Need larger text?

Update: Malaria Among Members of the U.S. Armed Forces, 2024

Image of 52915004. Malaria remains a risk for U.S. service members deployed or traveling to malaria-endemic regions.

4/1/2025

Share this page

Social Media Links

Abstract

Malaria infection remains a potential health threat to U.S. service members located in or near endemic areas due to duty assignments, participation in contingency operations, or personal travel. In 2024, a total of 30 active and reserve component service members were diagnosed with or reported to have malaria, a 23.1% decrease from the 39 cases identified in 2023. Over half of U.S. service member malaria cases in 2024 were caused by Plasmodium falciparum (56.7%, n=17), followed by unspecified types of malaria (33.3%, n=10) and P. vivax (10.0%, n=3). Malaria cases were diagnosed or reported from 18 different medical facilities in the U.S., Germany, Africa, Japan, Middle East, and South Korea. Of the 27 cases with a known location of diagnosis, 11 (40.7%) were reported or diagnosed outside the U.S.

What are the new findings?

This report documents a total of 30 malaria cases in 2024, a 23.1% decrease from 39 cases in 2023, mainly due to declines in Africa and other or unspecified locations. As in 2023, Plasmodium falciparum continues to constitute over half of new malaria cases (n=17, 56.7%) among active and reserve component U.S. service members.

What is the impact on readiness and force health protection?

Malaria poses a risk for service members deployed to endemic regions or during travel to such areas for personal reasons. P. falciparum, the most dangerous malaria strain, with a high risk of serious sequelae, including death, was diagnosed in more than half of cases in 2024. This finding emphasizes the need for continued preventive measures and heightened awareness of potential diagnostic challenges, particularly in areas where P. falciparum is endemic.

Background

Malaria, a life-threatening disease spread to humans through the bite of Anopheles mosquitoes, is transmitted mostly in tropical countries.1 The World Health Organization estimated 263 million malaria cases (incidence rate of 60.4 cases per 1,000 population at risk) in 2023 and 597,000 deaths (mortality rate of 13.7 per 100,000) within 83 endemic countries. Of those 83 countries with known malaria cases, 29 countries accounted for nearly 95% of cases and 96% of deaths.2 The five countries with the greatest estimated burdens of malaria are Nigeria (26%), Democratic Republic of the Congo (13%), Uganda (5%), Ethiopia (4%), and Mozambique (4%).2

Four species of Plasmodium account for the most significant burdens of malaria disease in humans: P. falciparum, P. vivax, P. malariae, and P. ovale. P. falciparum is the most dangerous form of malaria, accounting for over 90% of malaria-related deaths.3 While P. falciparum is most prevalent in Africa, P. vivax is the most widely distributed parasite species geographically, with relatively high prevalences of infection in the regions of Southeast Asia, the western Pacific, and eastern Mediterranean, as well as less densely populated areas of the Americas.4

Malaria is not endemic in the U.S. but remains a significant threat to its military service members deployed to tropical and subtropical regions. This risk to U.S. service members is due to operational constraints, lack of compliance with available preventive measures, in addition to continuing emergence of drug-resistant malarial parasites.5 The U.S. Armed Forces have long maintained policies and prescribed measures effective against vector-borne diseases such as malaria, including chemoprophylactic drugs, permethrin-impregnated uniforms and bed nets, and topical insect repellents. During planning for overseas military operations, geographically-associated presence or absence of malaria risk is usually known and can be anticipated, but implementation of preventive measures can be complex and dependent upon individual adherence to personal protective measures. When cases and outbreaks of malaria occur, they are generally due to poor adherence to chemoprophylaxis and other personal preventive measures.6-9

Since 1999, MSMR has published regular updates on malaria incidence among U.S. service members. MSMR’s sustained focus on malaria reflects both historical trends about this mosquito-borne disease and the continuing threat it poses to military readiness and service member health. This update describes the epidemiological patterns of malaria incidence among service members in the active and reserve components of the U.S. Armed Forces from 2015 through 2024.

