Rapid Serological Tests Research Articles

Laboratory Examination of Syphilis

Syphilis, is sexually transmitted disease caused by spirochete Treponema pallidum subsp.pallidum. It have many diverse clinical manifestations that occur in distinct stages. Early diagnosis and management are the main things to prevent transmission and complication. Direct test or morphological observation is the definitive diagnosis of syphilis. This can be done through animal inoculation test, dark field microscopy, direct fluorescence antibody (DFA), and nucleid acid amplification test (NAAT). While the indirect test is a nontreponemal serologic test consist of Wasserman test, venereal disease research laboratory (VDRL), toluidine red unheated serum test (TRUST), unheated serum reagin (USR), rapid plasma reagin (RPR) and treponemal serologic test, such as T. pallidum passive particle agglutination (TPPA), T. pallidum haemagglutination assay (TPHA), fluorescent treponemal antibody absorption (FTA-Abs), enzyme immunoassay (EIA) and rapid test. The algorithm of serologic test can be divided into traditional or reverse.

Laboratory Examination of Syphilis

Syphilis, is sexually transmitted disease caused by spirochete Treponema pallidum subsp.pallidum. It have many diverse clinical manifestations that occur in distinct stages. Early diagnosis and management are the main things to prevent transmission and complication. Direct test or morphological observation is the definitive diagnosis of syphilis. This can be done through animal inoculation test, dark field microscopy, direct fluorescence antibody (DFA), and nucleid acid amplification test (NAAT). While the indirect test is a nontreponemal serologic test consist of Wasserman test, venereal disease research laboratory (VDRL), toluidine red unheated serum test (TRUST), unheated serum reagin (USR), rapid plasma reagin (RPR) and treponemal serologic test, such as T. pallidum passive particle agglutination (TPPA), T. pallidum haemagglutination assay (TPHA), fluorescent treponemal antibody absorption (FTA-Abs), enzyme immunoassay (EIA) and rapid test. The algorithm of serologic test can be divided into traditional or reverse.

Comparison of rapid serological diagnostic test in diagnosing typhoid fever in a tertiary care centre in western Uttar Pradesh

: In the study we compare the sensitivity and specificity of two commonly used rapid serological test, Widal test and Typhidot, in the diagnosing of Typhoid fever. Serum samples coming to the microbiology laboratory for routine testing over the period from September 2019 to November 2020 were analysed for the comparison for the presence of the Salmonella antibodies by carrying out the Typhidot and Widal tube agglutination test in tertiary care centre.: Out of 580 blood specimen, 49.3% cases were positive by Typhidot and 38.6% cases were positive by Widal method.Typhidot is a rapid and more sensitive test for early diagnosis of typhoid fever. It is now commercially available for the diagnosis of typhoid fever in areas with limited resources. Widal test showed the sensitivity and specificity of 37% & 62.4% respectively. Typhi dot test showed sensitivity of 41.4% and specificity of 56.5%.

Evaluation of the performance of health extension workers on malaria rapid diagnostic tests and predictor factors in Bahir Dar Zuria district, northwest Ethiopia: A cross-sectional study

BackgroundIn Ethiopia, anti-malaria treatment is initiated after parasitological confirmation using blood film microscopy at health centers and hospitals, or serological rapid diagnostic tests at health posts. At health posts, the diagnosis is performed by health extension workers using rapid diagnostic tests after little training. However, there is paucity of data about the health extension workers’ performance on rapid diagnostic tests. Hence, periodic monitoring of the performances of health extension workers on malaria rapid diagnostic tests and predicted factors plays a pivotal role for the control of malaria.MethodsA cross sectional study was conducted in May 2020, among 75 health extension workers working at health posts in Bahir Dar Zuria district, Northwest Ethiopia. Their performance on malaria rapid diagnostic tests was assessed by distributing known positive and negative samples as confirmed by investigators using both rapid diagnostic test and blood film microscopy. Test results from health extension workers were then compared with that of investigators. Procedural errors committed while performing the tests were assessed using observational checklist. Data were analyzed using SPSS software version 20.ResultsThe overall sensitivity and specificity of health extension workers in detecting Plasmodium species were 96.8% and 98.7%, respectively with 97.3% result agreement between the health extension workers and investigators (kappa value = 0.949). The most common procedural errors committed by health extension workers was ‘not checking expiry date of the test kits’ followed by ‘not adhering to the appropriate time of reading results’ that 70.7% and 64% of the participants committed these errors, respectively. Total number of procedural errors committed by those who have got in-service training was decreased by 47.3% as compared to those without in-service training.ConclusionsHealth extension workers had high performance on malaria rapid diagnostic tests. However, in-service training and periodic supervision should be given in order to maximize performance on these tests.

