Investigating a possible linkage of working with migrant workers and new leprosy cases among indigenous populations of Shimla, Himachal Pradesh, India

This study was initiated in 2015, when an association of occurrence of leprosy in a rich apple orchard owner and his working with migrant workers from leprosy endemic state was observed. Further 21/27 (more than 70%) cases in Shimla districts were contributed by migrant workers during 2016-17 indicating the potential risk of spread to local population. We started an investigation of all new indigenous cases for the year 2015 of district Shimla and tracked their history of contact with any migrant labourers. Indirect correlation was found in overall decrease in leprosy cases among migrants associated with decrease in indigenous leprosy cases as well. The migrants carrying leprosy infection may be spreading it as infected droplets into the air and into the orchard soil and other fomites through exhalation of bacilli and also while blowing their noses in open air and in temporary sheds/rooms where migrant workers/ labourers and owners work together for apple grading. Sharing of temporary airspaces and fomites need to be investigated by classical epidemiological approaches as well as newer molecular technologies for studying such transmission and evidence based effective measures should be considered and taken to protect the population in leprosy free or low endemic settings such as in Himachal Pradesh. There is need to educate locals regarding hidden nature of leprosy infection that can spread from unsuspecting carrier migrants from leprosy endemic states of India and Nepal which is still an leprosy endemic country. Migrants from leprosy endemic districts need to be screened by an appropriate strategy and treated with MDT to effectively control leprosy spread. For that purpose innovative methods of screening, diagnosis and treatment of leprosy among migrant population, understanding the dynamics of such possible mode of transmission by molecular technology as well as awareness generation in the local population should be given due importance for effective control of leprosy in India.