Proportion Of Asymptomatic Cases Research Articles

The Proportion of Asymptomatic Cases Among SARS-CoV-2 Infected Patients: A Systematic Review

Even though some reports unveiled that coronavirus 2019 (COVID-19) cases can be manifested as asymptomatic, there is limited information on how much these cases are significant. Understanding the possible proportion of asymptomatic cases among confirmed patients might help in re-considering of who should be tested for the SARS-CoV-2 infection. Therefore, this study was aimed to summarize the proportion of asymptomatic cases among SARS-COV-2 infected people since the outbreak of COVID-19. <i>Methods</i>: Different studies were searched from databases (PubMed, Medline) by using searching terms. Finally, all eligible articles were selected by using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2009 flow diagram. <i>Results</i>: A total of 14 articles that reported asymptomatic cases of COVID-19 were included in this systematic review. The sample size of the studies was ranged from 8 to 2143. Out of the total cases, the overall proportion of asymptomatic cases was 25.9% that ranged from 3.23% to 78%. This systematic review also summarized that there was 17. 6%, 4.8%, and 3.23% to 62.2% of asymptomatic cases among pregnant mothers, children, and the adult general population, respectively. <i>Conclusion and Remarks</i>: This review showed that the proportion of asymptomatic SARS-CoV-2 infected people is high. Hence, to tackle COVID-19, all concerned bodies should strengthen the screening of asymptomatic cases as part of contact tracing efforts.

GLOBAL RESPIRATORY ILLNESS OUTBREAK COVID-19 AND ITS GLOBAL CONSEQUENCES: AN OVERVIEW

Global Respiratory illness outbreak COVID-19 is a new public health crisis threatening humanity across the globe with the emergence and spread from central China in late 2019. The virus originated around Wuhan, Hubei province, China in December 2019 in bats and was transmitted through unknown intermediary sources to humans. The clinical presentation of viral infection ranges from asymptomatic to severe pneumonia with acute pulmonary distress syndrome is designated as COVID-19. WHO has characterized the disease as a pandemic due to its severity, as well as the shifting of epidemic zones across the globe from epicentre zone, China through a different stage of transmission by contact or inhalation with infected droplets and the incubation period, varies between 2 - 14 days. Treatment is essentially supportive; the effective role of antiviral agents is yet to be established and secondly without knowing the entire genome sequence of COVID- 19, no drug or vaccine can be effectively administered. Prevention entails home isolation of suspected cases and those with mild illnesses and strict infection control measures at hospitals that include contact and droplet precautions. The highest risk of healthcare-associated transmission is in the absence of standard precautions, when basic infection prevention and control measures for respiratory infections are not in place, and when handling patients where COVID infection is yet to be confirmed. The pandemic acceleration of COVID-19 indicates that the initial sporadic spreading worst hit the epicentre, China. But later on, epidemic zone shifts to nearly all continents. Several countries are experiencing sustained local transmission, including Europe and America at the end of February 2020. Current status indicates that confirmed and death cases pattern is rapidly varied among the different continents and emerged as an alarming health crisis of the nd Era in countries like Italy, Spain, U.K, Iran, and the USA. Although India is now in the 2 stage of transmission and too rd far from the 3 stage but till government has already taken deceive control measures. At the same time some of the Asian countries like South Korea, Japan has been reporting a slowdown in the growth of COVID-19 cases due to adoption concept of "Testing is central" to outbreak response that leads to early detection to minimizes further spread. The proportion of asymptomatic cases is currently unknown and hampers the realistic assessment of the virus epidemic potential and complicates the outbreak response. WHO has already announced a large global trial, called SOLIDARITY th on 27 March 2020 which is focusing on the most promising panacea therapies including remdesivir; chloroquine and hydroxychloroquine; a combination of two HIV drugs, lopinavir, and ritonavir; and that same combination plus interferon-beta. The coronavirus (COVID-19) outbreak has already brought considerable human suffering and major economic disruption. In the current scenario, the exact global impact and extension of COVID 19 pandemic acceleration nd rd and reoccurrences of 2 and 3 waves are yet uncertain in globally. Therefore the corona pandemic is unprecedented in its global impact and reach, posing alarming challenges to policymakers, researchers and health workers.

