Serologic Test Results Research Articles

Challenges of laboratory diagnosis of Lyme disease ‒ Questionnaire survey results.

The accuracy in diagnostic testing for Lyme disease in the early stages of infection is an important factor necessary for delivering proper treatment to patients. Atotal of 173 individuals with confirmed Lyme disease or with laboratory testing underway participated in the quantitative survey. ELISA was the first test conducted in 51% of the respondents, 28% of whom yielded positive findings of both IgM and IgG antibody classes. The positivity of ELISA test findings was confirmed by Western blot in 100% of results. Negative results of ELISA were consistent with Western blot only in less than half of the patients. More than half of the respondents had not been tested for any bacterial or viral co-infections. The results of serological testing were not consistent with clinical findings in all cases, including those with clinically discernible skin manifestation of erythema migrans. The comparison of results obtained by ELISA and Western blot revealed significant discrepancies. Simultaneous infections by vectors with several pathogens were detected (Tab. 3, Fig. 2, Ref.15).

Clinicopathological Reclassification of Idiopathic Inflammatory Myopathy to Match the Serological Results of Myositis-Specific Antibodies.

Advances in serological tests are transforming the classification of idiopathic inflammatory myopathy (IIM). The new criteria suggested by the 119th European Neuromuscular Center international workshop divide IIM cases into four main diseases according to clinical and pathological findings, adding immune-mediated necrotizing myositis and nonspecific myositis to the classic categories of polymyositis and dermatomyositis. Seventy one cases of IIM with sufficient available clinical and pathological data were reviewed to be reclassified according to the new criteria. Most of the cases previously classified as polymyositis (77.8%, 35/45) were reclassified as immune-mediated necrotizing myopathy. The results of myositis-specific antibodies matched well with the new clinicopathological classification. This new clinicopathological classification for IIM in combination with serological test results could be applied to our previous case series. Adoption of the new criteria will lead to a better understanding of the disease and hence new therapeutic insights.

Support Vector Machine Outperforms Other Machine Learning Models in Early Diagnosis of Dengue Using Routine Clinical Data.

Background: There is a dire need for the establishment of active dengue surveillance to continuously detect cases, circulating serotypes, and determine the disease burden of dengue fever (DF) in the country and region. Predicting dengue PCR results using machine learning (ML) models represents a significant advancement in pre-emptive healthcare measures. This study outlines the comprehensive process of data preprocessing, model selection, and the underlying mechanisms of each algorithm employed to accurately predict dengue PCR outcomes. Methods: We analyzed data from 300 suspected dengue patients in Islamabad and Rawalpindi, Pakistan, from August to October 2023. NS1 antigen ELISA, IgM and IgG antibody tests, and serotype-specific real-time polymerase chain reaction (RT-PCR) were used to detect the dengue virus (DENV). Representative PCR-positive samples were sequenced by Sanger sequencing to confirm the circulation of various dengue serotypes. Demographic information, serological test results, and hematological parameters were used as inputs to the ML models, with the dengue PCR result serving as the output to be predicted. The models used were logistic regression, XGBoost, LightGBM, random forest, support vector machine (SVM), and CatBoost. Results: Of the 300 patients, 184 (61.33%) were PCR positive. Among the total positive cases detected by PCR, 9 (4.89%), 171 (92.93%), and 4 (2.17%) were infected with serotypes 1, 2, and 3, respectively. A total of 147 (79.89%) males and 37 (20.11%) females were infected, with a mean age of 33 ± 16 years. In addition, the mean platelet and leukocyte counts and the hematocrit percentages were 75,447%, 4189.02%, and 46.05%, respectively. The SVM was the best-performing ML model for predicting RT-PCR results, with 71.4% accuracy, 97.4% recall, and 71.6% precision. Hyperparameter tuning improved the recall to 100%. Conclusion: Our study documents three circulating serotypes in the capital territory of Pakistan and highlights that the SVM outperformed other models, potentially serving as a valuable tool in clinical settings to aid in the rapid diagnosis of DF.

