Skip to main content

Military Health System

Description of a COVID-19 Beta Variant Outbreak, Joint Base Lewis-McChord, WA, February–March 2021

Image of U.S. Army Soldiers from 1-17th Infantry Battalion, 2nd Stryker Brigade, 2nd Infantry Division, clear an objective during the training exercise Bayonet Focus 19-02 at Yakima Training Center, Wash., May 6, 2019. Bayonet Focus is a training exercise designed to assess Soldiers’ ability to preform tasks and complete objectives under conditions experienced during combat situations. (U.S. Army photo by Spc. Angel Ruszkiewicz). U.S. Army Soldiers from 1-17th Infantry Battalion, 2nd Stryker Brigade, 2nd Infantry Division, clear an objective during the training exercise Bayonet Focus 19-02 at Yakima Training Center, Wash., May 6, 2019. Bayonet Focus is a training exercise designed to assess Soldiers’ ability to preform tasks and complete objectives under conditions experienced during combat situations. (U.S. Army photo by Spc. Angel Ruszkiewicz)

Recommended Content:

Medical Surveillance Monthly Report

Abstract

An outbreak of SARS CoV-2 infection occurred in an infantry battalion from Joint Base Lewis-McChord following participation in a field training exercise in the vicinity of Yakima, WA in February of 2021. Extreme weather during the exercise disrupted planned COVID-19 mitigation measures and caused 110 soldiers to be sheltered in a small aircraft hangar for several nights. The probable index case reported to sick call with symptoms compatible with COVID-19, but the soldier was not diagnosed with COVID-19, was returned to duty, and was allowed to remain in the enclosed hangar for 3 additional days. In total, 143 individuals with epidemiologic ties to the field training exercise tested positive for SARS-CoV-2 during the outbreak. Nine samples sent for sequencing were determined to be the SARS-CoV-2 Beta variant. This report illustrates important lessons learned whose implementation in the future will enable better protection of service members from COVID-19 and similar health risks associated with training.

What are the new findings?

COVID-19 is a threat to military exercises because of the virus's ability to cause illness in a large number of soldiers. Results of this investigation demonstrate the potential impact of a COVID-19 outbreak in land-based military congregate living settings, especially those with shared sleeping spaces.

What is the impact on readiness and force health protection?

In addition to immunization, pre-deployment screening, basic hygiene measures such as sufficient sleeping space, and ready access to appropriate clinical assessment and diagnostic testing can be important parts of mitigating the risk of a potential COVID-19 outbreak in military training settings.

Background

This report describes an outbreak of SARS-CoV-2, the causative agent of COVID-19, that peaked during Feb. 21–26, 2021 and was tied to a single military training event. A total of 143 laboratory-confirmed cases were identified. Nine samples collected within the first several days of the outbreak (Feb. 20–23, 2021) were sent for sequencing upon noting an increase in the baseline SARS-CoV-2 positivity rate among individuals in a congregate setting. All 9 samples were determined to be the SARS-CoV-2 variant B.1351, referred to by the World Health Organization naming scheme as the Beta variant.

The first case of SARS-CoV-2 infection known to be caused by the Beta variant (501Y.V2/B.1.351 lineage) was reported in South Africa on Dec. 18, 2020.1 The Beta variant was first reported in the U.S. in South Carolina on Jan. 28, 2021.2 By March 23, 2021, the Washington State Department of Health had reported 8 cases while the Centers for Disease Control (CDC) had reported 219 cases of Beta variant in 27 jurisdictions nationally.3,4 Similar to the Alpha (B.1.1.7) variant first reported in December 2020, the Beta variant has been linked to higher viral load and increased transmissibility compared to other SARS-CoV-2 variants that were identified at the time.5 Other known attributes of the variant include moderate reduction in neutralization by monoclonal antibody therapeutics, convalescent sera, and post-vaccination sera.6 Additionally, clinical trial data have also shown a decreased efficacy of some coronavirus disease 2019 (COVID-19) vaccines primarily due to antigenic changes in the SARS-CoV-2 spike protein.7,8 To date, there is no evidence suggesting that the Beta variant is associated with an increase in disease severity.9,10

This report aims to describe the setting, timeline, and characteristics of an outbreak of COVID-19 Beta variant among an infantry battalion from Joint Base Lewis-McChord (JBLM), WA following participation in a field training exercise at a local Army training center in Yakima, WA in February 2021.

Methods

Population and setting

During Feb. 4–19, 2021, an Infantry Battalion (herein Battalion A) of a Brigade (herein Brigade X) from JBLM conducted a tactical field training exercise at an Army training center in Yakima, WA. Brigade X is an infantry unit comprised of 8 battalions; battalions typically consist of about 1,000 soldiers distributed among 4 to 6 companies. Neither symptom-based nor laboratory-based COVID-19 screening of the soldier participants was performed prior to deployment. Soldiers of Battalion A conducted platoon- and company-level training in groups of approximately 40 or 275 personnel at a time rotating through different training iterations to maximize physical distance between soldiers as much as practically possible. Hand washing stations were placed near all tactical operations centers, latrines, and designated dining areas. Use of face covering was mandated by policy and enforced by leadership. Despite COVID-19 mitigation measures that were integrated in the planning of the field training exercise, extreme environmental conditions and logistical difficulties made these measures difficult to execute and maintain.

