Rattus tanezumi (R. tanezumi) is a major amplifying host for plague and an important reservoir host for multiple zoonotic pathogens, including leptospirosis and hantavirus. Its population dynamics in the Three Gorges Reservoir (TGR) Area of China are influenced by climate and reservoir-induced environmental changes, thereby impacting disease transmission risks. Based on rodent capture rate data collected using cage traps during night surveys in January, March, May, July, September, and November each year from 2015 to 2021, this study investigated the spatiotemporal dynamics of R. tanezumi and its association with key meteorological and environmental factors. Using Geographic Information Systems (GIS) for spatiotemporal analysis and a Generalized Additive Model (GAM), we identified the current month’s average temperature and relative humidity, together with 3-month-lagged precipitation and the Normalized Difference Vegetation Index (NDVI), as associated factors. The highest capture rate occurring at around 20 °C. Rat capture rate negatively correlated with both current relative humidity and lagged precipitation and a fluctuating decline with increasing lagged NDVI. This study demonstrates how climatic and environmental factors shape the spatiotemporal distribution of R. tanezumi population in the Three Gorges Reservoir Area. These findings provide insights that may inform predictions of rodent‑borne disease risks and support the development of targeted surveillance and control strategies in this ecologically vulnerable region.

INTRODUCTION:The gut microbiome plays a crucial role in health and disease. This study aims to investigate the composition, characteristics, and functional diversity of the intestinal microbiome by performing metagenomic sequencing on fecal samples from diarrheic and healthy Simmental cattle. RESULTS:This study compared the gut microbiome differences between two groups of Simmental cattle (5 diarrheic and 20 healthy) in Ningxia province, China. Metagenomic analysis revealed higher microbial heterogeneity in the diarrheic group, likely reflecting pathogen-driven ecological disruption, whereas the healthy group was dominated by butyrate-producing and fiber-degrading bacteria, maintaining intestinal homeostasis. Antibiotic resistance gene analysis detected glycopeptide resistance genes in both groups, but the healthy group also carried aminoglycoside/tetracycline resistance genes and poxtA. KEGG pathway analysis showed that the diarrheic group was enriched in purine synthesis-related pathways, while the healthy group exhibited dominant metabolic pathways such as glutamine synthase. Virulence factor analysis indicated that the diarrheic group had higher abundances of capsular polysaccharides and type IV secretion systems, potentially promoting bacterial colonization and immune evasion. In summary, diarrheic cattle harbored a gut microbiome dominated by opportunistic pathogens, accompanied by metabolic dysregulation and antimicrobial resistance risks, whereas healthy cattle maintained a microbial community rich in short-chain fatty acid producers. This study provides a theoretical foundation for gut microbiome modulation and antimicrobial resistance control in ruminants. CONCLUSION:This study revealed distinct gut microbiome composition and function between diarrheic and healthy cattle through sequencing analysis. The findings offer insights for ruminant diarrhea management and provide a basis for developing more scientific antibiotic management strategies in animal husbandry.

Rattus tanezumi ( R. tanezumi ), a major vector for plague, leptospirosis, and hantavirus, exhibits population dynamics in the Three Gorges Reservoir (TGR) Area of China that are influenced by climate and reservoir-induced environmental changes, thereby impacting disease transmission risks. This study investigated the spatiotemporal dynamics of R. tanezumi and its association with key meteorological and environmental factors from 2015 to 2021. Using Geographic Information Systems (GIS) for spatiotemporal analysis and a Generalized Additive Model (GAM), we identified the current month's average temperature and relative humidity, together with three-month-lagged precipitation and the Normalized Difference Vegetation Index (NDVI), as significant drivers. The relationship was modeled (Yi,t = α + s 1 (M0Avg_Temp) + s 2 (M0Avg_RHU) + s 3 (M3Precip) + s 4 (M3NDVI) + ε; R²= 0.12, Deviance explained = 14%, GCV = 0.4438), revealing an optimal proliferation temperature around 20°C. Density showed negative correlations with both current relative humidity and lagged precipitation, and a fluctuating decline with increasing lagged NDVI. As the first investigation of its kind, this study demonstrates how climatic and environmental factors shape the spatiotemporal distribution of R. tanezumi in the TGR Area, providing critical insights for predicting outbreaks and formulating targeted surveillance and control strategies against rodent-borne diseases in this vulnerable region.

