[Analysis of serum IgM antibody and viral nucleic acid test results in measles and rubella cases in China from 2014 to 2023].

Objective: To analyze the results of serum IgM antibody and viral nucleic acid testing in measles and rubella cases in China from 2014 to 2023. Methods: Surveillance data on measles and rubella during 2014-2023 were obtained from the Chinese Disease Prevention and Control Information System, and cases that underwent measles/rubella IgM antibody testing and viral nucleic acid testing were included in the study. Information on the number of cases, vaccination status, and laboratory test results was collected, and laboratory test results were compared among cases with different times of rash or onset and different doses of vaccination. Results: From 2014 to 2023, the total number of measles and rubella surveillance cases was 581 746, and the number of measles and rubella cases that underwent both IgM antibody and viral nucleic acid testing was 39 124 and 21 766, respectively, with a double-positive rate of IgM antibody and viral nucleic acid testing of 63.73% (for measles) and 41.68% (for rubella). The single-positive rate for IgM antibody was 21.12% (for measles) and 27.15% (for rubella). The single-positive rate for viral nucleic acid tests was 13.84% (for measles) and 28.19% (for rubella). According to different days of rash or onset (0-3, 4-5, 6-10 and >10), samples of 24 629 (62.95%) measles cases and 15 785 (72.52%) rubella cases were from within 3 days of rash or onset, and the single positive rate of viral nucleic acid detection was 16.90% (for measles) and 32.07% (for rubella). The single positive rate of IgM antibody increased gradually with the time of onset (measles: χ2trend=314.098, P<0.001, rubella: χ2trend=763.846, P<0.001), and reached 31.66% (for measles) and 53.12% (for rubella) after 10 days of rash or onset. Depending on the number of vaccination doses (1, 2,≥3), the single positive rate of viral nucleic acid detection ranged from 12.93% to 20.29% (for measles) and from 25.30% to 27.88% (for rubella). The single positive rate of IgM antibody detection ranged from 36.89% to 47.47% (for measles) and from 22.81 to 41.15% (for rubella). Conclusions: Combined testing of serum IgM antibody and viral nucleic acids could facilitate laboratory confirmation of measles and rubella cases and was also important for measles and rubella elimination efforts.

Multiplex Bead Assay for the Serological Surveillance of Measles and Rubella.

There is increasing interest in evaluating antibody responses to multiple antigen targets in a single assay. Immunity to measles and rubella are often evaluated together because immunity is provided through combined vaccines and because routine immunization efforts and surveillance for measles and rubella pathogens are combined in many countries. The multiplex bead assay (MBA) also known as the multiplex immunoassay (MIA) described here combines the measurement of measles- and rubella-specific IgG antibodies in serum quantitatively according to international serum standards and has been successfully utilized in integrated serological surveillance.

Seroprevalence of Toxoplasma gondii, Rubella, Group A Streptococcus, CMV and HSV-1 in COVID-19 Patients with Vitamin D Deficiency.

<b>Background and Objective:</b> In recent years, respiratory tract viral infections have caused many pandemics that impact the whole world. To investigate the seropositivity of <i>Toxoplasma gondii</i>, rubella, CMV, HSV-1 and group A <i>Streptococcus</i> in recovered COVID-19 patients and correlate these findings with vitamin D levels. <b>Materials and Methods:</b> A total of 417 COVID-19 patients with diarrhoea were enrolled in this study. Vitamin D and seroprevalence for <i>Toxoplasma gondii</i>, rubella, CMV, HSV-1 and group A <i>Streptococcus</i> were evaluated and correlated. <b>Results:</b> It was found that recent infection in COVID-19 patients with HSV-1, rubella, <i>Toxoplasma</i> and CMV, respectively. IgG was detected indicating the development of adaptive immunity with all microbes. <b>Conclusion:</b> Current study detected a correlation between vitamin D levels and HSV-1 and no correlation between this infection and vitamin D deficiency with the other microbes.

Optimization and Stability Testing of Four Commercially Available Dried Blood Spot Devices for Estimating Measles and Rubella IgG Antibodies.

