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International Journal of Environmental... Jan 2023Little is known about the long-term consequences of asymptomatic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to review the... (Meta-Analysis)
Meta-Analysis Review
Little is known about the long-term consequences of asymptomatic infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to review the data available to explore the long-term consequences of asymptomatic SARS-CoV-2 infection in the real world. We searched observational cohort studies that described the long-term health effects of asymptomatic SARS-CoV-2 infections. Random-effects inverse-variance models were used to evaluate the pooled prevalence (PP) and its 95% confidence interval (CI) of long-term symptoms. Random effects were used to estimate the pooled odds ratios (OR) and its 95%CI of different long-term symptoms between symptomatic and asymptomatic infections. Five studies involving a total of 1643 cases, including 597 cases of asymptomatic and 1043 cases of symptomatic SARS-CoV-2 infection were included in this meta-analysis. The PPs of long-term consequences after asymptomatic SARS-CoV-2 infections were 17.13% (95%CI, 7.55−26.71%) for at least one symptom, 15.09% (95%CI, 5.46−24.73%) for loss of taste, 14.14% (95%CI, −1.32−29.61%) for loss of smell, and 9.33% (95%CI, 3.07−15.60) for fatigue. Compared with symptomatic SARS-CoV-2 infection, asymptomatic infection was associated with a significantly lower risk of developing COVID-19-related sequelae (p < 0.05), with 80% lower risk of developing at least one symptom (OR = 0.20, 95%CI, 0.09−0.45), 81% lower risk of fatigue (OR = 0.19, 95%CI, 0.08−0.49), 90% lower risk of loss of taste/smell (OR = 0.10, 95%CI, 0.02−0.58). Our results suggested that there were long-term effects of asymptomatic SARS-CoV-2 infection, such as loss of taste or smell, fatigue, cough and so on. However, the risk of developing long-term symptoms in asymptomatic SARS-CoV-2 infected persons was significantly lower than those in symptomatic SARS-CoV-2 infection cases.
Topics: Humans; COVID-19; SARS-CoV-2; Ageusia; Asymptomatic Infections; Fatigue
PubMed: 36674367
DOI: 10.3390/ijerph20021613 -
Frontiers in Cellular and Infection... 2022Herein, we tested the hypothesis that Asymptomatic (Pv) infected individuals (Asym) feature different epidemiological, clinical and biochemical characteristics, as well...
INTRODUCTION
Herein, we tested the hypothesis that Asymptomatic (Pv) infected individuals (Asym) feature different epidemiological, clinical and biochemical characteristics, as well as hematological parameters, potentially predictive of clinical immunity in comparison to symptomatic Pv infected individuals (Sym).
METHODOLOGY
Between 2018 - 2021, we conducted 11 population screenings (PS, Day 0 (D0)) in 13 different riverine communities around Iquitos city, in the Peruvian Amazon, to identify Pv Sym and Asym individuals. A group of these individuals agreed to participate in a nested case - control study to evaluate biochemical and hematological parameters. Pv Asym individuals did not present common malaria symptoms (fever, headache, and chills), had a positive/negative microscopy result, a positive qPCR result, reported no history of antimalarial treatment during the last month, and were followed-up weekly until Day 21 (D21). Control individuals, had a negative malaria microscopy and qPCR result, no history of antimalarial treatment or malaria infections during the last three years, and no history of comorbidities or chronic infections.
RESULTS
From the 2159 individuals screened during PS, data revealed a low but heterogeneous Pv prevalence across the communities (11.4%), where most infections were Asym (66.7%) and submicroscopic (82.9%). A total of 29 Asym, 49 Sym, and 30 control individuals participated in the nested case - control study (n=78). Ten of the individuals that were initially Asym at D0, experienced malaria symptoms during follow up and therefore, were included in the Sym group. 29 individuals remained Asym throughout all follow-ups. High levels of eosinophils were found in Asym individuals in comparison to Sym and controls.
CONCLUSION
For the first-time, key epidemiological, hematological, and biochemical features are reported from Pv Asym infections from the Peruvian Amazon. These results should be considered for the design and reshaping of malaria control measures as the country moves toward malaria elimination.
Topics: Asymptomatic Infections; Humans; Malaria; Malaria, Vivax; Peru; Prevalence
PubMed: 36118037
DOI: 10.3389/fcimb.2022.901423 -
Journal of Medical Virology May 2023This study aimed to evaluate the effects of different vaccine regimens on mild and asymptomatic infections with SARS-CoV-2 Omicron BA.2 variant in Shanghai. All...
