Search

Leprosy is a disabling chronic infection, with insidious onset that often evades early detection. In order to detect new leprosy cases in a timely manner, we conducted surveillance visits in some difficult-to-reach mountain areas in South West China where the disease is still prevalent. Our data confirm that Chinese multibacillary (MB) leprosy patients have strong antibody responses against Mycobacterium leprae antigens ND-O-BSA and LID-1. Contacts of clinically diagnosed patients were then monitored at regular intervals by both physical examinations and the laboratory determination of antibody responses in sera collected during these examinations. Elevations in antibody titers indicated the onset of MB leprosy in one of the contacts, and diagnosis was subsequently confirmed on physical examination. Our data indicate that rising antibody titers can be used as a trigger for physical examination or increased monitoring of particular individuals in order to provide early leprosy diagnosis.

Objective: To explore the factors influencing the steady transmission of leprosy as indicated by new case detection rate in Qiubei county, Yunnan province, China despite the implementation of MDT for the last 25 years., Methods: Information related to case-finding was collected. ELISA and PCR were applied to detect anti-PGL-1 antibody in sera and Mycobacterium leprae in nasal secretions respectively, in leprosy patients, their household contacts and the general population. M. leprae by PCR was also detected from water in the highly endemic villages. VNTR typing was performed to explore the mode and chain of transmission of M. leprae., Results: Prior to 2001, the proportion of new cases detected from the examination of household contacts of leprosy patients was low (number, compared to), while the proportion of patients whose identification was delayed by more than 2 years, was high (number, compared to). Qualities of these two indicators has been improved, along with the improvement of leprosy control program since 2001, but the detection rates has been steady at 4-5/100 000 during 1986 - 2010. The PGL-1 seropositivity rate was 20% - 30% in general population, with the peak rate (30%) detected in the teenage population in the endemic villages. In addition to the fact that M. leprae was detected in nasal secretion from patients, their contacts and from water, the M. leprae VNTR genotypes were found to be highly similar between skin biopsy and nasal secretion in untreated cases. Families with multi-cases were clustered and located in the Northern part of the County, and the genotypes of M. leprae were identical within those families. The percentage of clusters was considerably higher in Northern rather than Southern parts of the County., Conclusion: Results from this molecular study demonstrated evidence that transmission of leprosy within the families and in the endemic-villages was severe. M. leprae were detected in waters from the endemic villages and others areas which might have a relation to the continued transmission of leprosy.

Objective: To investigate the incidence of welder's pneumoconiosis in container manufacturing industries in Guangdong province and present some preventive and curative strategy., Methods: Occupational epidemiology study methods were used to study the incidence of welder's pneumoconiosis in two container manufacturing enterprises (enterprise A and enterprise B)., Results: Before 2004, the rate of up-to-standard of weld fume concentration in the workplaces was relatively low (< or = 40%), and the maximum value of time weighted average (TWA) was 26.7 mg/m(3). After 2004, with the system of dust control, the rate of up-to-standard was 85% in the enterprise A. Of the 813 weld workers examined, 19 were diagnosed as welder's pneumoconiosis (stage I was 15, while I (+) was 4 ) and the incidence was 2.34% (19/813). The age of electric welders suffering from welder's pneumoconiosis and the duration of dust exposure were (33.45 + 4.64) and (8.04 + 1.97) years respectively. Chest radiographic examination showed mainly small round opacities "p". The value of MVV, FEF25%, FEF50% and FEF75% in lung function tests were significantly lower than those of the control group (P < 0.05 or P < 0.01)., Conclusion: The main features of welder's pneumoconiosis in container manufacturing industries are the short duration of dust exposure, and small round opacities "p" in the chest radiographs. Therefore, it should be the key point of the prevention and treatment of occupational diseases in this industry to control the harmful weld fume.

