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Background Novel coronavirus disease 2019 (COVID-19) has become a global pandemic. This study aims to explore the relationship between key natural and social factors and the transmission of COVID-19 in China. Methods This study collected the number of confirmed cases of COVID-19 in 21 provinces and cities in China as of February 28, 2020. Three provinces were included in the sample: Hainan, Guizhou, and Qinghai. The 18 cities included Shanghai, Tianjin and so on. Key natural factors comprised monthly average temperatures in the January and February 2020 and spatial location as determined by longitude and latitude. Social factors were population density, Gross Domestic Product (GDP), number of medical institutions and health practitioners; as well as the per capita values for GDP, medical institutions, and health practitioners. Excel was used to collate the data and draw the temporal and spatial distribution map of the prevalence rate (PR) and the proportion of local infection (PLI). The influencing factors were analyzed by SPSS 21.0 statistical software, and the relationship between the dependent and independent variables was simulated by 11 models. Finally, we choose the exponential model according to the value of R2 and the applicability of the model. Results The temporal and spatial distribution of the PR varies across the 21 provinces and cities identified. The PR generally decreases with distance from Hubei, except in the case of Shenzhen City, where the converse is observed. The results of the exponential model simulation show that the monthly minimum, median, and maximum average temperatures in January and February, and the latitude and population density are significant and thus will affect the PLI. The corresponding values of R2 are 0.297, 0.322, 0.349, 0.290, 0.314, 0.339, 0.344, and 0.301. The effects of other factors were not statistically significant. Conclusions Among the selected key natural and social factors, higher temperatures may decrease the transmission of COVID-19. From this analysis, it is evident that if the temperature decreases by 1℃, the average PLI increases by 0.01. Further, it was established that locations at more northern latitudes had a higher PLI, and population density showed an inverse relationship with PLI.

Background: A novel coronavirus (SARS-CoV-2) has spread widely and led to high disease burden around the world. This study aimed to explore key parameters of SARS-CoV-2 infection and to assess the effectiveness of interventions to control the coronavirus disease 2019 (COVID-19).Methods: A susceptible – exposed – infectious – asymptomatic – recovered (SEIAR) model was developed for the assessment. Data of symptomatic and asymptomatic infection of SARS-CoV-2 were collected to calculate the key parameters of the model in Ningbo City, China.Results: A total of 157 confirmed COVID-19 cases (including 51 imported cases and 106 secondary cases) and 30 asymptomatic infections were reported in Ningbo City. The proportion of asymptomatic has an increasing trend. The proportion of asymptomatic of elder people was lower than younger people, and the difference was statistical significant (Fisher’s Exact Test, P = 0.034). There were 22 clusters associated with 167 SARS-CoV-2 infections, among which 29 cases were asymptomatic, with a proportion of 17.37%. We found that the secondary attack rate of asymptomatic was almost the same as that of symptomatic cases, and no significance was observed (χ2 = 1.350, P = 0.245) by Kruskal-Wallis test. The effective reproduction number (Reff) was 1.43 which revealed that the transmissibility of SARS-CoV-2 was moderate. If the interventions were not strengthened, the duration of the outbreak would last about 16 months with a simulated attack rate of 44.15%. The total attack rate and duration of the outbreak would increase along with the increasing delay of intervention.Conclusions: SARS-CoV-2 had moderate transmissibility in Ningbo City, China. Asymptomatic infection has the same transmissibility as symptomatic. The integrated interventions were implemented at different stages during the outbreak, which found to be exceedingly effective in China.

Background In this study, we aimed to quantify the contribution of different transmission routes of the Middle East respiratory syndrome (MERS) and determine its transmissibility. Methods Based on the natural history and transmission features of MERS in different countries, a susceptible-exposed-symptomatic-asymptomatic-recovered/death (SEIARD) model and a multi-route dynamic model (MMDM). The SEIARD model and MMDM were adopted to simulate MERS in South Korea and Saudi Arabia, respectively. Data on reported MERS cases in the two countries were obtained from the World Health Organization. Thereafter, the next generation matrix method was employed to derive the equation for the basic reproduction number (R0), and the model fitting procedure was adopted to calculate the R0 values corresponding to these different countries. Results In South Korea, ‘Person-to-Person’ transmission was identified as the main mode of MERS transmission in healthcare settings, while in Saudi Arabia, in addition to ‘Person-to-Person’ transmission, ‘Host-to-Host’ and ‘Host-to-Person’ transmission also occurred under certain scenarios, with camels being the main host. Further, the fitting results showed that the SEIARD model and MMDM fitted the data well. The mean R0 value was 8.59 (95% confidence interval [CI]: 0–28.02) for MERS in South Korea, and for MERS in Saudi Arabia, it was 1.15 and 1.02 (95% CI: 0.86–1.44) for the ‘Person-to-Person’ and ‘Camel-to-Camel’ transmission routes, respectively. Conclusions The SEIARD and MMDM model can be used to simulate the transmission of MERS in different countries. Additionally, in Saudi Arabia, the transmissibility of MERS was almost the same among hosts (camels) and humans.