On Feb. 12, 2021, the training center experienced extreme weather with temperatures reaching 13 °F (-10 °C) with roughly 2 inches (5 cm) of snow and wind gusts up to 14 mph. Because of these conditions, 110 soldiers (an infantry company of 103 soldiers and a group of 7 medics from a separate supporting company) were moved into a relatively small aircraft hangar on the night of Feb. 12, 2021, for protection from freezing temperatures; this was the sleeping arrangement for the remainder of the field training exercise. The aircraft hangar was approximately 75 ft (23 m) x 85 ft (26m) or 6,375 square feet (592 square meters) in size (Figures 1, 2). The hangar had no mechanical heating or ventilation system and the windows were kept closed to keep the heat in. Furthermore, because of limited space, many soldiers slept on the ground in their military issued 5-component modular sleep systems with roughly 2 feet of space between soldiers. Based on minimum acceptable sleeping space allowance of 72 square feet of floor space per person,11 the aircraft hangar had a maximum capacity of 88 personnel (6,375/72=88.5). By housing 110 soldiers in this space, the unit's use of the hangar exceeded recommended public health capacity by 22 soldiers.

The unit returned earlier than planned to JBLM on Feb. 18–19, 2021, using buses within which recommended physical distancing could not be achieved. Shortly after returning to JBLM, a small number of soldiers began reporting symptoms of COVID-19. On Feb. 20, 2021, the Battalion physician assistant was notified of what was later identified as the index case of this outbreak; the case had tested positive for SARS-CoV-2 earlier the same day. The affected soldier reported initial symptoms of fever (101.6 °F, 38.7 °C) and chills that started on Feb. 16, 2021. This soldier was evaluated by medics in the field on the day of his symptom onset but was not suspected as having COVID-19. The soldier was rehydrated and was promptly returned to duty where he resumed normal training activities for the next 3 days among other soldiers, including sleeping in the enclosed hangar. When the presence of an outbreak was confirmed, representative respiratory samples were collected and sent for sequencing; these samples were from cases that were among the first diagnosed and most highly connected to other cases.

Case identification

All cases identified (service members and beneficiaries) were diagnosed using PCR testing through Madigan Army Medical Center's laboratory. Case interview and contact tracing were performed for all individuals with laboratory-confirmed COVID-19 infection by the unit medical section with assistance from JBLM Department of Public Health. Close contact was defined using CDC's criteria of being within 6 feet of someone with laboratory-confirmed SARS-CoV-2 infection for a cumulative total of 15 minutes or more over a 24-hour period during the window of high-risk viral transmission (2 days prior to symptom onset or if asymptomatic, prior to a positive test, until completion of the isolation period). Contact tracing included civilian close contacts. Genome sequencing for variants was completed on an Illumina MiSeq (Illumina, San Diego, CA) at U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID).

Results

Outbreak investigation

The index case described above was the first symptomatic soldier from the hangar to test positive for COVID-19. Identification of this case triggered immediate contact tracing by the Battalion medical section which resulted in 21 individuals being quarantined for close contact with the index case. On Feb. 21, 2021, the day after the first laboratory-confirmed case was reported, 2 additional individuals tested positive for SARS-CoV-2 COVID-19 (Figure 3). Although these 2 individuals were not identified as close contacts by the index case as they worked in different sections, they were found to have slept in the same enclosed hangar during the field training exercise. The identification of these cases triggered the quarantine and testing of 7 additional soldiers. By the end of the day on Feb. 21, a total of 18 individuals had tested positive for COVID-19 from Battalion A. Contact tracing for the first 3 positive cases revealed a total of 28 individuals (including civilians and beneficiaries) as close contacts who were subsequently quarantined and tested. By 24 February 2021, 46 individuals from the infantry company had tested positive for COVID-19. At this point the remainder of the company was placed into quarantine and tested.

Following several iterations of contact tracing, the total number of positive cases from this company reached 87. Forty-two additional positive cases were identified in the support company to which the medical detachment belonged. These 2 companies accounted for 129 (90.8%) of the 142 positive cases in Battalion A from Feb. 21 to March 4, 2021. An additional 19 cases were identified as part of this outbreak that were not part of the battalion, but were linked epidemiologically. As above, 9 samples from the outbreak were sent for sequencing, all of which were determined to be SARS-CoV-2 Beta variant.

