillance system used by de Laval and colleagues, it would serve as a model for acute febrile illness surveillance in deployed military populations.
Even in austere, remote locations where local laboratories may lack capacity to identify serotypes, store blood samples at appropriate temperatures, and ship samples for confirmatory testing, this approach could work. Matheus and colleagues recently reported detecting dengue serotypes by (reverse transcription polymerase chain reaction) in 90% of blood samples from NS1-positive dengue patients presenting in the French West Indies, using venous blood specimens collected on filter paper (via a finger prick) and shipped at ambient temperature to French Guiana for analysis. Such sample collection methods would afford opportunity to capture events that may occur in the field, far from a military medical facility.
While the US military conducts surveillance for disease and non-battle injury (DNBI) in deployed forces, limitations of its DNBI surveillance include incomplete data capture in deployed settings and lack of systematic laboratory testing for patients with infectious syndromes. Better surveillance for infectious diseases using field-expedient sample collection methods would lead to better public health prevention and treatment in deployed forces, and also could enhance vaccine research and development efforts through better understanding of pathogen molecular epidemiology. Specifically for dengue, phase 3 vaccine trials are underway, and understanding global epidemiologic patterns will be important in any future vaccine field effectiveness trials, particularly among deployed military populations that would be a target population for vaccination. In addition, such a surveillance system could also be integrated with vector surveillance programs to yield a robust early warning system for infectious disease threats.
Enhancing surveillance efforts among deployed military personnel is also important from global health and geopolitical perspectives. History shows that military populations can introduce new diseases into local populations, most dramatically during the influenza pandemic of 1918 in Europe and more recently from the possible importation of cholera into Haiti. The need for improved military surveillance is especially significant in Africa, where US military engagement is expanding as part of its mission to achieve a more stable environment that promotes political and economic growth there. US military personnel continue to contract malaria[10-12] and dengue during overseas operations. However, there is no systematic, integrated syndromic and laboratory-based surveillance for acute febrile illness in US military personnel in Africa.
The United States has more than 3,000 service members deployed to Djibouti, an epidemiologically important country in the Horn of Africa with migrant populations traveling from Somalia, Eritrea, and Ethiopia, and a major port for produce and animal exports. Because of this geographic niche and limited local surveillance capacity, there is an important need to characterize infectious disease risks in the region. There are several other foreign militaries operating in Djibouti, including the French (who have had a longer presence in the region) and German militaries, who have initiated a collaborative expansion of the French Armed Forces electronic syndromic surveillance system.
The US military could contribute to and benefit from this collaboration. In the Horn of Africa and elsewhere, the US military could draw on its expertise in electronic syndromic surveillance[14, 15] and its global public health and laboratory network,[16, 17] including World Health Organization (WHO) Collaborating Center laboratories in Egypt and Kenya, to enhance such surveillance among US service members in Africa and establish a model military surveillance platform.
Under the International Health Regulations [IHR(2005)], which entered into force in 2007, all countries must develop core capacities for disease surveillance to avert “public health emergencies of international concern,” such as potential pandemics. Militaries can contribute to global health security and IHR(2005) implementation by strengthening their disease surveillance systems, so that outbreaks are detected, and contained, before spreading further. They should “join forces” with the civilian public health community, and be part of the inter-sector collaboration that the World Health Assembly (the decision-making body of the WHO, comprising delegations from all WHO Member States) recently called on WHO Member States to strengthen in support of IHR(2005).
We call on US and other military public health leadership to critically evaluate the current gaps in public health surveillance capacity among deployed populations, and to adapt current “best” practices utilized by other militaries to implement effective infectious disease surveillance systems in deployed settings. These systems will help protect US and other military personnel from ever-changing infectious disease threats, and dually serve an important role in informing global health.