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Frontiers in Cellular and Infection... 2023The clinical outcome of DENV and other Flaviviruses infections represents a spectrum of severity that ranges from mild manifestations to severe disease, which can... (Review)
Review
The clinical outcome of DENV and other Flaviviruses infections represents a spectrum of severity that ranges from mild manifestations to severe disease, which can ultimately lead to death. Nonetheless, most of these infections result in an asymptomatic outcome that may play an important role in the persistent circulation of these viruses. Also, although little is known about the mechanisms that lead to these asymptomatic infections, they are likely the result of a complex interplay between viral and host factors. Specific characteristics of the infecting viral strain, such as its replicating efficiency, coupled with host factors, like gene expression of key molecules involved in the immune response or in the protection against disease, are among crucial factors to study. This review revisits recent data on factors that may contribute to the asymptomatic outcome of the world's widespread DENV, highlighting the importance of silent infections in the transmission of this pathogen and the immune status of the host.
Topics: Humans; Dengue Virus; Dengue; Asymptomatic Infections; Flavivirus Infections; Flavivirus
PubMed: 38076464
DOI: 10.3389/fcimb.2023.1284651 -
Clinical Microbiology and Infection :... Jul 2016A detailed understanding of asymptomatic chronic viral infections is critical to analyse their pathogenesis, assess the severity and burden of disease and, where... (Review)
Review
A detailed understanding of asymptomatic chronic viral infections is critical to analyse their pathogenesis, assess the severity and burden of disease and, where required, optimize public health control measures. Recent studies on herpesviruses showed that the host-virus interactions are modulated by co-infections, emphasizing the relevance of co-infections in determining the clinical expression (from asymptomatic to symptomatic infections) and the severity of herpesvirus-associated diseases (either neoplastic or infectious diseases). To demonstrate causality between viruses (virome) and diseases, Koch's postulates should be adapted adding new knowledge on host-microbe relationship and microbial interactions. In the present review we aim to provide an update on asymptomatic chronic infections and criteria for causality and on the virological, immunological and host-virus interactions in asymptomatic chronic infections in human hosts, focusing on herpetic infections.
Topics: Asymptomatic Infections; Causality; Herpesviridae; Herpesviridae Infections; Humans; Microbiological Techniques; Microbiology; Microbiota
PubMed: 27450587
DOI: 10.1016/j.cmi.2016.07.016 -
Journal of Mathematical Biology Apr 2023We formulate a general age-of-infection epidemic model with two pathways: the symptomatic infections and the asymptomatic infections. We then calculate the basic...
We formulate a general age-of-infection epidemic model with two pathways: the symptomatic infections and the asymptomatic infections. We then calculate the basic reproduction number [Formula: see text] and establish the final size relation. It is shown that the ratio of accumulated counts of symptomatic patients and asymptomatic patients is determined by the symptomatic ratio f which is defined as the probability of eventually becoming symptomatic after being infected. We also formulate and study a general age-of-infection model with disease deaths and with two infection pathways. The final size relation is investigated, and the upper and lower bounds for final epidemic size are given. Several numerical simulations are performed to verify the analytical results.
Topics: Humans; Asymptomatic Infections; Epidemics; Basic Reproduction Number; Probability; Models, Biological
PubMed: 37154967
DOI: 10.1007/s00285-023-01920-w -
Journal of Advanced Research Jul 2022Different COVID-19 vaccine efficacies are reported, with remarkable effectiveness against severe disease. The so called sterilizing immunity, occurring when vaccinated...
INTRODUCTION
Different COVID-19 vaccine efficacies are reported, with remarkable effectiveness against severe disease. The so called sterilizing immunity, occurring when vaccinated individuals cannot transmit the virus, is still being evaluated. It is also unclear to what extent people with no symptoms or mild infection transmit the disease, and estimating their contribution to outbreaks is challenging.
OBJECTIVE
With an uneven roll out of vaccination, the purpose of this study is to investigate the role of mild and asymptomatic infections on COVID-19 vaccine performance as vaccine efficacy and vaccine coverage vary.
METHODS
We use an epidemiological SHAR (Susceptible-Hospitalized-Asymptomatic-Recovered) model framework to evaluate the effects of vaccination in different epidemiological scenarios of coverage and efficacy. Two vaccination models, the vaccine V protecting against severe disease, and the vaccine V, protecting against infection as well as severe disease, are compared to evaluate the reduction of overall infections and hospitalizations.