The distribution of daily counts of positive tests for SARS-CoV-2 infection among soldiers in each of the battalions represents an outbreak from Feb. 14, 2021 to March 5, 2021 (Figure 3). Cases from Battalion A caused a sudden and dramatic increase of daily COVID-19 cases in Brigade X beginning Feb. 21, 2021 and ending Feb. 26, 2021, clearly marking the beginning and end of the peak outbreak period. The index case was not included in the peak outbreak period as this soldier tested positive on Feb. 20. Of note, it is likely that many of the cases identified in the first few days of the outbreak may have become infected earlier. Battalion A accounted for 92.3% (132/143) of the cases during this period, and the daily average of COVID-19 cases during the peak outbreak period was 24. Comparatively, the daily average of COVID-19 cases during the 7 days preceding the outbreak (Feb. 14–20, 2021, the pre-outbreak period) was less than 1. In the late-outbreak period (Feb. 27–March 5, 2021), the average daily COVID-19 case count decreased to 2, a 91.7% decrease compared to the peak outbreak period.

The distribution of COVID-19 cases before, during, and after the peak period of the outbreak reflect the age distribution of the infantry units involved, the concentration of cases in Battalion A, and the high proportion of infected soldiers who were asymptomatic but were identified through methodical contact tracing (Table). In total, 164 individuals from the study cohort sample tested positive for SARS-CoV-2 from Feb. 14 through March 5, 2021. The field training exercise (FTX) was held from Feb. 9–19, 2021. The majority of samples tested were collected in the days immediately following the FTX (dates of collection Feb. 21–26, 2021). The majority of those testing positive were male (92.1%; n=151). The average age was 24, (range=7–43 years) with a majority in aged 20– 29 (71.3%; n=117). The majority were active duty soldiers (99.4%; n=163), with the remaining individual being a young (under 18 years old) family member of an active duty soldier. Battalion A accounted for 144 of the individuals testing positive (87.8%). Among the 154 individuals whose reasons for testing were specified, a majority experienced no symptoms (68.8%; n=106) while a minority did experience symptoms (n=48; 31.2%). No cases reported symptoms as being severe (data not shown). For an additional 10 individuals, no data were available as to whether they experienced symptoms (unspecified) (Table). The most common reason for testing was being identified as a close contact to a positive case only (62.2%; n=102).

During the peak outbreak period, 67.8% (97/143) of COVID-19 cases were asymptomatic close contacts who were tested primarily as the result of contact tracing efforts stemming from the index case (Table). Conversely, none of the cases during the pre-outbreak period and one-third (5/15) of the cases in the late-outbreak period were tested due to close contact. Furthermore, just one-quarter (36/143) of peak outbreak cases reported symptoms while two-thirds (4/6) of pre-outbreak cases and a little more than half (8/15) of late outbreak cases reported symptoms. Of note, at the time of this outbreak, COVID-19 vaccine was not widely available. Only 2 medics from the medical detachment were fully vaccinated. Neither of the vaccinated medics who were tested during the outbreak period contracted COVID-19 whereas 4 of the 5 unvaccinated medics tested positive for SARS-CoV-2.

Editorial Comment

This report describes a COVID-19 outbreak tied to a single military training event that affected almost a quarter (23.8%) of soldiers in an infantry battalion. The current findings demonstrate that highly contagious variants could be of particular concern in military congregate living settings, especially those with shared sleeping spaces. Disease severity during the outbreak was generally mild in an otherwise healthy population; however, the results underscore the negative impact (i.e., 24% of a battalion isolated or quarantined) that a COVID-19 outbreak, especially of a highly contagious variant, can have on readiness. Intensive contact tracing, testing, and command-implemented isolation and quarantine contributed to quick extinction of the outbreak. These control efforts resulted from an investigation of the outbreak that featured robust two-way communication between JBLM Public Health and the medical and command assets of the affected units.

In addition, the experience of the 2 vaccinated medics supports the effectiveness of vaccinations in combating COVID-19 transmission.

Military leaders are tasked with optimizing and maintaining combat readiness of their soldiers and the unit. The COVID-19 pandemic presents a unique challenge to leaders in balancing combat readiness against mitigation of SARS-CoV-2 transmission. Although this battalion's leadership took additional steps to ensure COVID-19 mitigation measures were incorporated into every aspect of the field training exercise, this outbreak was not prevented.

Three key issues appear to have contributed to this outbreak. First, the unit did not include pre-deployment COVID-19 screening as part of operational plans. Symptom-based or temperature-based screening might have mitigated viral transmission risk by identifying soldiers displaying symptoms of COVID-19 who needed to be tested and isolated prior to deployment. Furthermore, lab-based screening might have identified asymptomatic spreaders and potentially prevented this outbreak. As a result of this outbreak, the leadership of the training base has implemented a screening protocol for members of units undergoing training activities.

However, it should be noted that the apparent index case did not develop symptoms until the 13th day of the exercise, so pre-exercise screening might not have been helpful in detecting his infection.

