First-generation Cases Research Articles

Test-Treat-Track-Test-Treat Strategy for Control of Schistosomiasis in Two Low-Prevalence Villages in Northwestern Tanzania.

Mass drug administration of praziquantel becomes a less attractive strategy for elimination of schistosomiasis in low-prevalence areas due to cost implications and low treatment compliance. We aimed to determine the feasibility of a Test-Treat-Track-Test-Treat (5T) strategy in two low-prevalence villages; the 5T strategy has been successfully implemented in diseases such as malaria. A total of 200 school children aged 6-12 years were randomly selected from two schools and tested for Schistosoma mansoni infection using the point-of-care circulating cathodic antigen test. Schistosoma mansoni-positive children, referred to as first-generation cases (FGCs), were tracked and treated including up to five members of their families. Second-generation cases, identified by the FGCs as their close, non-relative contacts, were also tracked, tested, and treated, including up to five members of their families. The prevalence of schistosomiasis among screened FGCs was 16.5% (33/200) in both villages. Twenty-four FGCs were included in the study. Prevalence among 94 contacts of FGCs was 46.8% (44/94). The proportion was higher in Muda than Bulunga village (61.2% versus 31.1%, χ2 = 10.6611, P = 0.005). Prevalence among SGCs and their contacts was 37.5% (9/24) and 47.1% (49/104), respectively. Overall, the 5T strategy identified 102 additional cases out of 222 tracked from FGCs, 95% of whom were treated, at a total time of 52 hours. Our data demonstrate the potential of the 5T strategy in identifying and treating additional cases in the community and hence its practicality in schistosomiasis control in low-prevalence settings at relatively low time and resources investment.

A stochastic contact network model for assessing outbreak risk of COVID-19 in workplaces.

The COVID-19 pandemic has drastically shifted the way people work. While many businesses can operate remotely, a large number of jobs can only be performed on-site. Moreover as businesses create plans for bringing workers back on-site, they are in need of tools to assess the risk of COVID-19 for their employees in the workplaces. This study aims to fill the gap in risk modeling of COVID-19 outbreaks in facilities like offices and warehouses. We propose a simulation-based stochastic contact network model to assess the cumulative incidence in workplaces. First-generation cases are introduced as a Bernoulli random variable using the local daily new case rate as the success rate. Contact networks are established through randomly sampled daily contacts for each of the first-generation cases and successful transmissions are established based on a randomized secondary attack rate (SAR). Modification factors are provided for SAR based on changes in airflow, speaking volume, and speaking activity within a facility. Control measures such as mask wearing are incorporated through modifications in SAR. We validated the model by comparing the distribution of cumulative incidence in model simulations against real-world outbreaks in workplaces and nursing homes. The comparisons support the model’s validity for estimating cumulative incidences for short forecasting periods of up to 15 days. We believe that the current study presents an effective tool for providing short-term forecasts of COVID-19 cases for workplaces and for quantifying the effectiveness of various control measures. The open source model code is made available at github.com/abhineetgupta/covid-workplace-risk.

Infectivity, susceptibility, and risk factors associated with SARS-CoV-2 transmission under intensive contact tracing in Hunan, China

Several mechanisms driving SARS-CoV-2 transmission remain unclear. Based on individual records of 1178 potential SARS-CoV-2 infectors and their 15,648 contacts in Hunan, China, we estimated key transmission parameters. The mean generation time was estimated to be 5.7 (median: 5.5, IQR: 4.5, 6.8) days, with infectiousness peaking 1.8 days before symptom onset, with 95% of transmission events occurring between 8.8 days before and 9.5 days after symptom onset. Most transmission events occurred during the pre-symptomatic phase (59.2%). SARS-CoV-2 susceptibility to infection increases with age, while transmissibility is not significantly different between age groups and between symptomatic and asymptomatic individuals. Contacts in households and exposure to first-generation cases are associated with higher odds of transmission. Our findings support the hypothesis that children can effectively transmit SARS-CoV-2 and highlight how pre-symptomatic and asymptomatic transmission can hinder control efforts.

