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Epidemiology and Infection Jun 2020At the present time, COVID-19 is spreading rapidly [1]. The global prevention and control of COVID-19 is focused on the estimation of the relevant incubation period,...
At the present time, COVID-19 is spreading rapidly [1]. The global prevention and control of COVID-19 is focused on the estimation of the relevant incubation period, basic reproduction number (R0), effective reproduction number (Rt) and death risk. Although the prevention and control of COVID-19 requires a reliable estimation of the relevant incubation period, R0, Rt and death risk. Another key epidemiological parameter-asymptomatic ratio that provides strength and range for social alienation strategies of COVID-19, which is widely defined as the proportion of asymptomatic infections among all disease infections. In fact, the ratio of asymptomatic infection is a useful indicator of the burden of disease and a better measurement of the transmissibility of the virus. So far, people have not paid enough attention to asymptomatic carriers. The asymptomatic carriers discussed in this study are recessive infections, that is, those who have never shown symptoms after onset of infection. We will discuss three aspects: detection, infectivity and proportion of healthy carriers.
Topics: Asymptomatic Infections; COVID-19; China; Contact Tracing; Coronavirus Infections; Female; Humans; Male; Pandemics; Pneumonia, Viral
PubMed: 32525469
DOI: 10.1017/S0950268820001235 -
Frontiers in Public Health 2022The comprehensive understanding of the characteristics of asymptomatic cases are helpful for the identification and management of patients with asymptomatic COVID-19... (Meta-Analysis)
Meta-Analysis
UNLABELLED
The comprehensive understanding of the characteristics of asymptomatic cases are helpful for the identification and management of patients with asymptomatic COVID-19 infection. Four electronic databases were searched from December 1, 2019 to February 8, 2022 for relevant articles. Data synthesis, subgroup analysis, and sensitivity analysis were performed on the included studies. and Q tests were applied to evaluate heterogeneity across studies. The risk of publication bias was assessed and visualized using a funnel plot. A total of 45 studies consisting of 2,655 patients with no symptoms at the screening point were included. Pooled results showed that in China, 65% of initial no-symptoms COVID-19 patients did not present any COVID-19-related symptom during follow-up or by end of disease course (asymptomatic infections). High proportions of initial no-symptoms COVID-19 patients (76%) and patients with asymptomatic infection (55%) had abnormal CT features at the screening point. High proportion of patients with asymptomatic infection had been detected Ig G (72%) and/or Ig M (57%) at the screening point. The chest CT scan and SARS-CoV-2-specific antibody testing could serve as effective supplementary methods to identify asymptomatic cases in the early stage of SARS-CoV-2 infection. However, the chest CT scan and the SARS-CoV-2-specific IgM and IgG testing should not replace reverse transcription-polymerase chain reaction (RT-PCR) for screening in asymptomatic patients. The combination of repeated RT-PCR, chest CT scans, and the SARS-CoV-2-specific IgM and IgG testing should be performed for those highly suspected SARS-CoV-2 infections.
SYSTEMATIC REVIEW REGISTRATION
https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier: CRD 42021261130.
Topics: Antibodies, Viral; Asymptomatic Infections; COVID-19; Humans; Immunoglobulin G; Immunoglobulin M; SARS-CoV-2
PubMed: 35433622
DOI: 10.3389/fpubh.2022.808471 -
BMJ (Clinical Research Ed.) Jul 2021
Topics: Asymptomatic Infections; COVID-19; COVID-19 Testing; Humans; SARS-CoV-2
PubMed: 34233894
DOI: 10.1136/bmj.n1733 -
The Cochrane Database of Systematic... Feb 2018Asymptomatic bacteriuria, defined as bacteriuria without signs or symptoms of urinary tract infection (UTI), occurs in 17% to 51% of kidney transplant recipients and is... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Asymptomatic bacteriuria, defined as bacteriuria without signs or symptoms of urinary tract infection (UTI), occurs in 17% to 51% of kidney transplant recipients and is thought to increase the risk for a subsequent UTI. No consensus exists on the role of antibiotics for asymptomatic bacteriuria in kidney transplantation.
OBJECTIVES
To assess the benefits and harms of treating asymptomatic bacteriuria in kidney transplant recipients with antimicrobial agents to prevent symptomatic UTI, all-cause mortality and the indirect effects of UTI (acute rejection, graft loss, worsening of graft function).
SEARCH METHODS
We searched the Cochrane Kidney and Transplant Register of Studies up to 1 September 2017 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.
SELECTION CRITERIA
All randomised controlled trials (RCTs) and quasi-RCTs in any language assessing treatment of asymptomatic bacteriuria in kidney transplant recipients at any time-point after transplantation.