Methods

The surveillance population for this report includes service members of the U.S. Army, Navy, Air Force, Marine Corps, Space Force, and Coast Guard. The surveillance period was January 1, 2015 through December 31, 2024. Records from the Defense Medical Surveillance System were searched to identify qualifying evidence of a malaria diagnosis from reportable medical events, hospitalizations, outpatient encounters (in military and non-military facilities), and laboratory results from military facilities.

Case definition criteria for malaria included either 1) an RME record of confirmed malaria, 2) a hospitalization record with a primary diagnosis of malaria, 3) a hospitalization record with a non-primary diagnosis of malaria due to a specific Plasmodium species, 4) a hospitalization record with a non-primary diagnosis of malaria plus a diagnosis of anemia, thrombocytopenia, and related conditions, or malaria-complicating pregnancy in any diagnostic position, 5) a hospitalization record with a non-primary diagnosis of malaria plus diagnoses of signs or symptoms consistent with malaria in each diagnostic position preceding malaria, or 6) a positive malaria antigen test plus an outpatient record with a diagnosis of malaria in any diagnostic position within 30 days of the specimen collection date.10 The relevant International Classification of Diseases, 9th and 10th Revision (ICD-9/ICD-10) codes used to identify cases are shown in Table 1.

This analysis restricted each service member to one episode of malaria per 365-day period. When multiple records documented a single episode, the date of the earliest record was considered the date of clinical onset. Records within 30 days of the clinical onset date were reviewed for evidence of a Plasmodium species.

Presumed locations of malaria acquisition were estimated with a hierarchical algorithm: 1) cases diagnosed in a malaria-endemic country were considered acquired in that country, 2) RMEs that listed exposures to malaria-endemic locations were considered acquired in those locations, 3) RMEs not listing exposures to malaria-endemic locations but were reported from installations in malaria-endemic locations were considered acquired in those locations, 4) cases diagnosed among service members during or within 30 days of deployment or assignment to a malaria-endemic country were considered acquired in that country, and 5) cases diagnosed among service members deployed or assigned to a malaria-endemic country within two years before diagnosis were considered acquired in those countries. All remaining cases were considered to have acquired malaria in unknown locations.

Results

In 2024, a total of 30 U.S. service members were diagnosed with, or reported to have, malaria (Table 2), resulting in a rate of 1.5 per 100,000 persons (data not shown). The annual total for 2024 represents a 23.1% decrease in malaria cases from the 39 cases reported in 2023 (Figure 1).

FIGURE 1. Numbers of Malaria Cases by Species and Calendar Year of Diagnosis or Report, Active and Reserve Components, U.S. Armed Forces, 2015–2024. This graph presents 10 stacked vertical columns, each of which represents the total number of malaria cases reported each year from 2015 until 2024. The segments of each column depict the species of each case of malaria diagnosed. Total cases in 2024 declined to only 30. The highest numbers of malaria cases were reported in 2016 and 2018, with 60 cases each, respectively; cases in the intervening year, 2017, were dramatically lower, at 34. In 2019 cases dropped dramatically again, to 34, and declined in 2021 to the lowest number, 21 cases, during the surveillance period, but rose again to 35 and 39 cases in 2022 and 2023, respectively. Numbers of Plasmodium falciparum cases were generally consistent each year, but when case numbers spiked in 2016 and 2018, it was due to increased numbers of Plasmodium vivax (and unspecified) cases. In 2022 and 2023, however, Plasmodium vivax cases remained low and unspecified malaria case species constituted the greatest increases.

Fifteen (50.0%) of the 30 cases in 2024 were identified from RME records. The remaining 15 cases were identified through additional case definition criteria: 11 cases from hospitalization records and 4 cases from a positive malaria antigen test plus an outpatient record with a diagnosis of malaria in any diagnostic position within 30 days of specimen collection date.

As in previous years, the majority of U.S. military members diagnosed with malaria in 2024 were men (96.7%), members of the active component (86.7%), and in the Army (56.7%). No cases were reported in the Space Force or Coast Guard. Non-Hispanic Black service members and those aged 30-34 years accounted for the most cases of malaria (56.7% and 40.0%, respectively) (Table 2).

Examination of the 15 malaria case records reported as RMEs revealed that 6 of the case exposures were classified as deployment-related, 6 as non-duty-related, 2 as duty-related but not deployment-related, and 1 case was missing exposure classification. All of the 6 non-duty exposure cases were considered to have been acquired in Africa (data not shown).