Index and First-Generation Cases in a COVID-19 Outbreak - Jilin Province, China, 2021.

What is already known on this topic? Contact tracing and testing with isolated medical care of identified cases is a key strategy for interrupting chains of transmission of COVID-19 and reducing mortality associated with COVID-19. At the early phases of the COVID-19 pandemic, due to test capacity limitations, case finding often started from suspected cases. What is added by this report? The index patient infected 74 individuals who were close contacts that were identified through contact tracing, and exposed individuals were monitored in quarantine with daily polymerase chain reaction (PCR) testing. All individuals were asymptomatic initially, but all PCR-positive individuals eventually developed symptoms. Infectivity was documented up to 8 days before being confirmed as a symptomatic case, approximately 4 days before turning PCR positive. What are the implications for public health practice? During an outbreak, we suggest tracing close contacts from both PCR-positive individuals and suspected cases, rather than from suspected cases alone. Due to the long period of infectivity before turning PCR positive or developing symptoms, close contacts that had contact with a newly PCR positive case within 4 days should be judged as at risk of being infected; close contacts that had contact within 8 days of a newly symptomatic case should be judged as at risk being infected.

Epidemiological characteristics of clustering outbreaks of 51 cases of COVID-19 in Xinyang, He’nan

Objective To analyze the occurrence characteristics and epidemic regularity of a new epidemic situation of COVID-19, and we provide scientific basis for formulating strategies and measures for epidemic prevention and control. Methods According to the “Guidelines for Epidemiological Investigation of Aggregated Epidemic Situation of COVID-19 (Trial Version)” by the National Health and Medical Commission, 274 confirmed cases of COVID-19 and 11 asymptomatic infections reported from January 13 to March 2, 2020 were carried out epidemiological investigations. Results There were a total of 51 cases of COVID-19 epidemic outbreaks in Xinyang City. The first case had 31 cases (60.78%) with travel or residence history in Wuhan and other places. The median incubation period was 7 days, and the median number of infections was 2. Including family gatherings were 45 cases (88.24%), mixed gathering 4 cases (7.84%), working gathering 2 cases (3.92%). A total of 139 confirmed cases and 10 asymptomatic infections were involved, accounting for 52.28% of the city′s total number of cases. There were 48 imported cases (32.21%), 101 local cases (67.79%); 85 first-generation cases (57.05%), 63 second-generation cases (42.28%), and 1 third-generation case (0.67%). In the history of exposure, there were 84 cases (56.38%) living together, 51 cases (34.23%) sharing dinner together, 12 cases (8.05%) in close working place, and 2 cases (1.34%) gathering in entertainment places. Conclusion The 51 cases of clustered epidemic is dominated by families. The exposure history of the cases is mostly living together and eating together. The first case of most clustered epidemics is those who traveled or lived in Wuhan and other places. The causes of most cases were linked with the outbreak of COVID-19 in Wuhan, Hubei. 摘要：目的 分析新型冠状病毒肺炎聚集性疫情的发生特点和流行规律, 为制定疫情防控策略和措施提供科学依 据。 方法 根据国家卫健委《新型冠状病毒肺炎聚集性疫情流行病学调查指南 (试行第一版) 》, 对 2020 年 1 月 13 日—3 月 2 日报告的 274 例新型冠状病毒肺炎确诊病例及 11 例无症状感染者开展流行病学调查研究。 结果 信阳市新冠肺 炎聚集性疫情共发生 51 起, 首例病例有武汉等地旅行或居住史者 31 起 (60.78%) , 发病潜伏期中位数为 7 d, 传染人数 中位数为 2 人。包括家庭聚集 45 起 (88.24%) , 混合聚集 4 起 (7.84%) , 工作聚集 2 起 (3.92%)。共涉及 139 例确诊病例 及 10 例无症状感染者, 占全市总病例数的 52.28%。输入性病例 48 例 (32.21%) , 本地病例 101 例 (67.79%) ; 一代病例 85 例 (57.05%) , 二代病例 63 例 (42.28%) , 三代病例 1 例 (0.67%)。暴露史有共同居住生活的 84 例 (56.38%) , 共同聚餐的 51 例 (34.23%) , 工作场所密切接触的 12 例 (8.05%) , 娱乐场所聚集的 2 例 (1.34%)。 结论 51 起聚集性疫情以家庭聚 集性为主; 病例的暴露史多为有共同居住生活史和共同聚餐史; 多数聚集性疫情的首例病例有武汉等地旅行或居 住史。