Vertical Flow Cellulose-Based Assays for SARS-CoV-2 Antibody Detection in Human Serum.

Rapid and inexpensive serological tests for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies are essential to conduct large-scale seroprevalence surveys and can potentially complement nucleic acid or antigen tests at the point of care. During the COVID-19 pandemic, extreme demand for traditional lateral flow tests has stressed manufacturing capacity and supply chains. Motivated by this limitation, we developed a SARS-CoV-2 antibody test using cellulose, an alternative membrane material, and a double-antigen sandwich format. Functionalized SARS-CoV-2 antigens were used as both capture and reporter binders, replacing the anti-human antibodies currently used in lateral flow tests. The test could provide enhanced sensitivity because it labels only antibodies against SARS-CoV-2 and the signal intensity is not diminished due to other human antibodies in serum. Three-dimensional channels in the assay were designed to have consistent flow rates and be easily manufactured by folding wax-printed paper. We demonstrated that this simple, vertical flow, cellulose-based assay could detect SARS-CoV-2 antibodies in clinical samples within 15 min, and the results were consistent with those from a laboratory, bead-based chemiluminescence immunoassay that was granted emergency use approval by the US FDA.

Seroprevalence of SARS-CoV-2-Specific Antibodies in Cancer Patients Undergoing Active Systemic Treatment: A Single-Center Experience from the Marche Region, Italy.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence in cancer patients may vary widely dependent on the geographic area and this has significant implications for oncological care. The aim of this observational, prospective study was to assess the seroprevalence of SARS-CoV-2 IgM/IgG antibodies in solid cancer patients referred to the academic institution of the Marche Region, Italy, between 1 July and 26 October 2020 and to determine the accuracy of the rapid serological test. After performing 3767 GCCOV-402a rapid serological tests on a total of 949 patients, seroconversion was initially observed in 13 patients (1.4%). Ten (77% of the total positive) were IgG-positive, 1 (8%) were IgM-positive and 2 (15%) IgM-positive/IgG-positive. However, only 7 out of 13 were confirmed as positive at the reference serological test (true positives), thus seroprevalence after cross-checking was 0.7%. No false negatives were reported. The kappa value of the consistency analysis was 0.71. Due to rapid serological test high false positive rate, its role in assessing seroconversion rate is limited, and the standard serological tests should remain the gold standard. However, as rapid test negative predictive value is high, GCCOV-402a may instead be useful to monitor patient immunity over time, thus helping to assist ongoing vaccination programs.

Consistency of the results of rapid serological tests for SARS-CoV-2 among healthcare workers in a large national hospital in Tokyo, Japan.

We assessed the consistency of seropositive results of three rapid immunoassays (Kits A, B, and C) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) compared to highly accurate serological tests (Abbott and Roche) among healthcare workers in a hospital in Tokyo. The seroprevalence of SARS-CoV-2 immunoglobulin G was 0.41%, 2.36%, and 0.08% using Kits A, B, and C, respectively. Of the 51 samples that were seropositive on any rapid test, all were seronegative on both the Abbott and the Roche assays. Given that the seroprevalence of SARS-CoV-2 immunoglobulin G varied widely according to the choice of rapid test and the rapid test results were inconsistent with the results of highly accurate tests, the diagnostic accuracy of rapid serological tests for SARS-CoV-2 should be assessed before introducing these tests for point-of-care testing or surveillance.