RESULTS
Vaccine performance is driven by the ability of asymptomatic or mild disease cases transmitting the virus. Vaccines protecting against severe disease but failing to block transmission might not be able to reduce significantly the severe disease burden during the initial stage of a vaccination roll out programme, with an eventual increase on the number of overall infections in a population.
CONCLUSION
The different COVID-19 vaccines currently in use have features placing them closer to one or the other of these two extreme cases, V and V, and insights on the importance of asymptomatic infection in a vaccinated population are of a major importance for the future planning of vaccination programmes. Our results give insights on how to best combine the use of the available COVID-19 vaccines, optimizing the reduction of hospitalizations.
Topics: Asymptomatic Infections; COVID-19; COVID-19 Vaccines; Humans; Vaccination; Vaccines
PubMed: 35777906
DOI: 10.1016/j.jare.2021.10.012 -
The American Journal of Tropical... Dec 2022Mapping asymptomatic malaria infections, which contribute to the transmission reservoir, is important for elimination programs. This analysis compared the spatiotemporal...
Mapping asymptomatic malaria infections, which contribute to the transmission reservoir, is important for elimination programs. This analysis compared the spatiotemporal patterns of symptomatic and asymptomatic Plasmodium falciparum malaria infections in a cohort study of ∼25,000 people living in a rural hypoendemic area of about 179 km2 in a small area of the Chittagong Hill Districts of Bangladesh. Asymptomatic infections were identified by active surveillance; symptomatic clinical cases presented for care. Infections were identified by a positive rapid diagnostic test and/or microscopy. Fifty-three subjects with asymptomatic P. falciparum infection were compared with 572 subjects with symptomatic P. falciparum between mid-October 2009 and mid-October 2012 with regard to seasonality, household location, and extent of spatial clustering. We found increased spatial clustering of symptomatic compared with asymptomatic infections, and the areas of high intensity were only sometimes overlapping. Symptomatic cases had a distinct seasonality, unlike asymptomatic infections, which were detected year-round. In a comparison of 42 symptomatic Plasmodium vivax and 777 symptomatic P. falciparum cases from mid-October 2009 through mid-March 2015, we found substantial spatial overlap in areas with high infection rates, but the areas with the greatest concentration of infection differed. Detection of both symptomatic P. falciparum and symptomatic P. vivax infections was greater during the May-to-October high season, although a greater proportion of P. falciparum cases occurred during the high season compared with P. vivax. These findings reinforce that passive malaria surveillance and treatment of symptomatic cases will not eliminate the asymptomatic reservoirs that occur distinctly in time and space.
Topics: Humans; Asymptomatic Infections; Plasmodium falciparum; Cohort Studies; Bangladesh; Prevalence; Malaria, Falciparum; Malaria, Vivax; Plasmodium vivax; Malaria
PubMed: 36122682
DOI: 10.4269/ajtmh.21-0121 -
Canadian Family Physician Medecin de... Nov 2018I am aware of how common pediatric urinary tract infection (UTI) is, and of the potential long-term sequelae if left untreated. Therefore, in our practice we treat... (Review)
Review
I am aware of how common pediatric urinary tract infection (UTI) is, and of the potential long-term sequelae if left untreated. Therefore, in our practice we treat every child who presents with symptomatic UTI with antibiotics. However, should the same practice be applied to children with bacteriuria that is asymptomatic? Historically, asymptomatic bacteriuria (ABU) was treated with antibiotics in all populations, including in children. However, more recent evidence has shown no benefit and often harm associated with the use of antibiotics to treat pediatric ABU. Some studies suggest that owing to the different microbiology associated with ABU it should not be considered in the spectrum of UTI. These children should not be treated with antibiotics unless they have received a renal transplant or have undergone invasive urologic procedures.
Topics: Anti-Bacterial Agents; Asymptomatic Infections; Bacteriuria; Child; Humans; Kidney Transplantation; Risk Assessment
PubMed: 30429177
DOI: No ID Found -
Journal of Clinical Virology : the... Jun 2022We clinically characterized PCR detected breakthrough infections among partially/fully vaccinated cases with majority given an inactivated vaccine, CoronaVac. From 1...