Associação dos alelos de risco HLA-DQ2 e HLA-DQ8 à lesão intestinal e sorologia em pacientes com doença celíaca

ABSTRACT Objective This study aims to describe the distribution of main celiac disease risk alleles related to human leucocyte antigen complex and their association to the severity of intestinal injury, serological test results, CD-associated diseases and symptomatology. Methods The DNA of 140 celiac disease patients was analyzed, and the distribution of the three most important risk alleles to the celiac disease development was identified (DQA1*05:01, DQB1*02:01 and DRB1*04, the last one as a DQB1*03:02/DQA1*03/DRB1*04 haplotype marker). Data on serological tests, biopsy results, symptomatology and incidence of CD-associated diseases were collected by using a previously validated questionnaire. Results It was found that 98% of patients presented at least one copy of the studied alleles. Patients carrying simultaneously both HLA-DQ2 risk alleles were highly prevalent (75%), and 20.7% patients carried the HLA-DQ8 haplotype. Positive patients for both HLA-DQ2 risk alleles presented positive association to anti-gliadin (p=0.037), anti-endomysium (p=0.001) and anti-transglutaminase (p=0.032) serological tests, and a higher prevalence of osteoporosis and hypothyroidism. Patients carrying one or none of those alleles often presented negative serological results. In addition, it was found an association between intestinal injury severity and genetic profile (No-BreakpNo-Break<0.001). Conclusion Results suggest that the HLA-DQ genotyping are associated to serological tests and the severity of intestinal damage in celiac disease patients.

Prevalence of Toxoplasma gondii IgM and IgG positive cats in Los Angeles County, California.

The objective of this study was to determine the prevalence of Toxoplasma gondii IgM and IgG positive cats in Los Angeles County, California. T gondii antibodies are common in sera from cats in most reported studies around the world. Although the majority of infected cats never develop clinical disease, development of acute infection and recrudescence of latent infection secondary to immunosuppression has been reported. Knowledge of the serologic status of T gondii may be important when considering immunosuppressive treatments. T gondii IgM and IgG antibody titers were measured in 225 cats. Sera from owned cats tested at a multispecialty veterinary hospital were included both retrospectively and prospectively (n = 125). Sera from feral cats tested through a collaborating humane society were included prospectively (n = 100). Of the 13 (5.8%) cats with IgM titers, 10 were positive at the minimal cut-off titer (1:64), one cat was clinically ill and none were currently positive for IgG antibodies, suggesting false-positive results for nine cats, giving an adjusted IgM prevalence rate of 1.8% (95% CI 0.7-4.5). A total of five (2.2%) cats were positive for IgG antibodies and no cat was positive for both antibodies. Most studies of T gondii antibodies in cat sera from California have shown higher prevalence rates, suggesting the cats in this municipality have a low risk of exposure. The study emphasizes that serological test results do not necessarily correlate to the presence of clinical illness.

Identification and Blood Transfusion of a Rare A1.02/BA.02 Genotype.

The aim was to analyze the serological and molecular genetic characteristics of a rare B(A) subtype pedigree, explore its pathogenesis, and discuss transfusion strategies. ABO blood typing serological tests were conducted on a female subject and her family member using standard serological methods. Sequencing analysis of the ABO gene exons 6 and 7 was performed using PCR technique for the female subject and her family member to examine the blood types of the participants. The serological test results showed a discrepancy between the forward and reverse typings of the female subject. The forward typing was similar to that of AB subtype serological forward typing, while the reverse typing indicated AB blood type. Based on the sequencing results, it is inferred that the female subject and her son have 8 mutations on one BA.02 chain: 297A>G, 526C>G, 657C>T, 700C>G, 703G>A, 796C>A, 803G>C, and 930G>A. Comparing these eight mutation sites with the Blood Group Antigen Gene Mutation Database (BGMUT), it was found that the female subject had a heterozygous mutation at c.700C>G in the 7th exon of the B.01 gene, consistent with the characteristics of the BA.02 allele. The genotype of the female subject was determined as A1.02/ BA.02, while the genotype of her son was determined as O.01.01/BA.02. The serological presentation of the B(A) subtype for the female subject reported in this study was unique. It differed from previously reported cases, indicating that the determination of B(A) subtypes cannot solely rely on serological testing. It requires a comprehensive analysis combining the results of genetic testing and pedigree investigation.

Верифікація алгоритмів тестування на ВІЛ з використанням швидких тестів

Верифікація алгоритмів тестування на ВІЛ з використанням швидких тестів

Virus-specific humoral immune response in Bulgarian COVID-19 patients with varying disease severity.

