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.

A measles outbreak in Kansai International Airport, Japan, 2016: Analysis of the quantitative difference and infectivity of measles virus between patients who are immunologically naive versus those with secondary vaccine failure

Since the elimination of the measles virus, patients with vaccination records for the measles-containing vaccine have increased in Japan. According to several studies, the transmission risk from previously immunized patients, especially those with secondary vaccine failure (SVF), is lower than that from those with primary measles infections. Immunological features of SVF were identified per specific immunoglobulin G (IgG) induction with high avidity and high plaque reduction neutralization antibody concentration. However, the virological features of SVF have not been well investigated. To examine not only immunological but also virological differences between SVF and immunologically naive patients, throat swabs and blood and urine specimens of 25 patients with confirmed measles infection after an outbreak at the Kansai International Airport in 2016 were analyzed. Patients were categorized as naive (n = 3) or with SVF (n = 22) based on measles-specific IgG antibody concentrations and their avidity. Virus isolation and quantitative real-time polymerase chain reaction were performed to quantify the viral load in clinical specimens and estimate the infectivity in each specimen. The number of viral genome copies in the blood specimens of those with SVF was significantly different and approximately 1 out of 100 of that in immunologically naive patients. However, genome copy numbers in throat swabs and urine specimens were not significantly different between the groups. The virus was isolated only from those in the naive group. Our study indicated low transmission risk of the virus in patients with SVF.

The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

BACKGROUND

The COVID-19 pandemic has disrupted routine measles immunisation and supplementary immunisation activities (SIAs) in most countries including Kenya. We assessed the risk of measles outbreaks during the pandemic in Kenya as a case study for the African Region.

METHODS

Combining measles serological data, local contact patterns, and vaccination coverage into a cohort model, we predicted the age-adjusted population immunity in Kenya and estimated the probability of outbreaks when contact-reducing COVID-19 interventions are lifted. We considered various scenarios for reduced measles vaccination coverage from April 2020.

RESULTS

In February 2020, when a scheduled SIA was postponed, population immunity was close to the herd immunity threshold and the probability of a large outbreak was 34% (8-54). As the COVID-19 contact restrictions are nearly fully eased, from December 2020, the probability of a large measles outbreak will increase to 38% (19-54), 46% (30-59), and 54% (43-64) assuming a 15%, 50%, and 100% reduction in measles vaccination coverage. By December 2021, this risk increases further to 43% (25-56), 54% (43-63), and 67% (59-72) for the same coverage scenarios respectively. However, the increased risk of a measles outbreak following the lifting of all restrictions can be overcome by conducting a SIA with ≥ 95% coverage in under-fives.

CONCLUSION

While contact restrictions sufficient for SAR-CoV-2 control temporarily reduce measles transmissibility and the risk of an outbreak from a measles immunity gap, this risk rises rapidly once these restrictions are lifted. Implementing delayed SIAs will be critical for prevention of measles outbreaks given the roll-back of contact restrictions in Kenya.

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.

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.

Sero-epidemiological study in prediction of the risk groups for measles outbreaks in Vojvodina, Serbia

Background

Age-stratified serologic surveys provide insight into the gaps of measles-specific immunity as well as estimates of the age-specific seroprevalence. The aim of this study was to describe the measles sero-epidemiology in Vojvodina before the occurrence of outbreak in 2017/18 and to discuss preventive measures for potential future epidemics.

Methods

A seroprevalence study was conducted from April 2015 to June 2017 on serum bank of 3199 residual samples. Study was performed prior to the last measles outbreak in Vojvodina that occurred between 12th November 2017 and 30th June 2018. Measles-specific IgG antibodies were determined using an indirect chemiluminescent immunoassay (CLIA).

Results

Median age of enrolled participants was 20 years (IQR 11–37). Overall, 86.9% serum samples were seropositive. The highest proportion of measles seronegativity was observed in children aged 12–23 months of age and in adults aged 20–39 years (56.1% and 18.5%, respectively). Prevalence of measles seronegativity above WHO target levels susceptibility was observed in the following age groups: 2, 7, 13, 15, and among all adults aged between 20 and 49 years. Out of total measles outbreak cases (177), there were 91 (51.4%) participants aged 20–39 years. A significant positive correlation was observed between measles seronegativity and the number of reported measles cases aged ≥ 12 months (r = 0.4675, p = 0.0213).

