Towards the elimination of leprosy in Yunnan, China: A time-series analysis of surveillance data

Spatiotemporal pattern of leprosy in southwest China from 2010 to 2020: an ecological study

BACKGROUND

Despite many efforts to control leprosy worldwide, it is still a significant public health problem in low- and middle-income regions. It has been endemic in China for thousands of years, and southwest China has the highest leprosy burden in the country.

METHODS

This observational study was conducted with all newly detected leprosy cases in southwest China from 2010 to 2020. Data were extracted from the Leprosy Management Information System (LEPMIS) database in China. The Joinpoint model was used to determine the time trends in the study area. Spatial autocorrelation statistics was performed to understand spatial distribution of leprosy cases. Spatial scan statistics was applied to identify significant clusters with high rate.

RESULTS

A total of 4801 newly detected leprosy cases were reported in southwest China over 11 years. The temporal trends declined stably. The new case detection rate (NCDR) dropped from 4.38/1,000,000 population in 2010 to 1.25/1,000,000 population in 2020, with an average decrease of 12.24% (95% CI: -14.0 to - 10.5; P < 0.001). Results of global spatial autocorrelation showed that leprosy cases presented clustering distribution in the study area. Most likely clusters were identified during the study period and were frequently located at Yunnan or the border areas between Yunnan and Guizhou Provinces. Secondary clusters were always located in the western counties, the border areas between Yunnan and Sichuan Provinces.

CONCLUSIONS

Geographic regions characterized by clusters with high rates were considered as leprosy high-risk areas. The findings of this study could be used to design leprosy control measures and provide indications to strengthen the surveillance of high-risk areas. These areas should be prioritized in the allocation of resources.

The burden of physical disability among patients with newly detected leprosy in Yunnan, China, 1990-2020: A population-based, cross-sectional survey

BACKGROUND

Physical disability is the main complication of leprosy. Although understanding the leprosy rate, prevalence, spatiotemporal distribution, and physical nerve characteristic trends is crucial for the implementation of leprosy control programs and identification of remaining challenges, these data are still unclear. We assessed physical disability trends among newly detected leprosy cases over the past 31 years in 129 counties and territories in Yunnan, China.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed the data of newly detected leprosy cases from the Leprosy Management Information System in Yunnan, China, from 1990-2020. All available data related to physical disability were analyzed, including demographic characteristics (sex, age, ethnicity, education level); clinical characteristics (diagnosis duration, detection mode, contact history, leprosy reaction, skin lesions, nerve lesions, disability classification); World Health Organization (WHO) leprosy physical disability indicators; and nerve and eyes, hands and feet (EHF) involvement. A total of 10758 newly diagnosed leprosy cases were identified, and 7328 (65.60%), 1179 (10.55%) and 2251 (20.15%) were associated with grade 0, 1, and 2 disability (G0D, G1D, and G2D), respectively. Male sex, older age, Han ethnicity, urban employment, a longer diagnosis duration, a contact history, greater nerve involvement, and tuberculoid-related forms of leprosy were associated with increased prevalence rates of physical disability. The rates of physical disability in newly detected leprosy cases per 1 million population decreased from 5.41, 2.83, and 8.24 in 1990 to 0.29, 0.25, and 0.54 per 1 million population in 2020, with decreases of 94.64%, 91.17%, and 93.44% in G2D, G1D and total physical disability (G1D + G2D) rates, respectively. In the same period, the proportions of G2D, G1D and total physical disability decreased from 28.02%, 14.65%, and 42.67% in 1990 to 10.08%, 11.76%, and 21.85% in 2020, with decreases of 64.03%, 19.73%, and 48.79%, respectively. Nerve thickening was more common than nerve tenderness, and claw hand, plantar insensitivity, and lagophthalmos were the most frequently reported EHF-related disabilities.

CONCLUSIONS

Despite general progress in reducing the prevalence of leprosy-related physical disability, the proportion of physical disability among leprosy disease remains high, especially in specific counties. This implies that leprosy cases are being detected at a later stage and that transmission in the community still exists. Further efforts focusing on early detection are crucial for leprosy control and the elimination of the disease burden.