The exhaust device of gas-driven fan propulsion system (for a VTOL aircraft) adopts vector exhaust guide vane (VEGV) to achieve vector thrust in the range of 0-90°, which requires that the deflection angle of the VEGV reach about ± 45 ∘ and the total pressure recovery coefficient above 0.985. Therefore, the exhaust device needs a wide-range and low-loss VEGV to ensure efficient operation of the propulsion system. And the key of this VEGV is to eliminate the separation of the suction side under large deflection angle. So, this paper designed a new type of VEGV that can meet the demands by reducing the inverse pressure gradient of the suction surface (one of the necessary conditions for two-dimensional separation). In order to realize this design process, the spectral method of small disturbance equation (SMSDE) for two-dimensional subsonic flow was developed. Then, two VEGVs were designed by the SMSDE and verified by numerical simulation with Reynolds number 106 and blade solidity 1.18. The results show that the two VEGVs eliminate the separation of suction side at inlet Mach number of 0.25 and blade stagger angle of 45°. And the VEGV with lateral blade guarantees this characteristic up to Mach 0.3. Besides, when the inlet Mach number is below 0.3, the VEGV with lateral blade can ensure that the total pressure recovery coefficient is greater than 0.985, the outlet area ratio is greater than 0.95 and the exhaust angle error is less than 3.5°. Finally, Experimental verification of the vector exhaust device using the VEGV with lateral blade was carried out. The results show that the new VEGV has a higher total pressure recovery coefficient and outlet area ratio than the traditional VIGV at large deflection angles.

Background: The optimal vaccination is an essential public health strategy to control the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aims to simulate the optimal vaccination strategy to control the virus epidemic by developing an age-specific model based on the transmission of coronavirus disease 2019 (COVID-19) in Wuhan City, China. Methods: An age-specific mathematical model based on the data of COVID-19 cases in Wuhan City from December 2, 2019 to March 16, 2020 was developed, with two scenarios for controlling transmission and reducing severity to estimate the effectiveness of SARS-CoV-2 vaccination strategy. Findings: Before the lockdown of the Wuhan City, the highest transmissibility of SARS-CoV-2 was among 14-44 years old (effective reproduction number, Reff = 4·28), followed by 14-44 to 45-64 years old (Reff = 2·61), and 14-44 to ≥ 65 years old (Reff = 1·69). We found that the first priority for controlling transmission should be to vaccinate nearly 90% individuals of 14-44 years old, followed by 90% individuals of 45-64 years old. However, the optimal vaccination strategy for reducing severity defined individuals ≥ 65 years old in vaccination priority groups, followed by 14-44 years old groups. Interpretation: The scenario analyses suggested that the optimal vaccination strategy aimed at controlling the transmission of COVID-19 might be to vaccinate about 90% of 15-44 years old individuals; while for reducing severity, the vaccination priority should focus on the older population. Furthermore, we also presented evidence about the heterogeneity of age-specific transmission and vaccination in different areas. Funding Statement: Bill & Melinda Gates Foundation, and the Science and Technology Program of Fujian Province. Declaration of Interests: The authors declare no competing interests.