SARS-CoV-2 was already circulating in Italy, in early December 2019.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) identified in China, in December 2019 determines COronaVIrus Disease 19 (COVID-19). Whether or not the virus was present in Italy earlier the first autochthonous COVID-19 case was diagnosed is still uncertain. We aimed to identify anti-SARS-CoV-2 antibodies in sera collected from 4th November 2019 to 9th March 2020, in order to assess the possible spread of the virus in Italy earlier than the first official national diagnosis. Anti-SARS-CoV-2 antibodies were evaluated in retrospective serum samples from 234 patients with liver diseases (Hep-patients) and from 56 blood donors (BDs). We used two rapid serologic tests which were confirmed by a validated chemoluminescence assay. Via rapid tests, we found 10/234 (4.3%) IgG-positive and 1/234 (0.4%) IgM-positive cases in the Hep-patient group. Two/56 (3.6%) IgG-positive and 2/56 (3.6%) IgM-positive cases were detected in BD group. Chemoluminescence confirmed IgG-positivity in 3 Hep-patients and 1 BD and IgM-positivity in 1 Hep-patient. RNAemia was not detected in any of the subjects, rendering the risk of transfusion transmission negligible. Our results suggest an early circulation of SARS-CoV-2 in Italy, before the first COVID-19 cases were described in China. Rapid tests have multiple benefits; however, a confirmation assay is required to avoid false positive results.

A randomized controlled trial evaluating combination detection of HIV in Malawian sexually transmitted infections clinics.

IntroductionHIV diagnosis is the necessary first step towards HIV care initiation, yet many persons living with HIV (PLWH) remain undiagnosed. Employing multiple HIV testing strategies in tandem could increase HIV detection and promote linkage to care. We aimed to assess an intervention to improve HIV detection within socio‐sexual networks of PLWH in two sexually transmitted infections (STI) clinics in Lilongwe, Malawi.MethodsWe conducted a randomized controlled trial to evaluate an intervention combining acute HIV infection (AHI) screening, contract partner notification and social contact referral versus the Malawian standard of care: serial rapid serological HIV tests and passive partner referral. Enrolment occurred between 2015 and 2019. HIV‐seropositive persons (two positive rapid tests) were randomized to the trial arms and HIV‐seronegative (one negative rapid test) and ‐serodiscordant (one positive test followed by a negative confirmatory test) persons were screened for AHI with HIV RNA testing. Those found to have AHI were offered enrolment into the intervention arm. Our primary outcome of interest was the number of new HIV diagnoses made per index participant within participants’ sexual and social networks. We also calculated total persons, sexual partners and PLWH (including those previously diagnosed) referred per index participant.ResultsA total of 1230 HIV‐seropositive persons were randomized to the control arm, and 561 to the intervention arm. Another 12,713 HIV‐seronegative or ‐serodiscordant persons underwent AHI screening, resulting in 136 AHI cases, of whom 94 enrolled into the intervention arm. The intervention increased the number of new HIV diagnoses made per index participant versus the control (ratio: 1.9; 95% confidence interval (CI): 1.2 to 3.1). The intervention also increased the numbers of persons (ratio: 2.5; 95% CI: 2.0 to 3.2), sexual partners (ratio: 1.7; 95% CI: 1.4 to 2.0) and PLWH (ratio: 2.3; 95% CI: 1.7 to 3.2) referred per index participant.ConclusionsCombining three distinct HIV testing and referral strategies increased the detection of previously undiagnosed HIV infections within the socio‐sexual networks of PLWH seeking STI care. Combination HIV detection strategies that leverage AHI screening and socio‐sexual contact networks offer a novel and efficacious approach to increasing HIV status awareness.

SARS-CoV-2 prevalence associated to low socioeconomic status and overcrowding in an LMIC megacity: A population-based seroepidemiological survey in Lima, Peru.