DATA COLLECTION AND ANALYSIS
Two authors independently determined study eligibility, assessed quality and extracted data. Primary outcomes were incidence of symptomatic UTI and incidence of antimicrobial resistance. Other outcomes included incidences of all-cause mortality, graft loss, graft rejection, graft function, hospitalisation for UTI, adverse reactions to antimicrobial agents and relapse or persistence of asymptomatic bacteriuria. We expressed dichotomous outcomes as absolute risk difference (RD) or risk ratio (RR) with 95% confidence intervals (CI) and continuous data as mean differences (MD) with 95% CI. Data were pooled using the random effects model.
MAIN RESULTS
We included two studies (212 participants) comparing antibiotics versus no treatment, and identified three on-going studies. Overall, incidence of symptomatic UTI varied between 19% and 31% in the groups not treated for asymptomatic bacteriuria. Antibiotic treatment had uncertain effects on preventing symptomatic UTI (2 studies, 200 participants: RR 0.86, 95% CI 0.51 to 1.45). Risk for selecting multidrug-resistant organisms was uncertain with antibiotic treatment (1 study, 112 participants: RR 1.21, 95% CI 0.60 to 2.41). Persistence of asymptomatic bacteriuria was high regardless of treatment. Antibiotics also have uncertain effects on other important patient and graft outcomes, for instance on all-cause mortality (1 study, 112 participants: RR 2.23, 95% CI 0.21 to 23.86), graft loss (1 study, 112 participants: RR 1.11, 95% CI 0.07 to 17.36), acute rejection (1 study, 112 participants: RR 0.93, 95% CI 0.44 to 1.97), hospitalisation for UTI (1 study, 112 participants: RR 0.74, 95% CI 0.13 to 4.27), graft function (2 studies, 200 participants, MD in serum creatinine concentration -0.06 mg/dL, 95% CI -0.19 to 0.08) and adverse reactions (1 study, 112 participants: no severe adverse event attributable to the antibiotic treatment). Evidence quality was low for all outcomes.
AUTHORS' CONCLUSIONS
Currently, there is insufficient evidence to support routinely treating kidney transplant recipients with antibiotics in case of asymptomatic bacteriuria after transplantation, but data are scarce. Further studies assessing routine antibiotic treatment would inform practice and we await the results of three ongoing randomised studies, which may help resolve existing uncertainties.
Topics: Anti-Bacterial Agents; Asymptomatic Infections; Bacteriuria; Cause of Death; Drug Resistance, Bacterial; Graft Rejection; Humans; Kidney; Kidney Transplantation; Randomized Controlled Trials as Topic; Transplant Recipients; Urinary Tract Infections
PubMed: 29390169
DOI: 10.1002/14651858.CD011357.pub2 -
International Journal of Biological... 2022Asymptomatic infection with SARS-CoV-2 is a major concern in the control of the COVID-19 pandemic. Many questions concerning asymptomatic infection remain to be...
Asymptomatic infection with SARS-CoV-2 is a major concern in the control of the COVID-19 pandemic. Many questions concerning asymptomatic infection remain to be answered, for example, what are the differences in infectivity and the immune response between asymptomatic and symptomatic infections? In this study, based on a cohort established by the Wuchang District Health Bureau of Wuhan in the early stage of the COVID-19 pandemic in Wuhan in 2019, we conducted a comprehensive analysis of the clinical, virological, immunological, and epidemiological data of asymptomatic infections. The major findings of this study included: 1) the asymptomatic cohort enrolled this study exhibited low-grade but recurrent activity of viral replication; 2) despite a lack of overt clinical symptoms, asymptomatic infections exhibited ongoing innate and adaptive immune responses; 3) however, the immune response from asymptomatic infections was not activated adequately, which may lead to delayed viral clearance. Given the fragile equilibrium between viral infection and host immunity, and the delayed viral clearance in asymptomatic individuals, close viral monitoring should be scheduled, and therapeutic intervention may be needed.
Topics: Asymptomatic Infections; COVID-19; Humans; Immunity; Immunity, Innate; Pandemics; SARS-CoV-2
PubMed: 35874943
DOI: 10.7150/ijbs.72963 -
PloS One 2018In the Greater Mekong Sub-region (GMS), malaria elimination efforts are targeting the asymptomatic parasite reservoirs. Understanding community perceptions about...
BACKGROUND
In the Greater Mekong Sub-region (GMS), malaria elimination efforts are targeting the asymptomatic parasite reservoirs. Understanding community perceptions about asymptomatic malaria infections and interventions that target this reservoir is critical to the design of community engagement. This article examines knowledge, attitudes, perceptions and practices related to asymptomatic malaria infections and mass drug administration (MDA) in malaria-endemic villages in southern Savannakhet Province, Laos.
