Leprosy Mailing List – March 27, 2020
Ref.: (LML) Armadillos and Hansen's Disease in Brazil
From: Patricia Deps, Victória, Brazil
Dear Pieter,
The risk to human health of contact with armadillos infected with Mycobacterium leprae is uncertain, but evidence from Brazil and other countries appears to show a link between contact with armadillos and increased risk of Hansen's Disease in people. In the United States of America, Hansen's Disease is considered a zoonosis and contact with armadillos is a risk factor for the disease. In Brazil, the source of bacilli has been considered, almost exclusively, from those untreated multibacillary cases. However, we suppose that how much of Hansen's Disease in the human population is caused by contact with armadillos will depend on the size of the risk, the type and frequency of contact and how common it is in the population, and the role of other (human-to-human) transmission routes for Mycobacterium leprae (1).
In 2002, the first study demonstrating natural infection of Mycobacterium leprae in wild armadillos in Brazil was published (2). In the sequence, other studies were performed and antibodies anti-PGL-1 in wild armadillos were detected by ELISA and ML Flow test (3-5). In addition, a case control study conducted with persons affected by Hansen's Disease in the State of Espirito Santo (Brazil) also showed that direct contact with armadillo was a risk factor for developing the disease when compared with controls (6).
This week, a systematic review and meta-analysis about prevalence of Mycobaterium leprae infection in wild armadillos all over Brazil was published in PLOS Neglected Tropical Diseases (1). The 10 included studies represented a total sample of 302 armadillos comprising 207 (69%) Dasypus novemcinctus, 67 (22%) Euphractus sexcinctus, 16 (5%) Priodontes maximus, 10 (3%) Cabassous unicinctus, and 2 (1%) Cabassous tatouay from 7 different states (1).
I would like to share with you some key messages from this study:
1. The average prevalence of M. leprae in studies performed to date is equivalent to 1 in 10 armadillos being infected with M. leprae. However, we are not saying that 1 in 10 armadillos in Brazil are infected with M. leprae.
2. In a continental country as Brazil, three studies found zero infected armadillos, one study found that all of the captured armadillos were infected. The variation is what we would expect to see simply because the studies were relatively small. But it is also possible that there are real differences in M. leprae infection between armadillo populations in different parts of Brazil and in relation to the proximity of armadillo populations to human populations.
3. There were also some differences in methods between the studies, although all used a method for detecting M. leprae DNA which is highly sensitive.
4. Our results show that more of the same studies are not going to provide answers. Instead, we need bigger studies (capturing more animals across the whole of Brazil) and/or studies which investigate how M. leprae is carried in armadillo populations.
5. Finally, the proportion of Hansen's Disease in Brazil is attributable to contact with or consumption of armadillos is unknown. It might be a small proportion, and armadillos might just be part of an 'environmental pool' of M. leprae. But this might still have consequences for the elimination of Hansen's Disease in some communities. Therefore, it seems sensible to adopt the precautionary principle (discouraging people from capturing and eating armadillos). Thereby protecting people and armadillos.
References
1. Deps PD, Antunes JM, Santos AR, Collin SM (2020) Prevalence of Mycobacterium leprae in armadillos in Brazil: A systematic review and meta-analysis. PLoS Negl Trop Dis 14(3): e0008127. https://doi.org/10.1371/journal.pntd.0008127
2. Deps PD, Santos AR, Yamashita-Tomimori J. Detection of Mycobacterium leprae DNA by PCR in blood sample from nine-banded armadillo: preliminary results. Int J Lepr Other Mycobact Dis. 2002;70(1):34–5.
3. Deps PD. Pesquisa de Mycobacterium leprae em tatus selvagens da espécie Dasypus Novencintus do Estado do Espírito Santo [Doutorado]. São Paulo: Universidade Federal de São Paulo; 2003. Available from: http://repositorio.unifesp.br/handle/11600/18627
4. Deps PD, Antunes JM, Tomimori-Yamashita J. Detection of Mycobacterium leprae infection in wild nine-banded armadillos (Dasypus novemcinctus) using the rapid ML Flow test. Rev Soc Bras Med Trop. 2007;40(1):86–7.
5. Deps PD, Antunes JM, Faria C, Buhrer-Sekula S, Camargo ZP, Opromola DV, et al. Research regarding anti-PGL-I antibodies by ELISA in wild armadillos from Brazil. Rev Soc Bras Med Trop. 2008;41 Suppl 2(SUPPL. 2):73–6.
6. Deps PD, Alves BL, Gripp CG, Aragao RL, Guedes B, Filho JB, et al. Contact with armadillos increases the risk of leprosy in Brazil: a case control study. Indian J Dermatol Venereol Leprol. 2008;74(4):338–42.
Yours faithfully,
Patricia Deps
Full Professor at the Department of Social Medicina, Postgraduate Programme in Infectious Diseases, Universidade Federal do Espirito Santo, Vitória-Brazil.
pdeps@uol.com.br ; patricia.deps@ufes.br
Patricia Deps, MD, MSc, PhD
Dermatologist, Paleopathologist
Full Professor
Department of Social Medicine
Postgraduate Programme on Infectious Diseases
Federal University of Espirito Santo
Vitória-ES-Brazil
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << editorlml@gmail.com
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