Our study aimed to analyze virus-specific humoral immune responses in COVID-19 patients with varying disease severity. A total of 109 serum samples from 87 patients, symptomatic for COVID-19 were studied using anti-SARS-CoV-2 immunoassays detecting different classes of immunoglobulins. Clinical samples were divided into 2 groups - collected up to and more than 2 weeks post-onset of symptoms (PoS). In the first group, the highest percentage of positive samples was found for IgA class virus-specific antibodies (78.1%), followed by IgM (71.9%/59.4%) and IgG (56.3%/53.1%). In the second group, samples positive for virus-specific IgA class antibodies were also the most (97.7%) along with those positive for IgG. A total of 72 IgA and/or IgM and/or IgG positive samples were further tested for SARS-CoV-2 neutralizing antibodies (NAbs) - 89.1% and 100% of samples obtained up to and after 2 weeks PoS, respectively were positive. Serological test results were also analyzed depending on the severity of the disease - SARS-CoV-2 positive samples in mild forms of COVID-19 were fewer than in moderate and severe forms but this difference was not statistically significant. SARS-CoV-2 specific antibodies and a high virus neutralization capacity of these antibodies appear early PoS; Immunoglobulins of IgA class are of most significant diagnostic value for detection of SARS-CoV-2 infection; Timing of testing is the most important factor for positivity rate.

Short communication: Retrospective analysis of obligatory testing results for Equine virus arteritis reveals a decrease of its seroprevalence in stallions used for artificial insemination

Equine viral arteritis (EVA) can induce a persistent carrier state in stallions which then shed the virus via semen. About 30 years ago, obligatory EVA testing of stallions used for artificial insemination (AI) was implemented in the European Union. Information on the efficacy of these regulations on the prevalence of EVA in stallions are not yet available. Therefore, we retrospectively analyzed results of serological and virus antigen testing for EVA in sires of different age and breed referred to Vetmeduni Vienna for semen preservation or veterinary diagnostic procedures between 2001 and 2021. For analysis, stallions were grouped by age (1–5, 6–8, 9–12, >12 years) and breed. The EVA antibody titer was determined by serum neutralization test and semen was analyzed for EVA virus by PCR and/or virus isolation test. Of 308 stallions tested, 14.9% (n = 46) were EVA seropositive and in 12 stallions EVA virus was detected in semen (26% of seropositive stallions). The incidence of seropositive stallions decreased over time (P < 0.05, χ2 test). Differences in the seroprevalence of EVA antibodies existed among stallion age groups (P < 0.01, Fisher’s test) with the highest percentage of seropositive stallions being > 12 years old (43.5%). The EVA antibody titer increased with age (P < 0.01, Kruskal-Wallis test), potentially reflecting repeated virus challenge. In conclusion, analysis of monitoring results revealed a decrease of EVA seroprevalence and virus shedding in a European sire population. As monitoring for EVA was the only measure implemented Europe-wide, testing might be a major contributor to this development.

Estimation of foot-and-mouth disease virus sero-prevalence rates using novel computational approach for the susceptible bovine population in India during the period 2008–2021

Foot-and-mouth disease (FMD) is a severe contagious viral disease of cloven-hoofed animals. In India, a vaccination-based official FMD control programme was started, which got expanded progressively to cover entire country in 2019. The serological tests are used to determine non-structural protein based sero-prevalence rates for properly implementing and assessing the control programme. Since 2008, reporting of the FMD sero-surveillance was limited to the serum sample-based serological test results without going for population-level estimation due to lack of proper statistical methodology. Thus, we present a computational approach for estimating the sero-prevalence rates at the state and national levels. Based on the reported approach, a web-application (https://nifmd-bbf.icar.gov.in/FMDSeroSurv) and an R software package (https://github.com/sam-dfmd/FMDSeroSurv) have been developed. The presented computational techniques are applied to the FMD sero-surveillance data during 2008–2021 to get the status of virus circulation in India under a strict vaccination policy. Furthermore, through various structural equation models, we attempt to establish a link between India’s estimated sero-prevalence rate and field FMD outbreaks. Our results indicate that the current sero-prevalence rates are significantly associated with previous field outbreaks up to 2 years. Besides, we observe downward trends in sero-prevalence and outbreaks over the years, specifically after 2013, which indicate the effectiveness of various measures implemented under the FMD control programme. The findings of the study may help researchers and policymakers to track virus infection and identification of potential disease-free zones through vaccination.