This study aimed to evaluate the effects of different vaccine regimens on mild and asymptomatic infections with SARS-CoV-2 Omicron BA.2 variant in Shanghai. All asymptomatic patients and those with mild symptoms of Omicron infections were recruited from three major Fangcang shelter hospitals between March 26, 2022 and May 20, 2022. Nucleic acid for SARS-CoV-2 by real-time reverse-transcription polymerase chain reaction methods in nasopharyngeal swabs was assessed every day during the hospitalization. The value of cycle threshold lower than 35 was considered as positive result of SARS-CoV-2. A total of 214 592 cases were included in this study. The proportion of the asymptomatic patients was 76.90% and 23.10% of the recruited patients had mild symptoms. The median (interquartile range [IQR]: 25-75) duration of viral shedding (DVS) was 7 (5-10) days among all participants. The DVS varied greatly among different age groups. Children and the elderly had longer DVS compared with the adults. The booster shot of inactivated vaccine contributed to the shorter DVS in patients aged ≥70 years compared with the unvaccinated patients (8 [6-11] vs. 9 [6-12] days, p = 0.002]. Full inactivated vaccine regimen contributed to the shorter DVS in patients aged 3-6 years (7 [5-9] vs. 8 [5-10] days, p = 0.001]. In conclusion, the full inactivated vaccine regimen on children aged 3-6 years and booster inactivated vaccine regimen on the elderly aged ≥70 years appeared to be effective in reducing DVS. The booster vaccine regimen should be rigorously promoted and implemented.
Topics: Adult; Child; Aged; Humans; Asymptomatic Infections; COVID-19; SARS-CoV-2; China; Vaccination
PubMed: 37212341
DOI: 10.1002/jmv.28767 -
BMC Infectious Diseases Sep 2023Although many studies on asymptomatic norovirus infection in outbreaks have been conducted globally, structured data (important for emergency management of outbreaks) on... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Although many studies on asymptomatic norovirus infection in outbreaks have been conducted globally, structured data (important for emergency management of outbreaks) on the prevalence of this epidemic are still not available. This study assessed the global prevalence of asymptomatic norovirus infection in outbreaks.
METHODS
We identified publications on asymptomatic infections from norovirus outbreaks by searching the PubMed, Embase, Cochrane Library, Medline, and Web of Science databases and screening references from the articles reviewed. Prevalence of asymptomatic norovirus infection in outbreaks was employed as the primary summary data. The random-effects model of the meta-analysis was fitted to generate estimates of the prevalence in the overall and subgroup populations.
RESULTS
In total, 44 articles with a sample size of 8,115 asymptomatic individuals were included. The estimated pooled prevalence of asymptomatic norovirus infection in outbreaks was 21.8% (95%CI, 17.4-27.3). The asymptomatic prevalence of norovirus GII (20.1%) was similar to that of GI (19.8%); however, the proportion prevalence of asymptomatic individuals involved in the former (33.36%) was significantly higher than that of in the latter (0.92%) and the former (93.18%) was reported much more frequently than the latter (15.91%) in the included articles. These studies had significant heterogeneity (I = 92%, τ = 0.4021, P < 0.01). However, the source of heterogeneity could not be identified even after subgroup analysis of 10 possible influencing factors (geographical area, outbreak settings, outbreak seasons, sample types, norovirus genotypes, transmission routes, subjects' occupations, subjects' age, per capita national income, and clear case definition). Meta-regression analysis of these 10 factors demonstrated that the geographical area could be partly responsible for this heterogeneity (P = 0.012).
CONCLUSIONS
The overall pooled asymptomatic prevalence of norovirus in outbreaks was high, with genome II dominating. Asymptomatic individuals may play an important role in norovirus outbreaks. This knowledge could help in developing control strategies and public health policies for norovirus outbreaks.
