scholarly journals Identification of transmission chains and clusters associated with COVID-19 in Tunisia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mouna Safer ◽  
Hejer Letaief ◽  
Aicha Hechaichi ◽  
Chahida Harizi ◽  
Sonia Dhaouadi ◽  
...  
Keyword(s):  
Secondary Infection ◽  
Virus Transmission ◽  
Field Investigation ◽  
Screening Tests ◽  
Contact Tracing ◽  
Source Of Infection ◽  
Secondary Infections ◽  
Imported Cases ◽  
Large Clusters ◽  
Seven Generations

Abstract Background The aim of this study was to characterize the transmission chains and clusters of COVID-19 infection in Tunisia. Methods All cases were confirmed by Reverse Transcriptase Polymerase Chain Reaction of a nasopharyngeal specimen. Contact tracing is undertaken for all confirmed cases in order to identify close contacts that will be systematically screened and quarantined. Transmission chains were identified based on field investigation, contact tracing, results of screening tests and by assessing all probable mode of transmission and interactions. Results As of May 18, 2020, 656 cases out of a total of 1043 confirmed cases of Coronavirus disease 2019 belong to 127 transmission chains identified during the epidemic (mean age 42.36 years, Standard deviation 19.56 and sex ratio 0.86). The virus transmission is the most concentrated in the governorate of Tunis (31.5%), Ariana (10.2%) and Ben Arous (10.2%). Virus transmission occurred 50 times (9.72% of secondary transmission events) between two different governorates. A maximum of seven generations of secondary infection was identified, whereas 62% of these secondary infections belong the first generation. A total of 11 “super spreader” cases were identified in this investigation. Four large clusters have been identified. The evolution of secondary cases highlighted two peaks: one in 2nd April and a second in 16 th April whereas imported cases caused local transmission of virus during the early phase of the epidemic. Conclusion Correct contact tracing and early active case finding is useful to identify transmission chains and source of infection in order to contain the widespread transmission in the community.

scholarly journals Identification of Transmission Chains and Clusters Associated with COVID-19 in Tunisia

2020 ◽  
Author(s):  
Mouna Safer ◽  
Hejer Letaief ◽  
Aicha Hechaichi Hechaichi ◽  
Chahida Harizi ◽  
Sonia Dhaouadi ◽  
...  
Keyword(s):  
Secondary Infection ◽  
Virus Transmission ◽  
Field Investigation ◽  
Screening Tests ◽  
Contact Tracing ◽  
Source Of Infection ◽  
Secondary Infections ◽  
Imported Cases ◽  
Large Clusters ◽  
Seven Generations

Abstract Background: The aim of this study was to characterize the transmission chains and clusters of COVID-19 infection in TunisiaMethods: All cases were confirmed by RT-PCR of a nasopharyngeal specimen. Contact tracing is undertaken for all confirmed cases in order to identify close contacts that will be systematically screened and quarantined. Transmission chains were identified based on field investigation, contact tracing, results of screening tests and by assessing all probable mode of transmission and interactions.Results: As of May 18, 2020, 656 cases out of a total of 1043 confirmed cases of COVID-19 belong to 127 transmission chains identified during the epidemic (mean age 42.36 years, Standard deviation 19.56 and sex ratio 0.86). The virus transmission is the most concentrated in the governorate of Tunis (31.5%), Ariana (10.2%) and Ben Arous (10.2%). Virus transmission occurred 50 times (9.72% of secondary transmission events) between two different governorates. A maximum of seven generations of secondary infection was identified, whereas 62% of these secondary infections belong the first generation. A total of 11 “superspreader” cases were identified in this investigation. Four large clusters have been identified. The evolution of secondary cases highlighted two peaks: one in 2nd April and a second in 16 th April whereas imported cases caused local transmission of virus during the early phase of the epidemic.Conclusion: Correct contact tracing and early active case finding is useful to identify transmission chains and source of infection in order to contain the widespread transmission in the community.

scholarly journals Subcritical Transmission in the Early Stage of COVID-19 in Korea

2021 ◽  
Vol 18 (3) ◽  
pp. 1265
Author(s):  
Yong Sul Won ◽  
Jong-Hoon Kim ◽  
Chi Young Ahn ◽  
Hyojung Lee
Keyword(s):  
Incubation Period ◽  
Early Stage ◽  
Probability Distributions ◽  
Likelihood Estimation ◽  
Contact Tracing ◽  
Statistical Characterization ◽  
Serial Interval ◽  
Imported Cases ◽  
The Mean ◽  
Reporting Delays

