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Journal of Microbiology, Immunology,... Feb 2021Since the outbreak of coronavirus disease 2019 (COVID-19) in late December 2019, it has brought significant harm and challenges to over 200 countries and regions around...
Since the outbreak of coronavirus disease 2019 (COVID-19) in late December 2019, it has brought significant harm and challenges to over 200 countries and regions around the world. However, there is increasing evidence that many patients with COVID-19 are asymptomatic or have only mild symptoms, but they are able to transmit the virus to others. There are difficulties in screening for asymptomatic infections, which makes it more difficult for national prevention and control of this epidemic. This article reviews the characteristics, treatment, and outcomes of asymptomatic infections with COVID-19, hoping it would be helpful for early prevention and control of this severe public health threat worldwide.
Topics: Asymptomatic Infections; COVID-19; COVID-19 Nucleic Acid Testing; Disease Outbreaks; Humans; SARS-CoV-2; Treatment Outcome
PubMed: 32425996
DOI: 10.1016/j.jmii.2020.05.001 -
Infectious Disease Clinics of North... Mar 2014Urinary tract infection (UTI) is a commonly diagnosed infection in older adults. Despite consensus guidelines developed to assist providers in diagnosing UTI,... (Review)
Review
Urinary tract infection (UTI) is a commonly diagnosed infection in older adults. Despite consensus guidelines developed to assist providers in diagnosing UTI, distinguishing symptomatic UTI from asymptomatic bacteriuria (ASB) in older adults is problematic, as many older adults do not present with localized genitourinary symptoms. This article summarizes the recent literature and guidelines on the diagnosis and management of UTI and ASB in older adults.
Topics: Aged; Algorithms; Anti-Bacterial Agents; Asymptomatic Infections; Bacteriuria; Humans; Middle Aged; Phytotherapy; Practice Guidelines as Topic; Proanthocyanidins; Risk Factors; Urinary Tract Infections; Vaccinium macrocarpon
PubMed: 24484576
DOI: 10.1016/j.idc.2013.10.004 -
Infectious Diseases of Poverty Jun 2020
Topics: Asymptomatic Infections; Betacoronavirus; COVID-19; China; Coronavirus Infections; Humans; Pandemics; Pneumonia, Viral; SARS-CoV-2
PubMed: 32564770
DOI: 10.1186/s40249-020-00679-2 -
Pathogens and Global Health Dec 2022Presently in India, high endemic zones of malaria are shifting towards low endemic zones and in this changing scenario, tackling the asymptomatic and low-density...
Presently in India, high endemic zones of malaria are shifting towards low endemic zones and in this changing scenario, tackling the asymptomatic and low-density infections (LDI) would be an important factor. Role of the asymptomatic and LDI in transmitting parasites successfully to mosquito vectors needs to be systematically investigated. We here highlight the limited work done on the burden of asymptomatic Plasmodium infections in India with an emphasis on its infectiousness, and infrastructure available for the detection of LDI. Studies reporting the threshold of gametocytes required for transmission of parasites are lacking for Indian malaria vectors. In the wake of malaria elimination target by 2030, specific point of care test is required to be developed for the detection of low density infections and/or asymptomatic patients. Also, mapping of asymptomatic malaria burden pan India and the role of LDI in vector infectivity would guide the way forward in achieving malaria elimination goal in India.
Topics: Animals; Humans; Malaria, Falciparum; Plasmodium falciparum; Malaria; Mosquito Vectors; India; Asymptomatic Infections
PubMed: 35979713
DOI: 10.1080/20477724.2022.2113304 -
Frontiers in Cellular and Infection... 2021Blocking malaria transmission is critical to malaria control programs but remains a major challenge especially in endemic regions with high levels of asymptomatic... (Review)
Review
Blocking malaria transmission is critical to malaria control programs but remains a major challenge especially in endemic regions with high levels of asymptomatic infections. New strategies targeting the transmissible sexual stages of the parasite, called gametocytes, are needed. This review focuses on gametocytogenesis and . Highlighting advances made elucidating genes required for gametocyte production and identifying key questions that remain unanswered such as the factors and regulatory mechanisms that contribute to gametocyte induction, and the mechanism of sequestration. Tools available to begin to address these issues are also described to facilitate advances in our understanding of this important stage of the life cycle.
Topics: Animals; Asymptomatic Infections; Life Cycle Stages; Malaria; Malaria, Falciparum; Plasmodium falciparum
PubMed: 34926328
DOI: 10.3389/fcimb.2021.790067 -
Mathematical Biosciences and... Jul 2022In this paper, we propose a new mathematical model to study the epidemic and economic consequences of COVID-19, with a focus on the interaction between the disease...