Conclusions

In order to prevent new outbreaks and achieve the elimination of measles in Vojvodina, the vaccination coverage of both measles-mumps-rubella (MMR1 and MMR2) vaccines needs to be improved and sustained. Educational campaigns for the improvement of acceptance and timely vaccination with vaccine against measles among doctors and the general population are crucial. Our results indicate possible gap in measles protection in adults born during implementation of one dose of measles vaccine and prioritize supplementary immunization activities targeting adults in Vojvodina, Serbia.

Reduced immunity to measles in adults with major depressive disorder

BACKGROUND

Depression can impair the immunogenicity of vaccine administration in adults. Whereas many vaccinations are administered in childhood, it is not known whether adolescent or adult onset depression is associated with impairments in the maintenance of protection of childhood vaccines. This study tested the hypothesis that individuals with adolescent or adult onset mood disorders would display compromised immunity to measles, a target of childhood vaccination.

METHODS

IgG antibodies to measles were quantified using a solid phase immunoassay in volunteers with bipolar disorder (BD, n = 64, mean age of onset = 16.6 ± 5.6), currently depressed individuals with major depressive disorder (cMDD, n = 85, mean age of onset = 17.9 ± 7.0), remitted individuals with a history of MDD (rMDD, n = 82, mean age of onset = 19.2 ± 8.6), and non-depressed comparison controls (HC, n = 202), all born after the introduction of the measles vaccine in the USA in 1963.

RESULTS

Relative to HC, both the cMDD group (p = 0.021, adjusted odds ratios (OR) = 0.47, confidence interval (CI) = 0.24-0.90), and the rMDD group (p = 0.038, adjusted OR = 0.50, CI = 0.26-0.97) were less likely to test seropositive for measles. Compared with unmedicated MDD participants, currently medicated MDD participants had a longer lifetime duration of illness and were less likely to test seropositive for measles.

CONCLUSIONS

Individuals with adolescent or adult onset MDD are less likely to test seropositive for measles. Because lower IgG titers are associated with increased risk of measles infection, MDD may increase the risk and severity of infection possibly because of impaired maintenance of vaccine-related protection from measles.

Seroprevalence of measles vaccine antibody response in vertically HIV-infected children, in Morocco

BACKGROUND

The widespread use of an effective and safe vaccine to measles has substantially decreased morbidity and mortality from this epidemic. Nevertheless, HIV-infected children vaccinated against measles may develop an impaired vaccine response and remain susceptible to this disease. In Morocco, infants are routinely vaccinated against measles, regardless of their HIV serostatus. An evaluation of the immunization of these children may be of paramount importance to implement timely measures aimed at preventing measles transmission.

METHODS

In this study, we have enrolled 114 children vaccinated against measles, 50 children prenatally infected with HIV and 64 HIV-uninfected children. For all children, blood samples were taken to measure anti-measles IgG by EIA and CD4 count by flow cytometry. Additionally, HIV viral load was determined by automated real time PCR, for HIV-infected children.

RESULTS

The seroprotective rate of IgG anti-measles antibodies was significantly lower among HIV-infected children (26%) compared with HIV-uninfected children (73%) (p < 0.001). Within HIV-infected children group, the comparison of variables between children without seroprotective seroconversion to measles and those with seroprotective immunity, displayed that sex and age were not statistically different, p > 0.999 and p = 0.730, respectively. However, CD4 count was lower among children with negative serostatus to measles (23% versus 32%, p < 0.001). Furthermore, viral load was higher, with 2.91 log10 ± 2.24 versus 1.7 log10 ± 1.5 (p = 0.042). Finally, 62% of children with a negative vaccine response to measles were under HAART therapy, versus 92% (p = 0.008).