Second, the unit's contingency plan for extreme weather conditions did not incorporate adequate COVID-19 mitigation measures in indoor settings. Overcrowded indoor sleeping arrangements coupled with poor ventilation permitted conditions for widespread transmission of a highly contagious variant of COVID-19. This was potentially exacerbated by transport back to JBLM on buses where large numbers of soldiers in a shared air space could also promote disease transmission. Given the exigency of protecting the soldiers from severe weather conditions, the local public health authority was not consulted about these decisions made prior to the recognition of the first COVID case in the unit.

Third, despite the index case presenting to the platoon aid station with report of chills and a fever on Feb. 16, 2021, 4 days before laboratory-confirmed diagnosis of SARS-CoV-2 infection, this soldier was not evaluated for COVID-19 or placed in isolation. Instead, the soldier was returned to duty. This misstep could have been averted through the use of an effective screening protocol that triggered isolation and testing for anyone presenting with symptoms consistent with COVID-19. Early removal and testing of the index case might have significantly reduced the number of positive cases in this outbreak.

This study has some limitations that should be considered in light of the findings. The lack of access to COVID-19 testing at YTC may have led to delayed diagnoses in some cases. In addition, the absence of a licensed independent medical provider at the training event may have also led to delayed diagnosis. The scope of practice for medics assigned to this exercise included provision of OTC medications for sick-call and ordering quarantine/isolation for possible communicable disease, although no such determination (isolation) was made for the index case.

This study describes the characteristics of a Beta variant outbreak which may not be fully applicable to other more current or emerging SARS-CoV-2 variants. This study also describes the characteristics of an outbreak in a predominantly unvaccinated population which is no longer applicable to the current predominantly vaccinated military force.

The findings of this study can inform mitigation efforts in military units in a deployed or field training environment and are particularly applicable in the setting of the Delta variant as the predominant cause of COVID-19. Like Beta, Delta is highly contagious, suggesting the need for continued vigilance among medical personnel and leaders at all levels during deployment and training events. Similarly, the planning considerations that might have mitigated or prevented the outbreak described in this report could be valuable for medical and command elements preparing for training or deployment events.

Author Affiliations: Madigan Army Medical Center, Department of Public Health, JBLM, WA (LTC Mease, MAJ Yun, CPT Egbert, LTC Yassin, COL Faestel, CPT Moyer, COL Terrio); Department of Chemistry and Life Science, United States Military Academy, West Point, NY (MAJ Bateman).

Acknowledgements: The authors thank MAJ Jeremy McGuffey for his assistance in collecting details of the field training exercise which made this work possible. The authors also thank LTC Kurt Jerke for his laboratory expertise and input.

Funding: All work described herein was performed as part of paid regular duties as part of employment by the U.S. Government.

Conflicts of Interest: None.

Disclaimer: The views expressed herein are those of the authors and do not necessarily represent the views of the U.S. Army, Department of Defense, or U.S. Government.

References

1. Tracking SARS-CoV-2 variants. Accessed Jan. 28, 2022. https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/

2. Chappell B. South Carolina Reports 1st Known U.S. Cases Of Variant From South Africa. NPR. Published Jan. 28, 2021. Accessed Sept. 17, 2021. https://www.npr.org/sections/coronavirus-live-updates/2021/01/28/961609976/south-carolina-reports-1st-known-u-s-cases-of-variant-from-south-africa

3. CDC. COVID Data Tracker. Centers for Disease Control and Prevention. Published March 28, 2020. Accessed Sept. 17, 2021. https://covid.cdc.gov/covid-data-tracker

4. WA DOH. SARS-CoV-2 Sequencing and Variants in Washington State. Accessed April 15, 2021. https://www.doh.wa.gov/Portals/1/Documents/1600/coronavirus/data-tables/420-316-SequencingAndVariantsReport.pdf

5. Pearson CAB, Russell TW, Davis NG, et al. Estimates of severity and transmissibility of novel SARS-CoV-2 variant 501Y.V2 in South Africa. CMMID Repository. Published Jan. 11, 2021. Accessed Sept. 17, 2021. https://cmmid.github.io/topics/covid19/sa-novel-variant.html

6. CDC. Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention. Published Feb. 11, 2020. Accessed Sept. 17, 2021. https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html

7. Madhi SA, Baillie V, Cutland CL, et al. Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the BETA Variant. New Engl J Med. 2021;384(20):1885–1898. 

8. Mahase E. Covid-19: Novavax vaccine efficacy is 86% against UK variant and 60% against South African variant. BMJ. 2021;372:n296. 

