1.A study of CD4+T lymphocyte infiltration level in the thyroid of experimental autoimmune thyroiditis rat
Silu CUI ; Shoujun LIU ; Jun YU
Chinese Journal of Endemiology 2014;33(3):263-267
Objective To establish a experimental autoimmune thyroiditis(EAT) rat model and to observe pathological change levels of CD4 + T lymphocyte infiltration in thyroid tissues under different iodine nutrient conditions.Methods One hundred and thirty-five four weeks old female Lewis rats(body weight about 80 g) were divided into control(NC),model(TG),high iodine-Ⅰ (HⅠ),high iodine and model-Ⅰ (HⅠ + TG),high iodine-Ⅱ (H Ⅱ),high iodine and model-Ⅱ (H Ⅱ + TG) groups according to body weight by random number table.There were 20 rats in NC,HⅠ and H Ⅱ groups,and 25 rats in TG,H Ⅰ + TG and H Ⅱ + TG groups.The rats of HⅠ and HⅠ + TG groups drank deionized water containing iodine 25.7 mg/L; rats of HⅡl and H Ⅱ + TG groups drank deionized water containing iodine 423.3 mg/L; rats of NC and TG groups drank distilled water.Rats of TG,HⅠ + TG and H Ⅱ + TG groups were immunized with 0.1 ml thyroglobulin(Tg,8.0 g/L) in incomplete Freunds adjuvant (IFA),once two weeks for three times.Urine samples were collected after immunization for 8 weeks; after immunization for 15 weeks,rats were killed,blood samples and thyroid tissues were taken.Urinary iodine was determined by arsenic-cerium catalytic spectrophotometry; pathological changes in thyroid tissue were observed by Hematoxylin-Eosin (HE) method ; immunohistochemical method was used to identify the infiltration of inflammatory cells in thyroid tissue.Results The difference of rat thyroid relative quality between groups was statistically significant (F =44.428,P < 0.05).Compared with NC group (0.085 25 mg/g),thyroid relative qualities were increased in experimental groups (TG,HⅠ,HⅠ + TG,H Ⅱ,H Ⅱ + TG groups:0.095 22,0.092 85,0.097 48,0.096 55,0.095 33 mg/g,all P < 0.05).The difference of urinary iodine between groups was statistically significant(x2 =106.4,P< 0.05).Compared with NC group(456.45 μg/L),urinary iodine levels in TG,HⅠ,HⅠ +TG,HⅡ,HⅡ + TG groups(800.08,18 633.20,13 869.00,87 889.97,61 661.51 μg/L) were increased(all P < 0.05).The pathological changes of rats in each group were increased with increasing of iodine intake.Rats in NC group had normal thyroid structure; in TG,HⅠ groups,a small amount of lyrnphocytes were found between thyroid follicular; the lymphocytes infiltrated into the follicular in HⅠ + TG group; rats in H Ⅱ,H Ⅱ + TG groups had follicular fusion,and diffused inflammatory cell infiltration.There was a tendency of increased CD4+ T lymphocyte infiltration in rat thyroid with increasing of iodine intake.There was no CD4+ T lymphocyte positive staining in NC group; TG group had a small amount of positive cells; HⅠ group had scattered yellowish-brown positive cells.HⅠ + TG group had a focal lymphocyte infiltration; HⅡ group had follicular expansion obviously; follicular structure damage in HⅡ + TG group was serious,and showed a diffused yellow dye.Conclusion Excessive iodine intake and Tg immunization can induce and aggravate the incidence of autoimmune thyroiditis in rats,and pathological change situation has exacerbated with increasing of iodine intake; excessive iodine intake may also lead to an increased tendency of CD4+ T lymphocytes infiltration in thyroid tissue of EAT rat.