While the coronavirus disease 2019 (COVID-19) outbreak has been ongoing in Korea since January 2020, there were limited transmissions during the early stages of the outbreak. In the present study, we aimed to provide a statistical characterization of COVID-19 transmissions that led to this small outbreak. We collated the individual data of the first 28 confirmed cases reported from 20 January to 10 February 2020. We estimated key epidemiological parameters such as reporting delay (i.e., time from symptom onset to confirmation), incubation period, and serial interval by fitting probability distributions to the data based on the maximum likelihood estimation. We also estimated the basic reproduction number (R0) using the renewal equation, which allows for the transmissibility to differ between imported and locally transmitted cases. There were 16 imported and 12 locally transmitted cases, and secondary transmissions per case were higher for the imported cases than the locally transmitted cases (nine vs. three cases). The mean reporting delays were estimated to be 6.76 days (95% CI: 4.53, 9.28) and 2.57 days (95% CI: 1.57, 4.23) for imported and locally transmitted cases, respectively. The mean incubation period was estimated to be 5.53 days (95% CI: 3.98, 8.09) and was shorter than the mean serial interval of 6.45 days (95% CI: 4.32, 9.65). The R0 was estimated to be 0.40 (95% CI: 0.16, 0.99), accounting for the local and imported cases. The fewer secondary cases and shorter reporting delays for the locally transmitted cases suggest that contact tracing of imported cases was effective at reducing further transmissions, which helped to keep R0 below one and the overall transmissions small.

scholarly journals ORAL SECONDARY INFECTION IN STEVENS-JOHNSON SYNDROME PATIENT WITH ORAL INVOLVEMENT: A CASE REPORT

2021 ◽  
Vol 6 (1) ◽  
pp. 79
Author(s):  
Etis Duhita Rahayuningtyas ◽  
Indah Suasani Wahyuni ◽  
Irna Sufiawati
Keyword(s):  
Case Report ◽  
Secondary Infection ◽  
Severity Of Illness ◽  
The Body ◽  
Stevens Johnson Syndrome ◽  
High Dose ◽  
Oral Manifestation ◽  
Secondary Infections ◽  
Johnson Syndrome ◽  
Oral Involvement

ABSTRACTBackground: Stevens-Johnson syndrome (SSJ) is a hypersensitivity reaction that is often triggered by drugs but this case is rare. These reactions result in uncontrolled keratinocyte damage to the skin and mucosa throughout the body, including the oral mucosa, and are often life-threatening. The use of high doses of corticosteroids is a treatment that is often given but it can trigger secondary infections of fungal and viral in the oral cavity. Purpose: This case report discusses the management of oral manifestations and secondary infections in SSJ patients, and becomes guidance for health professionals. Case: A-42-years-old male patient was consulted from the Department of Dermatology and Venereology (DV) due to oral pain and eating difficulties. The severity-of-illness-score for toxic-epidermal-necrolysis (SCORTEN) was 1. Erosive serosanguinous crusts, tend to bleed were found on the lips. Intraoral clinically presented wide erosive lesions and multiple ulcers, accompanied by a pseudomembranous plaque, and teeth decay. Hematologic examination showed an increase in leukocytes, neutrophil segments, monocytes, SGOT, urea, and creatinine as well as decreased hemoglobin, hematocrit, erythrocytes, MCHC, protein, and albumin. Anti-HSV1 IgG increased almost 6 times than normal values. The patient was diagnosed with SJS with oral involvement, secondary infections of pseudomembranous candidiasis, and herpetic stomatitis. Case Management: Systemic therapy given were intravenous dexamethasone, ranitidine, calcium, and cetirizine, from the DV Department, while hydrocortisone lip ointment, Chlorhexidine digluconate 0.12%, and Nystatin oral suspension for oral problems. The lesions progressed in 24 days. Conclusion: Oral secondary infections may occur in SJS patients due to high-dose corticosteroid therapy.Keywords: Herpetic Stomatitis, Oral Manifestation, Oral Secondary Infection, Pseudomembranous Candidiasis, Stevens-Johnson Syndrome.

scholarly journals How effective was Newfoundland & Labrador’s travel ban to prevent the spread of COVID-19? An agent-based analysis

