Exposure-history Type and Characteristics of SARS-CoV-2 Infected Patients in Wuhan（Epicenter） Neighboring Shaanxi Province of China

Abstract Background Since December 2019, an increasing number of SARS-CoV-2 infected pneumonia cases have been identified in Wuhan and its surrounding areas. As of March 2020 more than 150 countries, areas or territories have reported the infected cases of SARS-CoV-2 and still the infected number is rapidly increasing globally. Methods The whole outbreak period in Shaanxi Province (from Jan 23, 2020 to Feb 20, 2020) was split into two consecutive stages. Epidemiological feature like exposure-history type and characteristics of the confirmed SARS-CoV-2 infected patients in Shaanxi Province were analyzed. Results A total of 245 patients were confirmed with SARS-CoV-2 infection in Shaanxi Province, among whom 133 (54.29%) were male and 112 (45.71%) were female. The percentage of the imported cases dropped from 53.94% in earlier stage (Jan 23-Feb 5, 2020) to 16.25% in second stage (Feb 6-Feb 20, 2020) while that of cases with no definite exposure history and other types increased from 27.88–70.00%. Conclusions As control measures were taken in earlier stage much less cases were confirmed in second stage. Our study contributes to the understanding of SARS-CoV-2 epidemiology and helps evaluate the effectiveness of control measures on local transmission.

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The COVID-19 outbreak in Sichuan, China: epidemiology and impact of interventions

10.1101/2020.07.20.20157602 ◽

2020 ◽

Author(s):

Quanhui Liu ◽

Ana I Bento ◽

Kexin Yang ◽

Hang Zhang ◽

Xiaohan Yang ◽

...

Keyword(s):

Public Health ◽

Control Strategies ◽

Public Health Emergency ◽

Control Measures ◽

Patient Records ◽

Epidemic Threshold ◽

Reproduction Numbers ◽

Imported Cases ◽

The Impact ◽

Local Transmission

In January 2020, a COVID19 outbreak was detected in Sichuan Province of China. The aim of this work is to characterize the epidemiology of the Sichuan outbreak and estimate the impact of the performed interventions. We analyzed patient records for all laboratory confirmed cases reported in the province for the period of January 21 to March 16, 2020. To estimate the basic and daily reproduction numbers, we used a Bayesian framework. In addition, we estimate the number of cases averted by the implemented control strategies. The outbreak resulted in 539 confirmed cases, lasted less than two months, and no further local transmission was detected after February 27. The median age of local cases was 8 years older than that of imported cases. Severity of symptoms increased with age. We estimated R0 at 2.4 (95% CI: 1.6-3.7). The epidemic was self sustained for about 3 weeks before going below the epidemic threshold 3 days after the declaration of a public health emergency by Sichuan authorities. Our findings indicate that, were the control measures be adopted four weeks later, the epidemic could have lasted 49 days longer (95%CI: 31-68 days), causing 9,216 (95%CI: 1,317-25,545) more cases and possibly overwhelming Sichuan healthcare system.

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Accounting for imported cases in estimating the time-varying reproductive number of COVID-19

10.1101/2021.02.09.21251416 ◽

2021 ◽

Author(s):

Tim K. Tsang ◽

Peng Wu ◽

Eric H. Y. Lau ◽

Benjamin J. Cowling

Keyword(s):

Public Health ◽

Control Measures ◽

Transmission Dynamics ◽

Reproductive Number ◽

Considerable Proportion ◽

Time Varying ◽

Health Measures ◽

Imported Cases ◽

The Impact ◽

Local Transmission

ABSTRACTBackgroundEstimating the time-varying reproductive number, Rt, is critical for monitoring transmissibility of an emerging infectious disease during outbreaks. When local transmission is effectively suppressed, imported cases could substantially impact transmission dynamics.MethodsWe developed methodology to estimate separately the Rt for local cases and imported cases, since certain public health measures aim only to reduce onwards transmission from imported cases. We applied the framework to data on COVID-19 outbreaks in Hong Kong.ResultsWe estimated that the Rt for local cases decreased from above one in the early phase of outbreak to below one after tightening of public health measures. Assuming the same infectiousness of local and imported cases underestimated Rt for local cases due to control measures targeting travelers.ConclusionsWhen a considerable proportion of all cases are imported, the impact of imported cases in estimating Rt is critical. The methodology described here can allow for differential infectiousness of local imported cases.

