Epidemiological Scenario of Leprosy in a Province in China: Long Delay in Diagnosis and High Rate of Deformity.

doi:10.21203/rs.3.rs-34383/v1

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Epidemiological Scenario of Leprosy in a Province in China: Long Delay in Diagnosis and High Rate of Deformity.

https://doi.org/10.21203/rs.3.rs-34383/v1

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published 25 Nov, 2020

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Background: This ecological study aimed to analyze both the tendency and the characteristics of leprosy in an endemic province in the Chinese Northwest.

Methods: The medical records of leprosy in the province of Shaanxi, China, 1998-2018 were collected from the leprosy management information system in China (LEPMIS). Epidemiological variables were analyzed in this study.

Results: 477 new cases were diagnosed between 1998-2018 in this area. The average rate of annual detection was 0.070/100,000, and the average annual prevalence was 0.305/100,000. The mean age of new patients was 46.71 years, and the ratio of male to female was 2.46:1. There were 399 cases (83.6%) of multibacillary (MB) forms. 148 cases (31.03%) had grade II disability. The mean delay in diagnosis for new cases was 62.01 months.

Conclusion: The epidemiological study showed that the characteristics of the new leprosy cases in our province were still long delay in diagnosis and high rate of deformity, which indicated the need of actions of stimulating early diagnosis and treatment, and strengthening the detection of leprosy in low prevalent areas.

Health Economics & Outcomes Research

Infectious Diseases

Health Policy

Leprosy

Mycobacterium leprae

China

Epidemiology

Leprosy, which is caused by mycobacterium tuberculosis, is a chronic infectious disease, and it mainly induces injuries of skin and peripheral nerves. In China, the epidemic of leprosy has a history of more than 2,000 years, and there is no effective vaccine by now^[1]. The long course, high deformity rate, and other medical problems may cause a series of social problems, such as low quality of life and low happiness index caused by discrimination^[2]. Since the founding of the People’s Republic of China in 1949, our government has carried out a great deal of public health work and taken a large number of effective measures of prevention and control. By 2018, the incidence rate of leprosy in Shaanxi province, China had been kept below 1/100,000 and basically eliminated. However, there are still sporadic new cases. As an important part of the Silk Road Economic Belt and the 21st-Century Maritime Silk Road (B&R), our province covers a total area of 205,800 square kilometers and has a resident population of 38.64 million (December, 2018). Due to different regional and population distribution, in order to explore the epidemic trend and characteristics of leprosy in this province, we retrospectively reviewed the leprosy cases between 1998 to 2018, and tried to provided basis for effective prevention and control of leprosy in low epidemic situation.

2.1 The diagnosis standard

The diagnoses of new and recurrent leprosy were based on Leprosy Prevention Manual for Primary Care Physicians (PCPs) and Leprosy Diagnosis Standard WS291-2008. Cases were classified according to the Leprosy Classification Standard, WHO, 1987. Disability classification was bases on the Disability Classification Standard for Leprosy, WHO, 1988.

2.2 Data sources

All new and recurrent leprosy cases were collected from the Leprosy Prevention and Control Management Information System in China (LEPMIS). Population data came from the Shaanxi Statistical Yearbook.

2.3 Statistical analysis

A new and recurrent leprosy cases database was established in EXCEL 2010. U test, χ² test, and t test were used for statistical analysis when appropriate in SPSS Statistics 19.0 (IBM Corp., Armonk, NY, USA).

3.1 The overall situation and changing trend

Between 1998 and 2018, 542 leprosy cases were found in Shaanxi province, with an annual rate of detection of 0.070/100,000, shown in Table 1. Among them, 477 were new cases, with a new detection rate of 0.061/100,000. 65 leprosy cases recurred, with a recurrence rate of 0.008/100,000. The current leprosy cases in this area was 2372, with an annual prevalence rate of 0.305/100,000. Compared with 1998, the 2018’s annual new detection rate dropped from 0.078/100,000 to 0.029/100,000, with a significant downtrend (χ² = 86.85,P༜0.01). The annual recurrence rate dropped from 0.014/100,000 in 1998 to 0.000/100,000 in 2018, with a significant downward trend (χ² = 16.14, p < 0.01). The annual detection rate dropped from 0.092/100,000 in 1998 to 0.029/100,000 in 2018, with a significant downtrend (χ² = 112.99, p < 0.01). The annual prevalence rate dropped from 0.309/100,000 in 1998 to 0.134/100,000 in 2018, with a significant downward trend (χ² = 671.15, p < 0.01), shown in Table 1.