Background: Three sub-types of coronavirus have led to pandemics: Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), and 2019 coronavirus disease ( COVID-19 ). This study aimed to investigate the transmissibility of MERS and compare it to SARS and COVID-19. Methods: The Susceptible-Exposed -Asymptomatic-Infectious-Recovered-Death (SEAIRD) model and the (Person)Susceptible-Exposed-Asymptomatic-Infectious-Recovered-Death - (Host)Susceptible-Exposed-Asymptomatic-Recovered (S1E1A1I1R1D1-S2E2A2R2) model was developed to fit the reported data obtained from the World Health Organization and calculate the basic reproduction number (R0) to evaluate the transmissibility of MERS. Findings: As for MERS in Republic of South Korea (RSK) , there is mainly ‘Person-to-Person’ transmission in healthcare settings, while in the Kingdom of Saudi Arabia (KSA), in addition to ‘Person-to-Person’ transmission, there is also ‘Host-to-Person’ transmission in some certain scenarios, where camel is considered as the Host. The results of our model show that the mean value of R0 was 8.59 (95% confidence interval [CI]: 0–28.02) for MERS in RSK. The R0 of MERS for ‘Person-to-Person’ and ‘Camel-to-Camel’ transmission was 1.15 (95% CI: 0.86–1.44) and 1.02 in KSA, respectively. Interpretation: The transmissibility of MERS in RSK in 2015 was higher than those of SARS in 2003 and COVID-19 in 2019; however, the transmissibility of MERS in KSA was lower than that of above three diseases. R 0 of SARS was relatively stable, while MERS was more volatile that 2015 RSK epidemic was much higher than the Middle East region. Therefore, we should not only pay attention to the stability of SARS-CoV-2 epidemic in one country or region but also be wary of the variability of transmissibility, such as that observed for MERS-CoV, which may further increase the risk of another pandemic. Funding Statement: This study was supported by Science and Technology Program of Fujian Province (No: 2020Y0002) and Emergency Response Program of Xiamen City for prevention and treatment of SARS-CoV-2 (No: 3502Z2020YJ03). Declaration of Interest: No conflicts of interest

Background: Novel coronavirus disease 2019 (COVID-19) causes an immense disease burden. Only drugs or vaccines can eliminate the virus. Methods: We adopted our age-specific transmission model by susceptible-exposed-infectious -critically ill-asymptomatic-removed (SEICAR) model. Effects of different drug types were simulated by changing transmission rate (β), critical case fatality rate (fc), and disease duration of each age group. Evaluation indexes were based on outbreak duration(OD), cumulative number of cases(CNC), total attack rate(TAR), peak date(PD), number of peak cases(NPC), and case fatality rate(f). Findings: When without intervention, changing in β and disease duration, as the age increased, OD decreased, TAR increased, PD advanced, CCN and NPC initially increased and then decreased, while f decreased first and then increased. When disease duration and β remained unchanged, changing fc did not affect the epidemic. All age groups had 40% shorter disease duration but unchanged fc, while β was reduced by 60%, which reduced TAR of group 1 (≤14 years) from 2·35% to 0·09%; f of group 4 (≥65 years) was reduced from 1·04% to 0·05%. Interpretation: Drugs had different age-dependent effects. If a drug can control the disease duration or β of all age groups, younger people would have the fastest transmission control and seniors will have the best improvement in disease severity. Funding: The Bill & Melinda Gates Foundation (INV-005834); the Science and Technology Program of Fujian Province (No: 2020Y0002), and the Xiamen New Coronavirus Prevention and Control Emergency Tackling Special Topic Program (No: 3502Z2020YJ03). Declaration of Interests: The authors declare no competing interests.

Tsutsugamushi disease (TD) is an acute infectious disease caused by Orientia tsutsugamushi. This study aimed to analyze the epidemiological features of TD, investigate chigger mites and their hosts, and investigate the meteorological factors affecting TD incidence and the host of O. tsutsugamushi in Xiamen city, China. Data on reported TD cases were collected from 2006 to 2018. Spearman’s correlation test were used for identifying the relationship between meteorological factors and TD incidence and whether meteorological factors affect the host of O. tsutsugamushi. The incidence of reported TD increased gradually from 2006, reached a peak of 4.59 per 100,000 persons in 2014, and then decreased gradually. The TD incidence was seasonal, with epidemic periods occurred mainly in summer and autumn. Patients aged 40–60 years had the highest proportion of cases, accounting for 44.44% of the total cases. Farmers had the largest number of cases among all occupational groups. Rattus Norvegicus was the most common host, accounting for the largest proportion of rats (73.00%), and the highest rat density was observed in March and October every year. There were significant positive correlations between the number of reported cases and average temperature, sunshine duration, and rainfall as well as between rat density and average temperature. On phylogenetic analysis, 7 sequences of hosts and human TD cases obtained from health records demonstrated the highest similarities to the Kato, Karp, and Gilliam strains. No correlations were observed between rat density, and sunshine duration and rainfall. The transmission of TD in Xiamen city, China, was seasonal, and its incidence was affected by several meteorological factors including average temperature, sunshine duration, and rainfall. However, the host of O. tsutsugamushi was only affected by average temperature., Author summary Tsutsugamushi disease (TD) is a natural focal disease caused by Orientia tsutsugamushi, which is widespread in some areas. The incidence of TD is greatly influenced by meteorological factors. Therefore, it is essential to analyze the epidemiological features of TD, investigate chigger mites and their hosts, and explore the relationship between meteorological factors and TD incidence and whether meteorological factors affect the host of O. tsutsugamushi in Xiamen city, China. The results showed significant positive correlations between the number of reported cases and average temperature, sunshine duration, and rainfall. A positive correlation between rat density and average temperature. No correlations were observed between the rat density and sunshine duration and rainfall. We believe our findings may provide scientific basis for studies or health strategies conducted in areas that are meteorologically similar in characteristics with Xiamen city, China.

