Leprosy Surge in US: Armadillos & Environmental Factors

The Sunshine State, Florida, is witnessing an uptick in leprosy cases, as revealed by a recent report from the U.S. Centers for Disease Control and Prevention (CDC). Since 2020, the state has accounted for one-fifth of the total new leprosy cases, with the central region bearing the brunt. This suggests that the infectious disease is endemic in the southeastern US, implying its constant presence in the region.

The United States has traditionally seen rare instances of leprosy. However, since 2000, there's been a gradual escalation, with the southeastern states experiencing more than a double rise in cases over the last decade. Central Florida seems to be the hotspot, with 81% of the state's cases and nearly 10% of the national cases.

Contrasted with the past, a higher percentage of cases now stem from infections contracted locally, rather than those imported from leprosy-prone regions. About 34% of new infections from 2015 to 2020 seem to have been locally acquired, bolstering the evidence that leprosy is indeed endemic in the southeastern US.

But how did this new wave manage to spread across the United States?

The source of the infection in the US is still a mystery. In the case of a 54-year-old Florida resident, a gardener with no travel history or contact with leprosy patients or armadillos (known carriers of the leprosy-causing bacterium in South Florida), researchers are exploring possible environmental sources of the disease.

The recent surge in Florida's leprosy cases seems to be linked to an animal reservoir. The report found a high incidence among individuals who spend considerable time outdoors, implying possible exposure to the pathogen through environmental contact.

Armadillos, known carriers of the leprosy bacterium in South Florida, cannot fully account for the increase in cases in other parts of the US where these creatures are not native.

Other traditional transmission methods include extended close contact with untreated individuals over several months. Conversely, casual and short-term interactions do not significantly contribute to the disease's spread.

Now, let's take a broader look at this disease. Leprosy, also referred to as Hansen's disease, is a bacterial infection primarily affecting the skin and peripheral nervous system, caused by Mycobacterium leprae (or the newer M. lepromatosis).

Although leprosy is not highly contagious, transmission can occur through contact with an infected person's lesions or through respiratory droplets during frequent contact with untreated cases.

Common symptoms of leprosy are discolored spots and rashes, foot ulcers, facial swelling, numbness, and potential paralysis. The disease can cause nerve damage, leading to a decreased sense of pain and unnoticed lesions in other body parts.

In extreme cases, it can lead to limb damage and potential amputation, although early diagnosis and antibiotic treatments have made this outcome relatively rare in recent years.

When did leprosy become widespread in Europe?

Finally, a historical hint. The 13th century saw the greatest spread of leprosy in Europe, probably introduced from the East following the Crusades. During this period it became endemic, although the debate is still open as to whether or not it was an epidemic. It remains incomprehensible how so many cases could have developed in Europe, touching 19,000 leprosariums, or places outside the cities where lepers were forced to live.