We clinically characterized PCR detected breakthrough infections among partially/fully vaccinated cases with majority given an inactivated vaccine, CoronaVac. From 1 March to 15 July 2021, we detected 182 SARS-CoV-2 infections among vaccinated cases with 129 classified as breakthrough infections. Majority were male, 30-39 y.o., and were asymptomatic or mildly symptomatic with few severe cases. Alpha, Beta and Delta VOCs were detected from sequenced breakthrough infections. Healthcare workers had significantly lower Ct values(higher viral loads) versus non-HCWs. Our results underscore the importance of regular PCR screening for HCWs due to the risk of SARS-CoV-2 transmission from asymptomatic breakthrough infections and provide evidence supporting administration of a booster dose especially to HCWs.
Topics: Asymptomatic Infections; COVID-19; COVID-19 Vaccines; Female; Humans; Male; Philippines; SARS-CoV-2
PubMed: 35413587
DOI: 10.1016/j.jcv.2022.105157 -
International Journal of Biological... 2021With ongoing research, it was found that asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was widespread in coronavirus disease 2019... (Review)
Review
With ongoing research, it was found that asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was widespread in coronavirus disease 2019 (COVID-19) populations. Studies have confirmed asymptomatic patients with COVID-19 have potential infectivity, and most of the transmission occurred before symptoms appear. Asymptomatic infection rates varied widely in different countries and regions. Identifying the asymptomatic infected persons and cutting off the infection source is an effective way to prevent the spread of this disease. However, asymptomatic patients have hidden clinical symptoms, and screening based only on the clinical symptoms of COVID-19 can easily lead to a missed diagnosis. Therefore, determining asymptomatic infection patients by SARS-CoV-2 nucleic acid testing is the gold standard. A series of prevention and control measures adopted by the Chinese government, especially the "Four Early" policy, have achieved outstanding achievements, which are worth learning from by other countries.
Topics: Asymptomatic Infections; COVID-19; China; Humans; SARS-CoV-2
PubMed: 33867834
DOI: 10.7150/ijbs.59374 -
Journal of Medical Virology Sep 2020On 31 March 2020, Chinese Health Authorization announced that numbers of asymptomatic cases with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection...
On 31 March 2020, Chinese Health Authorization announced that numbers of asymptomatic cases with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection will be made to the public daily. This was a very important step since different counties have different capacities for the detection of SARS-CoV-2 infection and control strategy for the Coronavirus Disease 2019 outbreak. We summarized the characteristics of asymptomatic SARS-CoV-2 infections and the transmission potential of asymptomatic cases. Then we provided guidelines for the management of asymptomatic cases through quarantine and nucleic acid/serology tests.
Topics: Asymptomatic Infections; COVID-19; China; Humans; Pandemics
PubMed: 32383171
DOI: 10.1002/jmv.25990 -
International Journal of Biological... 2020The existence of a substantial but unclear number of asymptomatic SARS-COV-2 patients worldwide has raised concerns among global public health authorities. In this... (Review)
Review
The existence of a substantial but unclear number of asymptomatic SARS-COV-2 patients worldwide has raised concerns among global public health authorities. In this review, according to the published literature, we provided the evidence that asymptomatic infections can result in person-to-person transmission. Four studies suggested that the virus can be transmitted by asymptomatic patients for at least two consecutive generations, indicating its strong infectivity. Asymptomatic infection tends to be, but is not only, identified among young people (<20 years old). The majority of asymptomatic patients appear to have a milder clinical course during hospitalization, but the severity of the symptoms of the secondary patients infected by SARS-COV-2 from asymptomatic patients varies with their physical constitution. The proportion of asymptomatic individuals among all confirmed cases widely differed (from 1.95% to 87.9%) according to the study setting and the populations studied. The increasing large-scale tests are expected to give more information about the true number of asymptomatic infections in the population. In China and other countries, various guidelines for management of asymptomatic cases have been issued. Importantly, early detection, early reporting, early isolation and early treatment of asymptomatic patients require the joint efforts of policy makers, clinicians, technicians, epidemiologists, virologists and patients.
Topics: Adolescent; Asymptomatic Infections; Betacoronavirus; COVID-19; COVID-19 Testing; Clinical Laboratory Techniques; Coronavirus Infections; Critical Illness; Hospitalization; Humans; Infection Control; Pandemics; Pneumonia, Viral; SARS-CoV-2; Young Adult
PubMed: 33061797
DOI: 10.7150/ijbs.48991