FIGURE 2. Numbers of Malaria Cases by Location of Acquisition, Active and Reserve Components, U.S. Armed Forces, 2015–2024. This graph presents 10 stacked vertical columns, each of which represents the total number of malaria cases reported every year from 2015 until 2024. The segments of each column depict the geographic location of acquisitions of each case of malaria diagnosed. Overall case numbers correspond to the numbers in Figure 1. In general, the majority or plurality of cases each year originated in Africa, with notable exception of 2018, when the number of cases acquired in Afghanistan, 21, equaled the number of cases acquired in Africa; in 2016 there were 13 cases acquired in Afghanistan but 22 acquired in Africa. With the withdrawal of troops from Afghanistan, those numbers were not present in 2021 and 2023, but cases acquired in other or unspecified areas increased significantly.

During the 2015-2024 surveillance period, malaria cases acquired in Africa (n=171, 44.6%) and other or unspecified locations (n=89, 23.2%) accounted for the largest numbers, followed by Korea (n=61, 15.9%), Afghanistan (n=60, 11.7%), and South and Central America (n=2, 0.5%) (Figure 2). The annual percentages of cases associated with Africa had the greatest variability, ranging from 34.5% in 2020 to 60.0% in 2021. Malaria cases were diagnosed or reported in 2024 from 18 different medical facilities in the U.S. (n=12), Germany (n=2), Africa (n=1), Japan (n=1), Middle East (n=1), and South Korea (n=1) (Table 3).

Over half of U.S. service member malaria cases in 2024 were caused by P. falciparum (56.7%, n=17). Of the 13 cases not attributed to P. falciparum, 3 (10.0%) were caused by P. vivax, while 10 were associated with other or unspecified types of malaria (33.3%) (Figure 3).

FIGURE 3. Numbers of Malaria Cases by Species Type and Location of Acquisition, Active and Reserve Components, U.S. Armed Forces, 2024. This graph presents three stacked vertical columns that depict the cumulative numbers of malaria diagnoses by geographic location and Plasmodium species in 2024. One column represents cases in Africa, another Korea, and the last column represents Other or Unspecified locations. Each location’s stacked column consists of segments that correspond to the number of cases of malaria categorized as Plasmodium falciparum, Plasmodium vivax, or Other/unspecified. Most Plasmodium falciparum cases, 10 in number or 58.8 percent, were acquired in or attributed to Africa. Plasmodium falciparum cases represented the majority, 56.7 percent, of cases in 2024. There were only three Plasmodium vivax cases reported in 2024, one in Other/unspecified locations and two in Korea. Other or unspecified species of malaria represented exactly one third of malaria cases reported in 2024.

In 2024, most cases acquired in Africa (n=13) were caused by P. falciparum (76.9%, n=10) (Figure 3). The 13 malaria cases acquired in Africa were linked to several countries, including Djibouti (n=3), Cameroon (n=2), Nigeria (n=2), Chad (n=1), Gabon (n=1), Ghana (n=1), Senegal (n=1), and Uganda (n=1); 1 case was associated with an unknown African location (data not shown).

Over the past 10 years, malaria caused by P. falciparum has accounted for the largest number of cases (n=186, 48.6%) followed by other or unspecified species (n=94, 24.5%), P. vivax (n=90, 23.5%), and other Plasmodium species (n=13, 3.8%). The annual percentages of cases attributed to P. vivax from 2015 through 2024 showed the greatest variability, ranging from 5.1% in 2023 to 51.7% in 2020 (data not shown).

Between 2015 and 2024, most non-P. vivax malaria cases (66.1%) were diagnosed or reported during the 6 months from the Northern Hemisphere middle of spring through the middle of autumn (i.e., May-October) (Figure 4). During the 10-year surveillance period, the proportions of non-P. vivax malaria cases diagnosed or reported from May through October varied by region of acquisition: Afghanistan (86.4%, n=19/22), Korea (79.2%, n=19/24), Africa (68.5%, n=113/165), and South and Central America (50.0%, n=1/2) (data not shown).

