Prevalence characteristics and space-time clustering of leishmaniasis in Shaanxi province

  Objective   To analyze prevalence characteristics, time-space clustering and long-term dynamic trend of leishmaniasis in Shaanxi province, and to provide evidences for implementing surveillance and prevention of the disease.

  Methods   We collected incidence data of leishmaniasis reported in Shaanxi province between July 1953 and December 2016 and conducted time-space clustering spatial autocorrelation analysis on the data with SaTScan 9.04 and ArcGIS 10.2 software.

  Results   During the period in the province, a total of 41 990 leishmaniasis incidences were reported, with an average annual incidence rate of 2.25/100 000, and totally 210 deaths due to the disease were registered, with a mean annual mortality of 0.01/100 000 and an overall case fatality rate of 0.50%. The incidence rate, mortality rate, and case fatality rate of the leishmaniasis were high during 1950's and then declined greatly from 1960's, but rose again slightly in 2004 with small scale outbreaks in some regions. More leishmaniasis cases (36.98% of all incidents) were reported between July and September of a year and the male to female ratio of the cases was 1.93:1. The majority of the cases were farmers and scattered-living children, accounting for 48.10% and 34.18% of all the cases, respectively. The leishmaniasis cases were reported in all administration regions (92 counties or districts) of the province. Five regions with space-time clustering of leishmaniasis cases were identified. The results of spatial autocorrelation analysis revealed the high-high cluster areas in central Shaanxi plain region during 1950's, northern Shaanxi from 1960's to 1990's, Hanzhong municipality during 2000's, and Yichuan county and Hancheng municipality during 2010's; all the high-high cluster areas were located in the border region of trans Loess Plateau and central Shaanxi plain.

  Conclusion   The morbidity of leishmaniasis epidemic generally showed a downward trend in Shaanxi province between 1953 and 2006 but increased in some areas recently; the results suggest surveillance on the disease should be strengthened to control the spreading the disease.