Topics: Humans; Asymptomatic Infections; Prevalence; Disease Outbreaks; Epidemics; Norovirus
PubMed: 37700223
DOI: 10.1186/s12879-023-08519-y -
Scientific Reports Jun 2023Asymptomatic Plasmodium infection raises a problem for the persistent transmission of malaria in low-endemic areas such as Asia. This systematic review was undertaken to... (Meta-Analysis)
Meta-Analysis
Asymptomatic Plasmodium infection raises a problem for the persistent transmission of malaria in low-endemic areas such as Asia. This systematic review was undertaken to estimate the prevalence and proportion of asymptomatic Plasmodium infection in Asia. The systematic review was registered at PROSPERO (ID: CRD42022373664). The research followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A comprehensive search of five databases, Ovid, Scopus, MEDLINE, PubMed, and Embase, was conducted to identify studies of asymptomatic Plasmodium infection in Asian countries. The pooled prevalence of asymptomatic Plasmodium infection, the pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals, and the associated 95% confidence intervals were estimated using a random-effects model. A total of 916 articles were retrieved, and 87 articles that met the criteria were included in the systematic review. The pooled prevalence of asymptomatic Plasmodium infection among enrolled participants in Southeast Asia, South Asia, and Western Asia was 5.8%, 9.4%, and 8.4%, respectively. The pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals in Southeast Asia, South Asia, and Western Asia was 89.3%, 87.2%, and 64.8%, respectively. There was a low prevalence of asymptomatic Plasmodium infection, but there was a high proportion of asymptomatic Plasmodium infection per all parasitised individuals in different parts of Asia. These results may support and facilitate elimination and control programs for asymptomatic Plasmodium infection in Asia.
Topics: Humans; Malaria, Falciparum; Prevalence; Malaria; Plasmodium; Asia; Asymptomatic Infections
PubMed: 37369862
DOI: 10.1038/s41598-023-37439-9 -
MEDICC Review Jan 2022The percentage of asymptomatic COVID-19 cases worldwide is estimated at 18-50%; 53% in Cuba specifically, and 58% in Havana, the Cuban capital and the 2020 epicenter of...
INTRODUCTION
The percentage of asymptomatic COVID-19 cases worldwide is estimated at 18-50%; 53% in Cuba specifically, and 58% in Havana, the Cuban capital and the 2020 epicenter of the country's COVID-19 epidemic. These figures, however, do not represent the transmission capacity or behavior of asymptomatic cases. Understanding asymptomatic transmission's contribution to SARS-CoV-2 spread is of great importance to disease control and prevention.
OBJECTIVE
Identify the epidemiological implications of asymptomatic SARS-CoV-2 infection in Havana, Cuba, during the first wave of the epidemic in 2020.
METHODS
We carried out a cross-sectional study of all confirmed COVID-19 cases diagnosed in Havana, Cuba, from March 16 through June 30, 2020. The information was obtained through review of the standardized form for investigation of suspected and confirmed cases. Examined variables included age, sex, occupation, case type and source of infection. Cases were divided into asymptomatic and symptomatic groups, and transmission was characterized through the creation of a contact matrix. Analysis was carried out in Epidat and R.
RESULTS
We studied 1287 confirmed cases, of which 57.7% (743) were asymptomatic, and 42.3% (544) were symptomatic. Symptomatic presentation was the most common for both imported and introduced cases, while asymptomatic presentation was more common in autochthonic cases and infections from an undetermined source. Asymptomatic infection was more common in groups aged ⟨20 and 20-59 years, while symptomatic infection was more common in those aged ⟩60 years. In the contact matrix, 34.6% of cases (445/1287) were not tied to other cases, and 65.4% (842/1287) were infectious-infected dyads, with symptomatic-symptomatic being the most common combination. The majority of primary cases (78.5%; 1002/1276) did not generate secondary cases, and 85.6% (658/743) of asymptomatic cases did not lead to other cases (although one asymptomatic superspreader led to 90 cases in a single event). However, 63.2% (344/544) of symptomatic primary cases generated secondary cases, and 11 symptomatic superspreaders spawned 100 secondary cases in different events.
CONCLUSIONS
Asymptomatic SARS-CoV-2 infection was the most common form of COVID-19 in Havana during the study period, but its capacity for contagion was lower than that of symptomatic individuals. Superspreader events under specific conditions played an important role in sustaining the epidemic.
Topics: Aged; Asymptomatic Infections; COVID-19; Cross-Sectional Studies; Cuba; Humans; SARS-CoV-2
PubMed: 35157635
DOI: 10.37757/MR2022.V24.N1.4 -
Trends in Parasitology Mar 2021The last malaria parasite standing will display effective adaptations to selective forces. While substantial progress has been made in reducing malaria mortality,... (Review)
Review
The last malaria parasite standing will display effective adaptations to selective forces. While substantial progress has been made in reducing malaria mortality, eradication will require elimination of all Plasmodium parasites, including those in asymptomatic infections. These typically chronic, low-density infections are difficult to detect, yet can persist for months. We argue that asymptomatic infection is the parasite's best asset for survival but it can be exploited if studied as a new model for host-pathogen-vector interactions. Regular sampling from cohorts of asymptomatic individuals can provide a means to investigate continuous parasite development within its natural host. State-of-the-art techniques can now be applied to such infections. This approach may reveal key molecular drivers of chronic infections - a critical step for malaria eradication.