2021 ◽  
Author(s):  
Dionne M. Aleman ◽  
Benjamin Z. Tham ◽  
Sean J. Wagner ◽  
Justin Semelhago ◽  
Asghar Mohammadi ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Spatial Location ◽  
Contact Tracing ◽  
Infection Rates ◽  
Case Scenario ◽  
Agent Based ◽  
Individual Level ◽  
Transmission Rates ◽  
Imported Cases ◽  
The Uk

AbstractBackgroundTo prevent the spread of COVID-19 in Newfoundland & Labrador (NL), NL implemented a wide travel ban in May 2020. We estimate the effectiveness of this travel ban using a customized agent-based simulation (ABS).MethodsWe built an individual-level ABS to simulate the movements and behaviors of every member of the NL population, including arriving and departing travellers. The model considers individual properties (spatial location, age, comorbidities) and movements between environments, as well as age-based disease transmission with pre-symptomatic, symptomatic, and asymptomatic transmission rates. We examine low, medium, and high travel volume, traveller infection rates, and traveller quarantine compliance rates to determine the effect of travellers on COVID spread, and the ability of contact tracing to contain outbreaks.ResultsInfected travellers increased COVID cases by 2-52x (8-96x) times and peak hospitalizations by 2-49x (8-94x), with (without) contact tracing. Although contact tracing was highly effective at reducing spread, it was insufficient to stop outbreaks caused by travellers in even the best-case scenario, and the likelihood of exceeding contact tracing capacity was a concern in most scenarios. Quarantine compliance had only a small impact on COVID spread; travel volume and infection rate drove spread.InterpretationNL’s travel ban was likely a critically important intervention to prevent COVID spread. Even a small number of infected travellers can play a significant role in introducing new chains of transmission, resulting in exponential community spread and significant increases in hospitalizations, while outpacing contact tracing capabilities. With the presence of more transmissible variants, e.g., the UK variant, prevention of imported cases is even more critical.

scholarly journals Estimating and interpreting secondary attack risk: Binomial considered biased

2021 ◽  
Vol 17 (1) ◽  
pp. e1008601
Author(s):  
Yushuf Sharker ◽  
Eben Kenah
Keyword(s):  
Los Angeles ◽  
Influenza A ◽  
Secondary Infection ◽  
Random Variable ◽  
Household Member ◽  
Primary Case ◽  
Multiple Generations ◽  
Secondary Infections ◽  
Influenza A H1n1 ◽  
Binomial Models

The household secondary attack risk (SAR), often called the secondary attack rate or secondary infection risk, is the probability of infectious contact from an infectious household member A to a given household member B, where we define infectious contact to be a contact sufficient to infect B if he or she is susceptible. Estimation of the SAR is an important part of understanding and controlling the transmission of infectious diseases. In practice, it is most often estimated using binomial models such as logistic regression, which implicitly attribute all secondary infections in a household to the primary case. In the simplest case, the number of secondary infections in a household with m susceptibles and a single primary case is modeled as a binomial(m, p) random variable where p is the SAR. Although it has long been understood that transmission within households is not binomial, it is thought that multiple generations of transmission can be neglected safely when p is small. We use probability generating functions and simulations to show that this is a mistake. The proportion of susceptible household members infected can be substantially larger than the SAR even when p is small. As a result, binomial estimates of the SAR are biased upward and their confidence intervals have poor coverage probabilities even if adjusted for clustering. Accurate point and interval estimates of the SAR can be obtained using longitudinal chain binomial models or pairwise survival analysis, which account for multiple generations of transmission within households, the ongoing risk of infection from outside the household, and incomplete follow-up. We illustrate the practical implications of these results in an analysis of household surveillance data collected by the Los Angeles County Department of Public Health during the 2009 influenza A (H1N1) pandemic.

“EPIDEMIOLOGICAL AND CLINICAL CHARACTERIZATION OF COVID19 PATIENTS: A RETROSPECTIVE OBSERVATIONAL STUDY OF 245 CASES IN A GOVERNMENT TEACHING INSTITUTE OF NORTH INDIA.”

