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Human conflict, from minor disruptions to the all-too frequent escalation of war, stretches people and the environment to its limits. At the same time, microorganisms create an equally devastating—but largely invisible—scene.

During times of human conflict, infections thrive among the wounded and overcrowded, and the surrounding environment is likely to become contaminated with heavy metals and unsafe water, which further propagates the spread of disease. Meanwhile, hospitals struggle to save lives with restricted resources (e.g., shortages of medical staff, medications and supplies), and people have difficulty accessing, or simply cannot access, health care if/when it is available.

In short, conflict fuels the uncontrolled spread of infections in environments where proper health care is hard to come by, which leads to misuse of antibiotics without proper diagnosis and treatment. This, in turn, allows pathogens to rapidly develop antimicrobial resistance (AMR).

Understanding the factors driving AMR in areas of conflict can be difficult, and take time to assess, as research, understandably, does not take precedence during triage. Yet, a look back at conflicts that have occurred over the past 20+ years reveals some noteworthy trends.

Hard Choices: Life Over AMR

During times of human conflict, medical professionals face impossible choices. For instance, in Gaza Strip,  individuals must prioritize immediate lifesaving interventions in locations that are often under continuous threat or bombardment. Every minute that could be spent determining appropriate antibiotic protocols is, instead, used to save a limb or a life, leaving limited capacity to monitor or address how far AMR may have spread during the war.

Research supports this concern: during the 2018 Great March of Return protests in Gaza—an event far less violent than the conflict that began in 2023—microbes isolated from wounded individuals showed . Although the data are not yet available, the current situation, with its greater scale of casualties and damage, likely presents an even more alarming escalation of AMR.

Antibiotic Chaos: Overuse Drives AMR

Regulated antibiotic use becomes nearly impossible when wars drive widespread infections, complicated wounds, collapsed health facilities and disrupted supply chains. : following the onset of civil war in 2011, which devastated domestic antibiotic production (previously covering 90% of national needs), antibiotics were sold without prescription in more than 85% of cases. This unregulated distribution creates ideal conditions for the development of resistance.

The effects of antimicrobial overuse in a conflict-ridden environment have also been realized as an increased prevalence of macrolide resistant Vibrio cholerae isolates in Yemen. By the time an began in Yemen in October 2016, the ongoing Yemen Civil War, which began in September 2014, had , leaving more than 14 million people with limited access to health care and creating ideal conditions for the cholera epidemic spread.

Physicians used macrolides extensively to combat Yemen’s cholera epidemic—the largest in the country’s history—which continued to spread even after the World Health Organization’s mass vaccination campaign in 2018. By early 2019, all tested V. cholerae organisms showed acquisition of (mobile genetic element) conferring resistance to many frontline antibiotics used to treat cholera, including macrolides. The outbreak continued until 2022.

AMR Without Borders

Population displacement represents another critical factor in AMR proliferation beyond conflict zones. since 2015, contributing to resistance spread across new regions. Similar patterns emerged in countries receiving people from Iraq, Libya, Syria and, more recently, Ukraine—the fastest-growing refugee crisis in Europe since World War II.

shows that Ukrainians displaced during the current conflict tested positive for multiple drug-resistant organisms (MDROs) at significantly higher rates than pre-conflict travelers from the same region. This pattern demonstrates how war conditions can rapidly transform regional resistance profiles.

. Approximately 1.5 million people have been displaced; 117,000 used hospitals as sanctuaries. Al-Shifa Hospital Complex alone hosted more than 50,000 internally displaced persons (IDPs). Two-thirds of hospitals became non-functional, while the remaining reported fuel shortages and a lack of medical staff. While we do not yet have data pertaining to the spread of resistance in this region, the above conditions create an environment where AMR is likely to thrive.

Environmental Accelerators

In addition to creating conditions of overcrowding, lack of access to medical care and population displacement, human conflict also introduces dangerous levels of environmental contamination. For example, infrastructure destruction breaks down water and sanitation systems, creating reservoirs for AMR organisms to multiply and spread. This scenario becomes more serious in regions where pre-existing contamination of water and the surrounding environment is already high. For example, prior to the 2023 Gaza War.

Heavily bombed sites may also show contamination with heavy metals, which can lead to the including , an opportunistic pathogen notorious for causing hospital-acquired infections. In Ukraine in 2022, A. baumannii strains showed , respectively.

AMR is a Global Challenge

AMR is not just a local problem confined to conflict zones—it represents a global health security threat that crosses borders. However, it is often masked by in conflict areas where microbiological laboratory activities are disrupted. This suggests that during times of conflict, AMR is significantly underreported, undetected and unaddressed.

Without a coordinated international response, conflict-accelerated AMR will continue to diminish our ability to treat infections, leading to increased mortality, morbidity and health care costs worldwide. Humanitarian responses to conflicts must integrate AMR strategies, even in the presence of competing urgent needs. This can be achieved by using available data, collected prior to the conflict, about local AMR patterns to train first responders to use the appropriate antibiotics (which should be included in their emergency kits). It is also critical to prioritize clean water supply and wastewater management in IDP camps.

Additionally, post-conflict reconstruction efforts should rebuild robust antimicrobial stewardship programs and surveillance systems, possibly by building on . Examples include Médecins sans Frontières' electronic clinical decision support system (E-care) in Kenya, which reduced 50% of antibiotic prescriptions for children under 5 in primary health settings, and the International Committee of the Red Cross, ICRC's 6-year antimicrobial stewardship program (2015-2021) at a reconstructive Lebanese surgical project, which established dedicated protocols, laboratory-guided prescribing and infection control measures that can be used as guide for the post-conflict systems.

The battle against unseen microbial enemies demands as much attention as the visible horrors of war if we are to preserve the effectiveness of our most critical medications for future generations.