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The COVID-19 outbreak in Sichuan, China: Epidemiology and impact of interventions

PLoS Computational Biology ◽

10.1371/journal.pcbi.1008467 ◽

2020 ◽

Vol 16 (12) ◽

pp. e1008467

Author(s):

Quan-Hui Liu ◽

Ana I. Bento ◽

Kexin Yang ◽

Hang Zhang ◽

Xiaohan Yang ◽

...

Keyword(s):

Public Health ◽

Control Strategies ◽

Public Health Emergency ◽

Control Measures ◽

Patient Records ◽

Epidemic Threshold ◽

Reproduction Numbers ◽

Imported Cases ◽

The Impact ◽

Local Transmission

In January 2020, a COVID-19 outbreak was detected in Sichuan Province of China. Six weeks later, the outbreak was successfully contained. The aim of this work is to characterize the epidemiology of the Sichuan outbreak and estimate the impact of interventions in limiting SARS-CoV-2 transmission. We analyzed patient records for all laboratory-confirmed cases reported in the province for the period of January 21 to March 16, 2020. To estimate the basic and daily reproduction numbers, we used a Bayesian framework. In addition, we estimated the number of cases averted by the implemented control strategies. The outbreak resulted in 539 confirmed cases, lasted less than two months, and no further local transmission was detected after February 27. The median age of local cases was 8 years older than that of imported cases. We estimated R0 at 2.4 (95% CI: 1.6–3.7). The epidemic was self-sustained for about 3 weeks before going below the epidemic threshold 3 days after the declaration of a public health emergency by Sichuan authorities. Our findings indicate that, were the control measures be adopted four weeks later, the epidemic could have lasted 49 days longer (95% CI: 31–68 days), causing 9,216 more cases (95% CI: 1,317–25,545).

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Modelling and Estimating the Transmissibility of COVID-19: Transmission Dynamics in Shaanxi Province of China as a Case Study

10.21203/rs.3.rs-122395/v1 ◽

2020 ◽

Author(s):

Xu-Sheng Zhang ◽

Wei Liu ◽

Huan Xiong ◽

Zhengji Chen

Keyword(s):

Infectious Diseases ◽

Emerging Infectious Diseases ◽

Control Measures ◽

Transmission Dynamics ◽

Shaanxi Province ◽

Infectious Agents ◽

Essential Information ◽

Infected People ◽

Strong Control ◽

Local Transmission

Abstract To control and contain the outbreaks of emerging infectious diseases such as COVID-19, it is important to know how easy and fast they transmit among people. To explore the essential information of the novel infectious agents, people always confront an inverse problem: using (partially) observed numbers of infected people by time and region to dig up the underlying characteristics of unknown infectious agents. Epidemics armed with advanced statistical inference and mathematical theory has been developed to help reconstruct transmission dynamics processes and to estimate key features of infectious diseases. In this study we use COVID-19 outbreak in Shaanxi province as an example to illustrate how the infectious disease dynamics method can be used to help build the transmission process and to estimate the transmissibility of COVID-19. Three transmission dynamics models were proposed for this. By separating continuous importation from local transmission and treating imported cases as the source rather than results of local transmission, the basic reproduction number of COVID-19 in Shaanxi province was estimated in the range from 0.46 to 0.61, well below the critical value of 1.0. This indicates that COVID-19 cannot self-sustain in Shaanxi province and reflects the timely and strong control measures taken in Shaanxi province.

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Effects of heterogeneity in infection-exposure history and immunity on the dynamics of a protozoan parasite

Journal of The Royal Society Interface ◽

10.1098/rsif.2007.1061 ◽

2007 ◽

Vol 4 (16) ◽

pp. 841-849 ◽

Cited By ~ 7

Author(s):

Maite Severins ◽

Don Klinkenberg ◽

Hans Heesterbeek

Keyword(s):

Dynamic Behaviour ◽

Protozoan Parasite ◽

Host Population ◽

Infection Process ◽

Control Measures ◽

Complex Dynamic ◽

Systems Models ◽

Exposure History ◽

The Relationship ◽

Initial Contamination

Infection systems where traits of the host, such as acquired immunity, interact with the infection process can show complex dynamic behaviour with counter-intuitive results. In this study, we consider the traits ‘immune status’ and ‘exposure history’, and our aim is to assess the influence of acquired individual heterogeneity in these traits. We have built an individual-based model of Eimeria acervulina infections, a protozoan parasite with an environmental stage that causes coccidiosis in chickens. With the model, we simulate outbreaks of the disease under varying initial contaminations. Heterogeneity in the traits arises stochastically through differences in the dose and frequency of parasites that individuals pick up from the environment. We find that the relationship between the initial contamination and the severity of an outbreak has a non-monotonous ‘wave-like’ pattern. This pattern can be explained by an increased heterogeneity in the host population caused by the infection process at the most severe outbreaks. We conclude that when dealing with these types of infection systems, models that are used to develop or evaluate control measures cannot neglect acquired heterogeneity in the host population traits that interact with the infection process.

