Tampa Florida. By. GETTY IMAGES
Recent studies by researchers at Kansas City University's Graduate Medical Education/Advanced Dermatology and Cosmetic Surgery Consortium have revealed a concerning increase in leprosy cases in Florida, particularly those lacking conventional risk factors.
According to the U.S. Centers for Disease Control and Prevention, this trend, along with a decrease in diagnoses among foreign-born individuals, suggests that leprosy may have become endemic in the southeastern United States. Consequently, travel to Florida should be considered when conducting leprosy contact tracing across states.
Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by Mycobacterium leprae. Primarily affecting the skin and peripheral nervous system, the disease course varies, mainly hinging on individual susceptibility to M. leprae. Despite a history of low leprosy incidence in the United States, with a peak around 1983 followed by a significant reduction through the 2000s, reports indicate a gradual resurgence in the country. The number of reported cases in southeastern states has more than doubled over the last decade. According to the National Hansen’s Disease Program, 159 new cases were reported in 2020, with Florida being among the top reporting states.
Central Florida accounted for 81% of Florida's reported cases and nearly a fifth of cases reported nationally. Contrary to previous trends where the disease primarily affected individuals immigrating from leprosy-endemic areas, about 34% of new cases between 2015-2020 seem to have been locally acquired. One noteworthy case involved a 54-year-old man in central Florida with no known risk factors for leprosy transmission.
Transmission of leprosy is still not entirely understood. Though prolonged person-to-person contact through respiratory droplets is the most recognized transmission route, recent studies have demonstrated a strong likelihood of zoonotic transmission, with a high percentage of unrelated leprosy cases carrying the same unique M. leprae strain as the nine-banded armadillos in the region. However, many cases in the eastern United States, including central Florida, lacked any exposure to zoonotic sources or recent travel outside the US.
These findings support the theory that international migration might be a source of autochthonous transmission. Yet, while leprosy incidence increases, new diagnoses in individuals born outside of the U.S. have been declining since 2002, suggesting that leprosy may be an endemic disease process in Florida. Therefore, researchers are calling for further studies on other autochthonous transmission methods.
In Florida, leprosy is a reportable condition primarily monitored through passive surveillance. Healthcare practitioners are obligated to report leprosy cases by the next business day. However, in many recent cases, including the 54-year-old patient mentioned, traditional risk factors such as travel, zoonotic exposure, occupational association, or personal contacts were not evident, highlighting the need to investigate environmental reservoirs as a potential transmission source.
In light of these developments, researchers suggest that central Florida could be an endemic location for leprosy. They emphasize the importance of considering leprosy in the clinical context for anyone traveling to the area, even if they lack other risk factors. By bolstering local physician efforts to report incidence and supporting further research into transmission routes, the hope is to effectively identify and curb the spread of the disease.