2.Effect of iodine on chemokine IP-10 expression in experimental autoimmunity thyroiditis rat
Silu CUI ; Fangang MENG ; Jun YU
Chinese Journal of Endemiology 2015;34(8):573-577
Objective To establish experimental autoimmune thyroiditis (EAT) rat model induced by bovine thyroglobulin (bTg) and to observe the effect of iodine on IP-10 in rat serum and IP-10 mRNA expression in rat thyroid tissue.Methods One hundred and thirty-five four-week old female Lewis rats were divided into normal control (NC,20 rats) group;TG group,25 rats;H Ⅰ group,20 rats;H Ⅰ + TG group,25 rats;H Ⅱ group,20 rats and H Ⅱ + TG group,25 rats according to a random number table.The water iodine concentration was 25.7 μg/L given to rats of HⅠ and H I + TG groups,and 423.3 μg/L of H Ⅱ and H Ⅱ + TG groups.Rats of NC and TG groups drank distilled water.Rats of TG,H Ⅰ + TG,H Ⅱ + TG groups were immunized with 0.1 ml bTg (8 g/L) in IFA.All rats were killed at the end of 15 weeks.Urinary iodine was determined by As3+-Ce4+ catalytic spectrophotometry (WS/T 107-2006).Pathological changes in thyroid tissue were observed by light microscope.Serum IP-10 was determined by enzyme-linked immunosorbent assay (ELISA),and IP-10 mRNA expression in thyroid was detected by real-time PCR.Results The differences of urinary iodine between groups were statistically significant (x2 =106.4,P < 0.05).Compared with NC group (456.45 μg/L) urinary iodine in other groups increased significantly (TG,H Ⅰ,H Ⅰ + TG,HⅡ,HⅡ + TG:800.08,18 633.20,13 869.08,87 889.97,61 661.51 μg/L,all P < 0.05).The pathological changes of rats in each group aggravated following increased iodine intake,NC group had normal thyroid structure;thyroid of TG group had a small amount of lymphocytes;thyroid of H Ⅰ group showed irregular follicular,part of the follicular was destroyed;a large number of lymphocytes infiltrated between follicular of H Ⅱ group;in H Ⅱ + TG group,the follicular was destroyed severely,diffuse inflammatory cell infiltration.The difference of serum IP-10 between groups no were statistically significant (F =1.462,P > 0.05).The expression of IP-10 mRNA of H Ⅰ + TG (2.80 ± 1.73) rats thyroid was higher than that in NC (1.65 ± 1.62) and H Ⅰ (1.07 ± 1.00) groups,H Ⅱ (0.64 ± 0.64),H Ⅱ + TG (0.80 ± 0.49) were lower than H Ⅰ + TG group (all P < 0.05).Conclusions Excessive iodine intake could have increased inflammatory cells in EAT rat and rats have showed more serious pathologic changes.These phenomena may be ralated with changed expression of IP-10 mRNA in EAT rat thyroid.
3.Whether the limitation of the phalangeal epiphysis "before the equal-diameter period" should be extended to "before the ultra-diameter period" in X-ray diagnosis of Kashin-Beck disease
Xianhao WU ; Xin ZHANG ; Yun CAI ; Silu CUI ; Yunqi LIU ; Liyan SUN
Chinese Journal of Endemiology 2021;40(2):150-154
Objective:To explore whether the limit of "before the equal-diameter period" is reasonable in the current criteria for "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010) in children, and to provide basic data and technical support for revision of the criteria for "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010).Methods:In 2018, the historical Kashin-Beck disease (KBD) areas in Heilongjiang Province were selected as the investigation sites. The right-hand X-ray films of all children aged 7-12 years old were taken. According to the different X-ray manifestations of the growth and development of the phalangeal epiphysis, they were divided into five periods: before the equal-diameter period, equal-diameter period, ultra-diameter period, pre-closure period and closure period. Firstly, after stratifying by basic data such as age and gender, the data were standardized and analyzed. Secondly, the detection rates of metaphysis-epiphysis (CRME) in each period were calculated and compared. Finally, based on the mean value of the detection rate of metaphyseal change in Linkou and Fuyu counties of Heilongjiang Province in 1990, the rates of expected detection and missed diagnosis of metaphyseal changes of KBD among investigated children were calculated and compared under the limitation of before the equal-diameter period, before the ultra-diameter period or age range reduction.Results:A total of 5 019 children were investigated. The proportion of children before the equal-diameter period was 53.94% (2 707/5 019), and that of before the ultra-diameter period was 77.92% (3 911/5 019). The results showed that the equal-diameter period mainly appeared in 7-10 years old, and showed a decreasing trend with the increase of age (χ 2trend = 390.10, P<0.05); the ultra-diameter period mainly occurred in 10-12 years old, showing a decreasing trend with the increase of age (χ 2trend = 65.39, P < 0.05); the pre-closure period mainly occurred in 10-12 years old, with an increasing trend with the increase of age (χ 2trend = 51.86, P<0.05); the closure period mainly occurred in 11-12 years old and increased with age (χ 2trend = 7.58, P<0.05). The CRME of children in ultra-diameter period was 14.78% (158/1 069), however CRME did not occur in children with equal-diameter period. Among children before equal-diameter period, before ultar-diameter period and aged 7-10 years old, the expected detection rates of metaphyseal changes of KBD were 5.90%, 8.53% and 7.42%, respectively. The expected missed diagnosis rates of metaphyseal changes of KBD were 5.06%, 2.45% and 3.52%, respectively. Conclusion:In order to improve the rate of expected detection and lower the rate of missed diagnosis of metaphyseal changes of KBD, children in "equal-diameter period" should be included in X-ray diagnosis and disease monitoring of KBD.