CONCLUSION

The majority of HIV-infected children vaccinated against measles develop a suboptimal seroprotective titer, and therefore remain at risk for this highly infectious disease. These data in combination with international recommendations, including recent WHO guidance on vaccination of HIV-infected children, suggest there is a need for national measures to prevent these children from measles.

Development of a robust and standardized immunoserological assay for detection of anti-measles IgG antibodies in human sera

Because of measles outbreaks there is a need for continuous monitoring of immunological protection against infection at population level. For such monitoring to be feasible, a cost-effective, reliable and high-throughput assay is necessary. Herein we describe an ELISA protocol for assessment of anti-measles antibody levels in human serum samples that fulfills the above criteria and is easily adaptable by various laboratories. A serum bank of anonymous patient sera was established (N > 3000 samples). Sera were grouped based on measles immunization schedules and/or changes in vaccine components since the introduction of the first measles vaccine in Hungary in 1969. Newly designed ELISA was performed by using Siemens BEP 2000 Advance System and data were confirmed using commercially available kits. Our indirect ELISA was compared to indirect immunfluoresence and to anti-measles nucleocapsid (N) monoclonal antibody-based sandwich ELISA. The results obtained are in high agreement with the confirmatory methods, and reflect measles vaccination history in Hungary ranging from pre-vaccination era, through the initial period of measles vaccination, to present. Based on measurement of 1985 sera, the highest ratio of low/questionable antibody level samples was detected in cluster '1978-1987' (~25.4%), followed by cluster '1969-1977' (~15.4%).Our assay is suitable for assessment of anti-measles immunity in a large cohort of subjects. The assay is cost-effective, allows high-throughput screening and has superior signal-to-noise ratio. This assay can serve as a first step in assessment of the effectiveness of all three components of the MMR vaccine.

Persistent high plasma levels of sCD163 and sCD14 in adult patients with measles virus infection

BACKGROUND AND AIMS

Measles is an infectious disease that represents a serious public health problem worldwide, being associated with increased susceptibility to secondary infections, especially in the respiratory and gastrointestinal tracts. The aim of this study was to evaluate sCD163 and sCD14 levels in measles virus (MV) infected patients, as markers of immune activation, in order to better understand their role in the pathogenesis of the disease. TNF-α plasma levels were also evaluated.

METHODS

sCD163, sCD14 and TNF-α were measured by ELISA in plasma samples of 27 MV infected patients and 27 healthy donors (HD) included as controls.

RESULTS

At the time of hospital admission, sCD163 and sCD14 levels were significantly higher in MV infected patients than in HD, while a decrease in TNF-α levels were found even if without statistical significance. sCD163 and sCD14 levels were significantly decreased after two months from acute infection compared to hospital admission although they remained significantly higher compared to HD. TNF-α levels increased significantly during the follow-up period. Considering clinical parameters, sCD163 levels positively correlated with aspartate aminotransferase, white blood cell count and neutrophils rate, while negatively correlated with the lymphocyte percentage. sCD14 levels positively correlated with the neutrophil and lymphocyte percentages.

CONCLUSIONS

These results indicate that, despite the resolution of symptoms, an important macrophage/monocyte activation persists in measles patients, even after two months from infection.

Identification of measles virus genotype B3 associated with outbreaks in Islamabad, Pakistan, 2013-2015

BACKGROUND

Measles virus infection remains a significant cause of childhood mortality and morbidity despite continued global efforts and the availability of a safe and effective vaccine. Molecular analysis of indigenous measles viruses could provide critical information on outbreak linkages and transmission pathways that can aid the implementation of appropriate control programs in Pakistan.

METHODS

Blood samples and throat swabs were collected from subjects suspected with measles in Islamabad, Pakistan from 2013 to 2015. Serum samples were tested for the presence of measles immunoglobulin M (IgM) antibodies using enzyme-linked immunosorbent assay (ELISA) while throat swabs were used for the isolation (Vero/SLAM cell line) and subsequent characterization and phylogenetic analysis of measles strains.