The Main Genome is a Source of Adaptogens and the Basis for the Development of a New Vaccination Technology

The appearance of viruses in mammals and plants is provoked by environmental factors - xenobiotics, formed mainly due to unreasonable human activity and resulting from the formation of an ecological (epidemiological) niche filled with molecular motifs of the microbiota - the intestines of mammals and the root system of plants. To do this, bacteria and archaea use retrovirus-like “cut and paste” mechanisms, including, for example, the CRISPR/Cas system, when the molecular motifs of the microbiota try to adapt the immune and hormonal systems. It all depends on how much xenobiotics damage the immune and hormonal systems. Therefore, viruses are not the cause, but the consequence of the disease. The fight against viruses with the help of vaccines prepared on their basis has been violating and restraining the natural mechanisms of regulation of biological processes in plants and mammals. Thus, molecular motifs arising from microbiota bacteria become either apaptogens (viruses) or adaptogens. In the first and second cases, genetic information is released into the environment. In the latter case, there is an adaptation or a kind of vaccination of others by a natural mechanism. This mechanism is also applicable to somatic diseases, such as cardiovascular, autoimmune, oncological, etc. As for the original properties of coronaviruses, it is their ability to suppress innate and acquired nonspecific viral immunity in the respiratory tract. This leads to the reactivation of chronic, mainly bacterial, respiratory infections - pneumococci, staphylococci, hemophiluses, however, fungal infections can also be observed – mucormycosis, aspergillosis, etc. This feature of the virus prompted doctors at the beginning of the epidemic (2020) to use a pneumococcal vaccine, which, as it turned out, similarly to the coronavirus vaccine reduces the severity of the disease and mortality. As for the diagnosis of coronavirus infection and its treatment, as practice has shown, everything depends on the stage of the disease, starting with a viral and ending with a bacterial infection. Similar and identical antigenic determinants in coronavirus and respiratory group bacteria often caused confusion when analyzing the results of serological and molecular biological diagnostic tests in patients with COVID-19. Moreover, the justified use of antibiotics in the post-viral, that is, in bacterial periods, made it possible to successfully treat patients with a positive PCR test for coronavirus on an outpatient basis.

The Minority and Rural Coronavirus Insights Study: Design and Baseline Characteristics of a Minority Cohort.

The Minority and Rural Coronavirus Insights Study (MRCIS) is an ongoing prospective cohort study examining health disparities associated with SARS-CoV-2 infection among medically underserved populations. This report describes procedures implemented to establish the MRCIS cohort and examines the factors associated with the molecular and serological assessment of SARS-CoV-2 infection status at participant enrollment. Participants were recruited from 5 geographically dispersed federally qualified health centers between November 2020 and April 2021. At baseline, participants completed a detailed demographic survey and biological samples were collected for testing. SARS-CoV-2 infection status was determined based on the combined molecular and serological test results. Chi-squared and logistic regression analyses were conducted to examine associations between sociodemographic factors, COVID-19 safety measures, existing comorbidities, and SARS-CoV-2 infection status. The final cohort included 3238 participants. The mean age of participants was 50.2 ± 15.8 years. Most participants identified as female (60.0%), heterosexual or straight (93.0%), White (47.6%), and Hispanic or Latino (49.1%). Approximately 26.1% of participants had at least one positive SARS-CoV-2 test result. The main effect model included age, sex, and race/ethnicity. Compared with adults ≥65 years, participants in all other age groups had ∼2 times increased odds of a positive SARS-CoV-2 test result. In addition, racial/ethnic minorities had ∼2 times increased odds of a positive SARS-CoV-2 infection status compared with non-Hispanic Whites. A unique cohort of a traditionally medically underserved minority population was established. Significant racial and ethnic disparities in SARS-CoV-2 infection status at baseline were discovered.

Association between severe acute respiratory syndrome coronavirus 2 antibody status and reinfection: A case-control study nested in a Colorado-based prospective cohort study