FIGURE 4. Cumulative Numbers of Malaria Cases by Species Type and Month of Clinical Presentation or Diagnosis, Active and Reserve Components, U.S. Armed Forces, 2015–2024. This graph presents 12 stacked columns, each of which depicts the cumulative numbers, from 2015 through 2024, of malaria diagnoses and reported cases by species for each month of the calendar year. The horizontal, or x-, axis is divided into 12 segments, each representing a month of the year. The vast majority, 70.2 percent, of malaria cases were diagnosed or reported during the six months from May through October, the middle of spring through the middle of autumn in the Northern Hemisphere, with September the month with the highest number of cumulative cases, 61. With the notable exception of June, in which a markedly lower total of cases has been reported, case numbers increase steadily from May through September.

Discussion

The 30 active and reserve component service members diagnosed with or reported to have malaria in 2024 represent a 23.1% decrease from the 39 cases reported in 2023. This decline may be attributed to effective countermeasures such as chemoprophylaxis and insecticide-treated uniforms or decreased risk of U.S. military personnel in areas of high malaria transmission. The most substantial decline in malaria cases reported from 2020 through 2021 may be attributed to progressive withdrawal of U.S. personnel from Afghanistan, along with restrictions on international travel due to the COVID-19 pandemic.

In 2024, P. falciparum persisted in more than half of U.S. service member malaria cases, demonstrating the need for continued focus on disease prevention, given its severity and mortality. The persistent burden of falciparum malaria acquired in Africa also emphasizes the importance of timely diagnostics for service members in deployed settings. The possibility of false negative results for P. falciparum on rapid diagnostic tests favored by units in resource-limited or austere locations was noted in 2019.11 Since then, the emerging prevalence of mutant pfhrp2/3-deleted P. falciparum parasites has been described in parts of U.S. Southern Command and Africa Command, highlighting the risk of hrp2-based rapid diagnostic tests as an unsuitable diagnostic tool for malaria in many countries.12 In 2019, WHO outlined new recommendations to use non-HRP2-based RDTs when the prevalence of pfhrp2/3 deletions that cause false-negative results exceeds 5% in the specified geographic area for malaria risk.13 These recommendations present a need for continued surveillance on the frequency and distribution of these mutant parasites where service members may deploy, as well as the development of alternative RDTs.14

Malaria continues to present a medical concern for service members traveling to endemic regions while on leave, as 40% of malaria cases in RMEs in 2024 occurred during non-duty travel. For service members traveling to malaria-endemic regions, pre-travel chemoprophylaxis should be emphasized; however, prescribing practices vary among Military Health System and civilian health care providers.14 While force health protection policy plays a major role in standardizing chemoprophylaxis regimens that may be indicated for a mission plan,15 solutions are needed to extend risk management and prevention policies beyond large-scale deployment conditions.14

This report does not assess prescribed chemoprophylaxis adherence, but several studies document low adherence and inadequate chemoprophylaxis during periods of deployment or travel to endemic regioms.16,17 In 2018, the CDC assessed 38 U.S. military personnel malaria cases using the National Malaria Surveillance System and National Notifiable Diseases Surveillance System, finding that 25 (65.8%) personnel members received any form of prophylaxis; of those, 7 (28.0%) took all doses of a correct regimen.18 Only half of the malaria cases among active and reserve component U.S. service members in 2024 identified in this report were from RME records, hindering full assessment of chemoprophylaxis use and adherence.

Seasonality patterns should be considered in force health protection plans for optimal vector control and drug-based intervention strategies.19 Non-P. vivax malaria case seasonality in this report is compatible with a presumption of greatest risk of malaria acquisition from May through October in temperate, climatic zones of the Northern Hemisphere. Rainfall and temperature are also significant factors for malaria seasonality; rainfall postpones onset of malaria transmission only in areas with high seasonal precipitation from September through November, as in sub-Saharan Africa; otherwise, malaria may be transmitted all year.20

Limitations to this report should be considered when interpreting its findings. Malaria case reporting, especially for reserve components and non-deployment exposures, is likely incomplete, contributing to under-estimation of rates; some cases treated in deployed or non-U.S. military medical facilities may not have been reported or otherwise ascertained at time of analysis. Malaria diagnoses documented only in outpatient settings without confirmatory testing and not reported as RMEs were not included in this report. Geographic location of malaria acquisition was estimated from reported information, with some cases reporting exposures in multiple malaria-endemic areas and others with no relevant exposure information. Personal travel or deployment to malaria-endemic countries was not documented unless specified in RMEs. Limited information on species type in RME records emphasizes the need for more complete attention to documentation of reportable conditions.