Detection of anti-M. leprae antibodies in healthy children in China: A systematic review of Chinese literature

Leprosy is an infectious disease caused by Mycobacterium leprae (M. leprae) that mainly involves the skin and peripheral nerves, causing lifelong deformities and social stigma. As evident from the practically stable number of new cases reported worldwide during the past decade, transmission is still ongoing. On route to leprosy elimination, an appropriate tool is needed to monitor M. leprae transmission. M. leprae-specific antibodies indicate infection with M. leprae, but do not differentiate between present and past infection. Nevertheless, detection of M. leprae infection in young children per definition indicates recent infection. Hence, seroprevalence in young children can be used to monitor recent M. leprae transmission. Despite having eliminated leprosy in most parts of the country, studies on transmission conducted in China are not sufficiently reported in the English literature. Therefore, we performed a systematic review of Chinese literature describing serological studies in healthy children in (former) leprosy endemic areas in China, available in the Chinese databases: China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang Database. From the 710 articles identified in these three Chinese databases, only four full-text articles fulfilled all inclusion criteria regarding sufficiently detailed descriptions of anti-M. leprae antibodies in healthy children. Two additional papers were identified through snowballing, resulting in a total of six articles considered for this review reporting quantitative serological data from three Chinese provinces between 1987 and 2003. All studies used ELISAs to quantify antibody levels. Seroprevalence in healthy children ranged from 7.93% (Yunnan) to 32.35% (Jiangsu). If the same method was used (in Jiangsu), direct comparison of studies at different time points indicated that decrease in disease prevalence (0.28 to 0.16 per 100,000) or new case detection rate (2.6 to 1.0 per 100,000) from 1987-1991 corresponded to decrease in anti-M. leprae antibody seroprevalence (30.86% to 22.61%) in healthy children. Thus, these findings are consistent with the previous finding that anti-M. leprae antibody seroprevalence in young children represents a surrogate indicator to monitor transmission.

Systematic Review of Survival Analysis in Leprosy Studies-Including the Following Outcomes: Relapse, Impairment of Nerve Function, Reactions and Physical Disability

Leprosy is a public health problem in South American, African and Oceanian countries. National programs need to be evaluated, and the survival analysis model can aid in the construction of new indicators. The aim of this study was to assess the period of time until the outcomes of interest for patients with or exposed to leprosy by means of survival analysis surveys. This review researched articles using the databases of PubMed, Science Direct, Scopus, Scielo and BVS published in English and Portuguese. Twenty-eight articles from Brazil, India, Bangladesh, the Philippines and Indonesia were included. The Kaplan-Meier method, which derives the log-rank test, and Cox's proportional hazards regression, which obtains the hazard ratio, were applied. The mean follow-up until the following outcomes were: (I) leprosy (2.3 years) in the population who were exposed to it, (II) relapse (5.9 years), (III) clinical manifestations before, during and after treatment-nerve function impairment (5.2 years), leprosy reactions (4.9 years) and physical disability (8.3 years) in the population of patients with leprosy. Therefore, the use of survival analysis will enable the evaluation of national leprosy programs and assist in the decision-making process to face public health problems.

Oscillatory properties of class C notifiable infectious diseases in China from 2009 to 2021

Background

Epidemics of infectious diseases have a great negative impact on people's daily life. How it changes over time and what kind of laws it obeys are important questions that researchers are always interested in. Among the characteristics of infectious diseases, the phenomenon of recrudescence is undoubtedly of great concern. Understanding the mechanisms of the outbreak cycle of infectious diseases could be conducive for public health policies to the government.

Method

In this study, we collected time-series data for nine class C notifiable infectious diseases from 2009 to 2021 using public datasets from the National Health Commission of China. Oscillatory power of each infectious disease was captured using the method of the power spectrum analysis.

Results

We found that all the nine class C diseases have strong oscillations, which could be divided into three categories according to their oscillatory frequencies each year. Then, we calculated the oscillation power and the average number of infected cases of all nine diseases in the first 6 years (2009-2015) and the next 6 years (2015-2021) since the update of the surveillance system. The change of oscillation power is positively correlated to the change in the number of infected cases. Moreover, the diseases that break out in summer are more selective than those in winter.

Conclusion

Our results enable us to better understand the oscillation characteristics of class C infectious diseases and provide guidance and suggestions for the government's prevention and control policies.

Risk factors for physical disability in patients with leprosy disease in Yunnan, China: Evidence from a retrospective observational study

BACKGROUND

Leprosy is potentially debilitating. The risk factors related to physical disabilities associated with leprosy disease in Yunnan, China was not clear.