4.Research progress of T-2 toxin metabolic kinetics
Chinese Journal of Endemiology 2021;40(7):599-602
As the main pollutant of food crops, T-2 toxin has toxic effects on human and animal digestive system, nervous system, reproductive development and so on. In Kashin-Beck disease related areas in China, the etiological substance of Kashin-Beck disease is the abnormal accumulation of T-2 toxin in the grain produced in the endemic area. The prevention and treatment of Kashin-Beck disease has achieved remarkable results through the comprehensive prevention and control measures, such as changing the production and life style, grain exchange, etc., but there are still pathogenic factors in the external environment of the disease area. In this paper, the metabolic kinetics of T-2 toxin is reviewed, and the physicochemical properties, distribution in the body, metabolic kinetics, biotransformation and damage of T-2 toxin and its metabolites to various organs are described, so as to provide new thinking for the study on the effects of T-2 toxin on various organs of the body.
5.Summary report of a national survey of Kashin-Beck disease prevalence in 2019
Silu CUI ; Qing DENG ; Junrui PEI ; Zhe JIAO ; Ning LIU ; Yanhong CAO ; Jun YU
Chinese Journal of Endemiology 2021;40(7):545-550
Objective:To master the status of Kashin-Beck disease (KBD) in 2019, to provide the basis for assessment of KBD control and elimination.Methods:Data of endemic areas basic information collection and children KBD examination were executed in all endemic villages from every endemic county (city, district, banner) of 13 endemic provinces. All children aged 7 - 12 years in endemic villages underwent clinical examination, and X-ray examination was performed for clinically positive children. When both the clinical examination and X-ray reexamination were positive, the diagnosis was KBD.Results:In monitoring of 823 365 7 - 12 years old children, a total of 3 057 children with similar clinical signs of KBD were suspected positive cases. The results of X-ray reexamination showed that the X-ray manifestations of 3 057 children were normal, and no X-ray positive changes were found, that is, there was no case of KBD in children. A total of 16 559 endemic villages in 13 endemic provinces were monitored, and all reached the criteria for KBD elimination. Surveillance of all endemic villages was completed except Tibet Autonomous Region, the KBD elimination rates of endemic villages were 100.00% in 12 endemic provinces and 99.01% (16 559/16 725) in all 13 endemic provinces.Conclusions:No children KBD case is detected in 2019, children KBD stays at its eliminating level throughout the country. And 100.00% endemic villages meet the criteria for KBD elimination in the remaining 12 endemic provinces except Tibet Autonomous Region.