Blood collection using dried blood spots (DBS) provides an easier alternative to venipuncture for sample collection, transport, and storage but requires additional processing that can cause variability in results. Whole-blood samples spotted on four DBS devices and respective paired serum samples were tested for antimeasles and antirubella IgG antibody concentrations by enzyme immunoassay. Elution protocols for DBS devices were optimized for comparability relative to serum samples using 12 adult volunteers. Stability of DBS collected on HemaSpot HF was assessed under various temperature conditions (+4, 22 to 25, and 45°C) at six time points (0, 7, 15, 30, 60, and 90 days) in a controlled laboratory setting using six adult volunteers. Devices were shipped and stored for 30 days at four settings with variable temperature and humidity conditions to assess the impact on antibody concentrations. Three DBS devices demonstrated comparable antibody concentrations with paired sera following optimization. Antibodies recovered from DBS were stable for at least 90 days at 4°C and for 30 days at ambient temperature (22 to 25°C) using the HemaSpot HF device. A drastic decline in antibody concentrations was observed at 45°C, resulting in quantitative and qualitative discrepancies by day 7. HemaSpot HF devices shipped to field sites and stored at ambient temperature and humidity resulted in quantitative, but not qualitative, variability. Measurement of antimeasles and antirubella IgG antibodies with DBS devices is an accurate alternative to testing serum, provided elution protocols are optimized. Stability of HemaSpot HF devices at ambient temperature enables broader use in surveys when serum processing and cold storage are not feasible. IMPORTANCE Dried blood spot (DBS) collection offers various advantages over conventional methods of blood collection, especially when collecting and transporting samples for a serosurvey. Yet use of DBS requires additional processing steps in the laboratory that can add to variability in results. We optimized a protocol to elute IgG antibodies against measles and rubella viruses in four DBS devices, demonstrating high concordance with paired venous sera for most devices. Extensive stability studies with various temperature and storage conditions in the laboratory and in the field were conducted using HemaSpot HF DBS devices prior to its use in one of the largest community-based measles and rubella serological surveys in the world.

Study of the teratogenicity of the vaccine strain of the Rubella virus «Orlov-V¼ (Matonaviridae: Rubivirus: Rubella virus) in experience on rhesus macaques.

INTRODUCTION: Rubella virus has pronounced teratogenic properties that can cause generalized and persistent intrauterine infection of the fetus. As a result, the control of the loss of teratogenicity inherent in «wild-type¼ virus strains is a necessary stage of a preclinical study of the vaccine strain for a live attenuated rubella vaccine.The purpose of the study is to comprehensively study the teratogenic properties of the vaccine strain of rubella virus «Orlov-V¼ in the experiment on rhesus macaques. MATERIAL AND METHODS: Seronegative to rubella virus female rhesus macaques in early pregnancy at the age of 4-7 years (n = 13) were used in the experiment. Animals of the experimental group (n = 9) received single immunization intramuscularly with a preparation from the «Orlov-V¼ strain. The control group of the monkeys (n = 3) were immunized with a commercial vaccine containing Wistar RA27/3 strain. The female of the control group (n = 1) was injected with a solvent used in the rubella vaccine. Study of possible teratogenic properties of vaccine strains of rubella virus was carried out using a complex of clinical, immunological, pathomorphological and virological methods. Clinical observations were made within 3 months after the monkeys' birth. Determination of antibody titers in the blood serum of immunized monkeys was performed in HI test on the 28th-30th day after infection. The ELISA method was applied to determine IgM antibodies in the blood serum of newborns within the first month of life. Detection of rubella virus RNA was performed by PCR with electrophoretic detection of amplicons. RESULTS: No markers of congenital rubella infection were found in infants born from monkeys vaccinated during the pregnancy. It is shown that PCR can be an informative method to confirm the absence of teratogenic properties of vaccine strains of rubella virus. DISCUSSION: The obtained data demonstrated that vaccine strains of the «Orlov-V¼ rubella virus and Wistar RA27/3 have lost their teratogenic properties. The possibility of using an alternative strategy for preclinical assessment of specific safety of antiviral vaccines including a complex of clinical, immunological, pathologic and virological methods instead of the classical pathologic method is discussed. CONCLUSION: The results obtained in this study showed the absence of teratogenic properties and high immunogenic activity of the vaccine strain of rubella virus «Orlov-V¼.