Cotton fabric (CF) is commonly used in wound treatment, however, its hemostatic efficiency is far from sufficient. In this study, modified cotton fabric (MCF-0.39) was obtained by a carboxymethylation process, which endowed MCF-0.39 with good swelling ability and water absorption capacity. Chitosan (CHI) was bound to MCF-0.39 by the binder sodium carboxymethyl cellulose (NaCMC) via flat-screen printing technique to prepare the hybrid hemostatic material (CHI-MCF-0.39). The blood clotting index (BCI) of CHI-MCF-0.39 was 3.15-fold lower than that of CF, demonstrating the good clotting ability of the material. In rat liver injury and femoral artery animal model, the groups using CHI-MCF-0.39 had less hemostasis time and blood loss compared with those groups using CF. All the above results indicate that the prepared CHI-MCF-0.39 has promising future applications as effective hemostatic material in trauma treatment.

Background Reversible splenial lesion syndrome (RESLES) is a disorder radiologically characterized by reversible lesion in the splenium of the corpus callosum (SCC). Most of patients with RESLES associated with encephalitis/encephalopathy were identified in Japanese population, but almost no Chinese patients were diagnosed as RESLES associated with encephalitis/encephalopathy. Methods Possible patients with reversible isolated SCC lesions were retrieved from January 2012 to July 2015 using keyword “restricted diffusion and isolated SCC lesion” in MRI report system from a large academic center. The clinical, laboratory and radiological data were summarized. Results A total of 15 encephalitis/encephalopathy patients (9 males and 6 females) were identified with a reversible isolated SCC lesion. Except for 13 patients with fever symptom, 8 patients also had cold symptoms before the onset of neurological symptoms. The neurological symptoms included headache, vertigo, seizure, disturbance of consciousness, and delirious behavior. Thirteen patients completely recovered within 1 month, but 2 patients who were subjected to mechanical ventilation had persistent neurological deficits. The initial MRI features showed isolated ovoid or extending SCC lesions with homogeneous hyperintense on diffusion weighted imaging (DWI) and decreased apparent diffusion coefficient (ADC) values. The follow-up MRI revealed that isolated SCC lesions with diffuse restriction disappeared at 10 to 32 days after the initial MRI study. Fractional anisotropy map revealed the decreased value of SCC lesion in a severe case with poor prognosis. Conclusions RESLES associated with encephalitis/encephalopathy is a reversible syndrome with an excellent prognosis in most patients, while a few patients required ventilator supporting at the early stage might have severe neurological sequelae. Reversible signal changes on DWI and ADC are identified in all patients, but fractional anisotropy values can be decreased in severe patient with neurological sequelae. Electronic supplementary material The online version of this article (doi:10.1186/s12883-016-0572-9) contains supplementary material, which is available to authorized users.

Reversible splenial lesion syndrome associated with encephalitis/encephalopathy presenting with great clinical heterogeneity. (52 kb)

Background Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) is an autosomal recessive inherited disease of metabolic dysfunction clinically characterized by fluctuating proximal muscle weakness, excise intolerance, and dramatic riboflavin responsiveness. Dropped head syndrome can occasionally be observed in some severe patients with late-onset MADD; however, bent spine syndrome as an initial symptom had not been reported in patients with late-onset MADD. Case presentation A 46-year-old man lost the ability to hold his trunk upright, and had difficulty in raising his head, but he had no obvious symptoms of limb weakness. Meanwhile, he developed persistent numbness of limbs and lips around. Myopathological features and combined elevation of multiple acylcarnitines indicated that the axial myopathy might be caused by lipid storage myopathy. Cervical and lumbosacral MRI revealed a lot of abnormal signals diffusing along paravertebral muscles, while the abnormal signals almost disappeared after riboflavin treatment. Nerve conduction study indicated the patient suffering from predominantly sensory neuropathy and mildly motor neuropathy. Muscle pathology also demonstrated no typical neurogenic change, which was consistent with the electrophysiological findings. Causative mutations were found in the ETFDH gene. Conclusion We report the first case of late-onset MADD with sensory neuropathy initially manifesting as bent spine syndrome and dropped head syndrome.

