CDC study highlights growing threat of tularemia in central United States

Rising tularemia cases require action. CDC highlights diagnostic breakthroughs and calls for targeted efforts to protect vulnerable communities.

Report: Tularemia — United States, 2011-2022. Image credit: Kateryna Kon / Shutterstock

In a recent study published in the journal Morbidity and Mortality Weekly ReportScientists at the U.S. Centers for Disease Control and Prevention (CDC) examined trends in the population patterns, geographic distribution, and incidence of tularemia (tularemia). Francisella tularensis. The disease can be transmitted to humans through a variety of routes, including insect bites, contaminated food or water, and inhalation.

background

Tularemia is a zoonotic disease caused by bacteria Francisella tularensis. Humans can contract the disease through contact with infected animals, insect bites, inhalation of contaminated particles, and ingestion of contaminated water. Symptoms can range from fever, localized infection, and severe respiratory illness.

Although the disease is treatable with antibiotics, tularemia can cause serious health problems, especially if it develops late. diagnosis. Historically, the disease has been reported in most states in the United States, with higher incidence in some regions and demographic groups. In particular, environmental and occupational exposures and access to wildlife contribute to these patterns. Additionally, people in central states and American Indian or Alaska Native communities often face a disproportionately high burden of disease.

Although surveillance efforts and laboratory advances have improved case detection in recent decades, the disease remains underreported and poorly understood. The lack of preventive vaccines and the variety of clinical manifestations further emphasize the importance of strengthening public health measures and medical education to reduce the impact on vulnerable populations.

Number of reported tularemia cases by region of residence — United States, 2011-2022

About research

This study utilized tularemia surveillance data reported to CDC from 2011 to 2022. Cases were classified into confirmed or probable categories based on clinical and laboratory criteria. Confirmed cases were determined based on the following isolations: tularemia fungus or antibody titers that show at least a 4-fold change between acute and convalescent serum samples.

Additionally, probable cases were identified by a single high-level test. Antibody titer or bacterial detection by fluorescence assay or polymerase chain reaction (PCR). The addition of PCR methods in 2017 has significantly advanced diagnostic criteria. Researchers analyzed annual incidence data across demographic groups, geographic locations, and case categories.

Additionally, we used U.S. Census Bureau population estimates to calculate rates per 100,000 individuals. This study also reviewed temporal trends in tularemia cases and assessed the impact of changes in surveillance standards and advances in laboratory diagnosis over the years.

Geographic distribution analysis included county-level mapping, and demographic data focused on age, gender, race, and ethnicity. This comprehensive analysis allowed us to identify patterns and differences in disease incidence. Differences in case detection methods, condition reporting practices, and testing techniques were also considered to contextualize observed trends.

Researchers also discussed study limitations, including potential underreporting, variation in state-level surveillance, and the impact of external factors such as the coronavirus disease 2019 (COVID-19) pandemic on data collection. . These factors highlight the need for consistent and robust monitoring practices across the state. The study results were intended to inform public health strategies to reduce the incidence of tularemia and improve diagnostic methods. The study was conducted in accordance with ethical standards and federal law.

Main findings

The study found that the incidence of tularemia in the United States increased by 56% from 2011 to 2022 compared to the previous 10 years. A total of 2,462 cases were reported during this period, with 40% being classified as confirmed and 60% as probable infection. The increase in probable cases is partially due to advances in diagnostic methods, such as the shift to enzyme-linked immunosorbent assays (ELISAs), which are more sensitive but less specific than previous agglutination tests. .

The annual incidence ranged from 0.041 to 0.064 per 100,000 population, with significant geographic and demographic disparities. The four central states of Arkansas, Missouri, Kansas, and Oklahoma accounted for half of all cases, indicating that infections are concentrated in these areas. Children aged 5 to 9 years and men aged 65 to 84 years had the highest age-specific incidence.

American Indian or Alaska Native populations experience morbidity rates approximately five times higher than white populations, presenting significant health disparities. Sociocultural and occupational activities, as well as the concentration of Native American reservations in the central states, may contribute to this increased risk. Furthermore, the seasonal pattern shows that most cases occurred between May and September, likely reflecting increased vector exposure during the warmer months.

Additionally, longitudinal analysis shows that the number of probable cases has consistently exceeded the number of confirmed cases since 2015, and the divergence began when testing standards, including PCR detection, were expanded in 2017. It became clear that there was. Although improved detection methods and increased case reporting likely contributed to the increased incidence, researchers believe that other factors, such as environmental and behavioral changes, may also be playing a role. There is.

This study highlights the need for prevention strategies that target at-risk populations and regions. The findings also educate health care workers to enhance early diagnosis and effective treatment, especially for those serving tribal populations with limited access to specialized health resources. I emphasized the importance of this.

conclusion

This study drew attention to the increasing incidence of tularemia across the United States due to better detection methods and increased case reporting. The geographic and demographic disparities observed in this study highlighted vulnerable populations that require targeted prevention and education efforts.

Addressing these disparities through tailored public health efforts, focused clinical education, and improved laboratory practices can reduce health inequalities and improve outcomes. CDC researchers believe that by addressing these disparities through public health efforts, early diagnosis, and timely treatment, we can mitigate the impact of disease, reduce health disparities, and protect those most at risk. We believe we can improve outcomes for people suffering from cancer.