6.Retrospective analysis of oral medication treatment in adult patients with Kashin-Beck disease
Zhe JIAO ; Junrui PEI ; Silu CUI ; Hui LIU ; Jun YU
Chinese Journal of Endemiology 2021;40(10):839-844
Objective:To investigate the oral medication treatment of adult patients with Kashin-Beck disease(KBD) in China, so as to provide theoretical basis for medication screening of KBD and to provide scientific guidance for clinical treatment of KBD.Methods:Based on the "Endemic Disease Prevention and Control Project of Special Funds for Local Public Health Subsidized by the Central Government" and "Major Public Health Service Endemic Disease Prevention and Control Project", the treatment information of adult patients with KBD in 11 provinces (autonomous regions, referred to as provinces) in China from 2006 to 2017 was collected, and the treatment coverage of adult patients with KBD in different years and regions was analyzed, and the curative effect of patients with different severity was evaluated.Results:From 2006 to 2017, the number of provinces participating in the treatment project was from 2 to 11. The actual total number of people treated in China was 68 061, with a completion rate of 78.10% (68 061/87 149); the annual number of people treated increased linearly; the overall clinical symptom remission rates of adult patients with KBD in all regions reached more than 50%, and the overall treatment effect showed an upward trend year by year; compared with patients with grade Ⅲ, after oral medication, the remission rates of clinical symptoms in patients with gradeⅠandⅡ were higher (the average remission rate of clinical symptoms was 84.13% for gradeⅠ, 80.71% for grade Ⅱ and 72.11% for grade Ⅲ, P < 0.05). Conclusions:Oral medication treatment can effectively alleviate the clinical symptoms of most adult patients with KBD of grade Ⅰ and Ⅱ. Patients of grade Ⅲ should be considered treating with oral medication combined with other treatment methods. A considerable number of patients are still ineffective in taking drugs at this stage, and it is urgent to carry out the screening, research and development of specific medications for KBD.
7.A comparative study of the efficacy of glucosamine sulfate and diacerein in the treatment of adult Kashin-Beck disease
Jiaxin LI ; Haichun ZHOU ; Silu CUI ; Yanhong CAO ; Xin ZHANG ; Chunhui LI ; Yujiao LIU ; Fang QI ; Qi ZHANG ; Jun YU
Chinese Journal of Endemiology 2021;40(10):849-853
Objective:To observe and compare the therapeutic effects of glucosamine sulfate (GS) and diacerein (DCN) on adult Kashin-Beck disease (KBD).Methods:A clinical randomized controlled trial was conducted in the historical severe KBD areas Fanrong Township, Fulu Town, Long'anqiao Town, Lianghe Town, Shaowen Township of Heilongjiang Province, and 240 patients were selected according to the criteria of "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010), then divided into GS and DCN groups (gender, age, and KBD condition balanced) via the random number table method, with 120 patients in each group. Followed up once a month to investigate the patient's medication and clinical symptoms, and distributed drugs for the next stage. Fasting blood samples and urine samples were collected before, during, and at the end of treatment (0, 90, and 180 days). Enzyme-linked immunosorbent assay (ELISA) was used to detect the serum interleukin (IL)-1β level and urine pyridinol (PYD) level. Visual analog scale (VAS) scores, evaluation of affected joints, self-evaluated efficacy, and evaluation of adverse reactions were carried out through questionnaires. Joint dysfunction scores and medications efficacy determination were performed according to the "Judgment of Kaschin-Beck Disease Treatment Effect" (WS/T 79-2011).Results:Expression of cytokines related to cartilage metabolism: after 180 days of treatment, serum IL-1β levels, urine PYD levels in GS group and urine PYD levels in DCN group were lower than those in the same group at 0 day of treatment ( Z = - 2.332, - 5.420, - 5.204, P < 0.05). VAS scores: after 90 days of treatment, the pain, stiffness scores of patients in GS group and the pain, stiffness, and function scores in DCN group were lower than those in the same group at 0 day of treatment ( Z = - 2.612, - 2.359, - 3.637, - 2.881, - 2.238, P < 0.05); after 180 days of treatment, the pain, stiffness and function scores of patients in GS and DCN groups were significantly lower than those of the same group at 0 day of treatment ( Z = - 6.738, - 9.530, - 7.781, - 5.428, - 3.761, - 3.587, P < 0.01). Evaluation of affected joints: after 90 and 180 days of treatment, except for pain of weather changes in DCN group, the scores of symptomatic joints in the two groups were lower than those at 0 day of treatment ( P < 0.05). Efficacy self-evaluation: after 180 days of treatment, the self-evaluated efficacy ratio of DCN group was higher than that of GS group and the same group after 90 days of treatment (χ 2 = 4.165, 4.022, P < 0.05). Evaluation of adverse reactions: after 90 and 180 days of treatment, the main adverse reactions of patients in GS and DCN groups were gastrointestinal symptoms. Joint dysfunction scores: after 90 days of treatment, the sum of the effective rate and the markedly effective rate of GS group was higher than that of DCN group (χ 2 = 4.993 , P < 0.05); while after the 180 days of treatment, there was no significant difference between the two groups (χ 2 = 0.417 , P > 0.05). Conclusions:Both GS and DCN have a certain therapeutic effect on adult KBD and can improve clinical symptoms. The GS takes effect quickly, and long-term use can protect cartilage from inflammatory factors to a certain extent.