BackgroundWorldwide, Peru has one of the highest infection fatality rates of COVID-19, and its capital city, Lima, accumulates roughly 50% of diagnosed cases. Despite surveillance efforts to assess the extent of the pandemic, reported cases and deaths only capture a fraction of its impact due to COVID-19′s broad clinical spectrum. This study aimed to estimate the seroprevalence of SARS-CoV-2 in Lima, stratified by age, sex, region, socioeconomic status (SES), overcrowding, and symptoms.MethodsWe conducted a multi-stage, population-based serosurvey in Lima, between June 28th and July 9th, 2020, after 115 days of the index case and after the first peak cases. We collected whole blood samples by finger-prick and applied a structured questionnaire. A point-of-care rapid serological test assessed IgM and IgG antibodies against SARS-CoV-2. Seroprevalence estimates were adjusted by sampling weights and test performance. Additionally, we performed RT-PCR molecular assays to seronegatives and estimated the infection prevalence.FindingsWe enrolled 3212 participants from 797 households and 241 sample clusters from Lima in the analysis. The SARS-CoV-2 seroprevalence was 20·8% (95%CI 17·2–23·5), and the prevalence was 25·2% (95%CI 22·5–28·2). Seroprevalence was equally distributed by sex (aPR=0·96 [95%CI 0·85–1·09, p = 0·547]) and across all age groups, including ≥60 versus ≤11 years old (aPR=0·96 [95%CI 0·73–1·27, p = 0·783]). A gradual decrease in SES was associated with higher seroprevalence (aPR=3·41 [95%CI 1·90–6·12, p<0·001] in low SES). Also, a gradual increase in the overcrowding index was associated with higher seroprevalence (aPR=1·99 [95%CI 1·41–2·81, p<0·001] in the fourth quartile). Seroprevalence was also associated with contact with a suspected or confirmed COVID-19 case, whether a household member (48·9%, aPR=2·67 [95%CI 2·06–3·47, p<0·001]), other family members (27·3%, aPR=1·66 [95%CI 1·15–2·40, p = 0·008]) or a workmate (34·1%, aPR=2·26 [95%CI 1·53–3·35, p<0·001]). More than half of seropositive participants reported never having had symptoms (56·1%, 95% CI 49·7–62·3).InterpretationThis first estimate of SARS-CoV-2 seroprevalence in Lima shows an intense transmission scenario, despite the government's numerous interventions early established. Susceptibles across age groups show that physical distancing interventions must not be relaxed. SES and overcrowding households are associated with seroprevalence. This study highlights the importance of considering the existing social inequalities for implementing the response to control transmission in low- and middle-income countries.

A study on clinical profile and laboratory parameters of dengue fever patients in Chennai, Tamil Nadu, India

Introduction: Dengue fever is the most important mosquito-borne viral disease, found to be endemic in tropical and subtropical countries. In recent decades, the incidence of dengue infection has increased around the world and has become a major public health concern. Materials and Methods: The prospective study was conducted during the period from July 2018 to December 2020 at Sri Muthukumaran Medical College, Hospital & Research Institute, Chennai, India. All the Serum samples were collected with clinically suspected cases of Dengue and then it was confirmed by (NS1 antigen, IgM & IgG antibody) rapid serological test kit. All the clinical details & Hematological parameters were also recorded. Result: During the study period, a total of 434 patients were suspected to have the Dengue infection. Majority of the cases were males 268 (62%) rather than Females 166 (38%). 146 (34%) samples were found to be positive for Dengue viral infection. Fever is the most common clinical presentation which was found in all the patients, followed by headache (56%), vomiting (52%), body pain (33.2%), Myalgia (32%), Joint pain (31.5%), Dry cough (29%), Nausea (22%), Abdominal pain (20%), Diarrhea (13%), Retro orbital pain (10%), Burning Micturition (8.2%), Hemoptysis (2.7%), and Rashes (0.2%). Hematological parameters such as Thrombocytopenia were 36 (24%), followed by Leucopenia 16 (11%), and raised Hematocrit 11 (7.2%). Conclusions: Study has revealed that clinical manifestation is varied considerably from fever, myalgia to life threatening situations like dengue hemorrhagic fever or dengue shock syndrome if not treated on time. Therefore, early recognition and prompt management is required to decrease the morbidity and mortality of illness. Keywords: Clinical profile, Dengue fever, Laboratory parameter.