In this paper, we propose a new mathematical model to study the epidemic and economic consequences of COVID-19, with a focus on the interaction between the disease transmission, the pandemic management, and the economic growth. We consider both the symptomatic and asymptomatic infections and incorporate the effectiveness of disease control into the respective transmission rates. Meanwhile, the progression of the pandemic and the evolution of the susceptible, infectious and recovered population groups directly impact the mitigation and economic development levels. We fit this model to the reported COVID-19 cases and unemployment rates in the US state of Tennessee, as a demonstration of a real-world application of the modeling framework.
Topics: Asymptomatic Infections; COVID-19; Humans; Models, Economic; Pandemics; SARS-CoV-2
PubMed: 35942777
DOI: 10.3934/mbe.2022449 -
Public Health Feb 2022Countries throughout the world are experiencing COVID-19 viral load in their populations, leading to potential transmission and infectivity of asymptomatic COVID-19... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
Countries throughout the world are experiencing COVID-19 viral load in their populations, leading to potential transmission and infectivity of asymptomatic COVID-19 cases. The current systematic review and meta-analysis aims to investigate the role of asymptomatic infection and transmission reported in family clusters, adults, children and health care workers, globally.
STUDY DESIGN
Systematic review and meta-analysis.
METHODS
An online literature search of PubMed, Google Scholar, medRixv and BioRixv was performed using standard Boolean operators and included studies published up to 17 August 2021. For the systematic review, case reports, short communications and retrospective studies were included to ensure sufficient asymptomatic COVID-19 transmission data were reported. For the quantitative synthesis (meta-analysis), participant data from a collection of cohort studies focusing on groups of familial clusters, adults, children and health care workers were included. Inconsistency among studies was assessed using I statistics. The data synthesis was computed using the STATA 16.0 software.
RESULTS
This study showed asymptomatic transmission among familial clusters, adults, children and health care workers of 15.72%, 29.48%, 24.09% and 0%, respectively. Overall, asymptomatic transmission was 24.51% (95% confidence interval [CI]: 14.38, 36.02) among all studied population groups, with a heterogeneity of I = 95.30% (P < 0.001). No heterogeneity was seen in the population subgroups of children and health care workers. The risk of bias in all included studies was assessed using the Newcastle Ottawa Scale.
CONCLUSIONS
For minimising the spread of COVID-19 within the community, this study found that following the screening of asymptomatic cases and their close contacts for chest CT scan (for symptomatic patients), even after negative nucleic acid testing, it is essential to perform a rigorous epidemiological history, early isolation, social distancing and an increased quarantine period (a minimum of 14-28 days). This systematic review and meta-analysis supports the notion of asymptomatic COVID-19 infection and person-to-person transmission and suggests that this is dependent on the varying viral incubation period among individuals. Children, especially those of school age (i.e. <18 years), need to be monitored carefully and follow mitigation strategies (e.g. social distancing, hand hygiene, wearing face masks) to prevent asymptomatic community transmission of COVID-19.
Topics: Adult; Asymptomatic Infections; COVID-19; Child; Humans; Quarantine; Retrospective Studies; SARS-CoV-2
PubMed: 35038628
DOI: 10.1016/j.puhe.2021.12.003 -
International Journal of Infectious... Sep 2023The burden of asymptomatic dengue infections is understudied. Therefore, we systematically reviewed the literature to estimate the global prevalence of asymptomatic... (Meta-Analysis)
Meta-Analysis
OBJECTIVES
The burden of asymptomatic dengue infections is understudied. Therefore, we systematically reviewed the literature to estimate the global prevalence of asymptomatic dengue infections.
METHODS
We searched cross-sectional studies reporting the prevalence of asymptomatic dengue infections from PubMed, Scopus, and Embase. Prevalence of asymptomatic dengue infections was pooled and reported as proportions with a 95% confidence interval (CI). This systematic review protocol was a priori registered in The International Prospective Register of Systematic Reviews (Reg: No. CRD42020218446).
RESULTS
We included 41 studies with 131,953 cases in our analysis. The overall pooled prevalence of asymptomatic dengue infections was 59.26% (95% CI: 43.76-74.75, I = 99.93%), with 65.52% (95% CI: 38.73-92.32, I = 99.95%) during outbreaks and 30.78% (95% CI: 21.39-40.16, I = 98.78%) during non-outbreak periods. The pooled prevalence among the acutely infected individuals was 54.52% (95% CI: 17.73-46.76, I = 99.91%), whereas, among primary and secondary asymptomatic dengue infections, it was 65.36% (95% CI: 45.76-84.96, I = 98.82) and 48.99% (95% CI: 27.85-70.13, I = 99.08%) respectively.