8.Effect of glucosamine sulfate, chondroitin sulfate and diacetarine on renal function in adult patients with Kashin-Beck disease
Qi ZHANG ; Haichun ZHOU ; Fang QI ; Silu CUI ; Yanhong CAO ; Zhe JIAO ; Ning LIU ; Jiaxin LI ; Xin ZHANG ; Jun YU
Chinese Journal of Endemiology 2021;40(11):866-870
Objective:To investigate the effects of glucosamine sulfate, chondroitin sulfate and diacetarine on urinary renal function indexes UREA, creatinine (CREA), urinary microprotein(mALB) and N-acetyl-β-D-glucosidase (NAG) in adult patients with Kashin-Beck disease.Methods:According to the criteria of "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010), adult patients with degrees Ⅰ and Ⅱ Kashin-Beck disease in Heilongjiang Province were selected in 2019. They were randomly divided into three treatment groups according to age, gender, disease classification and other condition by clinical randomized controlled trial, group A (glucosamine sulfate group), group B (chondroitin sulfate group) and group C (diacetarine group). Fasting mid-morning urine was collected at 0, 90 and 180 days of treatment. The levels of UREA, CREA, mALB and NAG were measured using an automatic biochemical analyzer. And the abnormal rates of the above indexes were analyzed.Results:At 0 day of treatment, there were 118, 99 and 116 people in the 3 groups, respectively; after 90 days of treatment, 115, 93 and 106 people remained in the 3 groups; after 180 days of treatment, 95, 80 and 93 people remained in the 3 groups. The results showed that there was no significant difference in the levels of UREA, CREA, NAG and mALB among the 3 groups at 0 and 180 days of treatment ( H = 0.055, 0.923, 0.276, 1.125, 1.635, 3.873, 1.045, 4.135, P > 0.05). After 90 days of treatment, there was no significant difference in CREA level among the 3 groups ( H = 1.719, P > 0.05), the levels of UREA and NAG in group C were higher than those in group B ( P < 0.05), and the level of mALB in group B was higher than that in group C ( P < 0.05). The comparison results of all indexes before and after treatment showed that after 90 days of treatment, the levels of mALB in the 3 groups were lower than those of 0 day ( Z = - 2.858, - 3.217, - 2.124, P < 0.05), the levels of NAG were higher than those of 0 day ( Z = - 3.700, - 2.222, - 4.672, P < 0.05); and the level of UREA in group C was higher than that of 0 day ( Z = - 2.393, P < 0.05). After 180 days of treatment, the levels of CREA in the 3 groups were higher than those of 0 day ( Z = - 5.853, - 6.984, - 6.255, P < 0.05), and the levels of mALB in the 3 groups were lower than those of 0 day ( Z = - 3.785, - 2.624, - 3.427, P < 0.05). The abnormal rates of CREA in the 3 groups after 180 days of treatment were higher than those of 0 and 90 days (χ 2 = 39.499, 37.707, 71.534, 57.959, 58.160, 55.129, P < 0.05). There was no significant difference in the abnormal rate of CREA between 0 day and 90 days of treatment (χ 2 = 0.004, 2.068, 0.053, P > 0.05). The abnormal rates of NAG in groups A and C after 90 days of treatment were higher than those of 0 day (χ 2 = 8.999, 11.227, P < 0.05). The abnormal rates of NAG in group C after 180 days of treatment was higher than that of 0 day (χ 2 = 5.006, P < 0.05). There was no significant difference in the abnormal rate of NAG between group A and group C after 90 days and 180 days of treatment (χ 2 = 1.976, 1.413, P > 0.05). The abnormal rates of mALB in groups A and B after 90 days and 180 days of treatment were lower than those of 0 day (χ 2 = 6.461, 8.881, 7.563, 4.999, P < 0.05), and there was no significant difference between 90 days of treatment and 180 days of treatment (χ 2 = 0.638, 0.013, P > 0.05). Conclusions:The effects of glucosamine sulfate, compound chondroitin sulfate and diacetarine on renal function of the patients are not significantly different after 180 days of medication, but the three drugs all have certain effects on CREA and NAG. Follow-up work should be done during drug treatment to closely monitor the changes of the two indicators.