Microarray-Based Allergy Diagnosis: Quo Vadis?

More than 30% of the world population suffers from allergy. Allergic individuals are characterized by the production of immunoglobulin E (IgE) antibodies against innocuous environmental allergens. Upon allergen recognition IgE mediates allergen-specific immediate and late-phase allergic inflammation in different organs. The identification of the disease-causing allergens by demonstrating the presence of allergen-specific IgE is the key to precision medicine in allergy because it allows tailoring different forms of prevention and treatment according to the sensitization profiles of individual allergic patients. More than 30 years ago molecular cloning started to accelerate the identification of the disease-causing allergen molecules and enabled their production as recombinant molecules. Based on recombinant allergen molecules, molecular allergy diagnosis was introduced into clinical practice and allowed dissecting the molecular sensitization profiles of allergic patients. In 2002 it was demonstrated that microarray technology allows assembling large numbers of allergen molecules on chips for the rapid serological testing of IgE sensitizations with small volumes of serum. Since then microarrayed allergens have revolutionized research and diagnosis in allergy, but several unmet needs remain. Here we show that detection of IgE- and IgG-reactivity to a panel of respiratory allergens microarrayed onto silicon elements is more sensitive than glass-based chips. We discuss the advantages of silicon-based allergen microarrays and how this technology will allow addressing hitherto unmet needs in microarray-based allergy diagnosis. Importantly, it described how the assembly of silicon microarray elements may create different microarray formats for suiting different diagnostic applications such as quick testing of single patients, medium scale testing and fully automated large scale testing.

SARS-CoV-2 seroconversion among 4040 Egyptian healthcare workers in 12 resource-limited healthcare facilities: A prospective cohort study

BackgroundWe examined Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) seroconversion incidence and risk factors 21 days after baseline screening among healthcare workers (HCWs) in a resource-limited setting. MethodsA prospective cohort study of 4040 HCWs took place at 12 university healthcare facilities in Cairo, Egypt; April-June 2020. Follow-up exposure and clinical data were collected through online survey. SARS-CoV-2 testing was done using rapid IgM and IgG serological tests and reverse transcriptase–polymerase chain reaction (RT-PCR) for those with positive serology. Cox proportional hazards modelling was used to estimate adjusted hazard ratios (HR) of seroconversion. Results3870/4040 (95.8%) HCWs tested negative for IgM, IgG and PCR at baseline; 2282 (59.0%) returned for 21-day follow-up. Seroconversion incidence (positive IgM and/or IgG) was 100/2282 (4.4%, 95% CI:3.6-5.3), majority asymptomatic (64.0%); daily hazard of 0.21% (95% CI:0.17-0.25)/48 746 person-days of follow-up. Seroconversion was: 4.0% (64/1596; 95% CI:3.1-5.1) among asymptomatic; 5.3% (36/686; 95% CI:3.7-7.2) among symptomatic HCWs. Seroconversion was independently associated with older age; lower education; contact with a confirmed case >15 min; chronic kidney disease; pregnancy; change/loss of smell; and negatively associated with workplace contact. ConclusionsMost seroconversions were asymptomatic, emphasizing need for regular universal testing. Seropositivity was three-fold that observed at baseline. Cumulative infections increased nationally by a similar rate, suggesting HCW infections reflect community not nosocomial transmission.

Assesment of SARS-CoV-2 infection-in dentists and supporting staff at a university dental hospital in Argentina