RESULTS

Of 373 blood samples, 66% tested positive for measles IgM. Male subjects were more often infected (58%) than female (42%) with the highest frequency of positive cases (63%) in the 0-5-years age group. Among the positive cases, only 13% had received one or two doses of the measles vaccine, while 87% were unvaccinated. Of 80 throat swabs, 29 (36%) showed a measles virus-specific cytopathic effect (CPE) and were characterized as genotype B3 through partial sequencing of the nucleoprotein (N) gene. Phylogenetic analysis revealed the Pakistani B3 strains to be closely related to strains from neighboring countries (Iran and Afghanistan) as well as with B3 viruses from the USA, Germany, and the UK.

CONCLUSIONS

The study results showed that despite the availability of an effective vaccine, the burden of measles infections is very high in Pakistan due to poor routine immunization coverage even in major cities, including the capital city of Islamabad. It is imperative that national health authorities take urgent strategic steps to improve routine immunization and implement adequate molecular identification methods to tackle future measles outbreaks.

Seroprotection status of hepatitis B and measles vaccines in children with type 1 diabetes mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is speculated to have an impaired immunological response to vaccines. This paper aimed to investigate the presence of specific antibodies against hepatitis B virus (HBV) and measles in diabetic children who had been immunized according to the standard national calendar of immunization.

METHODS

Two hundred and one diabetic children and 140 healthy controls were prospectively evaluated. Antibodies against hepatitis B (anti-HBs) and measles were detected in all individuals who completed the vaccination schedule. We noted onset of T1DM, duration of the disease, diabetes-related autoantibodies and mean HbA1c levels.

RESULTS

Some 72.6% of diabetics and 82.1% of controls had anti-HBs (+) (p=0.04). We found a reduced efficacy of measles vaccination in anti-HBs (-) diabetic children (p=0.009), even though there was no significant difference between the study and control groups. Onset of the disease was earlier in anti-HBs (-) diabetics than in controls (p=0.038). No difference with respect to other parameters was found.

CONCLUSIONS

Our data showed a reduced seroprotection rate for HBV vaccination in diabetic children and for measles with anti-HBs (-) diabetics. Larger studies should be encouraged to confirm the vaccine efficacy in diabetic children and to elucidate possible pathogenic mechanisms.

Seroepidemiology for measles among elementary school children in Northern Taiwan

BACKGROUND

Despite the high vaccination coverage in Taiwan, sporadic cases or small cluster of measles still occur every year. Nevertheless, few studies provided information about the serostatus for measles in recent years. This cross-sectional survey aimed to establish the seroepidemiologic data of measles among elementary school children in New Taipei City, Taiwan during 2012-2013.

METHODS

A multistage stratified sampling design using 14 variables was employed to obtain samples. All selected schoolchildren were bled for the serologic tests of measles by both chemiluminescence immunoassay (CLIA) and enzyme immunoassay (EIA).

RESULTS

A total of 856 schoolchildren from 14 schools were recruited in this study. Among these individuals, the overall seropositive rates for measles were 82.24% and 92.17% by the Liaison and NovaLisa assays, respectively. For schoolchildren in each grade, the seropositive rates were > 90% for Grade 1, and then decreased gradually to 70-80% for Grade 6 (p < 0.001 for both methods). A decay of measles-specific immunoglobulin G titers was also observed with the maximum drop between Grade 1 and Grade 2 (declining trend of p < 0.001 for both).

CONCLUSION

Although the seropositive rate of measles was > 90% for Grade 1, the rate for Grade 6 was only in the range of 70-80%, which may be a challenge to prevent outbreaks of measles in the future and should be monitored meticulously.