How much does it cost to measure immunity? A costing analysis of a measles and rubella serosurvey in southern Zambia.

BACKGROUND: Serosurveys are a valuable surveillance tool because they provide a more direct measure of population immunity to infectious diseases, such as measles and rubella, than vaccination coverage estimates. However, there is concern that serological surveys are costly. We adapted a framework to capture the costs associated with conducting a serosurvey in Zambia. METHODS: We costed a nested serosurvey in Southern Province, Zambia that collected dried blood spots from household residents in a post-campaign vaccine coverage survey. The financial costs were estimated using an ingredients-based costing approach. Inputs included personnel, transportation, field consumable items, social mobilization, laboratory supplies, and capital items, and were classified by serosurvey function (survey preparation, data collection, biospecimen collection, laboratory testing, and coordination). Inputs were stratified by whether they were applicable to surveys in general or attributable specifically to serosurveys. Finally, we calculated the average cost per cluster and participant. RESULTS: We estimated the total nested serosurvey cost was US $68,558 to collect dried blood spots from 658 participants in one province in Zambia. A breakdown of the cost by serosurvey phase showed data collection accounted for almost one third of the total serosurvey cost (32%), followed by survey preparation (25%) and biospecimen collection (20%). Analysis by input categories indicated personnel costs were the largest contributing input to overall serosurvey costs (51%), transportation was second (23%), and field consumables were third (9%). By combining the serosurvey with a vaccination coverage survey, there was a savings of $43,957. We estimated it cost $4,285 per average cluster and $104 per average participant sampled. CONCLUSIONS: Adding serological specimen collection to a planned vaccination coverage survey provided a more direct measurement of population immunity among a wide age group but increased the cost by approximately one-third. Future serosurveys could consider ways to leverage existing surveys conducted for other purposes to minimize costs.

Evaluation of Toxoplasma, Rubella, and Cytomegalovirus serological results in women of childbearing age.

OBJECTIVE This study aimed to determine the rates of IgG and IgM antibodies against cytomegalovirus, rubella, and Toxoplasma gondii (all of which may cause congenital infections) in women of childbearing age who were admitted to Bolu Abant Izzet Baysal University Training and Research Hospital. METHODS Between January 2015 and December 2017, Toxoplasma gondii, rubella, and cytomegalovirus IgM and IgG antibody levels were studied using the ELISA method (Architect i2000SR, Abbott, Germany) in patients aged 15 to 45 who attended the obstetrics and gynecology outpatient clinics. Toxoplasma gondii and cytomegalovirus IgG avidity levels were analyzed retrospectively. RESULTS A total of 13.470 tests were conducted in the laboratory. Seropositivity percentages of IgM antibodies were found to be 1.3%, 0.5%, and 1.6% for Toxoplasma (n = 3607), rubella (n = 3931), and cytomegalovirus (n = 3795), respectively. The seropositivity percentages of IgG antibodies were 22%, 94.2%, and 98.2% for Toxoplasma (n = 702), rubella (n = 693), and cytomegalovirus (n = 679), respectively. Primary infection (acute, recently acquired) was found in 7 (35%) patients with low Toxoplasma IgG avidity. One (3%) patient with low cytomegalovirus IgG avidity had a primary infection. CONCLUSION Toxoplasma gondii seronegativity was found to be high in the region. Therefore, screening women of childbearing age may be important for the prevention of congenital infections caused by Toxoplasma gondii.

Evaluation of two (02) platforms for chemiluminescence-based detection of anti-rubella IgG antibodies in a sub-Saharan country, Côte d'Ivoire.