Introduction Since November 2023, influenza has ranked first in reported cases of infectious diseases in China, with the outbreak in both northern and southern provinces exceeding the levels observed during the same period in 2022. This poses a serious health risk to the population. Therefore, short to medium-term influenza predictions are beneficial for epidemic assessment and can reduce the disease burden. Methods A transmission dynamics model considering population migration, encompassing susceptible-exposed-infectious-asymptomatic-recovered (SEIAR) was used to predict the dynamics of influenza before the Spring Festival travel rush. Results The overall epidemic shows a declining trend, with the peak expected to occur from week 47 in 2023 to week 1 in 2024. The number of cases of A (H3N2) is greater than that of influenza B, and the influenza situation is more severe in the southern provinces compared to the northern ones. Conclusion Our method is applicable for short-term and medium-term influenza predictions. As the spring festival travel rush approaches. Therefore, it is advisable to advocate for nonpharmaceutical interventions (NPIs), influenza vaccination, and other measures to reduce healthcare and public health burden.

This study aimed to investigate the epidemiological changes in scarlet fever before, during and after the COVID-19 pandemic (2005–2023) and predict the incidence of the disease in 2024 and 2025 in Chongqing Municipality, Southwest China. Descriptive analysis was used to summarize the characteristics of the scarlet fever epidemic. Spatial autocorrelation analysis was utilized to explore the distribution pattern of the disease, and the seasonal autoregressive integrated moving average (SARIMA) model was constructed to predict its incidence in 2024 and 2025. Between 2005 and 2023, 9,593 scarlet fever cases were reported in Chongqing, which resulted in an annual average incidence of 1.6694 per 100,000 people. Children aged 3–7 were the primary victims of this disease, with the highest average incidence found among children aged 6 (5.0002 per 100,000 people). Kindergarten children were the dominant infected population, accounting for as much as 54.32

What is already known about this topic? The World Health Organization (WHO) has reported a total of 48 cases by October 15, 2021. The continuous genomic reassortments of H5N6 and other subtype avian influenza viruses (AIVs) pose a long-term threat to public health and the poultry industry. What is added by this report? Three new cases of H5N6 that occurred from January to September 2021 in Chongqing Municipality, China were reported in this study. Epidemiological information of the three cases showed raising poultry and visiting live poultry market contributed to these infections, and there was no evidence of human-to-human transmission of H5N6 currently but a potential spatial cluster. An increase of H5N6 cases was recorded in the area. What are the implications for public health practice? In case of unexplained pneumonia or severe respiratory infection, the patients’ epidemiological history of contact with poultry or live poultry markets (LPMs) may be an important interrogation to help diagnose. Extensive and long-term surveillance of avian influenza viruses in LPMs is essential.

Until now, we have no thorough understanding the role of absolute humidity on influenza activity, especially in tropical and subtropical areas. In this study, we investigated the relationship between absolute humidity and influenza activity in seven municipalities/provinces covering different climatic zones in China. Weekly meteorological data and influenza surveillance data in seven provinces/municipalities in China were collected from January 2012 to December 2019. A distributed lag nonlinear model was adopted to investigate the association between absolute humidity (AH) and influenza activity in each study site. Then, seven study sites were grouped into three regions: northern, intermediate, and southernmost regions. A multivariate meta-analysis was applied to estimate the exposure-lag-response associations in three regions. The province-specific or municipality-specific curves appeared to be nonlinear, and the association between influenza activity and AH varied across regions. In Beijing and Tianjin, located in northern China, the cumulative relative risks (RRs) increased as weekly average AHmean fell below 3.41 g/m3 and 6.62 g/m3. In Guangdong and Hainan, located in southernmost China, the risk of influenza activity increased with rising average AHmean with 16.74 g/m3 and 20.18 g/m3 as the break points. In Shanghai, Zhejiang, and Chongqing, the relationship between weekly average AHmean and influenza could be described as U-shaped curves, with the lowest RRs when weekly average AHmean was 11.95 g/m3, 11.94 g/m3, and 15.96 g/m3, respectively. Meta-analysis results showed the cumulative RRs significantly increased as weekly average AHmean fell below 3.86 g/m3 in the northern region, whereas significantly increased as weekly average AHmean rose above 18.46 g/m3 and 15.22 g/m3 in intermediate and southernmost regions, respectively. Both low and high AH might increase influenza risk in China, and the relationship varies geographically. Our findings suggest that public health policies for climate change adaptation should be tailored to the local climate conditions.