The Unknown of the Pandemic: An Agent-based Model of Final Phase Risks

The decision of lifting social restrictions is one of the most critical that public health authorities face to, during a pandemic like the COVID-19 one. This work focuses on the risk associated to such decision. We have called 'final epidemic phase' the period from the re-opening decision to epidemic expiration and considered critical epidemic conditions possibly emerging in that final phase. Factors we have considered are: the proportion of asymptomatic cases, a mitigation strategy based on testing, and the average duration of infectious states. By assuming hypothetical configurations at the time of the re-opening decision and the partial knowledge about epidemic dynamics available to public health authorities, we analyzed the risk of the re-opening decision to be based on unreliable estimates. We present a discrete-time stochastic model with state-dependent transmission probabilities and multi-agent simulations. The results of our experiments show the different outcomes produced by different proportions of undetected asymptomatic cases, different probabilities of asymptomatic cases to be detected and contained, and a multivariate analysis of risk based on the average duration of the asymptomatic state and the contained state.Ultimately, the analysis we present highlights that the enduring uncertainty, characterizing the current pandemic, calls for risk analyses approaches to complement epidemiological studies.

Clinical and laboratory features of viral hepatitis A in children

Recent outbreaks of viral hepatitis A in non-endemic European countries and the potential outbreak risk in susceptible populations has led us to evaluate the clinical characteristics of children hospitalised with hepatitis A. Retrospective study included 118 children (68 boys and 50 girls) with the mean age of 8.5 years hospitalised at Hospital Na Bulovce in Prague from June 2008 to June 2009. The clinical course was symptomatic icteric in 57 (48.3 %) children, symptomatic anicteric in 23 (19.5 %), subclinical in 22 (18.6 %) and asymptomatic inapparent in 16 (13.6 %). The relapse of the disease occurred in three patients. There were no cases of fulminant hepatitis. The most frequent symptoms included jaundice (57 cases), abdominal pain/discomfort (38), vomiting (38), dark urine (37), subfebrility (29) and fever (25). Hepatic injury markers were substantially elevated in icteric patients, but moderate elevations were identified in anicteric and subclinical cases as well. Lower white blood cell and lymphocyte counts were independently associated with symptomatic and more severe clinical course. Active immunisation was provided to 22 patients, and as a post-exposure prophylaxis to 19 of them. The clinical course and laboratory parameters in vaccinated children were not significantly different from non-vaccinated children. The clinical course of hepatitis A was largely self-limiting and benign. Asymptomatic infections are frequent, representing risk for disease spread; however, they are associated with elevations of hepatic injury markers. The inclusion of significant proportion of asymptomatic cases that were identified and investigated only because of active epidemiological surveillance in the outbreak focus represents the particular asset of this study.

Eventual Role of Asymptomatic Cases of Dengue for the Introduction and Spread of Dengue Viruses in Non-Endemic Regions

In dengue virus infections the asymptomatic cases are much more frequent than the symptomatic ones, but their true role in the introduction and subsequent spread of dengue viruses in non-endemic regions remains to de clarified. We analyzed data from English and French literatures to assess if viremia in asymptomatic dengue infections might be sufficient to represent a true risk. During outbreaks of dengue a large number of individuals are infected and since viremia levels in symptomatic patients are known to vary by many orders of magnitude, it is reasonable to augur that a proportion of asymptomatic cases might reach levels of viremia sufficient to infect competent mosquitoes. In addition, a number of new ways of contamination in man by dengue viruses were recently described such as blood transfusion, bone marrow transplantation, and nosocomial infections that may be worth considering.

P5-S7.05 Chlamydia screening in an international resort community: an outreach program to expand access

ObjectiveTo evaluate an event-based outreach Chlamydia (CT) screening program pilot developed to address barriers to access in a resort community with an international, transient and disproportionally large young adult population....

Infections inapparentes chez l’Homme : un cheval de Troie pour l’introduction et la diffusion des arbovirus transmis par des moustiques dans les régions non endémiques ?