Objective: Multiple locus variable number-tandem repeat (VNTR) analysis (MLVA) had been proposed as a means of strain typing for tracking of source and studying the transmission chain of pathogens. However, empirical data for a defined population from scale and duration were lacking for studying the transmission chain of leprosy., Methods: MLVA on 7 VNTR loci was applied to the strain typing on prevalent Mycobacterium leprae isolates collected from Qiubei county, Yunnan province during 2002-2006 in the study on the relationship between geographic distribution and genotypes of M. leprae. The strain typing, combined with conventional epidemiological investigation was performed to trace the transmission chain., Results: (1) Phylogenetic analyses through application of PAUP 4.0, The M. leprae were grouped into A, B, C, D and E strains according to the allelic range 9, 11-13, 15-26 and > 26 on the GTA9 locus. The strains with 9 copies on GTA9 locus, was named A. (2) Genotypes of strains from the five multi-case families located at North and North-West parts were similar and belonged to A strains. VNTR patterns of intra-family were identical or similar but not identical inter-family. (3) Not only A cluster appeared higher proportion in total isolates but also distributes cluster, indicating ongoing transmission from recent findings., Conclusion: VNTR strain typing was suitable to trace the short chain of transmission in both small area and intra-families. Multi-case families might constitute epidemic foci and source of M. leprae in villages, causing the predominant strain or cluster which tends to be those identified in multi-case families and resulted in the spreading of leprosy. A long-term study was underway to reveal whether A strain was predominant strain and to observe the evolution of M. leprae in this spatially and temporally defined endemic population.

Objective: To understand the genotypic mapping of Mycobacterium leprae identified in China and to compare with those from other countries to select suitable alleles for epidemiological investigation in the transmission chain of leprosy., Methods: Various number of tandem repeat(VNTR) in genomic DNA of Mycobacterium leprae was used in the present genotyping study. 33 skin biopsies from Wenshan prefecture,Yunnan province and 17 from other parts of China were studied. DNA extracted from skin biopsies of leprosy patients was subjected to PCR followed by agarose gel analysis and DNA sequencing to determine the number of repeats., Results: Loci GGT-5,12-5,21-3 and 23-3 were as highly homogenous as 100%; The homogeneity of loci AC-8, 18-8, 27-5 and rpoT were 97%, 94%, 97% and 85% respectively. Loci GTA-9, AC-9 and 6-7 showed significant allelic diversity in isolates and the diversity of GTA-9 in Mycobacterium leprae isolated from China was also different from those identified other countries. We had subjected loci GTA-9 and the ten loci to phylogenetic tree analysis respectively., Conclusion: The present study revealed that the genotype of Mycobacterium leprae identified from China was close to the strains from the Philippines and India although a few loci were somehow differentiate. Locus 12-5 manifested as only 3 copies in China whereas 4-5 copies predominating in other countries. 12-5 locus might serve as a useful marker to diffrentiate Chinese strains from those in other countries. However, further study on the diversity of GTA-9 was needed in China. The molecular typing of Mycobacterium leprae from different geographic areas might be useful in studying the transmission of leprosy.

Objective: To assay and study the microwave leakage of 4 types of interphones., Methods: The radiation intensities of four types of 199 interphones were determined by the microwave leakage measure instrument of model ML-91 made in China., Results: The average intensities of microwave leakage at a distance of 5 cm from aerial part and other parts of interphones during launching [(1 316.0 +/- 144.3), (971.0 +/- 131.6) microW/cm(2) respectively] were significantly higher than during waiting [(14.4 +/- 5.3), (13.2 +/- 4.9) microW/cm(2) respectively] (P < 0.01). The average intensities of microwave leakage at a distance of 50 cm from different parts were (357.3 +/- 27.8) microW/cm(2). The daily average intensity of microwave leakage to which the head, chest and abdomen exposed was (945.5 +/- 447.1) microW.h/cm(2) in total, that exceeded the hygienic standard of microwave in China (400 microW.h/cm(2)), during the normal communication by interphones., Conclusion: The microwave leakage was higher during launching than during waiting, and was the highest at the aerial part of the interphones. The microwave radiation of most interphones was higher than the current national standard. It may lead to potential effects on the owner of interphone, so protection against it should be made.

Objective: To study the hazards of gem dusts and the epidemiological features of the occurrence of gem worker's silicosis (GWS)., Methods: Epidemiological investigation in a gem factory in Guangdong province was carried out., Results: The average dusts concentration in workshop was 2.3 mg/m(3), average free silica content was 94.64%. There were 47 patients diagnosed as silicosis. The prevalence of GWS was 4.58% (47/ 1,027). The age of patients suffering from silicosis and the duration of dust exposure were (27.04 +/- 3.25) years and (4.67 +/- 1.17) years respectively. Chest radiographic examination showed mainly small round opacities "q". The incidences of GWS complicated by pulmonary tuberculosis, spontaneous pneumothorax and pulmonary emphysema were 10.64%, 10.64%, 44.68% respectively., Conclusion: The hazards of gem dust to workers might be serious. Higher incidence, younger age suffered from silicosis, shorter duration of dust exposure, more complications, and poorer prognosis in gem workers appeared to be the main epidemiological features of GWS in Guangdong.