Epidemiology of scrub typhus and influencing factors in Yunnan province, 2006-2013 / 中华流行病学杂志

Objective: To understand the epidemiological characteristics of scrub typhus and influencing factors in Yunnan province, and provide further information for the prevention and control of scrub typhus. Methods: Based on the incidence data of scrub typhus reported in Yunnan from 2006 to 2013, the epidemiological characteristics of scrub typhus were analyzed and related environmental factors were identified with panel negative binomial regression model. Results: A total of 8 980 scrub typhus cases were reported during 2006-2013 in Yunnan. The average annual incidence was 2.46/100 000, with an uptrend observed. Natural focus expansion was found, affecting 71.3% of the counties in 2013. The epidemic mainly occurred in summer and autumn with the incidence peak during July-October. The annual incidence was higher in females than in males. More cases occurred in children and farmers, the proportions of cases in farmers and pre-school aged children showed an obvious increase. Panel negative binomial regression model indicated that the transmission risk of scrub typhus was positive associated with monthly temperature and monthly relative humidity. Furthermore, an "U" pattern between the risk and the increased coverage of cropland and grassland as well as an "inverted-U" pattern between the risk and increased coverage of shrub were observed. Conclusion: It is necessary to strengthen the scrub typhus surveillance in warm and moist areas as well as the areas with high coverage of cropland and grassland in Yunnan, and the health education in children and farmers who are at high risk.

Association between DRD2 gene polymorphisms and the dosage used on methadone maintenance treatment program / 中华流行病学杂志

Objective: To investigate the association between three single nucleotide polymorphism (SNP) genes DRD2 (rs1800497, rs6275, and rs1799978) and the dosage used on methadone maintenance treatment (MMT). Methods: From the methadone maintenance treatment centers, 257 MMT patients were recruited to participate in a case-control study and divided into two groups-control groups under low dosage (n=89) and case (n=168) group with high dosage. Quanto software was used to estimate the sample size as 180. Information related to social-demographic status, history on drug use and medication were collected. And DRD2 SNPs were genotyped to explore the relationship between polymorphism of DRD2 gene and the dosage of methadone maintenance treatment. Results: Distributions of DRD2 rs6275 between different groups were significantly different. Patients carrying TC genotype needed lower dose of methadone when compared to the patients that carrying CC genotype counterparts (OR=0.338, 95% CI: 0.115-0.986). Patients that carrying C allele at rs6275 needed lower methadone dose than those that carrying genotype TT (OR=0.352, 95% CI: 0.127-0.975). Distributions of genotypes, alles in the other two SNPs (rs1800497, rs1799978) were not significantly different between groups under different dosages. Conclusion: DRD2 rs6275 was associated with dosage of methadone used for the MMT patients. However, no significant associations were found between rs1800497, rs1799978 and the dosage of methadone.

Spatial epidemiology plays an important role in control and prevention of diseases / 中华流行病学杂志

Spatial epidemiology is a new branch of epidemiology that aims to map the spatial distribution and characteristics as well as to explore the associated influencing factors of diseases by using the geographic information system and other spatial technologies. In recent years, with the rapid development of information-related modern technology, improvement of accessibility on health - related services, natural environment, social and economic big data etc., spatial epidemiology has made considerable progress in both theory and practice and played more important roles in the public health area of China.

Mosquitoes, midges and related arboviruses in southeast Sichuan province / 中华流行病学杂志

Objective: To investigate the distribution patterns of mosquitoes, midges and related arboviruses in Sichuan province. Methods: Blood-sucking insects were collected from houses and pens, using the ultraviolet lights. Mosquito samples were classified according to morphologic characteristics and then stored at liquid nitrogen. All samples were incubated with BHK-21 and C6/36 cells for virus isolation and then detected for their viral genes. Sequences of the virus were identified and analyzed by molecular biological software, such as BioEdit 7.0.5.3, MEGA 6.0. Results: In total, 17 019 mosquitoes from 3 genera and 4 species and 12 700 midges were collected from the southeast regions of Sichuan province in 2016 and 2017. Among them, 79.4% (13 519/17 019) belonged to Culex tritaeniorhynchus with 11.1% (1 897/17 019) as Armigeres subalbatus, 5.5% (930/17 019) were Anopheles sinensis and 4.0% (673/17 019) were Anopheles sinensis 3 virus strains that isolated from Culex tritaeniorhynchus were identified as typeⅠ Japanese encephalitis virus. Seven pools of mosquitoes isolated from Hejiang county were identified Japanese encephalitis virus gene positive through PCR amplification. With 4 pool midges were detected positive for Akabane virus through PCR gene amplification while midges samples didn't have virus isolates. Conclusions: Culex tritaeniorhynchus appeared the predominant species in the southeast regions of Sichuan. Japanese encephalitis virus transmitted by mosquitoes and Akabane virus by midges were prevalent in southeast Sichuan province.