The diagnosis of rubella is mainly made in pregnant women and the newborn by specific IgG and/or IgM detection. In addition to HAI and ELISA techniques, new immunoanalytical methods have been developed. This study aimed to evaluate two chemiluminescence platforms, Architect i2000SR and Maglumi 800 for rubella biological diagnosis in Côte d'Ivoire. Blood samples were taken from 113 pregnant women aged 15 to 30 in prenatal care. Samples were analyzed for Rubella IgG detection at the NBTS laboratory on the evaluated platforms and the Cobas e601 used as a reference. The majority of women were in their second trimester of pregnancy. Among them, only 13.3% were vaccinated against rubella. The evaluated platforms showed good precision with coefficients of variation >10%. Regarding analytical performances, sensitivities were 97.53% and 96.29% whereas specificities were 100% and 96.88% for Architect I2000SR and Maglumi800, respectively. Both platforms showed good agreement with cobas e601 for antibody levels <200 IU/ml and <350UI/ml for Architect and Maglumi 800, respectively. Findings of the current study revealed that the two platforms have similar features with Cobas e601 and could be used routinely for the serological diagnosis of rubella. However, the results of one platform should not be extrapolated to another.

Evaluation of Toxoplasma, Rubella, and Cytomegalovirus serological results in women of childbearing age

SUMMARY OBJECTIVE This study aimed to determine the rates of IgG and IgM antibodies against cytomegalovirus, rubella, and Toxoplasma gondii (all of which may cause congenital infections) in women of childbearing age who were admitted to Bolu Abant İzzet Baysal University Training and Research Hospital. METHODS Between January 2015 and December 2017, Toxoplasma gondii, rubella, and cytomegalovirus IgM and IgG antibody levels were studied using the ELISA method (Architect i2000SR, Abbott, Germany) in patients aged 15 to 45 who attended the obstetrics and gynecology outpatient clinics. Toxoplasma gondii and cytomegalovirus IgG avidity levels were analyzed retrospectively. RESULTS A total of 13.470 tests were conducted in the laboratory. Seropositivity percentages of IgM antibodies were found to be 1.3%, 0.5%, and 1.6% for Toxoplasma (n = 3607), rubella (n = 3931), and cytomegalovirus (n = 3795), respectively. The seropositivity percentages of IgG antibodies were 22%, 94.2%, and 98.2% for Toxoplasma (n = 702), rubella (n = 693), and cytomegalovirus (n = 679), respectively. Primary infection (acute, recently acquired) was found in 7 (35%) patients with low Toxoplasma IgG avidity. One (3%) patient with low cytomegalovirus IgG avidity had a primary infection. CONCLUSION Toxoplasma gondii seronegativity was found to be high in the region. Therefore, screening women of childbearing age may be important for the prevention of congenital infections caused by Toxoplasma gondii.

RESUMO OBJETIVO O objetivo deste estudo foi determinar as taxas de anticorpos IgG e IgM contra citomegalovírus, rubéola e Toxoplasma gondii (todos os quais podem causar infecções congênitas) em mulheres em idade fértil que foram admitidas no Hospital de Pesquisa e Treinamento da Universidade Bolu Abant İzzet Baysal. MÉTODOS Entre janeiro de 2015 e dezembro de 2017, os níveis de anticorpos IgG e IgM para Toxoplasma gondii, rubéola e citomegalovírus foram estudados usando o método Elisa (Architect i2000SR, Abbott, Alemanha) em pacientes de 15 a 45 anos que compareceram a ambulatórios de obstetrícia e ginecologia. Os níveis de avidez de IgG para Toxoplasma gondii e citomegalovírus foram analisados retrospectivamente. RESULTADOS Um total de 13.470 testes foram realizados em laboratório. As porcentagens de soropositividade dos anticorpos IgM foram de 1,3%, 0,5% e 1,6% para Toxoplasma (n=3.607), rubéola (n=3.931) e citomegalovírus (n=3.795), respectivamente. As porcentagens de soropositividade dos anticorpos IgG foram 22%, 94,2% e 98,2% para Toxoplasma (n=702), rubéola (n=693) e citomegalovírus (n=679), respectivamente. Infecção primária (aguda, adquirida recentemente) foi encontrada em sete (35%) pacientes com baixa avidez para Toxoplasma IgG. Um (3%) paciente com baixa avidez para citomegalovírus IgG teve uma infecção primária. CONCLUSÃO A soronegatividade do Toxoplasma gondii foi alta na região. Portanto, testar mulheres em idade fértil pode ser importante para a prevenção de infecções congênitas causadas pelo Toxoplasma gondii.