IntroductionOral healthcare professionals are at increased risk of infection by SARS-CoV-2. The aim of this study was to evaluate the prevalence of COVID-19 in a population of workers who provided services during the COVID-19 pandemic at a dental care and educational institution in the Buenos Aires Metropolitan Area. Materials and methodsThis was a descriptive, cross-sectional study including 358 workers who provided essential services during the first 180 days of the COVID-19 pandemic at the Dental Hospital at Buenos Aires University School of Dentistry (FOUBA). Following epidemiological data, these workers underwent diagnostic testing for COVID-19 (1- nasal or throat swab tests; 2- blood test for enzyme-linked immunosorbent assays [ELISA]; 3- commercial rapid serology test). ResultsThree diagnostic tests were implemented. Rapid tests were performed on 290 subjects, with 255 negative results (88%; CI95: 84%–91%) and 35 positive (12%; CI95: 9%–16%); ELISA on 317 subjects, with 308 negative (97%; CI95: 95%–98%) and 9 positive (3%; CI95: 2%–5%); and PCR on 204 subjects, with 196 negative (96%; CI95: 92%–98%) and 8 positive (4%; CI95: 2%–8%). There were 358 subjects who were evaluated by ELISA or PCR, with 342 negative results (96%; CI95: 93%–97%) and 16 positives (4%; CI95: 3%–7%). ConclusionFor this sample of dentists, dental assistants and nonclinical personnel, the weighted prevalence of COVID-19 was 4%. Similar studies should be conducted at other dental care facilities in order to evaluate the worldwide impact of COVID-19 on the dental care community.

Ograničenja primene brzih seroloških testova na SARS-KoV-2 kod nevakcinisanih pacijenata u urgentnim kardioškim stanjima

In December 2019 in the city of Wuhan, in China, the first cases of infection caused by the new SARS-CoV-2 virus appeared, and later on, the disease caused by this virus was named COVID-19. Shortly after this, on March 11 th , 2020, the WHO characterized COVID-19 as a global pandemic. The symptoms of COVID-19 and acute cardiovascular disorders (e.g., heart failure, pulmonary embolism or myocardial ischemia) frequently overlap, which poses a challenge for the establishing of a differential diagnosis in clinical practice. Rapid serological tests, which detect IgM and IgG classes of antibodies for SARS-CoV 2, have been developed with the primary purpose of screening the population's immunological response to the SARS-CoV-2 virus. However, rapid serological tests are often used outside their original purpose, i.e., for the triage of possibly infected, non-vaccinated individuals, because they offer quick results, which may be particularly relevant in emergency settings. If serological testing is used to guide the admission of non-vaccinated patients with acute cardiovascular disorders to either an isolation unit for suspected COVID-19 positive individuals, or to hospital facilities for non-infected patients, it is important to recognize its limitations, in order to reduce the risk of false-positive or false-negative results. Hence, appropriate patient selection and cautious test interpretation is necessary to avoid misdiagnosis. The aim of this paper is to illustrate how serological testing may be used as a screening tool to inform the management of non-vaccinated patients with acute cardiovascular disorders requiring urgent hospital admission. As an illustration, we describe two clinical situations, in which serological testing produced meaningful results.

High Seroprevalence of Antibodies Against SARS-CoV-2 Among Healthcare Workers 8 Months After the First Wave in Aden, Yemen

Background: The true burden of COVID-19 in Yemen is underestimated as testing remains limited. MSF needed to rapidly identify and manage staff illness in the MSF Aden Trauma Centre. In this study we aimed to screen staff, offer PCR testing to symptomatic individuals, and conduct serological rapid tests to determine past infection. Methods: Four months after the peak of the first wave, we offered all the staff at the MSF Aden Trauma Centre PCR if symptomatic, and a baseline SARS-CoV-2 serology screening followed by follow-up screenings. A final round was scheduled four months after the baseline. A rapid serology lateral flow test, NG-Test® IgM-IgG was used in all rounds and in the final round, an electrochemiluminescence immunoassay (ECLIA) (Elecsys® Anti-SARS-CoV-2 assay). Univariate and multivariate analyses were used to identify risk factors for seropositivity. The level of agreement between the different serology assays used was investigated. Findings: Overall 69 out of 356 participants (19.4%, 95% CI 17.9 – 20.8) tested positive by NG-Test® between September and November 2020. A sub-sample of 161 staff was retested in January 2021. Of these, the NG-Test® detected only 13 positive cases, whereas the ECLIA detected 109 positive cases. The adjusted seroprevalence by ECLIA was 59% (95%CI 52.2 – 65.9). Those who were non-medical had significantly lower odds of seropositivity compared to the medical staff (AOR 0.43, 95% CI 0.15 – 0.7, p<0.001). The positive percent agreement between the two tests was very low (11%). Interpretation: Our results suggest a very high SARS-CoV-2 seroprevalence in healthcare workers in Yemen, highlighting the need for regular testing and rapid vaccination of all healthcare workers in the country. Rapid serological tests are likely to under-estimate true infection rates. Funding Information: Medecins Sans Frontieres, Epicentre Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: Written informed consent was obtained. This protocol was approved by the MSF Ethics Review Board on July 30, 2020, reference number 2056a, and by Aden University Institutional Review Board on August 9, 2020 (Research Code: REC-79-2020).