Anti-rubella, Mumps and Measles IgG Antibodies in Medical Students of Tehran University

Measles, mumps and rubella are viral infectious diseases that may result in serious complications. Since the production of vaccines, the number of cases of these diseases has been dropped. Nevertheless, these infectious diseases are still one of the major health problems in developing countries. In this study, in order to evaluate the protective responses against measles, mumps and rubella, the level and avidity of virus-specific IgG antibodies were measured in 53 medical students of Tehran University, aged between 20-30 years. Except for mumps vaccine, all the students had been vaccinated against measles and rubella according to Iran's nationwide mass vaccination protocol for all persons aged 5-25 in 2003. Our results showed that 96.2% of the volunteers had a protective level (>15 IU/ml) of IgG against rubella, 79.2% had a protective level (>11 IU/ml) of IgG against measles and 64.16% had a protective level (>11 IU/ml) of IgG against mumps. Over ten years after nationwide measles-rubella vaccination campaign, most young adults aged 20-30 had protective levels of humoral immunity against measles and rubella. However, Iranian young population is still unvaccinated against mumps, and therefore relatively large number of young adults had no protective level of IgG against it. This finding may be due to reduction in circulating of wild strain. We recommend screening of medical students for immunity against infectious agents such as measles, mumps, rubella, because they are at a high risk of these infectious agents.

Multicenter Safety and Immunogenicity Trial of an Attenuated Measles Vaccine for NHP

Measles is a highly contagious viral disease in NHP. The infection can range from asymptomatic to rapidly fatal, resulting in significant morbidity and mortality in captive populations. In addition to appropriate quarantine practices, restricted access, the immunization of all personnel in contact with NHP, and the wearing of protective clothing including face masks, measles immunization further reduces the infection risk. Commercially available measles vaccines are effective for use in NHP, but interruptions in their availability have prevented the implementation of ongoing, consistent vaccination programs. This need for a readily available vaccine led us to perform a broad, multicenter safety and immunogenicity study of another candidate vaccine, MVac (Serum Institute of India), a monovalent measles vaccine derived from live Edmonston-Zagreb strain virus that had been attenuated after 22 passages on human diploid cells.

[Assessment of measles diagnostic from gingival fluid in Côte d'Ivoire]

After the adoption of the Global Initiative for Measles Elimination in 2001, Côte d'Ivoire has created monitoring case by case. Thus, the diagnosis of measles from the gingival fluid was implemented, through a pilot project. This study aimed to evaluate the performance of this diagnostic test. We conducted a cross-sectional survey, in four health districts of Abidjan, during a period from July 2010 to December 2012. The study consisted in collecting gingival fluid and serum samples in all suspected measles children. These samples were analyzed by ELISA test at Pasteur Institute of Côte d'Ivoire. Standard formulas were used to calculate sensitivity, specificity, positive predictive value and negative predictive value of oral fluid compared to serum taken as the "gold standard" and confidence intervals were estimated with error alpha risk (α =0.05). The concordance of kappa coefficient (k) was used to estimate agreement level between the results of oral fluid analysis and those of serum. The sensitivity and specificity of the test were 98% and 82% respectively while the positive predictive value and the negative predictive value were 84% and 98%. The comparison of oral fluid with the reference test showed high agreement, between 0.61 and 0.80. The diagnostic test on gingival fluid is acceptable because its sensitivity, specificity and negative predictive value had high level. Therefore it can be extended to all sanitary districts.

Cellphone-Based Hand-Held Microplate Reader for Point-of-Care Testing of Enzyme-Linked Immunosorbent Assays

Standard microplate based enzyme-linked immunosorbent assays (ELISA) are widely utilized for various nanomedicine, molecular sensing, and disease screening applications, and this multiwell plate batched analysis dramatically reduces diagnosis costs per patient compared to nonbatched or nonstandard tests. However, their use in resource-limited and field-settings is inhibited by the necessity for relatively large and expensive readout instruments. To mitigate this problem, we created a hand-held and cost-effective cellphone-based colorimetric microplate reader, which uses a 3D-printed opto-mechanical attachment to hold and illuminate a 96-well plate using a light-emitting-diode (LED) array. This LED light is transmitted through each well, and is then collected via 96 individual optical fibers. Captured images of this fiber-bundle are transmitted to our servers through a custom-designed app for processing using a machine learning algorithm, yielding diagnostic results, which are delivered to the user within ∼1 min per 96-well plate, and are visualized using the same app. We successfully tested this mobile platform in a clinical microbiology laboratory using FDA-approved mumps IgG, measles IgG, and herpes simplex virus IgG (HSV-1 and HSV-2) ELISA tests using a total of 567 and 571 patient samples for training and blind testing, respectively, and achieved an accuracy of 99.6%, 98.6%, 99.4%, and 99.4% for mumps, measles, HSV-1, and HSV-2 tests, respectively. This cost-effective and hand-held platform could assist health-care professionals to perform high-throughput disease screening or tracking of vaccination campaigns at the point-of-care, even in resource-poor and field-settings. Also, its intrinsic wireless connectivity can serve epidemiological studies, generating spatiotemporal maps of disease prevalence and immunity.