9. What you need to know about the 501Y.V2 (BETA) South African Variant of SARS-CoV-2. Ask a Scientist. Published Jan. 19, 2021. Accessed Sept. 17, 2021. https://www.thermofisher.com/blog/ask-a-scientist/what-you-need-to-know-about-the-501y-v2-b-1-351-south-african-variant-of-sars-cov-2/

10. CDC. Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention. Published Feb. 11, 2020. Accessed Sept. 17, 2021. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/scientific-brief-emerging-variants.html

11. HQ, Department of the Army, Facility Sanitation Controls and Inspections. March 1, 2019. TB MED 531: 44-45. Accessed Sept. 17, 2021. https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN16903_tbmed531_FINAL.pdf

FIGURE 1. Exterior of hangar used to house soldiers at an Army training center during a field training exercise

FIGURE 2. Interior of hanger used to house soldiers at an Army training center during a field training exercise

FIGURE 3. Epidemic curve depicting the daily counts of positive tests for SARS-CoV-2 infection among soldiers in each of the battalions in the brigade affected by the outbreak, 14 February–5 March 2021

TABLE. Background characteristics of SARS-CoV-2 positive soldiers by outbreak period, 14 February–5 March 2021

You also may be interested in...

Modeling Lyme Disease Host Animal Habitat Suitability, West Point, New York

Article
4/1/2019
A deer basks in the morning sun at Joint Base San Antonio-Fort Sam Houston, Texas.  (Photo Courtesy: U.S. Air Force)

As the most frequently reported vector-borne disease among active component U.S. service members, with an incidence rate of 16 cases per 100,000 person-years in 2011, Lyme disease poses both a challenge to healthcare providers in the Military Health System and a threat to military readiness. Spread through the bite of an infected blacklegged tick, infection with the bacterial cause of Lyme disease can have lasting effects that may lead to medical discharge from the military. The U.S. Military Academy at West Point is situated in a highly endemic area in New York State. To identify probable areas where West Point cadets as well as active duty service members stationed at West Point and their families might contract Lyme disease, this study used Geographic Information System mapping methods and remote sensing data to replicate an established spatial model to identify the likely habitat of a key host animal—the white-tailed deer.

Recommended Content:

Medical Surveillance Monthly Report

Incidence, Timing, and Seasonal Patterns of Heat Illnesses During U.S. Army Basic Combat Training, 2014–2018

Article
4/1/2019
U.S. Marines participate in morning physical training during a field exercise at Marine Corps Base Camp Pendleton, California. (Photo Courtesy: U.S. Marine Corps)

Risk factors for heat illnesses (HIs) among new soldiers include exercise intensity, environmental conditions at the time of exercise, a high body mass index, and conducting initial entry training during hot and humid weather when recruits are not yet acclimated to physical exertion in heat. This study used data from the Defense Health Agency’s–Weather-Related Injury Repository to calculate rates and to describe the incidence, timing, and geographic distribution of HIs among soldiers during U.S. Army basic combat training (BCT). From 2014 through 2018, HI events occurred in 1,210 trainees during BCT, resulting in an overall rate of 3.6 per 10,000 BCT person-weeks (p-wks) (95% CI: 3.4–3.8). HI rates (cases per 10,000 BCT p-wks) varied among the 4 Army BCT sites: Fort Benning, GA (6.8); Fort Jackson, SC (4.4); Fort Sill, OK (1.8); and Fort Leonard Wood, MO (1.7). Although the highest rates ofHIs occurred at Fort Benning, recruits in all geographic areas were at risk. The highest rates of HI occurred during the peak training months of June through September, and over half of all HI cases affected soldiers during the first 3 weeks of BCT. Prevention of HI among BCT soldiers requires relevant training of both recruits and cadre as well as the implementation of effective preventive measures.

Recommended Content:

Medical Surveillance Monthly Report

Update: Exertional Hyponatremia, Active Component, U.S. Armed Forces, 2003–2018

Article
4/1/2019
Drink water the day before and during physical activity or if heat is going to become a factor. (Photo Courtesy: U.S. Air Force)

From 2003 through 2018, there were 1,579 incident diagnoses of exertional hyponatremia among active component service members, for a crude overall incidence rate of 7.2 cases per 100,000 person-years (p-yrs). Compared to their respective counterparts, females, those less than 20 years old, and recruit trainees had higher overall incidence rates of exertional hyponatremia diagnoses. The overall incidence rate during the 16-year period was highest in the Marine Corps, intermediate in the Army and Air Force, and lowest in the Navy. Overall rates during the surveillance period were highest among Asian/Pacific Islander and non-Hispanic white service members and lowest among non-Hispanic black service members. Between 2003 and 2018, crude annual incidence rates of exertional hyponatremia peaked in 2010 (12.7 per 100,000 p-yrs) and then decreased to 5.3 cases per 100,000 p-yrs in 2013 before increasing in 2014 and 2015. The crude annual rate in 2018 (6.3 per 100,000 p-yrs) represented a decrease of 26.5% from 2015. Service members and their supervisors must be knowledgeable of the dangers of excessive water consumption and the prescribed limits for water intake during prolonged physical activity (e.g., field training exercises, personal fitness training, and recreational activities) in hot, humid weather.