Seroprevalence of rubella in pregnant women in Southern Morocco.

Rubella is a generally benign but dangerous viral infection in early pregnancy, due to the teratogenic potential of the virus. Indeed, it causes spontaneous abortions, in-utero fetal death, premature labor and congenital malformations known as congenital rubella syndrome. The purpose of this study is to determine the immune status of rubella in pregnant women in southern Morocco. A prospective, multicentre study was conducted in 2017 for the detection of rubella IgG and IgM antibodies in 380 pregnant women aged 17 to 46 years, using the Architect i1000 chemiluminescent microparticle immunoassay. Eigthy for percent (84.7%) of women were seropositive. Ten percent of multiparous women remained seronegative despite recommendations for vaccination after delivery. Preventive measures against congenital rubella need to be strengthened, and vaccination is needed in non-immunized women. Vaccination awareness campaigns, especially among non-immunized multiparous women, remain essential.

Seroepidemiological study of rubella in Vojvodina, Serbia: 24 years after the introduction of the MMR vaccine in the national immunization programme.

Although rubella is usually a mild childhood disease, this infection in early pregnancy poses a serious problem due to its teratogenic effect. The goal of interrupted circulation and elimination of rubella virus was achieved in many countries in the world. The aim of this study was to determine the status of rubella immunity in Vojvodina and evaluate Serbia's progress toward this goal. A total of 3404 residual serum samples from patients of all ages (1 to 84 years) were included in the study. Samples were collected between May 2015 and December 2017 in Vojvodina. Rubella IgG antibodies were determined using an indirect chemiluminescent immunoassay. Percentage of participants seropositive for rubella antibodies was 92.9% in the entire sample. The highest number of seronegatives was in the youngest (1 year) age group (44.7%), followed by the group aged 24-49 (6.4%) and 2-11 years (6.2%). The absence of a higher percentage of children with protective anti-rubella antibodies in the group aged 2-11 can be explained by a lower immunization coverage during certain years. Participants in the group aged 24-49 were born during the pre-vaccination period with lower rubella incidence, leading to the conclusion that not all individuals of that age came into a contact with the virus. Comparing levels of anti-rubella IgG antibodies of seropositive males and females of different ages reveals that the immunity after a contact with the virus and a previously acquired infection is stronger than the immunity after the vaccination. Although the incidence rate of rubella in Vojvodina has been low for the last ten years, there is still a risk of an outbreak due to a decrease in immunization coverage. This study shows that the percentage of susceptible individuals is high, especially considering women aged 24-49, and that additional ("catch-up") immunization is required.

Rubella seroprevalence in pregnant women living with and without HIV in Soweto, South Africa.

OBJECTIVES: Rubella infection during pregnancy may cause foetal death or congenital rubella syndrome. In South Africa, the national public immunization programme does not include rubella vaccination. The aim of this study was to evaluate rubella sero-epidemiology in pregnant South African women living with and without HIV. METHODS: Serum samples obtained from women living with HIV (n=552) and without HIV (n=552) were tested for rubella immunoglobulin G antibodies using an ELISA. The proportions of women with seronegative titres (<8IU/ml) and seropositive titres (≥11IU/ml), and geometric mean titres (GMT) were compared by age group and HIV status. RESULTS: The overall proportion of rubella seropositivity was 97.8%. The proportion of seropositive women increased with age group (18-25 years: 97.0%; 26-32 years: 97.7%; 33-40 years: 99.3%; p=0.047 after adjusting for HIV status). Similar proportions of women living with and without HIV were seropositive. CONCLUSIONS: Rubella immunity was high among South African pregnant women living with and without HIV in the absence of rubella vaccination in the public immunization programme. However, a lower percentage of younger women had seropositive titres, indicating the need for routine rubella vaccination after an increase in vaccine coverage rates.