ObjectiveThe association between the presence of detectable antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and SARS-CoV-2 reinfection is not well established. The objective of this study was to determine the association between antibody seronegativity and reinfection. Methods: Participants in Colorado, USA, were recruited between June 15, 2020, and March 28, 2021, and encouraged to complete SARS-CoV-2 molecular ribonucleic acid (RNA) and serology testing for antibodies every 28 days for 10 months. Participants with reinfections (positive SARS-CoV-2 RNA test ≥ 90 days after the first positive RNA test) were matched to controls without reinfections by age, sex, date of the first positive RNA test, date of the last serology test, and serology test type. Using conditional logistic regression, case patients were compared to control patients on the last serologic test result, with adjustment for demographic and clinical confounders. Results: The cohort (n = 4,235) included 2,033 participants with ≥ 1 positive RNA test, of whom 120 had reinfection. Among the 80 case patients who could be matched, the last serologic test was negative in 12 of the cases (15.0 %) whereas the last serologic test was negative in 77 of 1,034 (7.5 %) controls. Seronegativity (adjusted OR [aOR] 2.24; 95 % CI 1.07, 4.68), Hispanic ethnicity (aOR 1.87; 95 % 1.10, 3.18), and larger household size (aOR 1.15; 95 % 1.01, 1.30 for each additional household member) were associated with reinfection. Conclusions: Seronegative status, Hispanic ethnicity, and increasing household size were associated with reinfection. Serologic testing could be considered to reduce vaccine hesitancy in higher risk populations.

Content and specificity of the Anti-SARS-CoV-2 antibodies in solutions for immunoglobulin replacement therapy

BackgroundSpecific antibodies are important for post-vaccination and post-infection immune responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The role of antibodies in preventing and treating Coronavirus disease 2019 (COVID-19) in high-risk populations has been highlighted through the use of virus-specific monoclonal antibodies, which has raised the question of immunoglobulin replacement therapy (IRT) used in immunocompromised patients. MethodsVirus-specific anti-receptor-binding domain (RBD) and anti-nucleocapsid protein (NCAP) antibodies (assessed using a chemiluminescence assay and virus-neutralizing antibodies (virus neutralization test against Delta and Omicron variants)) were analyzed in 20 batches of 10 % (100 mg/mL) immunoglobulin solutions for intravenous IRT from two commercially available producers between January 2022 and March 2023 for clinical use. ResultsAnti-RBD and anti-NCAP antibodies were detected in all 20 batches of assessed IRT solutions (mean concentrations of 2817 IU/mL and 2380 IU/mL, respectively). Notably, the concentration of the virus-specific antibodies increased continuously during the follow-up period (from 822.5 IU/mL to 4066.4 IU/mL and 102 IU/mL to 3455.9 IU/mL). These antibodies demonstrated high virus-neutralizing activity against the Delta variant (mean titers of 436 and 325) but were limited to the Omicron variant (mean titers 78 and 70). The differences observed between the two brands were not statistically significant. ConclusionIRT solutions contain high concentrations of anti-SARS-CoV-2 specific antibodies, which may prevent COVID-19; however, the efficacy can be influenced by variable virus-neutralizing activities against different viral strains. Therefore, appropriate IRT should be combined with other approaches, such as vaccination or pre- and post-exposure prophylaxis. Passively transmitted specific antibodies may also lead to false-positive serological test results.

Influence of infectious diseases on detection of antibodies to treponema pallidum

The problem of the spread of syphilis is becoming acute due to the rapid increase in the number of initially detected cases of the disease. When analyzing and interpreting the obtained laboratory data, there is always the possibility of obtaining contradictory results, both false positive and false negative, which do not coincide with the clinical picture of the patient. Since in practice false positive results of serological tests for syphilis are detected more often than false negative ones, special importance is attached to the identification and study of the causes of their occurrence. At the analysis stage, the cause may be the cross-reactivity of the test system with various ‘particles’ in the analyzed samples, due to the peculiarities of its design and antigenic composition. For this work, sets of reagents Abbott GmbH (CMIA), Mindray (CLIA), as well as reagents produced by Vector-Best (ELISA) were used. During the study, it was found that one of the possible ‘particles’ leading to cross-reactivity of test systems may be IgG antibodies to cytomegalovirus.

Differences of Hepatitis B Serological Tests in Cirrhosis and Hepatocellular Carcinoma Patients