(1) Background: To explore whether meteorological factors have an impact on the prevalence of mumps, and to make a short–term prediction of the case number of mumps in Chongqing. (2) Methods: K–means clustering algorithm was used to divide the monthly mumps cases of each year into the high and low case number clusters, and Student t–test was applied for difference analysis. The cross–correlation function (CCF) was used to evaluate the correlation between the meteorological factors and mumps, and an ARIMAX model was constructed by additionally incorporating meteorological factors as exogenous variables in the ARIMA model, and a short–term prediction was conducted for mumps in Chongqing, evaluated by MAE, RMSE. (3) Results: All the meteorological factors were significantly different (p < 0.05), except for the relative humidity between the high and low case number clusters. The CCF and ARIMAX model showed that monthly precipitation, temperature, relative humidity and wind velocity were associated with mumps, and there were significant lag effects. The ARIMAX model could accurately predict mumps in the short term, and the prediction errors (MAE, RMSE) were lower than those of the ARIMA model. (4) Conclusions: Meteorological factors can affect the occurrence of mumps, and the ARIMAX model can effectively predict the incidence trend of mumps in Chongqing, which can provide an early warning for relevant departments.

The incidence of scarlet fever has increased dramatically in recent years in Chongqing, China, but there has no effective method to forecast it. This study aimed to develop a forecasting model of the incidence of scarlet fever using a seasonal autoregressive integrated moving average (SARIMA) model. Monthly scarlet fever data between 2011 and 2019 in Chongqing, China were retrieved from the Notifiable Infectious Disease Surveillance System. From 2011 to 2019, a total of 5073 scarlet fever cases were reported in Chongqing, the male-to-female ratio was 1.44:1, children aged 3-9 years old accounted for 81.86% of the cases, while 42.70 and 42.58% of the reported cases were students and kindergarten children, respectively. The data from 2011 to 2018 were used to fit a SARIMA model and data in 2019 were used to validate the model. The normalised Bayesian information criterion (BIC), the coefficient of determination (R2) and the root mean squared error (RMSE) were used to evaluate the goodness-of-fit of the fitted model. The optimal SARIMA model was identified as (3, 1, 3) (3, 1, 0)12. The RMSE and mean absolute per cent error (MAPE) were used to assess the accuracy of the model. The RMSE and MAPE of the predicted values were 19.40 and 0.25 respectively, indicating that the predicted values matched the observed values reasonably well. Taken together, the SARIMA model could be employed to forecast scarlet fever incidence trend, providing support for scarlet fever control and prevention.

An outbreak of coronavirus disease 2019 (COVID-19) was reported in Yongchuan district of Chongqing, China in March 2022, while the source was unknown. We aimed to investigate the origin and transmission route of the virus in the outbreak. We conducted field investigations for all cases and collected their epidemiological and clinical data. We performed gene sequencing and phylogenetic analysis for the cases, and draw the epidemic curve and the case relationship chart to analyze interactions and possible transmission mode of the outbreak. A total of 11 cases of COVID-19, including 5 patients and 6 asymptomatic cases were laboratory-confirmed in the outbreak. The branch of the virus was Omicron BA.2 which was introduced into Yongchuan district by a traveler in early March. Patient F and asymptomatic case G had never contact with other positive-infected individuals, but close contact with their pet dog that sniffed the discarded cigarette butts and stepped on the sputum of patient B. Laboratory test results showed that the dog hair and kennel were positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the 10 isolates were highly homologous to an epidemic strain in a province of China. The investigation suggested that the contaminated dog by SARS-CoV-2 can act as a passive mechanical carrier of the virus and might transmit the virus to humans through close contact. Our findings suggest that during the COVID-19 pandemic, increasing hygiene measures and hand washing after close contact with pets is essential to minimize the risk of community spread of the virus.