2021 ◽  
pp. 50-53
Author(s):  
Divya Jain ◽  
Umesh Shukla ◽  
Jyotsna Madan ◽  
Bhanu K Bhakri ◽  
Devendra Kumar Gupta ◽  
...  
Keyword(s):  
Clinical Characteristics ◽  
North India ◽  
Contact Tracing ◽  
Mild Disease ◽  
Source Of Infection ◽  
Asymptomatic Patients ◽  
Care Workers ◽  
Study Population ◽  
The Mean ◽  
Novel Coronavirus

Background and objectives: Worldwide literature on presentation of patients infected with novel coronavirus shows huge variability in terms of severity and outcome depending on the demographic characteristics of the affected population. We aim to present epidemiological and clinical characteristics of COVID-19 patients admitted at our facility. Methods: Retrospective analysis of epidemiological, and clinical characteristics of patients admitted at a dedicated COVID hospital in North India. Results: Records of 245 patients were analyzed. The mean (SD) age was 32 (17.87) years ranging from 1 day to 81 years. Children <18 years of age constituted around 18% of the study population of which only about a fourth (23%) were symptomatic. About 52.4% of patients were males. Almost 40% cases were detected through contact tracing of known infected patients and in about 56% cases the source of infection was indeterminate. About 67% were asymptomatic and most of the symptomatic patients had mild disease. Among the symptomatic patients cough (19.9%) and fever (17.1%) were most common symptoms followed by throat irritation. Comorbidities were present in 32 (13.06%) patients, of which hypertension in 6.12% was the most common. There were 22 (8.97%) health care workers (HCW) among the patients. Majority of the affected HCW were working in areas with relatively low infection risk. Six (2.44%) patients required oxygen supplementation. The mean duration of stay in hospital was 9.6 ±.57 days. Interpretations & Conclusions: Our observations indicate a relatively younger age of affected population and high proportion of asymptomatic patients. Children are usually asymptomatic with relatively better prognosis.

Abstract 17113: Secondary Infections Are Common in Patients Hospitalized for COVID-19 and Are Associated With Severe Outcomes

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Elizabeth R Anderson ◽  
Tariq Azam ◽  
Husam Shadid ◽  
Michael Pan ◽  
Hanna Berlin ◽  
...  
Keyword(s):  
Prospective Observational Study ◽  
Viral Infections ◽  
Clinical Laboratory ◽  
Secondary Infection ◽  
Kidney Injury ◽  
Outcome Data ◽  
Hospitalized Patients ◽  
Secondary Infections ◽  
Life Threatening ◽  
The Mean

Background: Secondary infections occur in 10-15% of critically ill sepsis patients. Anecdotal reports suggest secondary infections are common in coronavirus disease 2019 (COVID-19), however data are lacking. We examine the rate of secondary infections in hospitalized patients with COVID-19 and its impact on the cytokine surge and in-hospital outcomes. Methods: The Michigan Medicine Covid-19 Cohort (M2C2) is an ongoing prospective observational study in which detailed clinical, laboratory and outcome data were collected from chart review of consecutive adult patients hospitalized for COVID-19. Patients who were positive for SARS-CoV-2 infection but without respiratory symptoms were not included in this cohort. We define secondary infections as physician-diagnosed and treated bacterial or viral infections secondary to SARS-CoV-2. Results: Of 553 COVID-19 patients hospitalized at Michigan Medicine, 191 (34.5%) developed a secondary infection during hospitalization. The mean age of patients with a secondary infection was 60 years, 61.3% were male compared to 58.8 years, 53.5% male in patients with no secondary infection. Bacterial pneumonia, including ventilator-associated pneumonia, was the most prevalent secondary infection among hospitalized patients (78.5%). Other secondary infections included urosepsis (14.1%), bacteremia (16.8%), and 17.3% of patients developed other types of infections such as shingles and clostridium difficile. 25.8% of patients without secondary infections received antibiotics during their admission compared to 47.1% of patients with secondary infections. Multiple secondary infections (>1) occurred in 43 (8.2%) of patients. Patients with secondary infections were more likely to develop acute kidney injury (78.0% vs. 38.3%, p<0.0001), acute respiratory distress syndrome (78.0% vs. 22.3%, p<0.0001), and death (26.2% vs. 10.2%, p<0.0001) during their hospitalization compared to patients without secondary infections. Conclusions: Secondary infections are common in hospitalized patients with COVID-19 and are associated with life-threatening complications and high mortality. This study suggests that secondary infection prevention may be especially important in COVID-19 patients.

scholarly journals Transmission heterogeneities, kinetics, and controllability of SARS-CoV-2

Science ◽  
2020 ◽  
pp. eabe2424 ◽  
Author(s):  
Kaiyuan Sun ◽  
Wei Wang ◽  
Lidong Gao ◽  
Yan Wang ◽  
Kaiwei Luo ◽  
...  
Keyword(s):  
Social Interactions ◽  
Population Level ◽  
Transmission Risk ◽  
Contact Tracing ◽  
Symptom Presentation ◽  
Secondary Infections ◽  
The Family ◽  
Infectious Disease Dynamics ◽  
Kinetics Of