Comparative Estimates of Crude and Effective Coverage of Measles Immunization in Low-Resource Settings: Findings from Salud Mesoamérica 2015

Timely and accurate measurement of population protection against measles is critical for decision-making and prevention of outbreaks. However, little is known about how survey-based estimates of immunization (crude coverage) compare to the seroprevalence of antibodies (effective coverage), particularly in low-resource settings. In poor areas of Mexico and Nicaragua, we used household surveys to gather information on measles immunization from child health cards and caregiver recall. We also collected dried blood spots (DBS) from children aged 12 to 23 months to compare crude and effective coverage of measles immunization. We used survey-weighted logistic regression to identify individual, maternal, household, community, and health facility characteristics that predict gaps between crude coverage and effective coverage. We found that crude coverage was significantly higher than effective coverage (83% versus 68% in Mexico; 85% versus 50% in Nicaragua). A large proportion of children (19% in Mexico; 43% in Nicaragua) had health card documentation of measles immunization but lacked antibodies. These discrepancies varied from 0% to 100% across municipalities in each country. In multivariate analyses, card-positive children in Mexico were more likely to lack antibodies if they resided in urban areas or the jurisdiction of De Los Llanos. In contrast, card-positive children in Nicaragua were more likely to lack antibodies if they resided in rural areas or the North Atlantic region, had low weight-for-age, or attended health facilities with a greater number of refrigerators. Findings highlight that reliance on child health cards to measure population protection against measles is unwise. We call for the evaluation of immunization programs using serological methods, especially in poor areas where the cold chain is likely to be compromised. Identification of within-country variation in effective coverage of measles immunization will allow researchers and public health professionals to address challenges in current immunization programs.

Serosurveillance of vaccine preventable diseases and hepatitis C in healthcare workers from Lao PDR

BACKGROUND AND AIMS

Healthcare workers (HCW) have an increased risk of exposure to infectious diseases and are a potential source of infections for their patients. The Lao People's Democratic Republic (Lao PDR) has no national policy regarding HCW vaccinations and routine vaccination coverage is low within the general population. This cross-sectional serostudy determines the level of exposure and risk of infection in Lao HCW against 6 vaccine preventable diseases and hepatitis C.

METHODS

1128 HCW were recruited from 3 central, 2 provincial and 8 district hospitals. Sera were tested by ELISA for the presence of antibodies and antigens to hepatitis B, hepatitis C, measles, rubella, varicella zoster, tetanus and diphtheria.

RESULTS

Only 53.1% of the HCW had protective anti-hepatitis B surface antigen antibodies (anti-HBs) with 48.8% having anti-hepatitis B core antibodies (anti-HBc), indicating previous exposure and 8.0% were hepatitis B surface antigen carriers. 3.9% were hepatitis C seropositive. Measles and rubella antibodies were detected in 95.4% and 86.2% of the HCW, with 11.9% of females being unprotected against rubella. Antibodies against varicella zoster, tetanus and diphtheria were detected in 95%, 78.8% and 55.3%, respectively. Seroprevalence varied according to age, gender and number of children.

CONCLUSION

An unacceptably high proportion of Lao HCW remain susceptible to infection with hepatitis B, diphtheria, tetanus and rubella. Furthermore, a high number of healthcare workers are chronically infected with hepatitis B and C viruses. These data emphasize the need for a robust HCW vaccination policy in addition to increased awareness within this subpopulation.

