Leprosy Mission Southern Africa

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Animals and Leprosy: What do We Know So Far?

nine-banded-armadillo

While leprosy is a disease that mostly affects people in the developing world,1 there’s been a recent rise in cases of leprosy in the first world too – specifically, in the state of Florida in the USA.2

159 new cases of leprosy were reported in the USA in 2020,2 and 225 new cases were recorded in 20233 – that’s a tiny amount considering the country has a population of over 340 million people.4 Florida is one of the top-reporting states.2,3 According to the Centers for Disease Control and Prevention (CDC), Central Florida accounted for one-fifth of nationally reported cases of leprosy in 2020,2 and healthcare professionals reported 15 new cases in the state in 2023.5

This uptick of leprosy in Florida has raised questions about whether local armadillos are spreading leprosy to humans. Here’s what we know about leprosy and armadillos, as well as other animals that have been linked to the disease over the years.

Armadillos and Leprosy

Like humans, armadillos can act as hosts to Mycobacterium leprae, the germ that causes leprosy.6  The disease has been found in the nine-banded armadillo, a small mammal that’s common in the southern United States and Central and South America.7 While this could explain some of the cases in Florida and further south, there are still plenty of patients who have had no contact with armadillos at all.2,8 The risk of transmission from armadillos to humans is low, although it is possible.9 It can be transmitted to humans when handling infected armadillos or eating their meat.6,8

Red Squirrels and Leprosy

In Medieval times, red squirrels in the British Isles carried leprosy.10 Scientists investigating archaeological sites have found genetic similarities between the leprosy strains found in squirrels and humans living in the Medieval era, suggesting the disease may have passed back and forth between the two species.10,11 This is the first time an animal host of leprosy has been found in the archaeological record, making these squirrels the earliest known non-human hosts of the disease.10,11 People back then had a lot more contact with squirrels than they do today, trading in their fur and keeping them as pets.10 There have been no definite cases of leprosy acquired in the UK since 1954,12 meaning that modern red squirrels carrying the disease likely pose little or no threat of transmission to humans.

Primates and Leprosy

Leprosy was found in sooty mangabey monkeys in Nigeria in the 1980s, and possible transmission from one monkey to another was recorded.13,14 Leprosy was later identified in wild chimpanzees for the first time in 2021, in Guinea-Bissau and the Ivory Coast.15,16 Research suggests that leprosy could potentially be transmitted from humans to non-human primates,17 but further research is needed to understand the relationship between leprosy and primates in the wild.17

Fast Facts about Leprosy

What is leprosy?

      • Leprosy is a chronic infectious disease caused by the germ Mycobacterium leprae which attacks the patient’s nerves, so they lose the ability to feel touch or pain in the affected areas.18

      • Leprosy patients will often injure themselves in the affected areas without noticing and treating the injuries.19 Untreated injuries can lead to infections and even deformities.19

    Transmission of leprosy

        • 95% of people are naturally immune to the leprosy germ.20

        • You can’t contract leprosy from casual contact with someone who has it. 20 You can only catch it through prolonged close contact with someone who has untreated leprosy.20

        • Shaking hands, hugging and sitting together with a leprosy patient are all safe.20

        • In some rare cases, humans can catch leprosy through direct contact with an infected animal.6-9

      Treating leprosy

          • Leprosy can be treated with multidrug therapy (MDT), using a combination of antibiotics.21

          • Treatment usually lasts 1-2 years and if the patient takes their medication as prescribed, they can make a full recovery.21

         

        For more information, read our blog post about debunking common leprosy myths. 

        Further Research Needed

        Understanding more about the distribution of leprosy in historic host species, like the Medieval red squirrel, can help us understand how the disease has changed over time and in turn help us understand the risks and public health strategies needed regarding animal hosts today.10 More research is needed to fully understand the relationships between leprosy, animals and humans.10

        The Leprosy Mission provides treatment to leprosy patients and also works to educate people about leprosy, break down the stigma attached to the disease and separate the myths from the facts. If you want to learn more about leprosy and how you can help those affected by it, visit The Leprosy Mission Southern Africa or follow our Facebook page for more information.

