Series of publications on "Hansen's Disease and Oral Health"

Persistence of Mycobacterium leprae in the oral mucosa and its importance in transmission to healthcare workers

by Pamela Barbosa,

Dentistry student, Federal University of EspĂ­rito Santo.

Mariana MacabĂş,

Medicine student, Federal University of EspĂ­rito Santo.

Fernanda Sales,

Medicine student, Federal University of EspĂ­rito Santo.

PatrĂ­cia Deps,

Department of Social Medicine, Federal University of EspĂ­rito Santo.

and Raquel B. Carvalho.

Department of Social Medicine, Federal University of EspĂ­rito Santo.

Hansen's disease (HD) is a chronic, infectious, curable, compulsorily notifiable disease caused mainly by Mycobacterium leprae which affects especially the skin, peripheral nerves and mucosa.(1)

Although there are some controversies, studies indicate that M. leprae infects the body through the nasal cavity, this being the primary site of infection.(2) The oral mucosa is another route of entry and exit of the bacillus in humans which has a potentially important role in the transmission of the microorganism.(3,4,5)

Colonisation of the oral mucosa occurs through the presence of resistant alcohol-acid bacilli in secretions from the nasopharynx and oropharynx which reach the oral mucosa. M. leprae may be present in the oral mucosa without any morphological alteration or clinical manifestations and, because of the resistance of this tissue to the development of lesions, only more sensitive laboratory tests can detect the presence of the bacillus.(3)

Some authors do not consider the oral cavity to be a relevant site for M. leprae transmission,(6) even though a person affected by the untreated multibacillary form of HD can eliminate a large quantity of bacilli into the environment by speaking, coughing, sneezing or spitting.(2) These microorganisms can survive for several days in the environment under certain conditions and consequently infect people or animals.(7, 8)

Some infected people who have not developed HD represent a subclinical stage. These individuals would be sources of bacilli dissemination because they present a transitory period of bacillary excretion.(2) However, they present a lower risk when compared to multibacillary forms of the disease. An important factor for the manifestation of the disease is the immunological susceptibility of the individual - M. leprae has high infectivity and low pathogenicity, meaning that it has the capacity to infect a great number of people, but few develop the disease.(9)

Lack of knowledge about the definitive aspects of M. leprae transmission promotes apprehension among some healthcare professionals around the risk of contamination through direct contact with lesions.(10) This misinformation leads many healthcare professionals to prioritize physical distance from the patient rather than the use of individual protection,(11) an approach that is contrary to the fight for the end of the stigma about the disease. World Health Organization and Brazilian biosecurity regulations stipulate the use of individual protection equipment.(12, 13) This minimizes the risk of cross-infection, especially when performing invasive and aerosol generating procedures on untreated patients affected by the multibacillary form of HD.(9) It is important to remember that dentists, doctors and nurses, especially those working in HD-endemic regions often come into contact with people diagnosed with HD who are not receiving multidrug therapy.(14)

The presence of non-specific oral and dental conditions such as periodontal disease and tooth loss, and specific signs such as papules, plaques and ulcerations in the oral cavity, are common clinical events in the course of HD, mean that dental surgeons have an important role in HD control programmes. The use of ultrasonic rotating instruments and working in the oral cavity means that dentists are particularly exposed to M. leprae in oral mucosa. Here the adoption of biosafety methods, such as the use of gloves, masks, aprons, and goggles during procedures that produce aerosols minimizes the risk of infection. The identification of individuals suspected of HD during dental care is paramount, and patients should be referred to a doctor who can confirm a diagnosis and start treatment or exclude the possibility of the disease.(9)


  1. Silva Junior, Geraldo Bezerra da, Elizabeth De Francesco Daher, Roberto da Justa Pires NETO, Eanes Delgado Barros Pereira, Gdayllon Cavalcante Meneses, Sônia Maria Holanda Almeida Araújo, Elvino José Guardão Barros, et al. “LEPROSY NEPHROPATHY: A REVIEW OF CLINICAL AND HISTOPATHOLOGICAL FEATURES”. Revista Do Instituto de Medicina Tropical de São Paulo 57, no 1 (fevereiro de 2015): 15–20.