MSMR annually publishes malaria cases identified through comprehensive surveillance—evaluation of RMEs, hospitalization records, and laboratory results generated from the MHS—to inform force health protection policy. Malaria infection remains a potential health threat to U.S. service members within or near endemic areas due to duty assignment, contingency operations, or personal travel.

Acknowledgments

The authors thank the Navy and Marine Corps Public Health Center, Portsmouth, for providing laboratory data for this analysis.

References

  1. World Health Organization. Malaria 2023. Accessed Mar. 27, 2025. https://www.who.int/news-room/fact-sheets/detail/malaria#:~:text=Malaria%20is%20a%20life%2Dthreatening,spread%20from%20person%20to%20person 
  2. Word Health Organization. World Malaria Report 2024. Accessed Mar. 27, 2025. https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2024 
  3. Centers for Disease Control and Prevention. Malaria. U.S. Dept. of Health and Human Services. Accessed Mar. 27, 2025. https://www.cdc.gov/dpdx/malaria/index.html#:~:text=Four%20species%20are%20considered%20true%20parasites%20of%20humans%2C,falciparum%2C%20P.%20vivax%2C%20P.%20ovale%20and%20P.%20malariae 
  4. World Health Organization. World Malaria Report 2022. Accessed Mar. 27, 2025. https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2022#:~:text=The%202022%20report%20is%20based%20on%20information%20received,opportunities%20and%20challenges%20for%20curbing%20and%20eliminating%20malaria   
  5. Armed Forces Health Surveillance Division. Malaria among members of the U.S. Armed Forces, 2013-2022. MSMR. 2023;30(3):10-15. Accessed Apr. 16, 2025. https://www.health.mil/news/articles/2023/03/01/malaria-update 
  6. Kotwal RS, Wenzel RB, Sterling RA, et al. An outbreak of malaria in U.S. Army Rangers returning from Afghanistan. JAMA. 2005;293(2):212-216. doi:10.1001/jama.293.2.212   
  7. Whitman TJ, Coyne PE, Magill AJ, et al. An outbreak of Plasmodium falciparum malaria in U.S. Marines deployed to Liberia. Am J Trop Med Hyg. 2010;83(2):258-265. doi:10.4269/ajtmh.2010.09-0774 
  8. Centers for Disease Control and Prevention. Case reports: malaria acquired in Haiti–2010. MMWR Morb Mortal Wkly Rep. 2010;59(8):217-219. Accessed Mar. 31, 2025. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5908a1.htm 
  9. Shaha DP, Pacha LA, Garges EC, Scoville SL, Mancuso JD. Confirmed malaria cases among active component U.S. Army personnel, January-September 2012. MSMR. 2013;20(1):6-9. Accessed Apr. 16, 2025. https://www.health.mil/reference-center/reports/2013/01/01/medical-surveillance-monthly-report-volume-20-number-1 
  10. Armed Forces Health Surveillance Division. Malaria Surveillance Case Definition. Defense Health Agency, U.S. Dept. of Defense. Accessed Mar. 37, 2025. https://health.mil/reference-center/publications/2014/12/01/malaria 
  11. Forshey BM, Morton L, Martin N, et al. Plasmodium falciparum rapid test failures threaten diagnosis and treatment of U.S. military personnel. Mil Med. 2020;185(1-2):e1-e4. doi:10.1093/milmed/usz256 
  12. Vesely BA, Cheng Q. Force protection risks in AFRICOM, INDOPACOM and SOUTHCOM due to rapid diagnostic tests failures for falciparum malaria, 2016-2022. MSMR. 2023;30(10)7-11. Accessed Apr. 16, 2025. https://www.health.mil/news/articles/2023/10/01/malaria-rdt-failures 
  13. World Health Organization. Statement by the Malaria Policy Advisory Group on the Urgent Need to Address the High Prevalence of pfhrp2/3 Gene Deletions in the Horn of Africa and Beyond. Accessed Mar. 28, 2025. https://www.who.int/news/item/28-05-2021-statement-by-the-malaria-policy-advisory-group-on-the-urgent-need-to-address-the-high-prevalence-of-pfhrp2-3-gene-deletions-in-the-horn-of-africa-and-beyond 
  14. Hickey PW, Mitra I, Fraser J, et al. Deployment and Travel Medicine Knowledge, Attitudes, Practices, and Outcomes Study (KAPOS): malaria chemoprophylaxis prescription patterns in the Military Health System. Am J Trop Med Hyg. 2020;103(1):334-343. doi:10.4269/ajtmh.19-0938 
  15. Gracey S, Keller A, Montgomery G, et al. United States military deployments: travel for work & other reasons. Centers for Disease Control and Prevention Yellow Book 2024. U.S. Dept. of Health and Human Services. Accessed Mar. 28, 2025. https://wwwnc.cdc.gov/travel/yellowbook/2024/work-andother-reasons/us-military-deployments 
  16. Saunders DL, Garges E, Manning JE, et al. Safety, tolerability, and compliance with long-term antimalarial chemoprophylaxis in American soldiers in Afghanistan. Am J Trop Med Hyg. 2015;93(3):584-590. doi:10.4269/ajtmh.15-0245 
  17. Collier RP, Lindholm DA, Lalani T, et al. 735. Malaria chemoprophylaxis adherence among U.S. active duty service members during deployment to endemic regions. Open Forum Infect Dis. 2021;8:s465-s466. doi:10.1093/ofid/ofab466.932 
  18. Mace KE, Lucchi NW, Tan KR. Malaria Surveillance–United States, 2018. MMWR Surveill Summ. 2022;71(8):1-35. doi:10.15585/mmwr.ss7002a1 
  19. Yamba EI, Fink AH, Badu K, Asare EO, Tompkins AM, Amekudzi LK. Climate drivers of malaria transmission seasonality and their relative importance in sub-Saharan Africa. Geohealth. 2023;7(2):e2022GH000698. doi:10.1029/2022gh000698 
  20. Selvaraj P, Wenger EA, Gerardin J. Seasonality and heterogeneity of malaria transmission determine success of interventions in high-endemic settings: a modeling study. BMC Infect Dis. 2018;18(1):413. doi:10.1186/s12879-018-3319-y