In mosquito-borne arbovirus infections in man the asymptomatic cases are much more frequent than the symptomatic ones, but their true role in the introduction and subsequent spread of such diseases in non-endemic areas remains to be clarified. We have collected pertinent data from English and French literature from 1952 to 2010 through Pubmed and other bibliographic sources. Data were analysed to assess if viremia in asymptomatic human arbovirus infections might be sufficient to represent a true risk for introduction in non-endemic areas. During dengue and chikungunya fever outbreaks, humans are believed to be the only vertebrate hosts. Since a very large number of individuals are infected and since viremic levels are known to vary by many orders of magnitude in symptomatic patients, it is reasonable to augur that a proportion of asymptomatic cases might reach levels of viremia sufficient to infect competent mosquitoes. Moreover, in both dengue and chikungunya fever, nosocomial infections have been identified representing an alternative opportunity for virus introduction in non-endemic areas. In zoonotic mosquito-borne arbovirus infections such as Japanese encephalitis or West Nile infection, the situation is quite different since humans are considered as "dead-end" hosts. However, the very large number of asymptomatic cases arising during outbreaks and the existence of newly recognised ways of contamination (blood transfusion, organ transplantation, transplacental way etc.) may also ensure their introduction and subsequent spread in new areas.

Changing Patterns and Present Status of Female Breast Cancer in China over 30 Years.

Abstract Introduction: As a metropolis with rapid social and economic development over the past three decades, Shanghai has a breast cancer incidence that surpasses all other cancer registries in China.Methods: In order to estimate the regular changing patterns of female breast cancer in urban Shanghai, population-based incidence data from 1975 to 2004 were studied. In addition, a one-hospital-based in-patient database of 9709 female breast cancer patients treated surgically between Jan-1990 and Dec-2008 were reviewed, retrospectively.Results: We observed that breast cancer incidence increased dramatically over the past 30 years and documented a peak incidence represented by the middle-age group (45-59 yrs), which emerged in the last 20 years. The incidence peak moved from the 40-44 year group in the previous two decades to the 50-54 year group in the most recent decade. Median age at diagnosis was earlier in Shanghai than in the western countries, although it increased from 47.5-yr in 1990 to 51-yr in 2008. Considerably higher exposure to reproductive risk factors and relatively fewer hormone-dependent cases were observed- only 49.2% of breast cancers were estrogen receptor(ER) positive, 46.1% were progesterone receptor positive. The proportion of asymptomatic cases detected by screening gradually increased, as well as that of early-stage cases (from 78.6% in 1990 to 87.9% in 2008 and carcinoma in situ (14.9% in 2008). Analysis of surgical treatment patterns suggested a trend of less-invasive options.Conclusions: Rapid socioeconomic growth and birth-control policies have revealed some unique risk factors, which pushed the pattern of breast cancer in Shanghai towards that of the western countries. Age of peak incidence as well as median age at diagnosis increase with time, which suggests that increased incidence trending along with increasing age will be observed in the future. The middle-age group born after 1950s would be involved in current birth-control policies and they are also the cohorts related to the incidence boom. Thus specific screening protocols should be refined for the Chinese population, considering not only increasing age but also birth cohorts. Improvements in breast cancer detection provide patients with more opportunities for less invasive treatment options. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2058.

Primary Biliary Cirrhosis

Primary biliary cirrhosis is a chronic liver disease of unknown etiology characterized by slowly progressive intrahepatic cholestasis due to an inflammatory destruction of small intrahepatic bile ducts. The clinical course of PBC is variable ranging from a few years in rapidly progressive cases to a normal life-expectancy in a proportion of asymptomatic cases. The typical patient is a middle-aged woman who may present with pruritus, increasing pigmentation of the skin, and eventually jaundice. The level of serum alkaline phosphatase is almost invariably elevated, serum mitochondrial antibodies are present in more than 90 per cent, and an elevated serum IgM is usually present. PBC is associated with many immunologic abnormalities and appears to be a classic autoimmune disease. Some of the immune defects may be epiphenomena; others such as a marked defect in suppressor T cell function seem to be related to the pathogenesis of the disease. All drug therapy that is aimed at slowing the disease process is experimental. A place for immunosuppressive drugs in the management of PBC would be anticipated. However, no drug has to date been definitively shown to have a beneficial effect on the disease. Currently, the main treatments used are aimed at preventing or correcting the complications of intractable cholestasis. Patients with PBC and evidence of hepatic decompensation and/or poor quality of life make good candidates for liver transplantation. The current aim of therapy is to find an effective regime of immunosuppression that will make hepatic transplantation redundant for this disease.