Risk of severe coronavirus disease in imported and secondary cases in Zhejiang province, China.

BackgroundTo our knowledge, no previous studies have focused on determining whether the virulence and case fatality rate of the severe acute respiratory coronavirus 2 (SARS-CoV-2) decreases as the virus continues to spread. Hence, our aim was to retrospectively explore the differences in the risk of severe or critical COVID-19 among imported, secondary and tertiary cases in Zhejiang, China.MethodsWe categorized COVID-19 cases reported by hospitals in Zhejiang as first-, second- and third-generation cases. Univariate and multivariate logistic regression analyses were performed to compare disease severity and case generation.ResultsOf 1187 COVID-19 cases, 227 (19.1%, 95% CI: 16.9–21.4) manifested severe or critical illness. The adjusted risk difference for severe or critical illness was lower for second- (odds ratio (OR) = 0.84, 95% confidence interval (CI): 0.52–1.36) and third-generation (OR = 0.55, 95% CI: 0.37–0.83) cases than for first-generation cases. Compared with hospitalized patients, cases identified at centralized isolation locations (OR = 0.62, 95% CI: 0.40–0.97) and those identified through active search or gateway screening (OR = 0.28, 95% CI: 0.08–1.04) were at a lower risk of severe or critical illness.ConclusionsSecond- and third-generation cases of COVID-19 have a lower risk of developing severe or critical illness than first-generation cases.

Clinical analysis of 150 cases of 2019 novel coronavirus infection in Nanyang City, Henan Province

Objective: To analyze the epidemiological characteristics and clinical features of the patients with 2019-nCoV infection in Nanyang City, so as to provide evidence for clinical diagnosis and treatment. Methods: The epidemiology, clinical symptoms, atory and radiologic data of 150 patients with 2019-nCoV infection admitted to the designated hospitals in Nanyang City from January 24,2020 to February 16, 2020 were retrospectively analyzed. Results: The 150 patients with 2019 nCov infection consisted of 67 men and 83 women, and the median age was (45±16) years; 69 of them were the first generation case,60 of them were the second generation case, 6 of them were the third generation case,the median incubation period of the first generation case was (5.4±2.2) days, and the second generation case was (6.7±3.1) days, and the first-generation cases are the majority in severe patients (69%) . The most common basic disease was hypertension (13 cases, 9%), diabetes (9 cases, 6%), and the most common symptom is fever(142 cases, 95%, 63% showed moderate fever) , cough and sputum(108 cases,72%), fatigue(23 cases,15%), anorexia(20 cases, 13%), headache, diarrhea, muscle soreness, sore throat as the first symptoms. The average time from onset of symptoms to consultation was (4.2±2.2) days for all patients. The changes in peripheral blood cells were mainly lymphonpenia (83 cases, 55%) and eosinophilia (95 cases, 63%), The lymphocyte count of the severe and critically ill patients was more significantly reduced, and some patients had increased myocardial enzymes, mainly LDH (47 cases, 31%), and a few patients had liver function damage, mainly manifested in ALT and AST. High, very few patients have renal impairment. Among the inflammation-related indicators, the main manifestations are increased CRP (66 cases, 43%) and ESR (86 cases, 57%), elevated D-Dimer in 29% of patients. 144 cases have different degrees of infective lesions in chest CT examination, with 30 cases (21%) on one side and 144 cases (79%) on both sides. Morphologically, most of the lesions were patchy ground glass lesions, which could be accompanied by air bronchus signs and some consolidation and paving stone signs. Of the cases showing "white lung", 87% were sever ill or critically ill. After active treatment, 45% of patients were discharged according to discharge standards. 33% of sever and critically ill patients were discharged, 49% of them were degraded hospitalization.The average length of hospitalization was (12±4) days. Conclusion: A history of epidemiological exposure, fever, chest CT with signs of pneumonia, normal or decreased WBC, and lymphocytopenia, eosinophilia are the clinical basis for the diagnosis of this disease, and most of the sever patients were the first generation cases. The degree of lymphocytopenia is related to the severity of the disease.