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Survey and control of small mammal populations on two hardwood plantations in southern Ontario

The Forestry Chronicle ◽

10.5558/tfc50181-5 ◽

1974 ◽

Vol 50 (5) ◽

pp. 181-185 ◽

Cited By ~ 3

Author(s):

Andrew Radvanyi

Keyword(s):

Small Mammal ◽

Late Summer ◽

Control Measures ◽

Effective Control ◽

Southern Ontario ◽

Live Trapping ◽

Surrounding Areas ◽

And Control ◽

Rodent Populations ◽

Ingredient Cost

Live trapping and tagging methods were employed to assess small mammal populations within two hardwood plantations in southern Ontario. Excessive girdling damage in past years to young planted trees necessitated an evaluation of rodent populations and development of effective control measures. The application of an anticoagulant rodenticide to oat groats bait broadcast over the study area at an ingredient cost of approximately three dollars per acre virtually wiped out the small mammals. Reinvasion from surrounding areas was, however, fairly rapid, particularly during late summer. Further research on longer term control measures using poisoned bait feeder stations is recommended.

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The effect of organic compost of Caryocar brasiliense waste against Meloidogyne javanica in two vegetable crops

Nematology ◽

10.1163/15685411-bja10103 ◽

2021 ◽

pp. 1-8

Author(s):

Fabíola de J. Silva ◽

Regina C.F. Ribeiro ◽

Adelica A. Xavier ◽

Vanessa A. Gomes ◽

Paulo V.M. Pacheco ◽

...

Keyword(s):

Integrated Control ◽

Meloidogyne Javanica ◽

Control Measures ◽

Vegetable Crops ◽

Root Knot Nematode ◽

Second Stage ◽

Tomato Roots ◽

Crop Development ◽

Caryocar Brasiliense ◽

Organic Compost

Summary Root-knot nematodes (Meloidogyne spp.) are responsible for various significant crop losses, which require taking integrated control measures. The present study aimed to identify a possible sustainable approach to the management of Meloidogyne javanica in vegetable crops using an organic compound based on pequi (Caryocar brasiliense) fruit residues. A pot experiment was conducted using cultivars of tomato and lettuce susceptible to M. javanica, with three amendments including inorganic fertiliser, cattle manure and five doses of organic compost with pequi residues. All treatments were inoculated with second-stage juveniles of M. javanica to simulate the root-knot nematode disease in field conditions. Increasing doses of organic compost with pequi residues from 5 kg m−3 to 30 kg m−3 promoted a significant decrease in the nematode population in both cultures evaluated. Organic compost (30 kg m−3) reduced the numbers of galls and eggs of M. javanica by 41.6 and 46.5% in tomato roots, and by 80.3 and 59.2% in lettuce roots, respectively, compared with non-treated control. Organic compost also increased crop development considerably. In general, there was a 43.0% increase in plant development compared to non-treated control. Hence, organic compost of pequi residues could be an alternative to toxic chemical nematicides and recommended as eco-friendly management of M. javanica in vegetable crops.

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Awareness of COVID-19 Before and After Quarantine Based on Crowdsourced Data From Rabigh City, Saudi Arabia: A Cross-Sectional and Comparative Study

Frontiers in Public Health ◽

10.3389/fpubh.2021.632024 ◽

2021 ◽

Vol 9 ◽

Author(s):

Mai Aldhahri ◽

Rana Alghamdi

Keyword(s):

Saudi Arabia ◽

Online Survey ◽

Control Measures ◽

Infection Prevention And Control ◽

Cross Sectional ◽

Second Stage ◽

Before And After ◽

Prevention And Control Measures ◽

Two Stages ◽

And Control

Background: Infection prevention and control measures are critical for the prevention of the spread of COVID-19.Aim: In this study, we aimed to measure and evaluate the level of awareness and knowledge of the prevention, symptoms, and transmission control of COVID-19 before and after quarantine among the residents of Rabigh city and adjacent villages in Saudi Arabia.Methods: A cross-sectional online survey was conducted in two stages: the first stage took place before quarantine and the second stage took place after quarantine. The survey was filled out electronically.Results: A total of 448 participants responded and filled out the questionnaires. Females (73.70%) formed the largest number of participants for both stages. The majority of the participants were <30 years old (50.90%) and had a high education level in various sectors and levels (97.1%). It was noticeable that during the first stage, the participants' awareness of COVID-19 symptoms was not very high: 13.62% did not know about the symptoms. However, by the second stage, awareness about symptoms had increased (9.6%).Conclusion: The residents of Rabigh city and the surrounding villages had good levels of knowledge about COVID-19.