Cirrhosis and hepatocellular carcinoma (HCC) are the most common complications of chronic hepatitis B. Hepatitis B Virus (HBV) reactivation occurs in the inactive phase, characterized by reappearance of HBsAg or negative HBsAg. The prevalence of occult hepatitis B infection in cirrhosis and HCC ranges from 20% to 60%. This study aimed to analyze the differences in hepatitis B serological tests in patients with cirrhosis and HCC for diagnosis of acute or chronic hepatitis B. The current research was analytical and descriptive with a cross-sectional study design. This study involved 177 patients, including 50 cirrhosis patients and 127 HCC patients. Hepatitis B serological tests (HBsAg, HBeAg, anti-HBe, total anti-HBc) were analyzed using VIDAS instruments by the Enzyme-Linked Fluorescent Immunoassay (ELFA) method. Hepatitis B serological test results were grouped based on the interpretation of serological test results. The data were processed with the statistical test Kolmogorov-Smirnov test, independent T-test, and Chi-Square, and results with p&lt;0.05 were reported as significant. This study found that most males suffer from cirrhosis and HCC due to chronic HBV infection, with a mean age of 57. Chronic hepatitis was most common in patients with cirrhosis and HCC (71.2%). There was no significant difference in the interpretation of the hepatitis B serological test between patients with cirrhosis and HCC, with a p-value of 0.230 (p &gt; 0.05). There was no significant difference in interpreting the hepatitis B serological test between cirrhosis and HCC. Both reactive HBsAg and non-reactive HBsAg can be obtained in cirrhosis and HCC.

Temporal tracheobronchial lymphadenopathy resolution is affected by initial severity and poorly correlated to serologic antibody testing in dogs with pulmonary coccidioidomycosis.

To determine associations between antibody serologic tests and tracheobronchial lymphadenopathy (TBL) in dogs with pulmonary coccidioidomycosis and identify variables associated with time to resolution of TBL. 32 client owned dogs with newly diagnosed pulmonary coccidioidomycosis from October 2020 to February 2021. Prospective cohort study. Thoracic radiographs and anti-Coccidioides spp antibody serology were performed at baseline and once every 3 months until remission or for a maximum of 12 months. Radiographic tracheobronchial lymph node height, length, and area were measured and recorded as ratios via comparison with the length of the T4 vertebral body (LT4) and length of the manubrium. Severity of TBL was also subjectively categorized as mild, moderate, or severe. Tracheobronchial lymphadenopathy was identified in 81% (26/32; 95% CI, 64% to 93%) of dogs. There was no relevant association between TBL presence or severity and antibody serology results. Tracheobronchial lymphadenopathy resolved in 72% (n = 18) of dogs at the 3-month evaluation. The median time to resolution of TBL after initiation of fluconazole was 96 days (range, 72 to 386 days). Univariate analysis identified increasing TBL severity (hazard ratio, 0.40; 95% CI, 0.19 to 0.84; P = .02) and length:LT4 ratio (hazard ratio, 0.41; 95% CI, 0.20 to 0.82; P = .01) as variables associated with reduced probability of resolution of TBL. Antibody serologic test results are not clinically useful to predict TBL presence or severity in dogs with pulmonary coccidioidomycosis, and larger tracheobronchial lymph nodes are more likely to take longer to resolve. Resolution of TBL occurs in most dogs within 3 to 6 months after fluconazole administration.

Assessing the contributions of phylogenetic and environmental determinants of allergic cosensitization to fungi in humans

BackgroundUnderstanding how allergies to 1 environmental fungus can lead to cosensitization to related fungi is important for the clinical management of allergies. Cosensitization can be caused by monosensitization combined with antibody cross-reactivity, or by coexposures driving independent sensitizations. A pioneering study showed that patterns of IgE cosensitization among 17 fungal species mirror fungal phylogeny. This could reflect either epitope or habitat similarity. Thanks to an improved understanding of fungal phylogeny, larger serologic testing datasets, and environmental data on household fungi, we can now characterize the relationship between cosensitization, species similarity, and likely coexposure with greater precision. ObjectiveTo assess the degree to which IgE cosensitization in a group of 17 fungi can be attributed to species similarity or environmental coexposure. MethodsCosensitization patterns among 17 fungal species were estimated from a dataset of approximately 8 million serologic tests on 1.6 million patients. Linear regression of cosensitization on phylogenetic distance and imputed coexposure was performed. In addition, branch lengths for the phylogenetic tree were re-estimated on the basis of cosensitization and compared with corresponding phylogenetic branch lengths. ResultsPhylogenetic distance explains much of the observed cosensitization (adjusted r2 = .68, p < .001). Imputed environmental coexposures and test co-ordering patterns do not significantly predict cosensitization. Branch length comparisons between the cosensitization and phylogenetic trees identified several species as less cosensitizing than phylogenetic distance predicts. ConclusionCombined evidence from clinical IgE testing data on fungi, along with phylogenetic and environmental exposure data, supports the hypothesis that cosensitization is caused primarily by monosensitization plus cross-reactivity, rather than multisensitization. A serologic test result should be interpreted as pointing to a group of related species that include the sensitizing agent rather than as uniquely identifying the agent. The identified patterns of cross-reactivity may help optimize test panel design.

