Internal Migration and Leprosy in Shanghai from 2000 to 2019: an Epidemiological Study of New Cases
Jianyu Zhu, Chao Shi, Degang Yang, Yeqiang Liu, Jia Chen, Meiping Ye, Chunjie Liao, Zhichun Jing, Pingyu Zhou
Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Massive internal migration from rural to urban areas poses new challenges for leprosy control in Shanghai, China. This retrospective epidemiological study examined new cases of leprosy diagnosed in Shanghai from 2000 to 2019, with emphasis on internal migration cases. There were 145 cases of leprosy in the study period; the majority of cases (89.0%) were internal migrants. Migrant cases had a mean of 25.4 months lag time from onset of symptoms to diagnosis, which was significantly longer than that of resident cases (mean 10.8 months, p < 0.001). Greater lag time from the first visit to diagnosis was observed in migrant cases (mean 23.2 months) compared with resident cases (mean 9.4 months, p < 0.001). A large majority of cases (91.0%) had been misdiagnosed. Internal migrant cases were responsible for most incidences of leprosy in Shanghai. They often did not receive timely diagnosis and treatment, which may have an adverse impact on the prevention of epidemic leprosy.
Internal migration of people from rural to urban areas in search of opportunities and better living is common in China. This migration may lead to an increased burden of leprosy in Shanghai urban areas. This study examines the cases of leprosy diagnosed in Shanghai, and compares the differences between indigenous cases of leprosy and cases in internal immigrants. Internal migrant cases were found to be responsible for most incidences of leprosy in Shanghai. Misdiagnosis was the main reason for delays in diagnosis of leprosy. Internal migrant cases of leprosy had a longer delay in diagnosis than resident cases.