Table 1

The detection and prevalence in Shaanxi province from 1998 to 2018.
Year	New cases	New detection rate (1/10⁶)	Relapse cases	Relapse rate (1/10⁶)	Detect cases	Annual detection rate (1/10⁶)	Existing cases	Morbidity (1/10⁶)
1998	28	0.078	5	0.014	33	0.092	111	0.309
1999	11	0.030	4	0.011	15	0.042	96	0.265
2000	34	0.094	1	0.003	35	0.097	115	0.319
2001	42	0.117	4	0.011	46	0.128	143	0.398
2002	31	0.086	2	0.006	33	0.092	152	0.423
2003	21	0.058	2	0.006	23	0.064	150	0.417
2004	24	0.067	7	0.019	31	0.086	161	0.447
2005	35	0.095	6	0.016	41	0.112	170	0.463
2006	40	0.107	7	0.019	47	0.126	162	0.433
2007	39	0.104	7	0.019	46	0.123	170	0.453
2008	16	0.043	4	0.011	20	0.053	157	0.418
2009	20	0.053	6	0.016	26	0.069	129	0.341
2010	21	0.056	2	0.005	23	0.061	102	0.270
2011	24	0.064	2	0.005	26	0.070	106	0.284
2012	16	0.041	0	0.000	16	0.041	86	0.221
2013	10	0.027	1	0.003	11	0.029	69	0.184
2014	13	0.035	1	0.003	14	0.037	64	0.171
2015	12	0.032	2	0.005	14	0.037	59	0.152
2016	14	0.038	1	0.003	15	0.041	61	0.167
2017	15	0.041	1	0.003	16	0.044	57	0.156
2018	11	0.029	0	0.000	11	0.029	52	0.134
Total	477	0.061	65	0.008	542	0.070	2372	0.305

3.2 Population Distribution

3.2.1 Gender distribution

Among 477 newly diagnosed leprosy patients, 339 were males and 138 were females, with a male-to female ratio of 2.46:1, with a significant difference between sexes in case composition (χ² = 304.17, p < 0.01), as shown in Table 2.

Table 2

The ratios of types, sexes, and II disability in new cases between 1998 and 2018.
Year	New detected cases
Year	Cases	MB	PB	Type ratio (n%)	Male	Female	Sex ratio (M/F)	Cases with II disablity	Rate of II disability (n%)
1998	28	25	3	89.29	19	9	2.11	3	10.71
1999	11	10	1	90.91	8	3	2.67	2	18.18
2000	34	30	4	88.24	22	12	1.83	7	20.59
2001	42	38	4	90.48	26	16	1.63	22	52.38
2002	31	25	6	80.65	26	5	5.20	6	19.35
2003	21	17	4	80.95	18	3	6.00	4	19.05
2004	24	23	1	95.83	17	7	2.43	6	25.00
2005	35	26	9	74.29	27	8	3.38	11	31.43
2006	40	30	10	75.00	26	14	1.86	15	37.50
2007	39	31	8	79.49	30	9	3.33	14	35.90
2008	16	12	4	75.00	12	4	3.00	3	18.75
2009	20	19	1	95.00	15	5	3.00	11	55.00
2010	21	16	5	76.19	14	7	2.00	4	19.05
2011	24	20	4	83.33	15	9	1.67	7	29.17
2012	16	14	2	87.50	10	6	1.67	5	31.25
2013	10	8	2	80.00	7	3	2.33	4	40.00
2014	13	11	2	84.62	10	3	3.33	6	46.15
2015	12	11	1	91.67	9	3	3.00	4	33.33
2016	14	9	5	64.29	11	3	3.67	8	57.14
2017	15	14	1	93.33	10	5	2.00	3	20.00
2018	11	10	1	90.91	7	4	1.75	3	27.27
Total	477	399	78	83.65	339	138	2.46	148	31.03

3.2.2 Age distribution

Between 1988 and 2018, the average age of the new diagnosed leprosy patients in Shaanxi was 45.21 years old, and the median age was postponed from 42 in 1998 to 51 in 2018, as shown in Table 3. During this period, 2 cases of 14-year-old children patients were detected (1: Ankang city, 2004; 1: Hanzhong city, 2007).