Measles and rubella seroprevalence among adults in Georgia in 2015: helping guide the elimination efforts.

A large-scale measles outbreak (11 495 reported cases, 60% aged ≥15 years) occurred in Georgia during 2013-2015. A nationwide, multistage, stratified cluster serosurvey for hepatitis B and C among persons aged ≥18 years conducted in Georgia in late 2015 provided an opportunity to assess measles and rubella (MR) susceptibility after the outbreak. Residual specimens from 3125 participants aged 18-50 years were tested for Immunoglobulin G antibodies against MR using ELISA. Nationwide, 6.3% (95% CI 4.9%-7.6%) of the surveyed population were seronegative for measles and 8.6% (95% CI 7.1%-10.1%) were seronegative for rubella. Measles susceptibility was highest among 18-24 year-olds (10.1%) and declined with age to 1.2% among 45-50 year-olds (P < 0.01). Susceptibility to rubella was highest among 25-29 year-olds (15.3%), followed by 18-24 year-olds (11.6%) and 30-34 year-olds (10.2%), and declined to <5% among persons aged ≥35 years (P < 0.001). The susceptibility profiles in the present serosurvey were consistent with the epidemiology of recent MR cases and the history of the immunization programme. Measles susceptibility levels >10% among 18-24 year-olds in Georgia revealed continued risk for outbreaks among young adults. High susceptibility to rubella among 18-34 year-olds indicates a continuing risk for congenital rubella cases.

Seroprevalence of measles, mumps, rubella, and varicella zoster virus antibodies among healthcare students: analysis of vaccine efficacy and cost-effectiveness.

OBJECTIVE: The aims of this study are to determine the seroprevalence for measles, mumps, rubella, and varicella zoster virus (VZV) in a cohort of nursing students, to evaluate vaccination response rates of nonimmune students, and to calculate the cost of vaccinating students based on seroprevalence screening. METHODS: A cross-sectional study was conducted August 2015-November 2016 among 326 healthy nursing students aged 14.1-18.1 years. Serum IgG antibodies were measured by ELISA. Results were analyzed by the Chi-square test; a p-value of < 0.05 was considered statistically significant. RESULTS: The number of seropositive participants (%) was 308 (94.5%) for rubella, 295 (90.5%) for VZV, 244 (74.9%) for measles, and 219 (67.2%) for mumps. A significant correlation was found between measles IgG and age. A relationship was also observed between VZV IgG and kindergarten attendance. Response rates to measles, rubella, VZV, and mumps vaccination were 96%, 92.3%, 87.5%, 78.8%, respectively. The total cost of vaccination after IgG screening was less than vaccination without screening. CONCLUSIONS: In this study, participants' immunity to measles and VZV was low. Prevaccination serological screening was cost-effectiveness method for preventing measles, mumps, rubella, and varicella infections. We believe that administering booster measles, mumps, and rubella (MMR) vaccine doses or developing a special MMR vaccination strategy for at-risk groups may prevent MMR outbreaks.

Diagnostic algorithm for the confirmation of cases of measles and rubella in Mexico

Due to the successful implementation of measles and rubella elimination strategies, Mexico announced the interruption of endemic transmission of measles in 1996 and that of rubella in 2008. After a verification process, the region of the Americas was declared free of rubella and congenital rubella syndrome in 2015 and of measles in 2016. In order to maintain the elimination status in Mexico, it is essential to continue laboratory surveillance within the framework of the Global Measles and Rubella Laboratory Network. The Institute of Epidemiological Diagnosis and Reference, through the National Network of Public Health Laboratories, guarantees timely and reliable results in view of the possible reintroduction of these and other emerging pathogens.

Seroprevalence of measles, mumps & rubella antibodies among 5-10 years old children in north India.