CONCLUSION
The majority of dengue cases are asymptomatic and may play a significant role in disease transmission. Public health strategies aimed at dengue outbreak response and mitigation of disease burden should include early detection of asymptomatic cases.
Topics: Humans; Prevalence; Cross-Sectional Studies; Asymptomatic Infections; Coinfection; Dengue
PubMed: 37463631
DOI: 10.1016/j.ijid.2023.07.010 -
PloS One 2020The transmission of human norovirus excreted from infected persons occasionally causes sporadic infections and outbreaks. Both symptomatic patients and asymptomatic...
The transmission of human norovirus excreted from infected persons occasionally causes sporadic infections and outbreaks. Both symptomatic patients and asymptomatic carriers have been reported to contribute to norovirus transmission, but little is known about the magnitude of the contribution of asymptomatic carriers. We carried out a 1-year survey of residents of a district of Bangkok, Thailand to determine the percentage of norovirus transmissions originating from asymptomatic individuals. We screened 38 individuals recruited from 16 families from May 2018 to April 2019 for GI and GII genotypes. Norovirus was detected every month, and 101 of 716 stool samples (14.1%) from individuals with no symptoms of acute gastroenteritis were norovirus-positive. The average infection frequency was 2.4 times per person per year. Fourteen genotypes were identified from the positive samples, with GII.4 being detected most frequently. Notably, 89.1% of the norovirus-positive samples were provided by individuals with no diarrhea episode. Similar to cases of symptomatic infections in Thailand, asymptomatic infections were observed most frequently in December. We detected 4 cases of NV infection caused by household transmission, and 3 of the 4 transmissions originated from asymptomatic individuals. We also identified a case in which norovirus derived from an asymptomatic individual caused diarrhea in a family member. These results suggest that asymptomatic individuals play a substantial role in both the maintenance and spreading of norovirus in a community through household transmission.
Topics: Adolescent; Adult; Aged; Asymptomatic Infections; Caliciviridae Infections; Child; Diarrhea; Disease Outbreaks; Feces; Female; Gastroenteritis; Genotype; Humans; Male; Middle Aged; Norovirus; Phylogeny; RNA, Viral; Young Adult
PubMed: 32702014
DOI: 10.1371/journal.pone.0236502 -
Epidemiologic Reviews Jan 2019The epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) since 2012 has been largely characterized by recurrent zoonotic spillover from dromedary... (Review)
Review
The epidemiology of Middle East respiratory syndrome coronavirus (MERS-CoV) since 2012 has been largely characterized by recurrent zoonotic spillover from dromedary camels followed by limited human-to-human transmission, predominantly in health-care settings. The full extent of infection of MERS-CoV is not clear, nor is the extent and/or role of asymptomatic infections in transmission. We conducted a review of molecular and serological investigations through PubMed and EMBASE from September 2012 to November 15, 2018, to measure subclinical or asymptomatic MERS-CoV infection within and outside of health-care settings. We performed retrospective analysis of laboratory-confirmed MERS-CoV infections reported to the World Health Organization to November 27, 2018, to summarize what is known about asymptomatic infections identified through national surveillance systems. We identified 23 studies reporting evidence of MERS-CoV infection outside of health-care settings, mainly of camel workers, with seroprevalence ranges of 0%-67% depending on the study location. We identified 20 studies in health-care settings of health-care worker (HCW) and family contacts, of which 11 documented molecular evidence of MERS-CoV infection among asymptomatic contacts. Since 2012, 298 laboratory-confirmed cases were reported as asymptomatic to the World Health Organization, 164 of whom were HCWs. The potential to transmit MERS-CoV to others has been demonstrated in viral-shedding studies of asymptomatic MERS infections. Our results highlight the possibility for onward transmission of MERS-CoV from asymptomatic individuals. Screening of HCW contacts of patients with confirmed MERS-CoV is currently recommended, but systematic screening of non-HCW contacts outside of health-care facilities should be encouraged.
Topics: Adult; Aged; Asymptomatic Infections; Coronavirus Infections; Female; Humans; Male; Middle Aged; Middle East Respiratory Syndrome Coronavirus; Registries; World Health Organization
PubMed: 31781765
DOI: 10.1093/epirev/mxz009