Data sharing and outbreaks: best practice exemplified

Data sharing and outbreaks: best practice exemplified

Epidemiological and clinical characteristics of three family clusters of COVID-19 transmitted by latent patients in China

From 21 January 2020 to 9 February 2020, three family clusters involving 31 patients with coronavirus disease 2019 were identified in Wenzhou, China. The epidemiological and clinical characteristics of the family cluster patients were analysed and compared with those of 43 contemporaneous sporadic cases. The three index cases transmitted the infection to 28 family members 2-10 days before illness onset. Overall, 28 of the 41 sporadic cases and three of 31 patients in the family clusters came back from Wuhan (65.12 vs. 9.68%, P< 0.001). In terms of epidemiological characters and clinical symptoms, no significant differences were observed between the family cluster and sporadic cases. However, the lymphocyte counts of sporadic cases were significantly lower than those of family cluster cases ((1.32 ± 0.55) × 109/l vs. (1.63 ± 0.70) × 109/l, P = 0.037), and the proportion of hypoalbuminaemia was higher in sporadic cases (18/43, 41.86%) than in the family clusters (6/31, 19.35%) (P < 0.05). Within the family cluster, the second- and third-generation cases had milder clinical manifestations, without severe conditions, compared with the index and first-generation cases, indicating that the virulence gradually decreased following passage through generations within the family clusters. Close surveillance, timely recognition and isolation of the suspected or latent patient is crucial in preventing family cluster infection.

The descriptive epidemiology of coronavirus disease 2019 during the epidemic period in Lu'an, China: achieving limited community transmission using proactive response strategies.

Hubei province in China has had the most confirmed coronavirus disease 2019 (COVID-19) cases and has reported sustained transmission of the disease. Although Lu'an city is adjacent to Hubei province, its community transmission was blocked at the early stage, and the impact of the epidemic was limited. Therefore, we summarised the overall characteristics of the entire epidemic course in Lu'an to help cities with a few imported cases better contain the epidemic. A total of 69 confirmed COVID-19 cases and 11 asymptomatic carriers were identified in Lu'an during the epidemic from 12 January to 21 February 2020. Fifty-two (65.0%) cases were male, and the median age was 40 years. On admission, 56.5% of cases had a fever as the initial symptom, and pneumonia was present in 89.9% of cases. The mean serial interval and the mean duration of hospitalisation were 6.5 days (95% CI: 4.8-8.2) and 18.2 days (95% CI: 16.8-19.5), respectively. A total of 16 clusters involving 60 cases (17 first-generation cases and 43 secondary cases) were reported during the epidemic. We observed that only 18.9% (7/37) index cases resulted in community transmission during the epidemic in Lu'an, indicating that the scale of the epidemic was limited to a low level in Lu'an city. An asymptomatic carrier caused the largest cluster, involving 13 cases. Spread of COVID-19 by asymptomatic carriers represents an enormous challenge for countries responding to the pandemic.