METHODOLOGY/PRINCIPAL FINDINGS

We studied 10644 newly detected leprosy patients from Yunnan, China, from 1990 to 2019. Factors associated with Grade 1 (G1D) and Grade 2 (G2D) physical disabilities or overall physical disabilities (combined G1D and G2D) associated with leprosy were analyzed using multinomial and ordinal logistic regression analyses. The following factors were associated with the development of physical disability in these patients with leprosy: delayed diagnosis [odds ratio (OR): 5.652, 4.399, and 2.275; 95% confidence intervals (CIs): 4.516-7.073, 3.714-5.212, and 2.063-2.509; for ≥ 10, 5-10 y, and 2-5 years, respectively], nerve damage (OR: 3.474 and 2.428; 95% CI: 2.843-4.244, and 1.959-3.008; for 2 and 1 damaged nerves, respectively), WHO classification of PB (OR: 1.759; 95% CI: 1.341-2.307), Ridley-Jopling classification (OR: 1.479, 1.438, 1.522 and 1.239; 95% CI: 1.052-2.079, 1.075-1.923, 1.261-1.838, and 1.072-1.431; for TT, BT, BB, and BL when compared with LL, respectively), advanced age (OR: 1.472 and 2.053; 95% CI: 1.106-1.960 and 1.498-2.814; for 15-59 and over 60 years old, respectively), zero skin lesions (OR: 1.916; 95% CI: 1.522-2.413), leprosy reaction (OR: 1.528; 95% CI: 1.195-1.952), rural occupation (OR: 1.364; 95% CI: 1.128-1.650), Han ethnicity (OR: 1.268; 95% CI: 1.159-1.386), and male sex (OR: 1.128; 95% CI: 1.024-1.243).

CONCLUSIONS

Delayed diagnosis, nerve damage, no skin lesions, WHO and Ridley-Jopling classifications, leprosy reactions, advanced age, rural occupation, Han ethnicity, and male sex were associated with disability in leprosy patients. Identifying risk factors could help to prevent physical disability.

The state of the leprosy epidemic in Yunnan, China 2011-2020: A spatial and spatiotemporal analysis, highlighting areas for intervention

BACKGROUND

Despite public health efforts to reduce the leprosy burden in Yunnan, China, leprosy remains an important public health problem in some specific areas. We analyzed the epidemiological characteristics and spatial distribution of leprosy in Yunnan, China, and provide data to guide disease prevention and control efforts.

METHODOLOGY/PRINCIPAL FINDINGS

The surveillance data of newly detected leprosy cases in Yunnan, China, during 2011-2020 were extracted from the LEPROSY MANAGEMANT INFORMATION SYSTEM IN CHINA (LEPMIS), and spatial distribution analysis, spatial autocorrelation analysis, and spatiotemporal scanning were performed with ArcGIS 10.6.1, GeoDa 1.8.8, and SaTScan 9.4.3 software, respectively. A total of 1907 newly detected leprosy cases were reported in Yunnan, China, during 2011-2020. The new case detection rate (NCDR) decreased from 0.62 in 2011 to 0.25 in 2020, with an annual incidence of 0.41/100,000 population. The proportions of multibacillary (MB) cases, cases in female patients, cases causing grade 2 physical disability (G2D), and cases in pediatric patients were 67.07%, 33.93%, 17.99%, and 2.83%, respectively. The number of counties with an incidence above 1/100,000 population decreased from 30 in 2011 to 8 in 2020. The Moran's I of leprosy in Yunnan, China, during 2011-2020 ranged from 0.076 to 0.260, indicating the presence of spatial clusters. Local spatial autocorrelation (LSA) analysis showed that high-high cluster areas (hot spots) were mainly distributed in the southeastern, northern, and northwestern regions. Spatiotemporal scanning showed three clusters with high NCDRs. The probably primary clusters, occurring during January 1, 2011-December 31, 2015, covered 11 counties in the southeastern region (RR = 5.046515, LRR = 271.749664, P = 0.000).

CONCLUSION

The number of leprosy cases in Yunnan decreased overall, although some high-NCDR regions remained. Geographic information system (GIS) analysis coupled with spatial analysis indicated regions with leprosy clusters. Continuous leprosy prevention and control strategies in Yunnan Province should be established, and interventions in high-risk regions should be prioritized and further strengthened.