This study was conducted to compare the safety of soybean meal prepared from genetically modified (GM) glyphosate-tolerant (Roundup Ready; RR) soybeans and conventional soybeans. Eighty Sprague-Dawley rats (40 males and 40 females) were randomly allotted to one of four groups according to sex and body weight for a 13-week feeding experiment. The rats were fed corn-based diets containing 60% conventional soybean meal, a mixture of 30% conventional and 30% RR soybean meal, 60% or 90% RR soybean meal. All diets were adjusted to an identical nutrient level except the 90% RR diet. The two soybean meals were similar in chemical analysis and amino acid composition. During the 13-week growth trial, body weight (P < 0.05) and feed intake (P < 0.05) decreased only in rats fed with 90% RR soybean meal at the first week. No treatment-related deaths occurred during the experiment. Gross necropsy findings, haematological or urinalysis values and clinical serum parameters showed no meaningful differences between rats fed the control and RR soybean meals. A 145 bp of cp4 epsps gene specific for the GM constructs from RR soybean meal or a 407 bp of lec gene from endogenous soybean DNA could not be detected in investigated masseter muscle samples. No adverse effects of glyphosate-tolerant soybean meal on rats were seen even at levels as high as 90% of the diet.

Objective: An open-label clinical trail was designed to observe the efficacy of domestic Adefovir dipivoxil (AGD, Fujian Cosunter Pharmaceutical Co, LTD) monotherapy for naive patients with chronic hepatitis B (CHB). Methods: Patients with CHB or HBV-related compensated cirrhosis were enrolled from 4 medical centers in Fujian province. Each patient was treated with AGD 10mg daily. Alanine aminotransferase (ALT), HBVDNA and HBeAg levels were followed up to evaluate AGD efficacy. Results: A total of 114patients with complete medical records were enrolled in this study. In this group, average age was 37±12 years, 88 (77.2%) were male patients. The mean ALT value is 252±261U/L, the mean HBVDNA value is 6.4±1.6 log10 copies/ml, and 66 patients were HBeAg positive. After taking AGD for 48 weeks, the HBVDNA negative rate at 24 and 48 week was 54.6% (59/108) and 69.0% (60/87), respectively. In the sub-group of HBeAgpositive patients, HBeAg seroconversion rate at 24 and 48 week was 25.8% (17/66) and 36.4% (24/66), respectively. One patient with HBeAg-positive CHB achieved HBsAg seroconversion at 48 weeks. Conclusions: In patients with CHB or compensated cirrhosis taking domestic AVD (AGD) 48 weeks, the HBVDNA negative rate could reach 25.8%, and HBeAg seroconversion rate was 36.4%. Although these data was an open-label trial without control, the primary result is encouraging at the higher HBeAg seroconversion rate after AGD monotherapy. Further follow-up is still being done.

Background Primary diffuse leptomeningeal gliomatosis (PDLG) is a lethal neoplasm that is characterized by glioma cells exclusively infiltrating into cerebral and spinal meninges. Intraventricular hemorrhage as an initial symptom in PDLG patient has not been reported in the literatures. Case presentation A 39-year-old man initially presented with intraventricular hemorrhage. The patient had an improved outcome at the early stage of hemorrhagic course; however, the clinical condition began to a sudden turn for deterioration with intracranial hypertension and cerebral hernia on day 15 after admission. Cerebral CT and MRI showed diffuse patchy signals with enhancement in bilateral cerebellopontine angle cistern, suprasellar cistern, ambient cistern, quadrigeminal cistern, bilateral cerebellum, cerebral hemisphere, and upper cervical cord surface. Pathological examination revealed that numerous spindled cells were scant of cytoplasm with hyperchromatic nuclei and various mitotic figures. Immunohistochemistry showed that the cells were positive to glial fibrillary acidic protein (GFAP) with about 5 % Ki-67 positive labeling. The pathological findings were consistent with the diagnostic criteria of anaplastic astrocytoma (WHO grade III). Conclusion We reported an interesting case that PDLG initially presented with intraventricular hemorrhage that might be caused by astrocytoma rupturing into pial vessels. Electronic supplementary material The online version of this article (doi:10.1186/s12883-015-0341-1) contains supplementary material, which is available to authorized users.