You also may be interested in...

Topic
May 29, 2025

Medical Surveillance Monthly Report

The Medical Surveillance Monthly Report, a peer-reviewed journal launched in 1995, is the Armed Forces Health Surveillance Division's flagship publication. The MSMR provides monthly evidence-based estimates of the incidence, distribution, impact, and trends of health-related conditions among service members.

Article
May 1, 2025

Update: Infertility Among Active Component Service Women, U.S. Armed Forces, 2019–2023

This update of infertility surveillance, analysis and reporting provides more recent estimates of infertility diagnosis incidence and prevalence of among active component U.S. service women. MSMR has published the incidence and prevalence of diagnosed female infertility among active component women since 2000, with assessments of annual rates of ...

Recommended Content Medical Surveillance Monthly Report
Article
May 1, 2025

Trends of Sepsis Hospitalizations Among Female Active Component U.S. Service Members, 2011–2022

This report on sepsis hospitalizations among service women is in response to studies of sepsis among active component U.S. military members that have shown markedly increased rates of sepsis hospitalizations, especially among women, among whom rates are higher than male service members as well as the general U.S. population.

Recommended Content Medical Surveillance Monthly Report
Article
Apr 25, 2025

Medical Surveillance Monthly Report "30th Anniversary" Issue Celebrates a Milestone

MSMR 30th anniversary issue celebrates a milestone

This year marks a significant milestone for the Medical Surveillance Monthly Report as we celebrate its 30th anniversary. Throughout its three decades, MSMR has continuously improved its content with the goal of providing readers with unbiased, scientifically rigorous, evidence-based medical surveillance information on the current status, trends, ...

Recommended Content Medical Surveillance Monthly Report
Skip subpage navigation
Refine your search