Recommended Content:

Medical Surveillance Monthly Report

Update: Exertional Rhabdomyolysis, Active Component, U.S. Armed Forces, 2014–2018

Article
4/1/2019
U.S. Marines sprint uphill during a field training exercise at Marine Corps Air Station Miramar, California. to maintain contact with an aviation combat element, teaching and sustaining their proficiency in setting up and maintaining communication equipment.  (Photo Courtesy: U.S. Marine Corps)

Among active component service members in 2018, there were 545 incident diagnoses of rhabdomyolysis likely due to exertional rhabdomyolysis, for an unadjusted incidence rate of 42.0 cases per 100,000 person-years. Subgroup-specific rates in 2018 were highest among males, those less than 20 years old, Asian/Pacific Islander service members, Marine Corps and Army members, and those in combat-specific or “other/unknown” occupations. During 2014–2018, crude rates of exertional rhabdomyolysis increased steadily from 2014 through 2016 after which rates declined slightly in 2017 before increasing again in 2018. Compared to service members in other race/ethnicity groups, the overall rate of exertional rhabdomyolysis was highest among non-Hispanic blacks in every year except 2018. Overall and annual rates were highest among Marine Corps members, intermediate among those in the Army, and lowest among those in the Air Force and Navy. Most cases of exertional rhabdomyolysis were diagnosed at installations that support basic combat/recruit training or major ground combat units of the Army or the Marine Corps. Medical care providers should consider exertional rhabdomyolysis in the differential diagnosis when service members (particularly recruits) present with muscular pain or swelling, limited range of motion, or the excretion of dark urine (possibly due to myoglobinuria) after strenuous physical activity, particularly in hot, humid weather.

Recommended Content:

Medical Surveillance Monthly Report

Update: Heat Illness, Active Component, U.S. Armed Forces, 2018

Article
4/1/2019
Drink water the day before and during physical activity or if heat is going to become a factor. (Photo Courtesy: U.S. Air Force)

In 2018, there were 578 incident diagnoses of heat stroke and 2,214 incident diagnoses of heat exhaustion among active component service members. The overall crude incidence rates of heat stroke and heat exhaustion diagnoses were 0.45 cases and 1.71 cases per 1,000 person-years, respectively. In 2018, subgroup-specific rates of incident heat stroke diagnoses were highest among males and service members less than 20 years old, Asian/Pacific Islanders, Marine Corps and Army members, recruit trainees, and those in combat-specific occupations. Subgroup-specific incidence rates of heat exhaustion diagnoses in 2018 were notably higher among service members less than 20 years old, Asian/Pacific Islanders, Army and Marine Corps members, recruit trainees, and service members in combat-specific occupations. During 2014–2018, a total of 325 heat illnesses were documented among service members in Iraq and Afghanistan; 8.6% (n=28) were diagnosed as heat stroke. Commanders, small unit leaders, training cadre, and supporting medical personnel must ensure that the military members whom they supervise and support are informed about the risks, preventive countermeasures, early signs and symptoms, and first-responder actions related to heat illnesses.

Recommended Content:

Medical Surveillance Monthly Report

Vasectomy and Vasectomy Reversals, Active Component, U.S. Armed Forces, 2000–2017

Article
3/1/2019
Sperm is the male reproductive cell  Photo: iStock

During 2000–2017, a total of 170,878 active component service members underwent a first-occurring vasectomy, for a crude overall incidence rate of 8.6 cases per 1,000 person-years (p-yrs). Among the men who underwent incident vasectomy, 2.2% had another vasectomy performed during the surveillance period. Compared to their respective counterparts, the overall rates of vasectomy were highest among service men aged 30–39 years, non-Hispanic whites, married men, and those in pilot/air crew occupations. Male Air Force members had the highest overall incidence of vasectomy and men in the Marine Corps, the lowest. Crude annual vasectomy rates among service men increased slightly between 2000 and 2017. The largest increases in rates over the 18-year period occurred among service men aged 35–49 years and among men working as pilots/air crew. Among those who underwent vasectomy, 1.8% also had at least 1 vasectomy reversal during the surveillance period. The likelihood of vasectomy reversal decreased with advancing age. Non-Hispanic black and Hispanic service men were more likely than those of other race/ethnicity groups to undergo vasectomy reversals.

Recommended Content:

Medical Surveillance Monthly Report

Testosterone Replacement Therapy Use Among Active Component Service Men, 2017

Article
3/1/2019
Image of Marines carrying a wooden log for physical fitness. Click to open a larger version of the image.

This analysis summarizes the prevalence of testosterone replacement therapy (TRT) during 2017 among active component service men by demographic and military characteristics. This analysis also determines the percentage of those receiving TRT in 2017 who had an indication for receiving TRT using the 2018 American Urological Association (AUA) clinical practice guidelines. In 2017, 5,093 of 1,076,633 active component service men filled a prescription for TRT, for a period prevalence of 4.7 per 1,000 male service members. After adjustment for covariates, the prevalence of TRT use remained highest among Army members, senior enlisted members, warrant officers, non-Hispanic whites, American Indians/Alaska Natives, those in combat arms occupations, healthcare workers, those who were married, and those with other/unknown marital status. Among active component male service members who received TRT in 2017, only 44.5% met the 2018 AUA clinical practice guidelines for receiving TRT.

