Rate Of Asymptomatic Infection Research Articles

Asymptomatic Middle East Respiratory Syndrome coronavirus infection using a serologic survey in Korea.

OBJECTIVESThe rates of asymptomatic infection with Middle East Respiratory Syndrome (MERS) coronavirus vary. A serologic study was conducted to determine the asymptomatic MERS infection rate in healthcare workers and non-healthcare workers by exposure status.METHODSStudy participants were selected from contacts of MERS patients based on a priority system in 4 regions strongly affected by the 2015 MERS outbreak. A sero-epidemiological survey was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunespecific assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Among the 1,610 contacts, there were 7 ELISA-positive cases, of which 1 exhibited positive IFA and PRNT results.RESULTSThe asymptomatic infection rate was 0.060% (95% confidence interval, 0.002 to 0.346). The asymptomatic MERS case was a patient who had been hospitalized with patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge, and had underlying diseases, including hypertension, angina, and degenerative arthritis.CONCLUSIONSThe asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serologic studies to include inpatient contacts who have no symptoms.

Asymptomatic Summertime Shedding of Respiratory Viruses.

To determine rates of both symptomatic and asymptomatic infection among ambulatory adults, we collected nasopharyngeal swab specimens, demographic characteristics, and survey information from 1477 adult visitors to a New York City tourist attraction during April-July 2016. Multiplex polymerase chain reaction analysis was used to identify specimens positive for common respiratory viruses. A total of 7.2% of samples tested positive for respiratory viruses; among positive samples, 71.0% contained rhinovirus, and 21.5% contained coronavirus. Influenza virus, respiratory syncytial virus, and parainfluenza virus were also detected. Depending on symptomatologic definition, 57.7%-93.3% of positive samples were asymptomatic. These findings indicate that significant levels of asymptomatic respiratory viral shedding exist during summer among the ambulatory adult population.

The Association between Mycoplasma Species Infection and Tubal Obstruction

Objectives: Numerous factors can cause infertility. Tubal factor accounts for approximately 30% of infertility in females. This study was conducted to evaluate the rate of asymptomatic Mycoplasma hominis and Ureaplasma urealyticum infection in females diagnosed with tubal obstruction. Methods: This is a retrospective case-control study conducted at New Life Fertility Centre. We have identified and reviewed the health records of 167 subfertile women that had HSG and an endocervical swab for Mycoplasma hominis and Ureaplasma urealyticum done. Results: We compared the endocervical swab results of ureaplasma and mycoplasma in the patients with tubal obstruction (group 1) to the patients with normal patent tubes (group 2). Diagnosis of tubal patency was based on the HSG results. Our results show that there is a significantly higher rate of Ureaplasma urealyticum/Mycoplasma hominis infection in group 1 compared to group 2. Conclusion: Our data shows that there is a high rate of U. urealyticum and M. hominis infection in patients diagnosed with tubal factor of infertility and it can be a marker in the prediction of the tubal pathology.

Revising rates of asymptomatic Zika virus infection based on sentinel surveillance data from French Overseas Territories

French Polynesia and the French Territories of the Americas (FTAs) have experienced outbreaks of Zika virus (ZIKV) infection. These territories used similar sentinel syndromic surveillance to follow the epidemics. However, the surveillance system only takes into account consulting patients diagnosed with ZIKV disease, while non-consulting cases, as well as asymptomatic cases, are not taken into account. In the French territories under study, the ratio of consulting to non-consulting patients was found to likely be as low as 1/3 to 1/4, and rough estimates of the ZIKV asymptomatic infections indicated a lower rate than previously reported (i.e., not more than half).

Identification of diagnostic peptide regions that distinguish Zika virus from related mosquito-borne Flaviviruses.

Zika virus (ZIKV) is a member of the Flavivirus genus of positive-sense single-stranded RNA viruses, which includes Dengue, West Nile, Yellow Fever, and other mosquito-borne arboviruses. Infection by ZIKV can be difficult to distinguish from infection by other mosquito-borne Flaviviruses due to high sequence similarity, serum antibody cross-reactivity, and virus co-circulation in endemic areas. Indeed, existing serological methods are not able to consistently differentiate ZIKV from other Flaviviruses, which makes it extremely difficult to accurately calculate the incidence rate of Zika-associated Guillain-Barre in adults, microcephaly in newborns, or asymptomatic infections within a geographical area. In order to identify Zika-specific peptide regions that could be used as serology reagents, we have applied comparative genomics and protein structure analyses to identify amino acid residues that distinguish each of 10 Flavivirus species and subtypes from each other by calculating the specificity, sensitivity, and surface exposure of each residue in relevant target proteins. For ZIKV we identified 104 and 116 15-mer peptides in the E glycoprotein and NS1 non-structural protein, respectively, that contain multiple diagnostic sites and are located in surface-exposed regions in the tertiary protein structure. These sensitive, specific, and surface-exposed peptide regions should serve as useful reagents for seroprevalence studies to better distinguish between prior infections with any of these mosquito-borne Flaviviruses. The development of better detection methods and diagnostic tools will enable clinicians and public health workers to more accurately estimate the true incidence rate of asymptomatic infections, neurological syndromes, and birth defects associated with ZIKV infection.