3.3 Regional distribution

542 new and recurrent cases belong to the local residents, and in 2018, 10 counties or districts in Shaanxi had newly diagnosed cases. By 2018, 28 counties or districts had existing cases, which mainly distributed in southern Shaanxi, including Hanzhong, Ankang, and shangluo. Leprosy scattered in Guanzhong, and no cases were found in northern Shaanxi for many years. By the end of 2018, there is still one county (Yangxian county) in Shaanxi that has not reached the basic leprosy elimination index stipulated by the Ministry of Health, China, and the prevalence rate of Yangxian county was 0.0129/100,000.

3.4 Types of cases and disability

3.4.1 Case types

In 477 newly discovered cases, 399 cases (83.6%) were MB, and 78 cases (16.4%) were paucibacillary (PB). The ratio of types was 5.12:1. No significant difference was found in the ratio of types between 1998 and 2018 (χ² = 0.002, P > 0.05). Statistical difference was found in the type ratio between the new detected and the recurrent cases (χ² = 192.92, p < 0.01).

3.4.2 Disability

Of 477 newly diagnosed cases, 148 (31.03%) were Class II disability. The rate of disability increased from 10.71% in 1998 to 27.27% in 2018.

3.5 Delay diagnosis in new cases

The average delay period in diagnosis of 477 newly detected cases was 62.0 (43.8-112.4) months. However, the average delay period was shorter in 2018 than in 1998 (47.6 vs 64.0 months), shown in Table 3.

Table 3

The average delay periods and median ages of new detected cases from 1998 to 2018.
Year	Average delay period (m)	Average ages	Median ages
1998	64.17	42.7	42.0
1999	62.11	43.6	43.0
2000	64.12	42.9	42.0
2001	62.14	43.8	43.0
2002	58.26	45.2	43
2003	43.80	43	41
2004	80.83	42	41.5
2005	43.94	46.2	47
2006	112.38	47	47
2007	97.97	48.9	46
2008	33.44	44.5	44
2009	58.65	43	40
2010	47.85	46.9	44
2011	47.21	43.7	42.5
2012	64.25	47.2	45.5
2013	52.45	51	58
2014	54.62	45.3	43.5
2015	71.42	36.7	40.5
2016	88.50	49.2	48
2017	46.50	49.5	49
2018	47.60	49.2	51

By the end of 2018, 11,789 leprosy patients have been diagnosed in Shaanxi province, 10,270 cases have been cured, and 502 patients relapsed. The prevalence rates of leprosy in over 95% of counties, cities, or districts in Shaanxi were controlled below 1/100,000, reaching our national target of basically eliminating leprosy. According to data above, 477 new diagnosed leprosy cases and 65 relapsed patients were found in Shaanxi between 1998 and 2018, 542 cases in total. The annual detection rate dropped from 0.092/100,000 in 1998 to 0.029/100,000 in 2018. The detection rate and prevalence rate of leprosy showed an impressively significant downward trend over the past 20 years, which indicated that we have achieved good results in the prevention and control of leprosy.

In 477 newly diagnosed patients, the male-female ratio is 2.46:1, which was basically consistent with previous reports in some other areas in China ^{[3, 4]}. The average age of the newly detected was 45.2 years old, which changed little in different years. In terms of newly diagnosed cases, the age distribution in different years were similar, and the average age were getting higher^[5]. The Leprosy Control Handbook (the 1989 edition and the 2002 edition) mentioned that it is generally believed that the average age of patients tend to rise as the incidence of leprosy declined (the prevalence of leprosy is controlled). This was also an evidence for the relatively low epidemic situation of leprosy in Shaanxi. However, this may also be related to the long delay period in diagnosis^[6], suggesting that the ability to detect new leprosy patients in Shaanxi still needed improvement. In terms of current leprosy cases, the average age during 21 years was relatively high, which may be related to the large number of MB leprosy cases in our province and the long Multidrug Therapy (MDT) course. This suggested that we should pay attention to the treatment and rehabilitation of current leprosy cases. From 1998 to 2018, only two children under 15 years old were diagnosed with leprosy, which may be related to the relatively low prevalence in Shaanxi. In terms of regional distribution, leprosy epidemic was mainly in Southern Shaanxi and the Central Shaanxi Plain^[7]. These areas above were also areas with high incidence rate of leprosy in history. The source of infection has not been completely and effectively controlled, suggesting that we should continue to improve prevention and control work in these areas.

