III. PREVENTIVE MEDICINE AND SURVEILLANCE

A. Preventive Medicine

During Operations Desert Shield and Storm, the US military initiated extensive disease prevention, control, and surveillance efforts.[18, 19] The preventive medicine (PM) activities among US Marine Corps troops provided one example of this comprehensive effort. When US Marines deployed to the Persian Gulf in August 1990, PM personnel were among the first to arrive. Because of the medical threats faced by Marine Corps units during deployments, highly trained PM specialists are "built into" the Marine Table of Organization at multiple levels. Preventive medicine experts are assigned to front line units of the Division and Wing, to the combat medical support elements of the Force Service Support Group (FSSG), and to the highest headquarters levels. These specialists know what illnesses might affect Marines and sailors in a particular arealike the Persian Gulfand how to prevent health problems in field settings.

Within the First Marine Division, an Environmental Health Officer (EHO) is assigned to the Division Surgeon's staff to advise on key PM issues, such as field sanitation, protection of food and water, proper immunizations, and the prevention of insect-borne diseases. At the unit level, a Preventive Medicine Technician (PMT) works within the battalion medical department to carry out basic PM measures. The PMTs and the EHOs worked together during the Persian Gulf deployment to insure that:

Preventive medicine personnel also advised unit leaders on the prevention of heat casualties and on the appropriate countermeasures for biting insects. The Marine Aircraft Wing had its own EHO assigned to the Wing Surgeon's staff, and PMTs at each Marine Aircraft Group performed similar functions. Naval Mobile Construction Battalions (SeaBees) assigned to Marine forces also have a similar PM capability built into their structure. From the beginning of Operation Desert Shield, PM personnel served at the front lines, using their knowledge and experience to identify and prevent potential health problems.

A large PM section was deployed in the medical battalion of the FSSG. The section consisted of EHOs, entomologists and a team of PMTs. The section was also augmented with additional personnel from the Navy Disease Vector Ecology and Control Center, Jacksonville, Florida. This section brought extensive PM equipment and supplies, including insect and rodent control products, water testing gear, and chlorine to purify water. Its mission was to provide high level back-up for the first line PM personnel at Division and Wing. It was positioned with Combat Service Support Detachments in support of forward Wing and Division units. In addition, the medical battalion PM section provided direct support to battalions in the FSSG. Together, the Marine Corps PM teams ensured the very best in field preventive measures where, and when, they were needed most.

B. Surveillance

One of the most important priorities in any PM effort is to recognize disease and non-battle injury (DNBI) problems early, while they can be more readily controlled. At the beginning of the Gulf deployment, PM personnel (for the first time in US Marine Corps history) established a system of DNBI surveillance to track key illness and injury rates at virtually every Marine and SeaBee Medical Aid Station. At the beginning of the operation, the Navy assigned a Navy Preventive Medicine physician to the Marine Central Command Surgeon's staff to continuously analyze DNBI rates and identify any unusual patterns. In addition, PM personnel continuously monitored all admissions to medical battalion facilities or Navy Fleet Hospitals throughout the Gulf deployment to detect unusual or unanticipated diseases.

By tracking actual DNBI rates and trends in nearly all units, PM personnel were in position to respond immediately to problems and apply appropriate countermeasures. Based on the expected medical threats in the Persian Gulf, special attention was focused on the following DNBI categories, which were established specifically to identify health problems that could degrade combat effectiveness:

Heat injury: one of the most significant health threats early in the deployment.

Diarrhea: a potentially epidemic problem in field conditions.

Skin conditions: a significant cause of lost man-days in many previous conflicts.

Respiratory conditions: colds, pneumonia and other respiratory problems are common and can be widespread during any deployment.

Injury/musculoskeletal conditions: a major cause of lost man-days from training and deployment activities.

Eye problems: eye infections, like "pink eye," can be epidemic in field conditions, also corneal abrasion from blowing sand was a risk in the desert.

Unexplained fevers: an unexplained fever may be the first sign of diseases, such as sand fly fever, malaria, and other serious infections.

Psychiatric conditions: the stresses of deployment and combat often cause psychiatric symptoms.

Other conditions: other problems seen at sick call not fitting into the above categories.