        References:

        1. Leprosy. World Health Organisation. Accessed May 20, 2024. https://www.who.int/news-room/fact-sheets/detail/leprosy.
        2. Bhukhan A, Dunn C, Nathoo R. Case report of leprosy in central Florida, USA, 2022. 2023;29(8). Emerg Infect Dis. CDC. doi:10.3201/eid2908.220367.
        3. National Hansen’s disease (leprosy) program caring and curing since 1894. Health Resources & Services Administration. Accessed May 20, 2024. https://www.hrsa.gov/hansens-disease.
        4. United States population (2024). Worldometer. Accessed May 20, 2024. https://www.worldometers.info/world-population/us-population/.
        5. What you need to know about leprosy on the rise in Florida. Nebraska Medicine. Accessed May 20, 2024. https://www.nebraskamed.com/health/conditions-and-services/what-you-need-to-know-about-leprosy-on-the-rise-in-florida.
        6. Truman RW, Singh P, Sharma R, et al. Probable zoonotic leprosy in the southern United States. N Engl J Med. 2011;364(17):1626-1633. doi:10.1056/NEJMoa1010536.
        7. Nine-banded armadillo – dasypus novemcinctus. Natureworks. Accessed May 21, 2024. https://nhpbs.org/natureworks/armadillo.htm.
        8. da Silva MB, Portela JM, Li W, et al. Evidence of zoonotic leprosy in Pará, Brazilian Amazon, and risks associated with human contact or consumption of armadillos. PLOS Neglected Tropical Diseases. 2018;12(6):e0006532. doi:10.1371/journal.pntd.0006532.
        9. How armadillos can spread leprosy. Smithsonian Magazine. Accessed May 21, 2024. https://www.smithsonianmag.com/smart-news/how-armadillos-can-spread-leprosy-180954440/.
        10. Urban C, Blom AA, Avanzi C, et al. Ancient Mycobacterium leprae genome reveals medieval English red squirrels as animal leprosy host. Current Biology. 2024;34(10):p2221-2230.e8. doi:https://doi.org/10.1016/j.cub.2024.04.006.
        11. Medieval squirrels and humans may have spread leprosy back and forth. Smithsonian Magazine. Accessed May 21, 2024. https://www.smithsonianmag.com/smart-news/medieval-squirrels-and-humans-may-have-spread-leprosy-back-and-forth-180984307/.
        12. Memorandum on leprosy 2023. GOV.UK. Accessed May 21, 2024. https://www.gov.uk/government/publications/leprosy-memorandum/memorandum-on-leprosy-2023.
        13. Walsh GP, Meyers WM, Binford CH, et al. Leprosy as a zoonosis: an update. Acta Leprol. 1988;6(1):51-60.
        14. Gormus BJ, Wolf RH, Baskin GB, et al. A second sooty mangabey monkey with naturally acquired leprosy: first reported possible monkey-to-monkey transmission. Int J Lepr Other Mycobact Dis. 1988;56(1):61-65.
        15. Hockings KJ, Mubemba B, Avanzi C, et al. Leprosy in wild chimpanzees. Nature. 2021;598(7882):652-656. doi:10.1038/s41586-021-03968-4.
        16. Leprosy seen in wild chimpanzees for the first time. CNN. Accessed May 21, 2024. https://www.cnn.com/2021/10/14/africa/wild-chimps-leprosy-intl-scli-scn/index.html.
        17. Honap TP, Pfister LA, Housman G, et al. Mycobacterium leprae genomes from naturally infected nonhuman primates. PLOS Neglected Tropical Diseases. 2018;12(1):e0006190. doi:10.1371/journal.pntd.0006190.
        18. Leprosy. World Health Organization. Accessed December 1, 2023. https://www.who.int/news-room/fact-sheets/detail/leprosy.
        19. World Leprosy Day. Centers for Disease Control and Prevention. Accessed December 1, 2023. https://www.cdc.gov/leprosy/world-leprosy-day/index.html.
        20. Transmission. Hansen’s disease (leprosy). Centers for Disease Control and Prevention. Accessed December 1, 2023. https://www.cdc.gov/leprosy/transmission/index.html.
        21. Diagnosis and treatment. Hansen’s disease (leprosy). Centers for Disease Control and Prevention. Accessed December 1, 2023. https://www.cdc.gov/leprosy/treatment/index.html