Rubella outbreak, Fort Bragg, North Carolina, 1995: A clash of two preventive strategies

Military Medicine, Sep 1999 by Craig, Stephen C

An outbreak of rubella occurred among visiting German troops involved in a combined military exercise at Fort Bragg, North Carolina, in April 1995. Public health and military operational concerns centered on the significant contact the German soldiers had had with host battalion dependents and the impact of the outbreak on the exercise. Ten of the 120 German soldiers were found to be nonimmune; six of these soldiers developed clinical rubella. The four nonimmune soldiers who did not develop skin rashes had received serum immune globulin within 12 hours of identification of the index case. The impact of this outbreak on the Fort Bragg community and its military operations, and the methods used to control the outbreak and salvage the military mission, are described.

Introduction

The introduction of rubella virus vaccination in 1969 provided an immunologic weapon with the potential to eliminate the devastating burden of congenital rubella syndrome (CRS). Although rubella vaccine was widely adopted in the developed world as an integral part of disease prevention programs, implementation strategies varied considerably. In the United States, a campaign for the universal immunization of all children younger than 12 months of age was initiated in 1969 and 1970.1,2 It interrupted rubella virus transmission, provided immediate protection to schoolchildren, and protected women of childbearing age by eliminating exposure.1 This strategy was extremely successful, reducing rubella cases by 94% from 1980 to 1988.3 Between 1989 and 1990, a resurgence of rubella and CRS was noted in all age groups in the United States, most notably in adults in colleges, prisons, hospitals, and workplaces. This resurgence was not the result of vaccine failure but rather of a failure to immunize all susceptible individuals.3 In 1991, a second dose of vaccine was recommended for administration to children at the time of school entry.4 Rubella immunization became standard practice in the U.S. Army in April 1979.

In a number of European countries, including Germany, an alternative immunization strategy evolved. Selective immunization designed to prevent CRS while minimizing the risk of adverse vaccine reactions in the population at large was felt to provide the lowest risk-benefit ratio. In these countries, only adolescent females (10-14 years old) and all women of childbearing age were targeted for immunization. This strategy succeeded in reducing the incidence of CRS; however, under such a program, the virus remains free to circulate in the population, and only when 100% of at-risk women are immunized is the risk of CRS eliminated.5

In Germany, recruits do not receive rubella vaccine on entry into military service. Rubella outbreaks are common in the late winter and early spring, and German military camps frequently are affected (personal communication with the military physician at the German paratrooper's home station). In the present report, we describe a rubella outbreak among German military personnel involved in a combined military exercise with U.S. troops at Fort Bragg, North Carolina, which had significant ramifications for both the public and military operational arenas.

Methods

Populations

Fort Bragg, located in the sandhills region of southeastern North Carolina, is one of the U.S. Army's largest military facilities. Home to approximately 40,000 active duty soldiers, Fort Bragg is the headquarters for the Army's Rapid Reaction Forces; these forces are spearheaded by the elite 82d Airborne Division, whose troops are involved in virtually constant training activities, often involving collaboration and exchange with soldiers of other nations.

On April 3, 1995, a 120-man contingent of German paratroopers arrived at Fort Bragg to prepare for military exercises with a host battalion of the 82d Airborne Infantry Division. The exercise, to be held at the Joint Readiness Training Center (JRTC), Fort Polk, Louisiana, began with a nighttime airborne assault followed by tactical ground maneuvers on the evening of April 14. The German soldiers were billeted together in four two-story frame barracks at Fort Bragg. During the 2-week training period before departure for JRTC, these soldiers had regular and constant face-to-face interactions with their host-- nation counterparts, frequently visited the homes and families of host battalion soldiers, and were allowed access to local restaurants and nightclubs in nearby Fayetteville, North Carolina.

Laboratory Methods

Rubella serology tests for the soldiers were performed under contract with Roche Biomedical Laboratories (Burlington, North Carolina). Specific anti-rubella immunoglobulin M (IgM) and immunoglobulin G (IgG) levels were determined in serum samples using Cobas Core Rubella IgM and Cobas Core Rubella IgG Enzyme Immunoassay (Roche Diagnostic Systems, Branchburg, New Jersey).

Results

The Outbreak

Late on the evening of April 12, three German soldiers who had developed maculopapular rashes presented to the emergency room at Womack Army Medical Center, Fort Bragg, for evaluation. Based on prodromal signs and symptoms (low-grade fever, coryza, conjunctivitis, malaise, and rash), a provisional diagnosis of rubella was made. These patients were admitted and placed in isolation, and the remainder of the German contingent was quarantined in their barracks. Over the next 2 days, seven additional German soldiers developed malaise, low-grade fever, and coryza, but only three of them developed rashes. As a result of telephone communication with German medical authorities at the unit's home station in Nagold, Germany, it was determined that a rubella outbreak had occurred there in mid-- March.