METHODS
A questionnaire consisting of questions on socio-demographic characteristics, knowledge, attitudes, perceptions and practices on malaria and MDA was administered to each household head or representative (n = 281) in four villages. These topics were also further discussed in 12 single-gender focus group discussions (FGDs). The FGDs were conducted in all four villages and consisted of eight to 10 participants.
RESULTS
A minority (14.2%; 40/281) of respondents agreed that a seemingly healthy person could have malaria parasite in his or her blood. Half (52%; 146/281) disagreed and one third (33.8%, 95/281) were unsure. Respondents who responded that "MDA aims to cure everyone" [AOR = 4.6; CI: 1.6-13.1], "MDA is to make our community malaria free" [AOR = 3.3; CI: 1.3-8.1] and "I will take part in future MDA" [AOR = 9.9; CI: 1.2-78.8] were more likely to accept the idea of asymptomatic malaria. During FGDs, respondents recalled signs and symptoms of malaria (fever, chills and headache), and described malaria as a major health problem. Symptomatic and asymptomatic malaria infections were associated with their work in the forest and living conditions. Measures described to eliminate malaria included using mosquito nets, wearing long-sleeved clothes and taking medicine when symptomatic. Most respondents were unaware of MDA as a tool to eliminate malaria.
CONCLUSIONS
Awareness of asymptomatic malaria infections, and MDA as a tool to eliminate malaria, was low. With the need to target asymptomatic malaria carriers for elimination efforts in the GMS, as well as informing target groups about asymptomatic infection, accompanying community engagement must build trust in interventions through the active collaboration of government stakeholders, key local persons and community members. This entails training and devolving responsibilities to the community members to implement and sustain the control and elimination efforts.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antimalarials; Asymptomatic Infections; Disease Reservoirs; Female; Health Knowledge, Attitudes, Practice; Humans; Laos; Malaria; Male; Middle Aged; Minority Groups; Mosquito Nets; Surveys and Questionnaires; Young Adult
PubMed: 30533024
DOI: 10.1371/journal.pone.0208912 -
Scientific Reports Apr 2022The COVID-19 pandemic has posed significant challenges in modeling its complex epidemic transmissions, infection and contagion, which are very different from known...
The COVID-19 pandemic has posed significant challenges in modeling its complex epidemic transmissions, infection and contagion, which are very different from known epidemics. The challenges in quantifying COVID-19 complexities include effectively modeling its process and data uncertainties. The uncertainties are embedded in implicit and high-proportional undocumented infections, asymptomatic contagion, social reinforcement of infections, and various quality issues in the reported data. These uncertainties become even more apparent in the first 2 months of the COVID-19 pandemic, when the relevant knowledge, case reporting and testing were all limited. Here we introduce a novel hybrid approach SUDR by expanding the foundational compartmental epidemic Susceptible-Infected-Recovered (SIR) model with two compartments to a Susceptible-Undocumented infected-Documented infected-Recovered (SUDR) model. First, SUDR (1) characterizes and distinguishes Undocumented (U) and Documented (D) infections commonly seen during COVID-19 incubation periods and asymptomatic infections. Second, SUDR characterizes the probabilistic density of infections by capturing exogenous processes like clustering contagion interactions, superspreading, and social reinforcement. Lastly, SUDR approximates the density likelihood of COVID-19 prevalence over time by incorporating Bayesian inference into SUDR. Different from existing COVID-19 models, SUDR characterizes the undocumented infections during unknown transmission processes. To capture the uncertainties of temporal transmission and social reinforcement during COVID-19 contagion, the transmission rate is modeled by a time-varying density function of undocumented infectious cases. By sampling from the mean-field posterior distribution with reasonable priors, SUDR handles the randomness, noise and sparsity of COVID-19 observations widely seen in the public COVID-19 case data. The results demonstrate a deeper quantitative understanding of the above uncertainties, in comparison with classic SIR, time-dependent SIR, and probabilistic SIR models.
Topics: Asymptomatic Infections; Bayes Theorem; COVID-19; Humans; Pandemics; Reinforcement, Social; SARS-CoV-2
PubMed: 35393500
DOI: 10.1038/s41598-022-09879-2 -
Acta Tropica Sep 2019Despite relatively successful control campaigns, malaria remains a relevant public health problem in the Peruvian Amazon. Several studies suggest that malaria...
Modeling asymptomatic infections and work-related human circulation as drivers of unstable malaria transmission in low-prevalence areas: A study in the Northern Peruvian Amazon.