Recommended Content:

Medical Surveillance Monthly Report

Brief Report: Male Infertility, Active Component, U.S. Armed Forces, 2013–2017

Article
3/1/2019
Sperm is the male reproductive cell  Photo: iStock

Infertility, defined as the inability to achieve a successful pregnancy after 1 year or more of unprotected sexual intercourse or therapeutic donor insemination, affects approximately 15% of all couples. Male infertility is diagnosed when, after testing both partners, reproductive problems have been found in the male. A male factor contributes in part or whole to about 50% of cases of infertility. However, determining the true prevalence of male infertility remains elusive, as most estimates are derived from couples seeking assistive reproductive technology in tertiary care or referral centers, population-based surveys, or high-risk occupational cohorts, all of which are likely to underestimate the prevalence of the condition in the general U.S. population.

Recommended Content:

Medical Surveillance Monthly Report

Sexually Transmitted Infections, Active Component, U.S. Armed Forces, 2010–2018

Article
3/1/2019
Anopheles merus

This report summarizes incidence rates of the 5 most common sexually transmitted infections (STIs) among active component service members of the U.S. Armed Forces during 2010–2018. Infections with chlamydia were the most common, followed in decreasing order of frequency by infections with genital human papillomavirus (HPV), gonorrhea, genital herpes simplex virus (HSV), and syphilis. Compared to men, women had higher rates of all STIs except for syphilis. In general, compared to their respective counterparts, younger service members, non-Hispanic blacks, soldiers, and enlisted members had higher incidence rates of STIs. During the latter half of the surveillance period, the incidence of chlamydia and gonorrhea increased among both male and female service members. Rates of syphilis increased for male service members but remained relatively stable among female service members. In contrast, the incidence of genital HPV and HSV decreased among both male and female service members. Similarities to and differences from the findings of the last MSMR update on STIs are discussed.

Recommended Content:

Medical Surveillance Monthly Report

Outbreak of Acute Respiratory Illness Associated with Adenovirus Type 4 at the U.S. Naval Academy, 2016

Article
2/1/2019
Malaria case definition

Human adenoviruses (HAdVs) are known to cause respiratory illness outbreaks at basic military training (BMT) sites. HAdV type-4 and -7 vaccines are routinely administered at enlisted BMT sites, but not at military academies. During August–September 2016, U.S. Naval Academy clinical staff noted an increase in students presenting with acute respiratory illness (ARI). An investigation was conducted to determine the extent and cause of the outbreak. During 22 August–11 September 2016, 652 clinic visits for ARI were identified using electronic health records. HAdV-4 was confirmed by real-time polymerase chain reaction assay in 18 out of 33 patient specimens collected and 1 additional HAdV case was detected from hospital records. Two HAdV-4 positive patients were treated for pneumonia including 1 hospitalized patient. Molecular analysis of 4 HAdV-4 isolates identified genome type 4a1, which is considered vaccine-preventable. Understanding the impact of HAdV in congregate settings other than enlisted BMT sites is necessary to inform discussions regarding future HAdV vaccine strategy.

Recommended Content:

Medical Surveillance Monthly Report

Update: Incidence of Glaucoma Diagnoses, Active Component, U.S. Armed Forces, 2013–2017

Article
2/1/2019
Glaucoma

Glaucoma is an eye disease that involves progressive optic nerve damage and vision loss, leading to blindness if undetected or untreated. This report describes an analysis using the Defense Medical Surveillance System to identify all active component service members with an incident diagnosis of glaucoma during the period between 2013 and 2017. The analysis identified 37,718 incident cases of glaucoma and an overall incidence rate of 5.9 cases per 1,000 person-years (p-yrs). The majority of cases (97.6%) were diagnosed at an early stage as borderline glaucoma; of these borderline cases, 2.2% progressed to open-angle glaucoma during the study period. No incident cases of absolute glaucoma, or total blindness, were identified. Rates of glaucoma were higher among non-Hispanic black (11.0 per 1,000 p-yrs), Asian/Pacific Islander (9.5), and Hispanic (6.9) service members, compared with non-Hispanic white (4.0) service members. Rates among female service members (6.6 per 1,000 p-yrs) were higher than those among male service members (5.8). Between 2013 and 2017, incidence rates of glaucoma diagnoses increased by 75.4% among all service members.

Recommended Content:

Medical Surveillance Monthly Report

Re-evaluation of the MSMR Case Definition for Incident Cases of Malaria

Article
2/1/2019
Anopheles merus

The MSMR has been publishing the results of surveillance studies of malaria since 1995. The standard MSMR case definition uses Medical Event Reports and records of hospitalizations in counting cases of malaria. This report summarizes the performance of the standard MSMR case definition in estimating incident cases of malaria from 2015 through 2017. Also explored was the potential surveillance value of including outpatient encounters with diagnoses of malaria or positive laboratory tests for malaria in the case definition. The study corroborated the relative accuracy of the MSMR case definition in estimating malaria incidence and provided the basis for updating the case definition in 2019 to include positive laboratory tests for malaria antigen within 30 days of an outpatient diagnosis.