目的 了解重庆市新型冠状病毒肺炎(COVID-19)聚集性疫情的流行特征,为改进防控措施提供依据.方法 采用2020年1月1日至3月14日重庆市卫生健康委员会官方网站、重庆市政府新闻发布、全国传染病监测信息系统、突发公共卫生事件信息系统调查报告和重庆市疾病预防控制中心COVID-19聚集性疫情调查报告,分析重庆市COVID-19聚集性疫情流行特征.结果 重庆市2020年1月1日至3月14日共报告COVID-19聚集性疫情120起,涉及感染者551例,其中确诊病例439例,占全市确诊病例数的76.2％ (439/576),无症状感染者112例,占全市无症状感染者的93.3％(112/120).以家庭聚集性疫情为主,占聚集性疫情总数的68.3％(82/120).高峰期在1月19日至2月6日.29个区县均有报告,占全市区县数量的74.3％(29/39).首发病例具有武汉及周边旅居史的聚集性疫情占79.2％(95/120).结论 重庆市COVID-19聚集性疫情以家庭聚集性疫情为主,首发病例的发病-诊断时间长于散发病例.

A systematic review and meta-analysis was conducted to estimate the pooled effect of influenza vaccinations for health workers (HWs). Nine databases were screened to identify randomized clinical trials and comparative observational studies that reported the effect of influenza vaccination among HWs. The risk ratio (RR), standardized mean difference, and 95% confidence interval (CI) were employed to study the effect size using fixed/random-effect models. Subgroup analyses and sensitivity analyses were conducted accordingly. Publication bias was examined. Sixteen studies (involving 7971 HWs from nine countries) were included after a comprehensive literature search. The combined RR regarding the incidence of laboratory-confirmed influenza was 0.36 (95% CI: 0.25 to 0.54), the incidence of influenza-like illness (ILI) was 0.69 (95% CI: 0.45 to 1.06), the absenteeism rate was 0.63 (95% CI: 0.46 to 0.86), and the integrated standardized mean difference of workdays lost was −0.18 (95% CI: −0.28 to −0.07) days/person. The subgroup analysis indicated that vaccination significantly decreases the incidence of laboratory-confirmed influenza in different countries, study populations, and average-age vaccinated groups. Influenza vaccinations could effectively reduce the incidence of laboratory-confirmed influenza, absenteeism rates, and workdays lost among HWs. It is advisable, therefore, to improve the coverage and increase the influenza vaccination count among HWs, which may benefit both workers and medical institutions.

ObjectiveTo understand the epidemiological characteristics of rabies in Chongqing in 2018 and provide evidence for the control and prevention of rabies. MethodsThe incidence data of rabies in Chongqing in 2018 were collected from national infectious disease reporting information management system, the data of case exposure and prophylaxis from the rabies investigation database of Chongqing, and the data of dogs biting events from national public health emergency management information system. Descriptive epidemiological methods were applied to analyze the epidemiological characteristics of rabies cases. ResultsA total of 18 rabies cases were reported in Chongqing in 2018, with a reported incidence of 0.06/100 000. The majority of the cases were people over 60 years old (61.11%) and farmers (88.89%). All the cases were from rural areas of suburb counties and districts. Two geographic epidemic clusters were identified in six districts and counties in western Chongqing and three districts and counties in northeastern Chongqing. Up to 94.44% of rabies cases were victims of dog bites or scratch, and 61.11% of the cases exposed to stray dogs. None of these cases received standard prophylaxis after rabies exposure. Up to 88.89% of the dog biting events occurred in rural areas and 18.52% of the dog biting events affected more than 10 people. ConclusionThe incidence of rabies in Chongqing continued to decline in 2018 and the areas affected by the epidemic further decreased. The disease mainly occurred in rural areas of several districts and counties in western and northeastern Chongqing. The most rabies affected population was the people over 60 years in rural areas. The rabies cases were mainly caused by dog biting, and the proportion caused by stray dog biting increased further, and all the cases received no substandard post-exposure prophylaxis.