Cross-protection to new drifted influenza A(H3) viruses and prevalence of protective antibodies to seasonal influenza, during 2014 in Portugal

IntroductionImmune profile for influenza viruses is highly changeable over time. Serological studies can assess the prevalence of influenza, estimate the risk of infection, highlight asymptomatic infection rate and can also provide data on vaccine coverage. The aims of the study were to evaluate pre-existing cross-protection against influenza A(H3) drift viruses and to assess influenza immunity in the Portuguese population. Materials and methodsWe developed a cross-sectional study based on a convenience sample of 626 sera collected during June 2014, covering all age groups, both gender and all administrative health regions of Portugal. Sera antibody titers for seasonal and new A(H3) drift influenza virus were evaluated by hemagglutination inhibition assay (HI). Seroprevalence to each seasonal influenza vaccine strain virus and to the new A(H3) drift circulating strain was estimated by age group, gender and region and compared with seasonal influenza-like illness (ILI) incidence rates before and after the study period. ResultsOur findings suggest that seroprevalences of influenza A(H3) (39.9%; 95% CI: 36.2–43.8) and A(H1)pdm09 (29.7%; 95% CI: 26.3–33.4) antibodies were higher than for influenza B, in line with high ILI incidence rates for A(H3) followed by A(H1)pdm09, during 2013/2014 season. Low pre-existing cross-protection against new A(H3) drift viruses were observed in A(H3) seropositive individuals (46%). Both against influenza A(H1)pdm09 and A(H3) seroprotection was highest in younger than 14-years old. Protective antibodies against influenza B were highest in those older than 65years old, especially for B/Yamagata lineage, 33.3% (95% CI: 25.7–41.9). Women showed a high seroprevalence to influenza, although without statistical significance, when compared to men. A significant decreasing trend in seroprotection from north to south regions of Portugal mainland was observed. ConclusionsOur results emphasize that low seroprotection increases the risk of influenza infection in the following winter season. Seroepidemiological studies can inform policy makers on the need for vaccination and additional preventive measures.

Cryptosporidiosis in children in the Indian subcontinent.

Cryptosporidiosis is a leading cause of diarrheal disease among children under two in developing countries. Previous estimates have shown a high burden of cryptosporidial diarrhea in children from Sub-Saharan Africa and South Asia. Asymptomatic cryptosporidial infections which go undetected and untreated have been shown to result in significant malnutrition. In this review, we carried out a literature search of studies published on cryptosporidiosis in children in the Indian subcontinent from 1983 to 2016. Of the 154 publications identified, 54 were included for final analysis with both hospital-based and community-based studies. There were wide variations in reported prevalence rates from hospital studies and highlight the need to be carry out these studies with uniform sampling and molecular tools for detection, especially in countries with a dearth of information. Community-based studies, however, showed similarities in spite of differences in when (the late 1990s up until recently) and where (South India or Bangladesh) they were conducted. When more sensitive detection methods were used, cryptosporidial diarrhea accounted for 7%–9% of all diarrhea episodes and 20%–30% of children in these cohorts experienced at least one cryptosporidial diarrheal episode. High rates of asymptomatic infections with increased detection by serology and multiple infections (symptomatic and asymptomatic) were also documented in all cohorts. This overview brings to light the high burden of disease associated with cryptosporidiosis in children in the subcontinent and the gaps in knowledge to be addressed.

Serological Analysis and Drug Resistance of Chlamydia pneumoniae and Mycoplasma pneumoniae in 4500 Healthy Subjects in Shenzhen, China.