Recommended Content:

Medical Surveillance Monthly Report

Update: Malaria, U.S. Armed Forces, 2018

Article
2/1/2019
Anopheles merus

Malaria infection remains an important health threat to U.S. service mem­bers who are located in endemic areas because of long-term duty assign­ments, participation in shorter-term contingency operations, or personal travel. In 2018, a total of 58 service members were diagnosed with or reported to have malaria. This represents a 65.7% increase from the 35 cases identi­fied in 2017. The relatively low numbers of cases during 2012–2018 mainly reflect decreases in cases acquired in Afghanistan, a reduction due largely to the progressive withdrawal of U.S. forces from that country. The percentage of cases of malaria caused by unspecified agents (63.8%; n=37) in 2018 was the highest during any given year of the surveillance period. The percent­age of cases identified as having been caused by Plasmodium vivax (10.3%; n=6) in 2018 was the lowest observed during the 10-year surveillance period. The percentage of malaria cases attributed to P. falciparum (25.9 %) in 2018 was similar to that observed in 2017 (25.7%), although the number of cases increased. Malaria was diagnosed at or reported from 31 different medical facilities in the U.S., Afghanistan, Italy, Germany, Djibouti, and Korea. Pro­viders of medical care to military members should be knowledgeable of and vigilant for clinical manifestations of malaria outside of endemic areas.

Recommended Content:

Medical Surveillance Monthly Report

Thyroid Disorders, Active Component, U.S. Armed Forces, 2008–2017

Article
12/1/2018

This analysis describes the incidence and prevalence of five thyroid disorders (goiter, thyrotoxicosis, primary/not otherwise specified [NOS] hypothyroidism, thyroiditis, and other disorders of the thyroid) among active component service members between 2008 and 2017. During the 10-year surveillance period, the most common incident thyroid disorder among male and female service members was primary/NOS hypothyroidism and the least common were thyroiditis and other disorders of thyroid. Primary/NOS hypothyroidism was diagnosed among 8,641 females (incidence rate: 43.7 per 10,000 person-years [p-yrs]) and 11,656 males (incidence rate: 10.2 per 10,000 p-yrs). Overall incidence rates of all thyroid disorders were 3 to 5 times higher among females compared to males. Among both males and females, incidence of primary/NOS hypothyroidism was higher among non-Hispanic white service members compared with service members in other race/ethnicity groups. The incidence of most thyroid disorders remained stable or decreased during the surveillance period. Overall, the prevalence of most thyroid disorders increased during the first part of the surveillance period and then either decreased or leveled off.31.6 per 100,000 active component service members in 2017. Validation of ICD-9/ICD-10 diagnostic codes for MetS using the National Cholesterol Education Program Adult Treatment Panel III criteria is needed to establish the level of agreement between the two methods for identifying this condition.

Recommended Content:

Medical Surveillance Monthly Report

Incidence and Prevalence of the Metabolic Syndrome Using ICD-9 and ICD-10 Diagnostic Codes, Active Component, U.S. Armed Forces, 2002–2017

Article
12/1/2018

This report uses ICD-9 and ICD-10 codes (277.7 and E88.81, respectively) for the metabolic syndrome (MetS) to summarize trends in the incidence and prevalence of this condition among active component members of the U.S. Armed Forces between 2002 and 2017. During this period, the crude overall incidence rate of MetS was 7.5 cases per 100,000 person-years (p-yrs). Compared to their respective counterparts, overall incidence rates were highest among Asian/Pacific Islanders, Air Force members, and warrant officers and were lowest among those of other/unknown race/ethnicity, Marine Corps members, and junior enlisted personnel and officers. During 2002–2017, the annual incidence rates of MetS peaked in 2009 at 11.6 cases per 100,000 p-yrs and decreased to 5.9 cases per 100,000 p-yrs in 2017. Annual prevalence rates of MetS increased steadily during the first 11 years of the surveillance period reaching a high of 38.9 per 100,000 active component service members in 2012, after which rates declined slightly to 31.6 per 100,000 active component service members in 2017. Validation of ICD-9/ICD-10 diagnostic codes for MetS using the National Cholesterol Education Program Adult Treatment Panel III criteria is needed to establish the level of agreement between the two methods for identifying this condition.

Recommended Content:

Medical Surveillance Monthly Report
<< < ... 11 12 13 > >> 
Showing results 166 - 180 Page 12 of 13
Refine your search
Last Updated: April 21, 2022
Follow us on Instagram Follow us on LinkedIn Follow us on Facebook Follow us on Twitter Follow us on YouTube Sign up on GovDelivery