Topics: Animals; Asymptomatic Infections; Chronic Disease; Disease Eradication; Host-Parasite Interactions; Humans; Malaria; Plasmodium
PubMed: 33127332
DOI: 10.1016/j.pt.2020.09.017 -
Infectious Disease Clinics of North... Jun 2024Asymptomatic bacteriuria is common, but usually benign. Inappropriate antimicrobial treatment of asymptomatic bacteriuria contributes to negative antimicrobial outcomes.... (Review)
Review
Asymptomatic bacteriuria is common, but usually benign. Inappropriate antimicrobial treatment of asymptomatic bacteriuria contributes to negative antimicrobial outcomes. Optimizing antimicrobial use for bacteriuria is a component of antimicrobial stewardship programs and includes key practices of dissemination and implementation of guidelines, laboratory practices which support stewardship, and programs to monitor and implement optimal antimicrobial treatment for urinary infection. These activities vary in their effectiveness, costs, and complexity to institute. Stewardship strategies targeting unique populations with a high prevalence of bacteriuria and for whom symptom assessment is not straightforward need to be further developed and evaluated to support optimal stewardship.
Topics: Humans; Bacteriuria; Anti-Bacterial Agents; Antimicrobial Stewardship; Asymptomatic Infections; Urinary Tract Infections
PubMed: 38575492
DOI: 10.1016/j.idc.2024.03.005 -
Malaria Journal Jun 2019Malaria eradication globally is yet to be achieved and transmission is sustained in many endemic countries. Plasmodium falciparum continues to develop resistance to...
BACKGROUND
Malaria eradication globally is yet to be achieved and transmission is sustained in many endemic countries. Plasmodium falciparum continues to develop resistance to currently available anti-malarial drugs, posing great problems for malaria elimination. This study evaluates the frequencies of asymptomatic infection and multidrug resistance-1 (mdr-1) gene mutations in parasite isolates, which form the basis for understanding persistently high incidence in South West, Nigeria.
METHODS
A total of 535 individuals aged from 6 months were screened during the epidemiological survey evaluating asymptomatic transmission. Parasite prevalence was determined by histidine-rich protein II rapid detection kit (RDT) in healthy individuals. Plasmodium falciparum mdr-1 gene mutations were detected by polymerase chain reaction (PCR) followed by restriction enzyme digest and electrophoresis to determine polymorphism in parasite isolates. Sequencing was done to confirm polymorphism. Proportions were compared using Chi-square test at p value < 0.05.
RESULTS
Malaria parasites were detected by RDT in 204 (38.1%) individuals. Asymptomatic infection was detected in 117 (57.3%) and symptomatic malaria confirmed in 87 individuals (42.6%). Overall, individuals with detectable malaria by RDT was significantly higher in individuals with symptoms, 87 of 197 (44.2%), than asymptomatic persons; 117 of 338 (34.6%), p = 0.02. In a sub-set of 75 isolates, 18(24%) and 14 (18.6%) individuals had Pfmdr1 86Y and 1246Y mutations.
CONCLUSIONS
There is still high malaria transmission rate in Nigeria with higher incidence of asymptomatic infections. These parasites harbour mutations on Pfmdr1 which contribute to artemisinin partner drug resistance; surveillance strategies to reduce the spread of drug resistance in endemic areas are needed to eliminate the reservoir of malaria parasites that can mitigate the eradication of malaria in Nigeria.
Topics: Asymptomatic Infections; Incidence; Malaria, Falciparum; Multidrug Resistance-Associated Proteins; Mutation; Nigeria; Plasmodium falciparum; Prevalence
PubMed: 31248414
DOI: 10.1186/s12936-019-2833-8 -
Veterinary Parasitology Oct 2020Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and... (Review)
Review
Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, control, and genetic diversity of T. gondii in sheep in the past decade. There is debate and uncertainty concerning repeat congenital infection as evidenced by finding T. gondii DNA in progeny of chronically infected sheep. However, there is no concrete evidence that T. gondii is the cause of repeated abortions in sheep. Recent data concerning pathogenesis of abortion in acutely infected sheep are reviewed. PCR-RFLP typing of T. gondii DNA derived from viable T. gondii isolates or tissues of infected sheep revealed low genetic diversity in sheep in Europe, Africa, Asia and North America but high diversity in South America. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.
Topics: Animals; Asymptomatic Infections; Prevalence; Sheep; Sheep Diseases; Sheep, Domestic; Toxoplasma; Toxoplasmosis, Animal
PubMed: 32979682
DOI: 10.1016/j.vetpar.2020.109195