Objective To understand the prevalence and distribution of Chlamydia pneumoniae (CP) and Mycoplasma pneumoniae (MP) in the population and to provide a basis for the prevention and treatment of respiratory tract infection. Methods This study included a total of 4500 healthy subjects who were given physical examination in Shenzhen People's Hospital from January to December in 2016. Venous blood was drawn from people to detect the MP- and CP-specific IgG and IgM in the serum using chemiluminescence immunoassay (CLIA). The relationship of MP and CP infections with patient age, seasons, and percentage of infections was analyzed. Conclusion CP and MP cause high rate of asymptomatic infection, which may be associated with the high incidence of CP and MP infection, especially in children and the elderly population. Therefore, the implementation of effective and practical prevention measures has become an urgent need. MP culture and drug sensitivity test should be performed as early as possible in patients with manifested MP infections in order to ensure timely and proper treatment and to reduce the emergence of drug-resistant strains.

Use of Pathogen-Specific Antibody Biomarkers to Estimate Waterborne Infections in Population-Based Settings.

This review discusses the utility of pathogen-specific antibody biomarkers for improving estimates of the population burden of waterborne infections, assessing the fraction of infections that can be prevented by specific water treatments, and understanding transmission routes and the natural history and ecology of disease in different populations (including asymptomatic infection rates). We review recent literature on the application of pathogen-specific antibody response data to estimate incidence and prevalence of acute infections and their utility to assess the contributions of waterborne transmission pathways. Advantages and technical challenges associated with the use of serum versus minimally invasive salivary antibody biomarkers in cross-sectional and prospective surveys are discussed. We highlight recent advances and challenges and outline future directions for research, development, and application of antibody-based and other immunological biomarkers of waterborne infections.

High Rates of Asymptomatic Chlamydia and Gonorrhea Infection Among Human Immunodeficiency Virus-Infected Men Who Have Sex With Men

High Rates of Asymptomatic Chlamydia and Gonorrhea Infection Among Human Immunodeficiency Virus-Infected Men Who Have Sex With Men

Seroprevalence of Asian Lineage Chikungunya Virus Infection on Saint Martin Island, 7 Months After the 2013 Emergence.

At the end of 2013, chikungunya virus (CHIKV) emerged in Saint Martin Island, Caribbean. The Asian lineage was identified. Seven months after this introduction, the seroprevalence was 16.9% in the population of Saint Martin and 39.0% of infections remained asymptomatic. This moderate attack rate and the apparent limited size of the outbreak in Saint Martin could be explained by control measures involved to lower the exposure of the inhabitants. Other drivers such as climatic factors and population genetic factors should be explored. The substantial rate of asymptomatic infections recorded points to a potential source of infection that can both spread in new geographic areas and maintain an inconspicuous endemic circulation in the Americas.

Effect of asymptomatic vaginal colonization with Candida albicans on pregnancy outcome.

Vaginal infection is a major causative factor of preterm delivery. The present study was performed to evaluate the effect of asymptomatic vaginal colonization with Candida albicans at early gestation on pregnancy outcome. From 2005 to 2014, a total of 8447 women with singleton pregnancies between 10(+0) and 16(+0) gestational weeks were routinely subjected to an antenatal infection screen-and-treat program. Vaginal smears were Gram-stained and microscopically evaluated, and data were retrospectively analyzed. Women exposed to Candida received clotrimazole and were re-tested after 4-6 weeks. Treatment was repeated in case of recurrence. Women with normal or intermediate vaginal flora were considered as non-exposed. Bacterial vaginosis and trichomoniasis were assessed and treated as well. Descriptive data analysis, chi-squared testing and multiple regression analysis with adjustment for potential confounders were performed. Rates of asymptomatic vaginal infections, preterm delivery and low birthweight served as the main outcomes measures. A normal or intermediate flora was found in 6708 (79.4%) of the screened women; 1142 women (13.5%) showed asymptomatic C. albicans infection. Of this group, 185 women (2.2%) had a recurrence of Candida on vaginal smears. Compared with the non-exposed women with normal or intermediate flora, those with recurrent candidiasis had higher rates of preterm delivery (11.9% vs. 9.5%) and of low birthweight (10.8% vs. 8.0%), as confirmed in the multiple model (p = 0.02). Recurrent asymptomatic vaginal colonization with Candida in early pregnancy is associated with preterm delivery and low birthweight. Routine screening and consequent treatment for candidiasis could improve pregnancy outcomes.

