Model-based risk assessment of dengue fever transmission in Xiamen City, China.

Background: Quantitative assessment of the risk of local transmission from imported dengue cases makes a great challenge to the development of public health in China. The purpose of this study is to observe the risk of mosquito-borne transmission in Xiamen City through ecological and insecticide resistance monitoring. Quantitative evaluation of mosquito insecticide resistance, community population and the number of imported cases affecting the transmission of dengue fever (DF) in Xiamen was carried out based on transmission dynamics model, so as to reveal the correlation between key risk factors and DF transmission. Methods: Based on the dynamics model and combined with the epidemiological characteristics of DF in Xiamen City, a transmission dynamics model was built to simulate the secondary cases caused by imported cases to evaluate the transmission risk of DF, and to explore the influence of mosquito insecticide resistance, community population and imported cases on the epidemic situation of DF in Xiamen City. Results: For the transmission model of DF, when the community population is between 10,000 and 25,000, changing the number of imported DF cases and the mortality rate of mosquitoes will have an impact on the spread of indigenous DF cases, however, changing the birth rate of mosquitoes did not gain more effect on the spread of local DF transmission. Conclusions: Through the quantitative evaluation of the model, this study determined that the mosquito resistance index has an important influence on the local transmission of dengue fever caused by imported cases in Xiamen, and the Brayton index can also affect the local transmission of the disease.

Impact of public health and social measures on contact dynamics during a SARS-CoV-2 Omicron variant outbreak in Quanzhou, China, March to April 2022.

OBJECTIVES: To evaluate the impact of early implementation of public health and social measures (PHSMs) on contact rates over time and explore contact behavior of asymptomatic versus symptomatic cases. METHODS: We used the largest contact tracing data in China thus far to estimate the mean contacts over time by age groups and contact settings. We used bootstrap with replacement to quantify the uncertainty of contact matrixes. The Pearson correlation was performed to demonstrate the number of contacts over time in relation to the evolution of restrictions. In addition, we analyzed the index cases with a high number of contacts and index cases that produced a high number of secondary cases. RESULTS: Rapidly adapted PHSMs can reduce the mean contact rates in public places while increasing the mean contact rates within households. The mean contact rates were 11.81 (95% confidence interval, 11.61-12.01) for asymptomatic (at the time of investigation) cases and 6.70 (95% confidence interval, 6.54-6.87) for symptomatic cases. The percentage of asymptomatic cases (at the time of investigation) meeting >50 close contacts make up more than 65% of the overall cases. The percentage of asymptomatic cases producing >10 secondary cases account for more than 80% of the overall cases. CONCLUSION: PHSMs may increase the contacts within the household, necessitating the need for pertinent prevention strategies at home. Asymptomatic cases can contribute significantly to Omicron transmission. By making asymptomatic people aware that they are already contagious, hence limiting their social contacts, it is possible to lower the transmission risk.

Inactivated vaccine effectiveness against symptomatic COVID-19 in Fujian, China during the Omicron BA.2 outbreak.

Objective: More than 90% of the Chinese population have completed 2 doses of inactivated COVID-19 vaccines in Mainland China. However, after China government abandoned strict control measures, many breakthrough infections appeared, and vaccine effectiveness against Omicron BA.2 infection was uncertain. This study aims to investigate the real-world effectiveness of widely used inactivated vaccines during the wave of Omicron variants. Methods: Test-negative case-control study was conducted in this study to analyze the vaccine effectiveness against symptomatic disease caused by the Omicron variant (BA.2) in Fujian, China. Conditional logistic regression was selected to estimate the vaccine effectiveness. Results: The study found the vaccine effectiveness against symptomatic COVID-19 is 32.46% (95% CI, 8.08% to 50.37%) at 2 to 8 weeks, and 27.05% (95% CI, 1.23% to 46.12%) at 12 to 24 weeks after receiving booster doses of the inactivated vaccine. Notably, the 3-17 years group had higher vaccine effectiveness after 2 doses than the 18-64 years and over 65 years groups who received booster doses. Conclusion: Inactivated vaccines alone may not offer sufficient protection for all age groups before the summer of 2022. To enhance protection, other types of vaccines or bivalent vaccines should be considered.

Assessing the Impacts of Meteorological Factors on COVID-19 Pandemic Using Generalized Estimating Equations.

Background: Meteorological factors have been proven to affect pathogens; both the transmission routes and other intermediate. Many studies have worked on assessing how those meteorological factors would influence the transmissibility of COVID-19. In this study, we used generalized estimating equations to evaluate the impact of meteorological factors on Coronavirus disease 2019 (COVID-19) by using three outcome variables, which are transmissibility, incidence rate, and the number of reported cases. Methods: In this study, the data on the daily number of new cases and deaths of COVID-19 in 30 provinces and cities nationwide were obtained from the provincial and municipal health committees, while the data from 682 conventional weather stations in the selected provinces and cities were obtained from the website of the China Meteorological Administration. We built a Susceptible-Exposed-Symptomatic-Asymptomatic-Recovered/Removed (SEIAR) model to fit the data, then we calculated the transmissibility of COVID-19 using an indicator of the effective reproduction number (Reff ). To quantify the different impacts of meteorological factors on several outcome variables including transmissibility, incidence rate, and the number of reported cases of COVID-19, we collected panel data and used generalized estimating equations. We also explored whether there is a lag effect and the different times of meteorological factors on the three outcome variables. Results: Precipitation and wind speed had a negative effect on transmissibility, incidence rate, and the number of reported cases, while humidity had a positive effect on them. The higher the temperature, the lower the transmissibility. The temperature had a lag effect on the incidence rate, while the remaining five meteorological factors had immediate and lag effects on the incidence rate and the number of reported cases. Conclusion: Meteorological factors had similar effects on incidence rate and number of reported cases, but different effects on transmissibility. Temperature, relative humidity, precipitation, sunshine hours, and wind speed had immediate and lag effects on transmissibility, but with different lag times. An increase in temperature may first cause a decrease in virus transmissibility and then lead to a decrease in incidence rate. Also, the mechanism of the role of meteorological factors in the process of transmissibility to incidence rate needs to be further explored.