SARS-CoV-2 Infections in Households in a Peri-Urban Community of Lima, Peru: A Prospective Cohort Study

Background: Few studies have prospectively evaluated SARS-CoV-2 infections in households. We assessed the prevalence and incidence of SARS-CoV-2 infections in a prospective study of households in Lima, Peru.Methods: We conducted a prospective cohort study in a peri-urban district of Lima, Peru. Households with at least a child, a young adult (age 18 to 50 years) and an older adult age >50 years, were followed with twice-a-week household visits during a two-month period for health surveillance. Nasal swabs and saliva specimens were collected twice weekly, and nasopharyngeal swabs were collected weekly from each participant, regardless of symptoms. Laboratory-confirmed SARS-CoV-2 infection was defined by two RT-PCR tests from any of the collected specimens within a week. Blood samples collected at enrolment and end of follow­-up were tested with rapid serological tests. We calculated the prevalence and incidence of laboratory-confirmed SARS-CoV-2 infections during the study period.Findings: We enrolled 132 participants from 44 households, including 44 children, 44 young adults and 44 older adults. A total of 13 SARS-CoV-2 infections were detected in 9 households, for an overall period prevalence of 9·85% (95% confidence interval [CI]:5·35-16·25). Most (66·67%) infections were symptomatic. Eight of 11 (72·73%) SARS-CoV-2 detections corresponded to the Lambda variant. During 218·79 person-months at risk of follow-up there were six new SARS-CoV-2 infections detected (2·74 per 100 person-month, 95% CI: 1·25– 6·04). At enrollment, 59 of 128 participants tested had positive SARS-CoV-2 IgG serology (46·09%, 95% CI: 37·25-55·12). Five of six new infections occurred among participants with negative baseline serology.Interpretation: We demonstrated high incidence of SARS-CoV-2 infections in households during periods of active circulation of the Lambda variant, especially among subjects without evidence of prior infection, most of them not detected by the Ministry of Health system.Funding Information: Consejo Nacional de Ciencia y Tecnología – CONCYTEC-PROCIENCIA, Lima, Peru (contract No. 082-2020); Vanderbilt University Medical Center, Nashville TN, USA; and Instituto de Investigación Nutricional, Lima, Peru. Declaration of Interests: None to declare. Ethics Approval Statement: The study was approved by the ethics review boards (ERBs) of the Instituto de Investigacion Nutricional and Vanderbilt University. All adults signed their own ERB approved written informed consent form (ICF). For individuals under 18 years of age, either the mother or the father signed an ICF. Additionally, children 8 years and older signed a written informed assent form.

Prevalence of SARS-CoV-2 infection in the workplace: results of a year of investigation in the Marche Nord companies.