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Risk Assessment of Novel Coronavirus COVID-19 Outbreaks Outside China

Journal of Clinical Medicine ◽

10.3390/jcm9020571 ◽

2020 ◽

Vol 9 (2) ◽

pp. 571 ◽

Cited By ~ 93

Author(s):

Péter Boldog ◽

Tamás Tekeli ◽

Zsolt Vizi ◽

Attila Dénes ◽

Ferenc A. Bartha ◽

...

Keyword(s):

Control Measure ◽

Mainland China ◽

Destination Country ◽

Control Measures ◽

Cumulative Number ◽

Travel Restrictions ◽

Imported Cases ◽

Major Outbreak ◽

Novel Coronavirus ◽

Local Reproduction

We developed a computational tool to assess the risks of novel coronavirus outbreaks outside of China. We estimate the dependence of the risk of a major outbreak in a country from imported cases on key parameters such as: (i) the evolution of the cumulative number of cases in mainland China outside the closed areas; (ii) the connectivity of the destination country with China, including baseline travel frequencies, the effect of travel restrictions, and the efficacy of entry screening at destination; and (iii) the efficacy of control measures in the destination country (expressed by the local reproduction number R loc ). We found that in countries with low connectivity to China but with relatively high R loc , the most beneficial control measure to reduce the risk of outbreaks is a further reduction in their importation number either by entry screening or travel restrictions. Countries with high connectivity but low R loc benefit the most from policies that further reduce R loc . Countries in the middle should consider a combination of such policies. Risk assessments were illustrated for selected groups of countries from America, Asia, and Europe. We investigated how their risks depend on those parameters, and how the risk is increasing in time as the number of cases in China is growing.

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Imported dengue in Spain: a nationwide analysis with predictive time series analyses

Journal of Travel Medicine ◽

10.1093/jtm/taz072 ◽

2019 ◽

Vol 26 (8) ◽

Cited By ~ 15

Author(s):

Lidia Redondo-Bravo ◽

Claudia Ruiz-Huerta ◽

Diana Gomez-Barroso ◽

María José Sierra-Moros ◽

Agustín Benito ◽

...

Keyword(s):

Time Series ◽

Control Measures ◽

Severe Dengue ◽

Vector Surveillance ◽

Case Scenario ◽

Worst Case ◽

Temporal Behaviour ◽

The Impact ◽

Near Future ◽

Local Transmission

Abstract Background Of febrile illnesses in Europe, dengue is second only to malaria as a cause of travellers being hospitalized. Local transmission has been reported in several European countries, including Spain. This study assesses the evolution of dengue-related admissions in Spain in terms of time, geographical distribution and individuals’ common characteristics; it also creates a predictive model to evaluate the risk of local transmission. Methods This is a retrospective study using the Hospital Discharge Records Database from 1997 to 2016. We calculated hospitalization rates and described clinical characteristics. Spatial distribution and temporal behaviour were also assessed, and a predictive time series model was created to estimate expected cases in the near future. Figures for resident foreign population, Spanish residents’ trips to endemic regions and the expansion of Aedes albopictus were also evaluated. Results A total of 588 dengue-related admissions were recorded: 49.6% were women, and the mean age was 34.3 years. One person died (0.2%), 82% presented with mild-to-moderate dengue and 7–8% with severe dengue. We observed a trend of steady and consistent increase in incidence (P < 0.05), in parallel with the increase in trips to dengue-endemic regions. Most admissions occurred during the summer, showing significant seasonality with 3-year peaks. We also found important regional differences. According to the predictive time series analysis, a continuing increase in imported dengue incidence can be expected in the near future, which, in the worst case scenario (upper 95% confidence interval), would mean an increase of 65% by 2025. Conclusion We present a nationwide study based on hospital, immigration, travel and entomological data. The constant increase in dengue-related hospitalizations, in combination with wider vector distribution, could imply a higher risk of autochthonous dengue transmission in the years to come. Strengthening the human and vector surveillance systems is a necessity, as are improvements in control measures, in the education of the general public and in fostering their collaboration in order to reduce the impact of imported dengue and to prevent the occurrence of autochthonous cases.

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