83.6% of the new cases were MB and 16.4% were PB, with a ratio of 5.1:1, which was higher than related reports in some other regions in China^[8], indicating that the number of MB cases was too high and there were potential risks. It also indicated that leprosy in Shaanxi was in a low epidemic state and under effective control. The type ratio of newly detected cases between 1998 and 2018 was relatively high (83.7%). According to the Leprosy Prevention Mannual (the 2002 edition), previous studies showed that the type ratio will rise in the low prevalence area of leprosy ^[9], which was similar with our data. The level II disability rate of new cases in Shaanxi between 1998 and 2018 was about 31.0%, which may be related to the longer delay in diagnosis and less newly detected cases. The average delay period of newly diagnosed patients was 46 months, which was much higher than that reported in relevant literatures in some other areas in China, such as Guangdong province^[5], indicating that leprosy cases in Shaanxi took a longer time from onset to diagnosis. This situation may be related to latent symptoms and atypical clinical manifestations in the early stage, low attention to patients, and lack of primary prevention and treatment experience, etc.^[10], suggesting that our province should further carry out leprosy monitoring and strengthen the ability of early detection and diagnosis.

Although the leprosy prevention and control in Shaanxi has achieved remarkable results and the leprosy epidemic has been at a relatively low level for a long time, the prevalence of leprosy was still relatively high in some areas, and the incidence of disability in new leprosy patients was still high in some places. The delay period in diagnosis still needed improvement. To achieve the goal of eliminating the damage caused by leprosy, we should further strengthen the detection ability and the treatment management of leprosy cases, and focus on how to shorten the period between symptom onset and diagnosis and reduce the rate of leprosy disability.

LEPMIS

The Leprosy Management Information System in China

Multibacillary

Paucibacillary

B&R

The Silk Road Economic Belt and the 21st-Century Maritime Silk Road

PCPs

Primary Care Physicians

MDT

Multidrug Therapy

6.1 Ethics approval and consent to participate: This retrospective study was reviewed and approved by the institutional ethics committee.

6.2 Consent for publication: All authors (G Li, QP Zhang, P Chen, ZX Lin, and C Li) have approved this manuscript for submission and publication on your journal.

6.3 Availability of data and material: The data that support the findings of this study are available from Health Commission of Shaanxi Province; however, restrictions apply regarding the availability of these data, which were used under a license for the current study, and the data are not publicly available. However, data are available from the authors upon reasonable request and with permission of the Health Commission of Shaanxi Province. Please contact the corresponding author: C Li: [email protected].

6.4 Competing interests: No competing interests exist in this study.

6.5 Funding: None.

6.6 Authors' contributions: QP Zhang and C Li led the study, P Chen, ZX Lin and G Li led their respective provincial teams and collected the data. G Li and C Li analyzed the data, contributed to the conceptualization of the study, as well as the interpretation of results, and reviewed drafts of the paper. All authors have read and approved the final version of the manuscript.

6.7 Acknowledgements: We would like to acknowledge Health Commission of Shaanxi Province, Shaanxi Provincial Institute for Endemic Disease Control, and Department of Xijing Hospital of the Fourth Military Medical University for their support in this program of research.

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Review #2 received at journal
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Editorial decision: Major revision
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Epidemiological Scenario of Leprosy in a Province in China: Long Delay in Diagnosis and High Rate of Deformity.

Status:

Journal Publication

Version 1

Abstract

1. Background

2. Methods

2.1 The diagnosis standard

2.2 Data sources

2.3 Statistical analysis

3 Results

3.1 The overall situation and changing trend

3.2 Population Distribution

3.2.1 Gender distribution

3.2.2 Age distribution

3.3 Regional distribution

3.4 Types of cases and disability

3.4.1 Case types

3.4.2 Disability

3.5 Delay diagnosis in new cases

4. Discussion

5. Conclusion

Abbreviations

Declarations

References

Status:

Journal Publication

Version 1