BACKGROUND
Despite relatively successful control campaigns, malaria remains a relevant public health problem in the Peruvian Amazon. Several studies suggest that malaria persistence in the area can be connected with a high prevalence of asymptomatic infections, which were subsequently shown to be connected with work-related exposure in areas of hyperendemic transmission. In this study, we tested the hypothesis that the infection reservoir represented by asymptomatic carriers in the northern Peruvian Amazon, combined with circular human movement to and from hyperendemic working areas, can capture the observed hypoendemic malaria transmission.
METHODS
We designed a set of agent-based models that represent local-scale malaria transmission in a typical riverine community in the northern Peruvian Amazon. The models include asymptomatic individuals as well as a full representation of human movements within the community and between the community and external hyperendemic working places. Several theoretical scenarios are explored to verify if and how malaria clinical immunity prevalence and human work-related movements influence the malaria morbidity registered in the community.
RESULTS
Agent-based simulations suggest that malaria incidence observed through passive case detection can be reproduced as exclusively generated by the asymptomatic infection reservoir. Scenarios analysis also show that, even if asymptomatic infections are completely eliminated, human movements to and from hyperendemic working areas generate a flow of imported cases that is enough to permit the persistence of transmission in the community. Simulation results were verified over a wide range of clinical immunity prevalence values and over a wide range of percentages of people working in remote hyperendemic areas. This context of unstable malaria transmission is observed to be vulnerable to severe outbreaks.
CONCLUSIONS
Asymptomatic malaria infection and occupational circular human movement to hyperendemic transmission areas are designated by agent-based models as possible exclusive causes of residual hypoendemic malaria transmission observed in the Peruvian Amazon. Control strategies are proposed to decrease asymptomatic infection prevalence and to block transmission from asymptomatic individuals to the malaria susceptible population.
Topics: Asymptomatic Infections; Disease Reservoirs; Humans; Incidence; Malaria; Models, Biological; Occupational Diseases; Peru; Plasmodium falciparum; Prevalence; Transients and Migrants
PubMed: 30703339
DOI: 10.1016/j.actatropica.2019.01.022 -
PloS One 2020The aims of this study were to investigate the prevalence and proportion of laboratory-confirmed urethral Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG)...
The aims of this study were to investigate the prevalence and proportion of laboratory-confirmed urethral Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections that were asymptomatic among individuals presenting to clinics in Shenzhen and the risk factors related to asymptomatic CT infection. In a cross-sectional study, eligible individuals were invited to participate in the questionnaire, and urine specimens were collected to identify CT and NG infections using a nucleic acid amplification test (NAAT). Considering the differences in the presentation of symptoms between men and women, this study was stratified by gender. Corresponding outcomes were analyzed by Chi-square test and multivariate logistic regression. A total of 2,871 participants were asymptomatic and included in our analyses: 1120 (39.0%) men and 1751 (61.0%) women. The prevalence of asymptomatic NG and CT infections was 0.9% and 6.2% in men, and 0.4% and 7.9% in women, respectively. The proportion of asymptomatic urethral CT among men with urethral CT was 28.3%; for women, it was 34.2%. For asymptomatic men with CT, 3 independent risk factors were identified: (1) men under the age of 30 (aOR, 1.83; 95% CI, 1.11-3.03); (2) being employed in the commercial service work (2.82; 1.36-5.84); and (3) being recruited through the urological department (2.12; 1.19-3.79). For asymptomatic women with urethral CT, age less than 30 years was a risk factor. In conclusion, a substantial prevalence of asymptomatic CT infections was found among men and women presenting to clinics in Shenzhen. The significant correlation between asymptomatic CT infection and these risk factors could help identify high-risk populations and guide screening.
Topics: Adult; Ambulatory Care Facilities; Asymptomatic Infections; China; Chlamydia Infections; Chlamydia trachomatis; Cross-Sectional Studies; Female; Gonorrhea; Humans; Male; Neisseria gonorrhoeae; Prevalence; Risk Factors; Sex Distribution
PubMed: 32516318
DOI: 10.1371/journal.pone.0234261 -
JAMA Jun 2021This study aims to describe an association between the Pfizer-BioNTech (BNT162b2) vaccine and decreased risk of symptomatic and asymptomatic infections with SARS-CoV-2...
This study aims to describe an association between the Pfizer-BioNTech (BNT162b2) vaccine and decreased risk of symptomatic and asymptomatic infections with SARS-CoV-2 in hospital employees.
Topics: Adult; Aged; Asymptomatic Infections; BNT162 Vaccine; COVID-19; COVID-19 Vaccines; Female; Humans; Male; Mass Screening; Middle Aged; Personnel, Hospital; Retrospective Studies
PubMed: 33956050
DOI: 10.1001/jama.2021.6564