A long-standing question in infectious disease dynamics concerns the role of transmission heterogeneities, driven by demography, behavior and interventions. Based on detailed patient and contact tracing data in Hunan, China we find 80% of secondary infections traced back to 15% of SARS-CoV-2 primary infections, indicating substantial transmission heterogeneities. Transmission risk scales positively with the duration of exposure and the closeness of social interactions and is modulated by demographic and clinical factors. The lockdown period increases transmission risk in the family and households, while isolation and quarantine reduce risks across all types of contacts. The reconstructed infectiousness profile of a typical SARS-CoV-2 patient peaks just before symptom presentation. Modeling indicates SARS-CoV-2 control requires the synergistic efforts of case isolation, contact quarantine, and population-level interventions, owing to the specific transmission kinetics of this virus.

scholarly journals Health system resilience in managing the COVID-19 pandemic: lessons from Singapore

2020 ◽  
Vol 5 (9) ◽  
pp. e003317
Author(s):  
Alvin Qijia Chua ◽  
Melisa Mei Jin Tan ◽  
Monica Verma ◽  
Emeline Kai Lin Han ◽  
Li Yang Hsu ◽  
...  
Keyword(s):  
Health System ◽  
Migrant Worker ◽  
Health Service Delivery ◽  
Contact Tracing ◽  
Legal Foundation ◽  
Imported Cases ◽  
Rapid Transmission ◽  
At Risk Populations ◽  
System Resilience ◽  
The Government

Singapore, one of the first countries affected by COVID-19, adopted a national strategy for the pandemic which emphasised preparedness through a whole-of-nation approach. The pandemic was well contained initially until early April 2020, when there was a surge in cases, attributed to Singapore residents returning from hotspots overseas, and more significantly, rapid transmission locally within migrant worker dormitories. In this paper, we present the response of Singapore to the COVID-19 pandemic based on core dimensions of health system resilience during outbreaks. We also discussed on the surge in cases in April 2020, highlighting efforts to mitigate it. There was: (1) clear leadership and governance which adopted flexible plans appropriate to the situation; (2) timely, accurate and transparent communication from the government; (3) public health measures to reduce imported cases, and detect as well as isolate cases early; (4) maintenance of health service delivery; (5) access to crisis financing; and (6) legal foundation to complement policy measures. Areas for improvement include understanding reasons for poor uptake of government initiatives, such as the mobile application for contact tracing and adopting a more inclusive response that protects all individuals, including at-risk populations. The experience in Singapore and lessons learnt will contribute to pandemic preparedness and mitigation in the future.

Hymenolepis diminuta: changes in intestinal morphology and the enterochromaffin cell population associated with infection in male C57 mice

Parasitology ◽  
1990 ◽  
Vol 101 (1) ◽  
pp. 107-113 ◽  
Author(s):  
D. M. Mckay ◽  
D. W. Halton ◽  
C. F. Johnston ◽  
I. Fairweather ◽  
C. Shaw
Keyword(s):  
Secondary Infection ◽  
Intestinal Morphology ◽  
Hymenolepis Diminuta ◽  
Enterochromaffin Cell ◽  
Villus Height ◽  
Post Secondary ◽  
Crypt Depth ◽  
Secondary Infections ◽  
Ec Cells ◽  
Mucosal Surface Area

SUMMARYMean villus height, crypt depth and the number of 5-HT-positive enterochromaffin (EC) cells have been examined in two regions of the small intestine (20–30° and 60–70° distance from the pylorus) of male, 6 to 8-week-old, C57 mice following a 5-cysticercoid infection of the rat tapeworm, Hymenolepis diminuta. Test mice and sham-infected controls were autopsied 0, 4, 8, 10, 14 and 28 days post-primary infection (p-1°-i) and 2, 4, 5, 7 and 14 days post-secondary infection (p-2°-i), administered 28 days p-1°-i. Morphometric analysis revealed a statistically significant increase in crypt depth in the 60–70°o intestine region in infected mice during both primary and secondary infections; no significant deviation from the control was observed for villus height in infected mice. Statistical analysis showed a significant increase in the number of 5-HT-positive EC cells in infected mice. This response occurred in the lower portion of the intestine on days 10-p-1°-i and 5-p-2°-i, and was not due to increased mucosal surface area in this region. Results are discussed with reference to murine cestode rejection and the possible involvement therein of the neuroendocrine system.

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