Screening for Asymptomatic Extragenital Gonorrhea and Chlamydia in Men Who Have Sex with Men: Significance, Recommendations, and Options for Overcoming Barriers to Testing

Men who have sex with men (MSM) have a disproportionately greater risk than other populations of acquiring Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC), the two most commonly reported notifiable diseases in the United States according to the Centers for Disease Control and Prevention (CDC). The presence of either of these diseases is a significant risk factor for the acquisition and transmission of human immunodeficiency virus (HIV). Recent studies have shown that significant rates of asymptomatic GC and CT infection are found at the extragenital oropharygeal and rectal sites in MSM, with or without concurrent urogenital infection. However, extragenital sites are not being routinely screened and, thus, many asymptomatic GC and CT infections at the oropharyngeal and rectal sites may go undiagnosed. This review will begin with the current evidence-based screening recommendations for extragenital GC and CT in MSM. This will be followed by recently reported extragenital GC and CT infection rates in asymptomatic MSM, and a discussion of the risks and potential implications of undiagnosed extragenital GC and CT infections. Finally, a discussion on the frequency of, and potential barriers to, screening will be presented with a summary of potential interventions for increasing screening frequency found in the literature. The scope of this review will focus primarily on U.S. recommendations, infection rates, and screening frequencies, with the inclusion of relevant international recommendations and studies for comparative and illustrative purposes.

Active Screening of Multi-Drug Resistant Bacteria Effectively Prevent and Control the Potential Infections

Our objective is to determine if actively screen the multi-drug resistant bacteria (MDRB) infection in intensive care unit (ICU) to prevent, control, and decrease the infection rate and transmission of MDRB. The patients admitted in ICU of one hospital in 2013 were analyzed. The throat swab, blood, defecation, and urine of patients were actively collected for bacteria cultures to screen Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii in patients. All patients received screening of MDRB infection and colonization within 2 days and after 2 days of admission, the results showed that there were 418 infectious bacterial strains in total and P. aeruginosa was the main bacterium. The asymptomatic infection rates of P. aeruginosa, K. pneumonia, E. coli, S. aureus, and A. baumannii were 39.02, 24.74, 44.00, 29.17, and 33.33 %, respectively; the symptomatic infection rates were 60.98, 75.26, 56.00, 70.83, and 66.67 %. 59.70 % patients received antibiotics treatment, 27.45 % patients received trachea cannula, 32.95 % patients received mechanism ventilation, 2.27 % patients received arterial cannula or venous cannula and 4.00 % patients received indwelling urinary catheters. The main MDRB in ICU is P. aeruginosa. The active screening of MDRB infection and colonization can provide the opportunity to take the life-saving measure against MDRB and treat patients. This can decrease the infection risk and the nosocomial transmission of MDRB.

Analysis of Patients With Chlamydia trachomatis Genital Infection in an STD Clinic

Background and objectivesChlamydia trachomatis genital infection is common in our setting and early treatment can prevent complications. The aim of this study was to report on patients diagnosed with C trachomatis genital infection in a sexually transmitted disease (STD) clinic. Material and methodsThis was a descriptive, cross-sectional, observational study of patients diagnosed with C trachomatis infection between 2010 and 2011. We recorded demographic data and information on sexual habits, concomitant sexually transmitted infections (STIs), and various aspects of treatment. ResultsIn total, 12.3% of the samples analyzed were positive for C trachomatis genital infection. Sixty-two patients (43 men) with a mean age of 31 years were studied; 75% were heterosexual and 87% had had a sexual partner in the previous 2 months. Condom use was inconsistent in 81%, 79%, and 65% of patients who practiced vaginal, oral, and anal sex, respectively. Thirteen percent of the patients had symptoms and anogenital warts were the most common associated STI. The most widely used treatment was doxycycline. ConclusionsA high prevalence of genital C trachomatis infection was detected in our STD clinic, and the majority of cases were found in young men. We observed a high rate of asymptomatic infection in patients who do not engage in high-risk sexual behavior and who had come to the clinic for another reason. Systematic screening of C trachomatis infection should be implemented in STD units to enable the early treatment of patients and their recent sexual partners.

Screening for Chlamydia infection in a sexually transmitted infection clinic: a missed opportunity?

Chlamydia trachomatis (CT) infection is the most common sexually transmitted infection (STI) reported in Europe. We aim to evaluate the overall prevalence of CT infection and the rate of asymptomatic infection in an STI clinic over a 5-year period. We will also discuss screening strategies with reference to attendees diagnosed with an STI and their sexual partners, and attendees with a non-infectious genital dermatosis. Clinical and laboratory data for all attendees at a university hospital STI clinic over a 5-year period were reviewed. Diagnosis of CT infection was made upon polymerase chain reaction (PCR) performed in first-void urine. The overall prevalence of CT infection was 4.0% (53/1310); the rate of asymptomatic infection was 84.9% (45/53). The prevalence of CT infection among attendees with an STI diagnosis and their sexual partners was 5.2% (50/963), whereas that among attendees with a non-infectious genital dermatosis was 0.9% (3/347; P<0.001). Infected attendees were younger than attendees without CT infection (median age: 31years vs. 40years; P<0.001). In 39.5% (17/43) of CT-infected attendees, it was possible to notify a sexual partner; CT infection was subsequently diagnosed in 58.8% (10/17) of partners. Asymptomatic CT infection had a representative frequency, which was more pronounced among young attendees with an STI diagnosis and their sexual partners, to whom screening should be offered. Issues of age limits for screening and whether screening should be directed to males in non-STI clinic settings should be carefully assessed.