[Analysis of metabolites of 4,5-dicaffeoylquinic acid in rat plasma and urine based on LC-MS].

Ultra high performance liquid chromatography tandem high field orbital trap mass spectrometry(UPLC-Orbitrap Elite-MS/MS) method was applied in this paper to analyze the metabolites of 4,5-dicaffeoylquinic acid in rat plasma and urine after oral administration. A gradient elution was performed by using Thermo C_(18) column(2.1 mm×100 mm, 1.9 µm), with 0.1% formic acid solution-acetonitrile as the mobile phase. Mass spectral data of biological samples were collected in negative ion mode. The data were extracted by Compound Discovery 2.1 software. Then the blank group samples and the drug samples were compared for exact molecular weight and the mass fragmentation information, and the secondary fragment fitting ratio was calculated to finally attribute the metabolites. As a result, 15 metabolites were detected in rat plasma, and 16 metabolites were detected in urine. The involving metabolic reactions included methylation, hydration, dehydration, reduction, glucuronide conjugation, and sulfation reaction. The metabolites in plasma and urine complemented each other and initially revealed the migration and excretion patterns of this compound in the body. A method for pre-processing biological samples, high-resolution LC-MS instrumentation data, and qualitative software was established in this study to identify metabolite structures, laying the foundation for the study of the active ingredients and in vivo pharmacodynamics forms of Chinese medicines.

[Effect of the folic acid and vitamin B2 on the diabetes mellitus rats with diabetic nephropathy].

OBJECTIVE: To explore the relationship among the folic acid, vitamin B12 and diabetic nephropathy and to discuss the mechanism of the diabetic microangiopathy. METHODS: We selected 80 SD rats, and then divided them into 2 groups randomly. Those were the control group and the model groups. During the process of this study, the control group was fed with the normal animal feeds; the model groups were fed with the high calorie diets for 10 weeks. At the end of the tenth week, the rats of the model group were induced to diabetes mellitus by intraperitoneal injection with streptozocin 30mg/kg, and then we divided the diabetes mellitus rats into 4 groups which measured the levels of the blood fat (total cholesterin, triglyceride), Fins, FBG, SOD, MDA, GSH-Px. Results (1) Through feeding the rats with the special feeds for a long time, and then injecting with streptozocin can make them develop to be the diabetes mellitus. The model groups' levels of the triglyceride, the cholesterin and the random blood glucose were (1.07 +/- 0.27), (2.29 +/- 0.42), (21.12 +/- 4.21) mmol/L, respectively, those were significantly higher than the control group's levels which were (1.11 +/- 0.20), (0.68 +/- 0.11), (5.73 +/- 0.26) mmol/L (P < 0.05). (2) After given different interference, for the group of the diabetes mellitus rats that without fed with vitamin B12 and folic acid, the degree of the pathological change of kidney tissue was the most serious through the method of periodic acid-Schiff' s staining (PAS), and the level of the MDA was also highest (P < 0.05), the level of the GSH-Px was lowest (P < 0.05) during the all groups. What' s more, both of the folic acid and the vitamin B12 could reduce the increase of the 24hours urinary albumin, especially using the folic acid and the vitamin B12 together. CONCLUSION: Using the special feeds to feed the SD rats for ten weeks and then inject STZ (30 mg/kg) from abdominal cavity can make them develop to be the diabetes mellitus. The supplement with folic acid and vitamin B12 had the effect of protecting the capillary of the kidney from damage, and the mechanism may have something to do with the effect of anti-oxygenation.

[Study on the public health emergent events in Fujian province in 2004--2007].

OBJECTIVE: To study the public health emergent events (PHEE) in Fujian province, from 2004 to 2007. METHODS: Descriptive and analytic methods were used to analyze the PHEE in Fujian province according to the internet-based surveillance reports. RESULTS: From 2004 to 2007, there were 304 emergency events being surveyed. Of all the events, there were 7 (2.30%) belonged to serious-degree of grade II, 57(18.75%) to grade III and 240 (78.95%) to grade IV, but with no grade I. Results showed that the attack rate in affected population was 25.82 per thousand, the mortality rate was 0.08 per thousand and the fatality rate was 0.32%. The numbers of emergency events decreased 2.82% on average, each year. A total number of 169 (55.60%) events occurred in schools with 71 (23.36%) in the countryside. Numbers due to infectious disease-born was 233 (76.64%) including avian flu, cholera and dengue fever were predominant pathogens of the grade II and grade III emergency events. 57 (18.75%) of the events was due to food poisoning. The epi-garph showed that there were two peaks. i.e. in Mar-Apr and Sep, contributed 43.1% to the total number of events. CONCLUSION: Emergency events showed a stable decrease in Fujian province with communicable disease and food poisoning the two major sources and more commonly seen in schools and countryside. We suggest that the government and community pay more attention to the emergency events of avian flu, cholera and dengue fever.