Background and aim:The world of work has been profoundly affected by the COVID-19 pandemic since workplace activities involving close contact with coworkers and customers can lead to transmission of SARS-CoV-2 and compromise continuity of operations of workplaces.The Covid-Lab of University of Urbino and the Confindustria Pesaro Urbino association signed an agreement to support the Marche Nord companies in the adoption of anti-contagion safety protocols.Methods:Antibodies detection was performed using a rapid immunochromatographic test. Total RNA from nasopharyngeal swab was subjected to a real-time RT-PCR multiplex for the detection of RdRp specific gene and E gene of the SARS-CoV-2, and the internal control (human RNase P).Results:Between May 2020 and Apr 2021, over 10,000 rapid serological tests had been carried out on workers of 35 companies and in 5% of cases IgG or IgM were found (519). All the 519 swabs gave a valid result (RNAse P Ct≤40) with 105 positive results (20%) for SARS-CoV-2 with a Ct value ≤45. Overall, only 1% of samples resulted positive for viral RNA (105/10000).Conclusions:The University of Urbino set up a rapid-response (within 24 h, generally <6 h) diagnostic centre for SARS-CoV-2 detection (Covid-Lab) allowing the companies to activate the optimal safety path to ensure the health and safety of workers in the workplace. Our observations during this first year of activity, highlight that in the workplace, the infection does not seem to spread if precautionary measures are followed and only 1% (1 worker out of 100) tested positive for the SARS-CoV-2 virus. (www.actabiomedica.it)

Robust correlations across six SARS-CoV-2 serology assays detecting distinct antibody features.

ObjectivesAs the world transitions into a new era of the COVID‐19 pandemic in which vaccines become available, there is an increasing demand for rapid reliable serological testing to identify individuals with levels of immunity considered protective by infection or vaccination.MethodsWe used 34 SARS‐CoV‐2 samples to perform a rapid surrogate virus neutralisation test (sVNT), applicable to many laboratories as it circumvents the need for biosafety level‐3 containment. We correlated results from the sVNT with five additional commonly used SARS‐CoV‐2 serology techniques: the microneutralisation test (MNT), in‐house ELISAs, commercial Euroimmun‐ and Wantai‐based ELISAs (RBD, spike and nucleoprotein; IgG, IgA and IgM), antigen‐binding avidity, and high‐throughput multiplex analyses to profile isotype, subclass and Fc effector binding potential. We correlated antibody levels with antibody‐secreting cell (ASC) and circulatory T follicular helper (cTfh) cell numbers.ResultsAntibody data obtained with commercial ELISAs closely reflected results using in‐house ELISAs against RBD and spike. A correlation matrix across ten measured ELISA parameters revealed positive correlations for all factors. The frequency of inhibition by rapid sVNT strongly correlated with spike‐specific IgG and IgA titres detected by both commercial and in‐house ELISAs, and MNT titres. Multiplex analyses revealed strongest correlations between IgG, IgG1, FcR and C1q specific to spike and RBD. Acute cTfh‐type 1 cell numbers correlated with spike and RBD‐specific IgG antibodies measured by ELISAs and sVNT.ConclusionOur comprehensive analyses provide important insights into SARS‐CoV‐2 humoral immunity across distinct serology assays and their applicability for specific research and/or diagnostic questions to assess SARS‐CoV‐2‐specific humoral responses.

Relationship between ocular abnormalities and hematologic alterations in patients infected naturally by Ehrlichia canis

ABSTRACT: To determine the association between ocular abnormalities and hematologic findings in Ehrlichia canis-infected dogs, 120 dogs suspected of canine ehrlichiosis were studied. All patients were subjected to rapid serologic diagnostic test for Ehrlichia canis, and the diagnosis was confirmed by quantitative PCR. PCR-positive patients underwent ophthalmologic examination and a hemogram and were grouped into patients with thrombocytopenia and anemia (G1), patients with thrombocytopenia (G2), and patients without hematologic disorders (G3). For ophthalmic evaluation, the patients were grouped into those having mild, severe, both mild and severe, and no ocular alterations. All patients presented with uveitis (100%). Severe ocular disorders predominated in G1 and G2 patients. Dogs with anemia and leukopenia showed severe ocular disorders. In dogs with a greater number of leukocytes and copies/µl of the TRAG gene, the intraocular pressure (IOP) tends to decrease and vice versa (r = −0.23, r = −0.26). In conclusion, uveitis is the earliest ocular alteration of canine ehrlichiosis. The severity of ocular abnormalities in patients with ehrlichiosis is associated with thrombocytopenia and may be aggravated by anemia and leukopenia. The hemogram and IOP are useful tools for predicting eye involvement in Ehrlichia canis-infected patients. In regions where Ehrlichia canis is endemic, the use of the tonometer should be routinely in dog general consultation.