目的 分析重庆市2014-2018年学校突发公共卫生事件特征,为有效处置学校突发公共卫生事件提供参考依据.方法 收集国家突发公共卫生事件报告管理信息系统所记录的重庆市2014-2018学校突发公共卫生事件信息,分析事件的流行特征.结果 2014-2018年,重庆市报告学校突发公共卫生事件共1 069起,发病31 725例,死亡1例;高峰出现在4-5月和11-12月;病种以水痘、手足口病、流行性腮腺炎、流行性感冒、诺如病毒感染为主,占96.54％;事件主要发生在小学和幼托机构,占85.13％;初次报告小于或等于10例的事件最终事件发展规模较初次报告大于10例的事件小(P＜0.001);不同发现方式的事件,其发现时间存在差异.结论 重庆市学校突发公共卫生事件以呼吸道传染病疫情为主,农村地区发现和防控能力较弱,应加强对学生身体状况的监测,早期识别学校突发公共卫生事件.

Background: To better understand the disease transmission pattern, a cluster of coronavirus disease 2019 (COVID-19) cases, with four generations of transmission, was investigated in Chongqing, China.Methods: The epidemiological and clinical data of infected cases and antibody testing of close contacts of the cluster were collected and evaluated. The attack rate, infection rate, incubation period, serial intervals, and IgM and IgG detection rates were reported.Findings: Between January 23 and March 2, 2020, there were 180 persons were involved and traced in the cluster with two imported cases. Among the 178 close contacts, there were 11 confirmed cases and 3 asymptomatic infections, which included mostly family members and work colleagues. The median incubation period of infection was 12 days (3-25 days). The median serial interval was 8 days (5 to 14 days). The infection rates of each generation were 21·9%, 6·5%, 3·3%, and 0%. Of the 118 close contacts tested for antibodies, 13 contacts (11·0%) had positive IgM or IgG or both positive.Interpretation: With each new generation of transmission, the infection rates progressively declined. The symptom onset of the secondary generation maybe earlier than the primary generation demonstrating that epidemiological investigation and tracing of close contacts of the cases is needed. The antibody test maybe a complementary method to identify lost infections demonstrating further nucleic acid test. Funding Statement: NoneDeclaration of Interests: The authors declare no competing interests.Ethics Approval Statement: The study was approved by the Ethics Committee of Chongqing Medical University.

PURPOSE:To estimate influenza-associated excess mortality rates (EMRs) in Chongqing from 2012 to 2018. METHODS:We obtained weekly mortality data for all-cause and four underlying causes of death (circulatory and respiratory disease (CRD), pneumonia and influenza (P&I), chronic obstructive pulmonary disease (COPD) and ischemic heart disease (IDH)), and influenza surveillance data, from 2012 to 2018. A negative-binomial regression model was used to estimate influenza-associated EMRs in two age groups (<65 years and ≥65 years). RESULTS:It was estimated that an annual average of 10025 influenza-associated deaths occurred in Chongqing, corresponding to 5.2% of all deaths. The average EMR for all-cause death associated with influenza was 33.5 (95% confidence interval (CI): 31.5-35.6) per 100 000 persons, and in separate cause-specific models we attributed 24.7 (95% CI: 23.3-26.0), 0.8 (95% CI: 0.7-0.8), 8.5 (95% CI: 8.1-9.0) and 5.0 (95% CI: 4.7-5.3) per 100 000 persons EMRs to CRD, P&I, COPD and IDH, respectively. The estimated EMR for influenza B virus was 20.6 (95% CI: 20.3-21.0), which was significantly higher than the rates of 5.3 (95% CI: 4.5-6.1) and 7.5 (95% CI: 6.7-8.3) for A(H3N2) and A(H1N1) pdm09 virus, respectively. The estimated EMR was 152.3 (95% CI: 136.1-168.4) for people aged ≥65 years, which was significantly higher than the rate for those aged <65 years (6.8, 95% CI: 6.3-7.2). CONCLUSIONS:Influenza was associated with substantial EMRs in Chongqing, especially among elderly people. Influenza B virus caused a relatively higher excess mortality impact compared with A(H1N1)pdm09 and A(H3N2). It is advisable to optimize future seasonal influenza vaccine reimbursement policy in Chongqing to curb disease burden.