Background & objectives: : Globally, there is an effort to eliminate the measles and control rubella as these diseases lead to considerable morbidity and mortality especially among under-five children and are important public health problems. This study was aimed to estimate the seroprevalence of measles, mumps and rubella (MMR) antibodies among children of age 5-10 yr in Chandigarh, north India, to provide evidence on prevalent immunity levels. Methods: : This cross-sectional study was conducted in Chandigarh, among 196 randomly selected healthy children (5-10 yr), who received either one or two doses of measles or MMR combination vaccine. Socio-economic background and immunization history were recorded. Blood sample (2 ml) was collected to estimate the MMR IgG antibody titres by using ELISA kits. Results: : Protective seroprevalence of MMR antibodies was 40.8, 75.5 and 86.2 per cent, respectively. The geometric mean titres of MMR IgG antibodies in the study children were 11.3, 50.6 and 54.3 international units (IU)/ ml, respectively. The proportion of seroprotected children for measles was significantly higher among those who had received two or more doses (46.4%) of measles vaccine compared to those who had received single dose (35.6%) (P <0.001). About 16 per cent of children had received single dose of MMR vaccine. Among these, 71.4 and 100 per cent were seroprotected against mumps and rubella, respectively. Interpretation & conclusions: : A large proportion of children aged 5-10 yr lacked protective immunity against measles (60%); about one-fourth (15-25%) were susceptible to infection with mumps and rubella virus. Mumps vaccination may be considered to be included in National Immunization Schedule for children with periodic serosurveillance.

Comparison of the LIAISON®XL and ARCHITECT IgG, IgM, and IgG avidity assays for the diagnosis of Toxoplasma, cytomegalovirus, and rubella virus infections.

This study compared the performance of the LIAISON®XL system of immunoglobulin (Ig) G and IgM immunoassays for the diagnosis of Toxoplasma gondii, cytomegalovirus (CMV), and rubella virus infections with that of the ARCHITECT system. Patient serum samples, previously screened and clinically diagnosed with T. gondii, CMV or rubella, were used to compare LIAISON®XL and ARCHITECT IgG and IgM immunoassays. LIAISON®XL Toxo and CMV IgG avidity assays were also compared with equivalent ARCHITECT assays and reference methods. Overall agreement between the LIAISON®XL and ARCHITECT assays was 99% and 92% for the Toxo IgG and IgM assays, respectively, 98% and 96% for the CMV IgG and IgM assays, respectively, and 93% and 98% for the rubella virus IgG and IgM assays, respectively. LIAISON®XL IgG Toxo and CMV avidity assays showed high concordance with the VIDAS® Toxo IgG avidity assay and an in-house CMV avidity assay (reference methods), and faster IgG avidity maturation in a larger number of samples collected months after the primary infection compared with equivalent ARCHITECT assays. LIAISON®XL assays for detection of anti-T. gondii, CMV and rubella virus IgG and IgM are at least equal to the competitor assays on the ARCHITECT platform.

Sample size calculation for estimating key epidemiological parameters using serological data and mathematical modelling.

BACKGROUND: Our work was motivated by the need to, given serum availability and/or financial resources, decide on which samples to test in a serum bank for different pathogens. Simulation-based sample size calculations were performed to determine the age-based sampling structures and optimal allocation of a given number of samples for testing across various age groups best suited to estimate key epidemiological parameters (e.g., seroprevalence or force of infection) with acceptable precision levels in a cross-sectional seroprevalence survey. METHODS: Statistical and mathematical models and three age-based sampling structures (survey-based structure, population-based structure, uniform structure) were used. Our calculations are based on Belgian serological survey data collected in 2001-2003 where testing was done, amongst others, for the presence of Immunoglobulin G antibodies against measles, mumps, and rubella, for which a national mass immunisation programme was introduced in 1985 in Belgium, and against varicella-zoster virus and parvovirus B19 for which the endemic equilibrium assumption is tenable in Belgium. RESULTS: The optimal age-based sampling structure to use in the sampling of a serological survey as well as the optimal allocation distribution varied depending on the epidemiological parameter of interest for a given infection and between infections. CONCLUSIONS: When estimating epidemiological parameters with acceptable levels of precision within the context of a single cross-sectional serological survey, attention should be given to the age-based sampling structure. Simulation-based sample size calculations in combination with mathematical modelling can be utilised for choosing the optimal allocation of a given number of samples over various age groups.