Hansen’s disease and Migration

Hansen’s disease is an infectious neglected tropical disease (NTD) which, if not treated early, can lead to permanent disabilities and impairments. Hansen’s disease is related to a set of environmental, socio-political and health characteristics that pose a challenge to public health policies. It is also a compulsory notifiable disease that mobilizes public authorities and society for control and prevention actions.

Hansen’s disease is a global public health problem - in 2019, 202,185 new cases were diagnosed worldwide - 27,863 were in Brazil, representing 93% of cases in the Americas (1). In Brazil, the disease is present throughout the country in an irregular pattern of distribution across regions and states, with higher endemicity in the north and central-west regions (2).

Hansen’s disease as a public health problem is embedded in the context of people living in vulnerable situations. This term is used in the health field to refer to the susceptibility of individuals to health problems and epidemics and is typically associated with low socioeconomic status (3). Vulnerability therefore refers to the degree of capacity or ability to anticipate, cope with, resist and recover from the impacts of health problems. Vulnerability is applicable to situations of isolated, unsafe and defenseless persons in the face of risk, shock or stress, during and after the process of migration (4).

For the epidemiological understanding of a condition such as Hansen’s disease when data are analyzed in relation to international migration flows, it is clear that migration corridors describe flows (from origin to destination) involving countries with diverse factors contributing to migration, including conflict. There is an association between migration and Hansen’s disease induced by displacement from areas of endemic disease. In 2019, 83% of internationally displaced persons came from ten countries, five of which (Myanmar, the Democratic Republic of the Congo, Somalia, South Sudan and Sudan) are among 23 Hansen’s disease priority countries and which together account for 5% of new cases (1,5). Although India and Brazil are not among the 10 countries with the highest number of international displacements, they are ranked first and second in the number of worldwide cases, together accounting for 70% of new Hansen’s disease cases in 2019 (1).

In Italy, 57 migrants were diagnosed with Hansen’s disease from 2009 to 2018, 18% of whom were from Central and South America, including seven from Brazil (6). Of 199 cases in persons born outside Spain from 2003-2018, 71 (36%) were from Brazil, 29 (15%) were from Paraguay, 15 (8%) and 14 (7%) were from Bolivia and Colombia respectively, with smaller case numbers from 21 other countries (7).

Longer length of stay in the endemic country of origin is associated with increased risk of developing Hansen’s disease in a foreign country, whilst delay in diagnosis of Hansen’s disease in the non-endemic country increases the risk of developing disabilities (8).

In general, historical and socio-cultural factors of poverty related to migration influence the transmission and distribution of Hansen’s disease and its control (4). Because of the clinical characteristics of the disease and its long incubation time, migrants affected by Hansen’s disease may face difficulties in obtaining a diagnosis in the host country (9). The diagnosis of imported Hansen’s disease is more challenging for professionals working in non-endemic areas because of their unfamiliarity with the disease and low index of clinical suspicion. To overcome this limitation, it was proposed that healthcare professionals responsible for assisting migrant populations should be trained to identify signs and symptoms suggestive of the disease, to ensure timely diagnosis and treatment (10).

We also need to be vigilant for a possible emergence of Hansen’s disease in regions where the disease has already been eliminated. In the current scenario of international migration flows, emergent and re-emergent communicable diseases pose a challenge for health services. This scenario exposes the serious situation of Hansen’s disease in the world, and its relationship with migration poses a further obstacle to its elimination (11).