Tularemia as a bioweapon

DEFINITION: Infection caused by the bacterium Francisella tularensis.

SIGNIFICANCE: Commonly known as rabbit fever, tularemia is a disease endemic in North America as well as parts of Europe and Asia. Its relevance to forensic science lies chiefly in its potential for use as a bioweapon.

Tularemia is a naturally occurring disease. Its primary hosts are rabbits, prairie dogs, muskrats, and other small mammals, but it can also be transmitted by ticks and deer flies and by handling infected animals, through inhalation, or by ingesting contaminated materials. After infection, onset is rapid. Symptoms include fever, headache, fatigue, dizziness, and nausea. If untreated, tularemia may result in death.

The US Centers for Disease Control and Prevention (CDC) regards Francisella tularensis as a viable bioterrorism agent because tularemia is highly infective and incapacitating yet has relatively low lethality, a consideration in its possible deployment near a civilian population. The bacterium is easy to distribute as an aerosol and it can potentially be used to contaminate municipal drinking water supplies. Aerosol release would have the most widespread effect on public health, especially if done in urban settings. F. tularensis is classified as a Category A agent, which means it has serious potential for inducing terror in a population (other Category A agents include Yersinia pestis, the bacterium that causes plague; Variola major, the virus that causes smallpox; Bacillus anthracis, the bacterium that causes anthrax; and Clostridium botulinum toxin, which causes botulism). The former Soviet Union and the United States have stockpiled F. tularensis in the form of offensive weapons and Japan is known to have researched its bioweapon potential at different times in history. It has been alleged that the Soviet army used the pathogen against the Germans during World War II in the Battle of Stalingrad; however, researchers and historians argued that the outbreaks were from natural causes.

Because the early symptoms of tularemia are similar to those of many ordinary or seasonal infections, an attack using F. tularensis on the general population in any given area in the United States could easily take health authorities by surprise. With an incubation range of one to twenty-one days and average onset of symptoms taking from three to five days, an attack might not be immediately detected. Security measures that have been taken against this possibility include the installation in more than thirty U.S. jurisdictions of sensors that constantly monitor the air for deadly pathogens. If epidemiologists suspect the deliberate or unexplained release of the tularemia organism, standard practice is for them to notify public health authorities and coordinate with the appropriate law-enforcement agencies immediately.

One of the things that makes the possibility of the use of the tularemia pathogen as a weapon particularly worrisome is that no vaccine against the disease is available to the public, in contrast to other possible bioterror agents such as anthrax and smallpox. Some comfort is provided by the availability of potent and effective antibiotics against tularemia. The use of a live attenuated vaccine started in the 1950s only for the protection of laboratory workers and other personnel working on the organism in the United States; however, it has not received approval from the Food and Drug Administration (FDA).

Bibliography

Centers for Disease Control and Prevention (CDC). “Clinical Signs and Symptoms of Tularemia.” Tularemia, 2024, www.cdc.gov/tularemia/hcp/clinical-signs/index.html. Accessed 17 Feb. 2026.

Centers for Disease Control and Prevention (CDC). “Tularemia Antimicrobial Treatment and Prophylaxis: CDC Recommendations for Naturally Acquired Infections and Bioterrorism Response—United States, 2025.” MMWR Recommendations and Reports, vol. 74, no. 2, Sept. 2025, pp. 1–33, doi:10.15585/mmwr.rr7402a1. Accessed 17 Feb. 2026.

Centers for Disease Control and Prevention (CDC). “Tularemia Data and Statistics.” Tularemia, 20 May 2024, www.cdc.gov/tularemia/data-research/index.html. Accessed 17 Feb. 2026.

Dembek, Zygmunt F., et al. “Missed Sentinel Case of Naturally Occurring Pneumonic Tularemia Outbreak: Lessons for Detection of Bioterrorism.” Journal of the American Board of Family Practice, vol. 16, no. 4, July–Aug. 2003, pp. 339–42.

Dennis, David T., et al. “Consensus Statement: Tularemia as a Biological Weapon: Medical and Public Health Management.” Centers for Disease Control and Prevention, emergency.cdc.gov/agent/tularemia/tularemia-biological-weapon-abstract.asp. Accessed 17 Feb. 2026.

MedlinePlus. “Tularemia.” MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine, 2026, medlineplus.gov/ency/article/000856.htm. Accessed 17 Feb. 2026.

Moradkasani, Safoura, et al. “Development, Strategies, and Challenges for Tularemia Vaccine.” Current Microbiology, vol. 81, no. 5, Apr. 2024, doi:10.1007/s00284-024-03658-0.

MSD Manual. “CDC High-Priority Biological Agents and Toxins.” MSD Manual Consumer Version, 2024, www.msdmanuals.com/home/multimedia/table/cdc-high-priority-biological-agents-and-toxins. Accessed 17 Feb. 2026.

Nelson, Christina, et al. “Tularemia: A Storied History, an Ongoing Threat.” Clinical Infectious Diseases, vol. 78, suppl. 1, Feb. 2024, pp. S1–S8, academic.oup.com/cid/article/78/Supplement_1/S1/7593852. Accessed 17 Feb. 2026.

Siderovski, Susan Hutton. Tularemia. Chelsea House, 2006.

World Health Organization. “WHO Publishes 54 Pathogen Background Documents to Support Safe Water and Sanitation Systems.” World Health Organization, 21 June 2025, www.who.int/news/item/21-06-2025-who-publishes-54-pathogen-background-documents-to-support-safe-water-and-sanitation-systems. Accessed 17 Feb. 2026.