Each week, unit aid stations reviewed their sick call logbooks and determined how many Marines or sailors were treated for the above categories of health problems. A unit-specific DNBI rate was then calculated for each category, based on how many Marines or sailors were assigned to the unit. These simple calculations allowed PM personnel to determine what percentage of the unit was treated during the prior week for these key problems. If the percentage was higher than expected, the cause was investigated. Figure 2 shows the total weekly rates of outpatient visits among approximately 40,000 Marine Corps ground troops stationed in northeastern Saudi Arabia during Desert Shield and Desert Storm.

Figure 2 - Marine Outpatient Rates

The DNBI surveillance system demonstrated that PM efforts were very successful in keeping Marines and sailors healthy during Operations Desert Shield and Desert Storm. On average, approximately six percent of the ground troops were treated per week for some type of illness or injury. This compares favorably to the DNBI rates in garrison troops at Camp Pendleton, California, where approximately four percent of personnel per week are treated. Furthermore, DNBI rates decreased during the deployment as troops adapted to field conditions and PM efforts identified and controlled health threats.

DNBI surveillance proved its worth early in the deployment, when elevated diarrhea rates were detected simultaneously in numerous US Marine units located throughout Saudi Arabia. The force-wide average diarrhea rate rose to approximately four percent per week, with some units experiencing significantly higher rates. Recognizing these elevated diarrhea rates early enabled PM personnel to rapidly identify specific problems with the contract food used in the initial stages of the deployment. The NFL found that the fresh produce initially procured outside of the normal supply system contained local, diarrhea causing bacteria.[20] This problem was rapidly corrected, and diarrhea rates quickly dropped below one percent per week for the remainder of the deployment. This rate of illness is only slightly higher than the normal diarrhea rate seen in garrison at Camp Pendleton.

Figure 3 shows the weekly rates of gastroenteritis among approximately 40,000 Marine Corps ground troops in northeastern Saudi Arabia during Desert Shield and Desert Storm.

Figure 3 - Marine Gastroenteritis Rates

Respiratory disease rates remained generally low during Operations Desert Shield and Desert Storm, with few cases requiring hospitalization. Rates of outpatient treatment were higher early in the deployment when troops tended to be crowded together during air travel and in staging areas. Respiratory disease rates rapidly declined as troops spread out, but rose again when the weather turned cold. These acute respiratory illness patterns are similar to what is typically seen in the US, and were not a significant problem for US Marines. The British also experienced increased rates of respiratory disease during periods of deployment and crowding.[21] Figure 4 shows the weekly rates of respiratory disease among outpatients in approximately 40,000 Marine Corps ground troops in Saudi Arabia during Desert Shield and Desert Storm. The arrows indicate the two primary periods when Marine Expeditionary Force personnel were being deployed.

Figure 4 - Marine Respiratory Disease Rates

In all other DNBI categories, illness rates were remarkably low. In spite of extremely hot and humid conditions at the beginning of the deployment, less than 0.3% of the force per week (3 cases per 1000 per week) required treatment at an aid station for heat injury. Strong command emphasis on providing abundant water and acclimatizing troops scored a major victory against this major health threat. In line with these low rates, only about one percent of the force was treated per week for skin problemsmainly fungal infections and heat rash. This rate is comparable to that seen in a garrison settings during hot and humid conditions.

Significantly, the surveillance system did not detect either sand fly fever or cutaneous leishmaniasis (which causes skin sores) among US Marines. These infectious diseases are transmitted by sand flies and were expected to be major problems in the Persian Gulf. Entomologists, PMTs, and EHOs were on constant lookout for sand fly vectorsvery few were identified.

All other DNBI rates, including injuries, eye problems, psychiatric conditions, and unexplained fevers were remarkably low throughout the deployment, and well within the expected norms. It is noteworthy that the rate of unexplained fevers remained essentially

Figure 5 - Marine Rates for Injuries, Eye Problems, Psychiatric
Evaluations, and Fevers

zero throughout the deployment. This DNBI category was designed as an early warning indicator to detect unusual insect-borne infections, such as sand fly fever, malaria, and dengue. Most of these infections take time to diagnose, but they typically begin with an acute fever. The absence of unexplained fevers was reassuring to medical and PM personnel, indicating that Marines and sailors were not experiencing serious infections. This finding was corroborated by the near absence of disease carrying sand flies and mosquitoes during the deployment. Furthermore, no individual was hospitalized for these illnesses during the deployment, except for one case of West Nile fever (an acute flu-like viral infection).[22] Figure 5 shows the weekly rates of outpatient visits for injuries, eye problems, psychiatric evaluations, and fevers among Marine Corps ground troops during Desert Shield and Desert Storm.


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