Syphilis Prevalence, Incidence, and Demographic Differences in a Longitudinal Study of Young Sexual and Gender Minority Adults Assigned Male at Birth.

Syphilis rates in the United States have increased. Few studies have examined syphilis incidence and prevalence prospectively among young sexual and gender minorities (YSGM). This study of YSGM assigned male at birth comes from a Chicago-based prospective cohort at 2 visits 6 months apart (N = 882). Syphilis cases were identified through serologic test results and self-reported history. In this sample, 25.1% had a lifetime prevalence, and 3.3% were incident cases with a crude incidence rate of 6.76 per 100 person-years. Lifetime syphilis and incidence are high in this sample of YSGM relative to general population samples.

B-062 A Self-Imposed Gray Area? Analysis of Anti-Tissue Transglutaminase and Anti-Endomysial Antibody Discordance in a Celiac Disease Screening Serology Testing Algorithm

Abstract Background Celiac disease (CD) is an autoimmune enteropathy affecting around 1% of the population. While occasionally asymptomatic, the disease can present in a variety of ways and can be triggered by dietary gluten at any age. CD serology, including anti-tissue transglutaminase (anti-tTG) IgA and/or IgG, anti-endomysial antibody IgA and/or IgG, and anti-deamidated gliadin peptide IgA and/or IgG, is a key tool for CD screening, diagnosis, and monitoring. Of these tests, the clinical utility of anti-EMA testing has been questioned due to its high cost and limited sensitivity: 5–10% of CD patients do not test positive for anti-EMA and a negative anti-EMA does not rule out CD. The objective of this study is to: 1) evaluate the concordance between anti-tTG and anti-EMA serology test results, and 2) assess the clinical validity of our current CD reflex testing algorithm in which every positive anti-tTG test result goes on for anti-EMA testing. Methods Using our laboratory’s information system, we conducted a retroactive study on patients who underwent CD serology testing at our institution. Query was performed for all patient data [pediatric (&amp;lt;18 years) and adult (&amp;gt;18 years)] collected between April 2020 and August 2022 for anti-tTG IgA performed on the BioPlex 2200 (BioRad Laboratories Inc., Hercules, CA) and anti-EMA IgA (Euroimmun, Germany) (N = 124 308). Vendor-supplied clinical sensitivity and specificity are as follows: anti-tTG IgA 94.3% sensitivity, 98.8% specificity; anti-EMA IgA 95.3% sensitivity and 98.0% specificity. Results From our data, we calculated a mean positive agreement between our anti-tTG IgA and anti-EMA test results of 53.2% (95% confidence interval (CI) 47.5–58.8%) for all anti-tTG IgA positive cases (N = 6691, 5.4% of total anti-tTG IgA test results). The agreement between anti-tTG IgA and anti-EMA test results is improved if multiples of the upper limit of normal (ULN) for anti-tTG IgA is applied. The mean positive agreement between anti-tTG IgA and anti-EMA test results when the anti-tTG result is &amp;gt;10x ULN is 98.4% (95% CI 97.7–99.2%). However, if an anti-tTG IgA cutoff of &amp;lt;10x ULN is employed a mean positive agreement of 32.3% (95% CI 25.8–38.7%) is observed. At an anti-tTG IgA cutoff of &amp;lt;3x ULN, the mean positive agreement is just 11.8% (95% CI 8.2–15.4%). These findings are consistent in both pediatric (N = 29 381) and adult (N = 94 961) populations and are problematic as 45.4% of our positive anti-tTG IgA test results are accompanied by a negative anti-EMA. Conclusion The agreement between anti-tTG IgA and anti-EMA is dependent on the value of anti-tTG IgA with greater agreement observed with increasing anti-tTG IgA values. As all specimens at our institution with positive anti-tTG IgA test results are automatically reflexed for anti-EMA testing, has led to physician confusion as the majority of patients are falling into a gray area with conflicting CD serology test results. Our algorithm is also out of line with most CD screening guidelines that suggest an initial positive anti-tTG test result is followed up with biopsy. Finally, discontinuing anti-EMA reflex testing could result in cost savings of approximately $120 000 CAD per year.