  1. Lockwood Dnj. Leprosy. In: Burns Da, Breathnach Sm, Cox Nh, Griffiths Cem, Editor. Rook’s Textbook Of Dermatology, 7th Ed. Oxford: Blackwell Publishing; 2004. P. 29.1 -29.21.

  1. Puneeta, Md Siraj UR Rahman, B. Subhada, Rahul Vinay Chandra Tiwari, M S Nabeel Althaf, e Monika Gahlawat. “Oral manifestation in leprosy: A cross-sectional study of 100 cases with literature review”. Journal of Family Medicine and Primary Care 8, no 11 (15 de novembro de 2019): 3689–94.

  1. Abdalla, Ligia Fernandes. “Pesquisa de Mycobacterium leprae no periodonto, saliva e em raspados intradérmicos de pacientes com hanseníase.”, 24 de junho de 2010.

  1. Filgueira, Adriano de Aguiar, Márcio Anderson Cardozo Paresque, Sandra Maria Flor Carneiro, e Ana Karine Macedo Teixeira. “Saúde bucal em indivíduos com hanseníase no município de Sobral, Ceará”. Epidemiologia e Serviços de Saúde 23, no 1 (março de 2014): 155–64.

  1. Martins MD, Russo MP, Lemos JB, Fernandes KP, Bussadori SK, CorrĂŞa CT, Martins MA. Orofacial lesions in treated southeast Brazilian leprosy patients: a cross-sectional study. Oral Dis. 2007 May;13(3):270-3. doi: 10.1111/j.1601-0825.2006.01275.x. PMID: 17448207.

  1. DESIKAN, K.V. Viability of Mycobacterium leprae outside the human body. Leprosy. Rev., v.48, p.231-35, 1977

  1. Costa A, Nery J, Oliveira M, Cuzzi T, Silva M. Oral lesions in leprosy. Indian J Dermatol Venereol Leprol. 2003 Nov-Dec;69(6):381-5. PMID: 17642946.

  1. Ministério Da Saúde (Br), Secretaria De Vigilância Em Saúde, Departamento De Vigilância E Doenças Transmissíveis: Guia Prático Sobre A Hanseníase 1. Ed. Versão Eletrônica, 2017.

  1. Mponda, Kelvin, George Anafi, Eric Thom Laja, Rapson Chidothe, Lawrence Mahuka, Ephraim Duncan, David Ng’oma, e Colette van Hees. “Knowledge About Leprosy Among Health Care Workers In Balaka District, Southern Malawi”. Preprint. In Review, 18 de setembro de 2020.

  1. Boccolini, Cristiano Siqueira, Patricia de Moraes Mello Boccolini, Giseli Nogueira Damacena, Arthur Pate de Souza Ferreira, Célia Landmann Szwarcwald, Cristiano Siqueira Boccolini, Patricia de Moraes Mello Boccolini, Giseli Nogueira Damacena, Arthur Pate de Souza Ferreira, e Célia Landmann Szwarcwald. “Factors Associated with Perceived Discrimination in Health Services of Brazil: Results of the Brazilian National Health Survey, 2013”. Ciência & Saúde Coletiva 21, no 2 (fevereiro de 2016): 371–78.

  1. Resolução CFM nº 1780/2005, parágrafo 2º.

  1. Ministério da Saúde. Secretaria de Vigilância em Saúde. Departamento de Vigilância Epidemiológica. Guia de Procedimentos Técnicos. Baciloscopia em Hanseníase. © 2010 Ministério da Saúde.

  2. Landeiro, Luana Gomes. “Inquérito Sorológico Para Hanseníase Em Profissionais De Saúde No Hospital Universitário Cassiano Antonio Moraes - Vitória - Espírito Santo - Brasil”, [S.D.], 72.