9.Effects of glucosamine sulfate, chondroitin sulfate and diacerein on liver function in patients with Kashin-Beck disease
Fang QI ; Qi ZHANG ; Silu CUI ; Yanhong CAO ; Zhe JIAO ; Ning LIU ; Jiaxin LI ; Xin ZHANG ; Jun YU
Chinese Journal of Endemiology 2022;41(12):1008-1012
Objective:To investigate the effects of glucosamine sulfate, chondroitin sulfate and diacerein on liver function in patients with Kashin-Beck disease.Methods:According to the criteria of "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010), 333 cases of Kashin-Beck disease were selected from the disease severely affected areas, and randomly divided into 3 groups according to the matching principle of age, gender and disease grading: glucosamine sulfate group (group A, 118 cases), chondroitin sulfate group (group B, 99 cases) and diacerein group (group C, 116 cases), and the patients in each group were treated for 180 days. Fasting venous blood samples were collected from the patients in the three groups at 0, 90 and 180 days after treatment. Serum was separated. The biochemical analyzer was used to determine the serum levels of albumin (ALB), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBIL), glutamyl transpeptidase (GGT), total bilirubin (TBIL), and total protein (TP) of the three groups of patients.Results:There was no difference in the expression levels of 8 liver function indexes between the groups on day 0 of treatment ( P > 0.05). After 90 days of treatment, the expression level of GGT in group B was higher than that in group A ( P < 0.05); compared with 0 day of treatment, ALB levels of groups A, B and C were all decreased, ALP and TBIL levels increased ( P < 0.05), the abnormal expression rate of ALB index decreased in all the three groups ( P < 0.001), the abnormal expression rate of TBIL index in group A was decreased ( P = 0.006). After 180 days of treatment, ALB level of group B was higher than that of group A, ALP level of group B was higher than that of groups A and C, and AST level of group B was higher than that of group C ( P < 0.05); compared with 90 days of treatment, ALB levels of groups A, B and C were all increased, ALP, ALT and AST levels of groups A and C were decreased, GGT levels of groups B and C were decreased ( P < 0.05); compared with 0 day of treatment, the abnormal expression rate of ALB index increased in all the three groups at 180 days of treatment ( P < 0.001), and the abnormal expression rate of ALP index decreased in group C ( P = 0.031). Conclusion:The liver function indicators ALB, ALP and TBIL should be monitored when taking the three oral drugs for a short time, especially the GGT, ALP and AST indicators when taking chondroitin sulfate for a long time.
10.Summary report of a national survey of Kashin-Beck disease prevalence in 2020
Silu CUI ; Junrui PEI ; Zhe JIAO ; Qing DENG ; Ning LIU ; Yanhong CAO ; Jun YU
Chinese Journal of Endemiology 2023;42(6):488-492
Objective:To investigate the dynamic prevalence of Kashin-Beck disease (KBD) in 2020, and to provide the basis for assessment of KBD control and elimination.Methods:According to the "Kashin-Beck Disease Monitoring Plan (2019 Edition)", collection of basic information of endemic areas and children KBD examination were executed in all endemic areas from every endemic county (city, district, banner) of 13 endemic provinces. All children aged 7 - 12 years in endemic areas underwent clinical examination, X-ray examination was performed for clinically positive children. According to the criteria of "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010), KBD cases were diagnosed by both clinical examination and X-ray check.Results:In monitoring of 827 986 children of 7 - 12 years old, a total of 703 children with similar clinical signs of KBD were suspected positive cases. X-ray results showed that 703 children were normal, with no X-ray positive change, they were not children KBD cases.Conclusions:In 2020, no cases of Kashin-Beck disease are detected in children nationwide, and the condition of Kashin-Beck disease in children nationwide continues to be at a level of elimination.