The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 asymptomatic individuals in the Wanzhou District who were diagnosed with RT–PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People’s Hospital for centralized isolation in accordance with policy1. The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15–26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6–10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8–38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys. A cohort of asymptomatic patients infected with SARS-CoV-2 had significantly lower levels of virus-specific IgG antibodies compared to a cohort of age- and sex-matched symptomatic infected patients.

OBJECTIVE:To examine the association between absolute humidity (AH) and influenza and pneumonia (P&I) mortality, and to quantify P&I mortality burden attributable to non-optimum AHs among elderly people aged ≥65 years in Chongqing, the largest municipality of China. METHODS:Daily data of P&I mortality from 2012 to 2018, and the contemporaneous meteorological data in the study area were collected. Distributed lag non-linear model (DLNM) was applied to estimate the non-linear and delayed effects of absolute humidity (AH) on P&I mortality. Then, attributable deaths were calculated for the dry and moist AH, defined as AH below and above the minimum mortality AH (MMAH), respectively. Moderate and extreme AHs were defined using cutoffs at the 2.5th and 97.5th percentiles of AH. RESULTS:The relationship between AH and P&I mortality was a U-shaped curve. The MMAH was 11.5 g/m3 (46.4th percentile). In total, 25.7% (95% confidence interval: 10.0-38.2) of P&I mortality (4673 deaths) was attributed to non-optimum AHs. Low AHs were responsible for 12.7% of the P&I death burden (95%CI: 0.2-20.1), while high AHs for 13.0% (95%CI: -9.4-25.7). Extreme low and high AHs accounted for 3.7% (95%CI: 0.1-6.8) and 3.0% (95%CI: 0-5.4) of P&I mortality. CONCLUSIONS:Our study showed that both low AHs and high AHs are responsible for considerable AH-related P&I mortality burden among elderly people. Our results may have important public health implications for the development of relevant intervention policies to reduce P&I deaths among the elderly.

Objective:To analyze the infection condition of close contacts exposed to confirmed and asymptomatic patients with COVID-19, and to evaluate the infectivity risk of COVID-19 under different exposure conditions.Methods:Information of COVID-19 cases and their close contacts in Chongqing was obtained from Information System of Chinese Center for Disease Control and Prevention until April 30th, 2020. The epidemiological, clinical features and nucleic acid results were analyzed to estimate the infection rate and incidence rate of close contacts under different exposures.Results:A total of 176 COVID-19 cases and 2 000 close contacts were tracked and investigated. The total infection rate was 6.80% and the total incidence rate was 4.35%. The infection rate of close contacts with underlying diseases was 25.00% (24/96) , which was significantly higher than those without underlying diseases ( χ 2=52.71, P<0.01) . The infection rates of close contacts exposed to confirmed cases and asymptomatic infected cases were 7.48% and 2.65%, respectively, with statistically significant difference ( χ 2=18.50, P<0.01) . The infection rates of after onset and latent contact were 9.94% and 3.23%, respectively, with statistically significant difference ( χ 2=15.84, P<0.01) . Infection rates of different means of contact were significant different ( χ 2=59.02, P<0.01) . Conclusions:The total infection rate of close contacts exposed to COVID-19 cases in Chongqing is high. The infectivity of confirmed cases is significantly higher than that of asymptomatic infected cases. People with underlying diseases are at higher risk of infection. The infectivity in symptomatic stage is significantly stronger than that in latent stage. Living together, recreational activities and dinner party are high risk factors for infection.