Chemiluminescent microparticle immunoassay based detection and prevalence of HCV infection in district Peshawar Pakistan.

BackgroundDue to the high rate of asymptomatic infections an advanced screening assay is of prompt importance to be used for the clinical diagnosis of HCV. Early detection of anti HCV is the first step in the management of chronic hepatitis and in the selection of patients needing treatments. In the current study we have first time used the advanced serological diagnostic technique i.e. Chemiluminescent Microparticle Immuno Assay (CMIA) for the detection of HCV infection in Peshawar Pakistan.MethodsA total number of 982 samples were collected among the general public belongs to the different areas of district Peshawar. The samples were centrifuged at high speed to obtain a clear supernatant serum. All the samples were run on Architect system a fully automated immuno analyzer CMIA base technology.ResultsOut of 982 blood samples analyzed in this study, 160 (15.9%) were confirmed to be positive for active HCV infection. The overall prevalence was found to be 13.4%. Gender wise prevalence was recorded to be higher in male (19.1%) than female (12.7%). The age group 21-30 years was identified as the highest risk group among the studied population.ConclusionAmong the tested samples, overall prevalence of active HCV infection was found to be 13.4% in the general population of Peshawar Pakistan. The young middle aged population of this region was at higher risk of HCV ailments compared to the other age groups.

Análisis de la población con infección genital por Chlamydia trachomatis en una consulta de enfermedades de transmisión sexual

Introduction and objectivesChlamydia trachomatis genital infection is common in our setting and early treatment can prevent complications. The aim of this study was to report on patients diagnosed with C trachomatis genital infection in a sexually transmitted disease (STD) clinic. Material and methodsThis was a descriptive, cross-sectional, observational study of patients diagnosed with C. trachomatis infection between 2010 and 2011. We recorded demographic data and information on sexual habits, concomitant sexually transmitted infections (STIs), and various aspects of treatment. ResultsIn total, 12.3% of the samples analyzed were positive for C trachomatis genital infection. Sixty-two patients (43 men) with a mean age of 31 years were studied; 75% were heterosexual and 87% had had a sexual partner in the previous 2 months. Condom use was inconsistent in 81%, 79%, and 65% of patients who practiced vaginal, oral, and anal sex, respectively. Thirteen percent of the patients had symptoms and anogenital warts were the most common associated STI. The most widely used treatment was doxycycline. ConclusionsA high prevalence of genital C. trachomatis infection was detected in our STD clinic, and the majority of cases were found in young men. We observed a high rate of asymptomatic infection in patients who do not engage in high-risk sexual behavior and who had come to the clinic for another reason. Systematic screening of C. trachomatis infection should be implemented in STD units to enable the early treatment of patients and their recent sexual partners.

An outbreak of Potato spindle tuber viroid in tomato is linked to imported seed

In 2011, an outbreak of the quarantine-regulated pathogen Potato spindle tuber viroid (PSTVd) occurred in a commercial glasshouse-grown tomato crop in Queensland, Australia. Phylogenetic studies showed that the genotype of this isolate grouped in a cluster of PSTVd genotypes from tomato and Physalis peruviana, and exhibited an interesting mutation (U257→A) that has previously been linked to lethal symptom expression in tomato. Transmission studies showed that the viroid could be mechanically transmitted from crushed fruit sap, but not from undamaged fruits. A low rate of asymptomatic infection was determined for plants in the affected glasshouse, demonstrating the efficacy of using symptoms to detect PSTVd infections in tomato. No PSTVd infections were detected in solanaceous weeds located outside of the infected glasshouse, excluding them from playing a role in the viroid epidemiology. Monitoring and subsequent testing of new tomato crops grown in the facility demonstrated successful eradication of the pathogen. A trace-back analysis linked the outbreak of PSTVd to an infected imported tomato seed-lot, indicating that PSTVd is transmitted internationally through contaminated seed.

Association between respiratory viruses and asthma exacerbations

Association between respiratory viruses and asthma exacerbations