[The multiplex method of estimation of humoral immunity to vaccine regulated childhood infections]

The goal of this work was to present the results of the laboratory tests of the multiplex dot immunoassay method using protein microarray for complex estimation of humoral immunity to measles, mumps, and rubella viruses. It was shown that the obtained results were in a good agreement with data of commercial monospecific ELISA kits. The developed method is fast, requires fewer resources, and may be used in the field.

Etiology of maculopapular rash in measles and rubella suspected patients from Belarus

As a result of successful implementation of the measles/rubella elimination program, the etiology of more and more double negative cases remains elusive. The present study determined the role of different viruses as causative agents in measles or rubella suspected cases in Belarus. A total of 856 sera sent to the WHO National Laboratory between 2009 and 2011 were tested for specific IgM antibodies to measles virus (MV), rubella virus (RV) and human parvovirus B19 (B19V). The negatives were further investigated for antibodies to enterovirus (EV) and adenovirus (AdV). Children of up to 3 years were tested for IgM antibodies to human herpesvirus 6 (HHV6). A viral etiology was identified in 451 (52.7%) cases, with 6.1% of the samples being positive for MV; 2.6% for RV; 26.2% for B19V; 9.7% for EV; 4.6% for AdV; and 3.6% for HHV6. Almost all measles and rubella cases occurred during limited outbreaks in 2011 and nearly all patients were at least 15 years old. B19V, EV and AdV infections were prevalent both in children and adults and were found throughout the 3 years. B19V occurred mainly in 3-10 years old children and 20-29 years old adults. EV infection was most common in children up to 6 years of age and AdV was confirmed mainly in 3-6 years old children. HHV6 infection was mostly detected in 6-11 months old infants. Laboratory investigation of measles/rubella suspected cases also for B19V, EV, AdV and HHV6 allows diagnosing more than half of all cases, thus strengthening rash/fever disease surveillance in Belarus.

[Evaluation of the commercial ELISA test-systems of different formats to detect specific IgM and IgG in the measles patients sera]

Nine commercial kits of "captured" and "indirect" format ELISA assay for the detection of specific IgM and IgG in sera of patients with measles were compared to each other. 72 sera specimens from typical medium-severity cases from a measles outbreak (2010) were collected on the 5-6th day after the rash onset. IgM was detected with "capture" tests (Vecto-Measles IgM, Vector Best, Measles IgM capture EIA, Microimmune Ltd) close to 100% of cases, irrespectively to the age and the initial vaccination status of the patients. The IgM result was negative in 23.6% by average while investigating using "indirect" format tests (Enzygnost Anti-Measles Virusll/IgM, Siemens; Anti-Measles Viruses ELISA (IgM), Eurominimum, Virion-Serion IgM (GmbH). These cases were in adults, the majority of which had 1-2 vaccinations in the past. The analysis of the presented data shows high correlation connection between the tests used and high confidence level for OD IgM and IgG of the sera of the patients with the primary and secondary immune response.

[Serological markers of Spanish and immigrant pregnant women in the south of Madrid during the period 2007-2010]

OBJECTIVE

The prevalence and evolution of the markers including in the serologic profile of pregnant woman was studied in our hospital during a period of 4 years.

MATERIAL AND METHODS

A retrospective study of the prevalence of antibodies against Treponema pallidum, human immunodeficiency virus (HIV), Toxoplasma gondii, rubeola virus and hepatitis B virus (HBV), was performed in our hospital among Spanish and immigrant pregnant women, from January 2007 to December 2010.

RESULTS

A total of 8,012 pregnant were studied, 2,752 (34.2%) of them were foreign. The non-treponemal tests (RPR) were positive in 40 (0.49%) women, being the prevalence slightly superior in foreigners than in natives (0.8 as opposed to 0.3%). The IgG anti-T. gondii global prevalence was 23,35% (1,874 patients). In Spanish pregnant this prevalence was 18%, and 33.8% in the immigrant women. Almost the total of Spanish pregnant (99.5%) displayed IgG antibodies against rubeola virus whereas in the foreigners this rate was 61.6%. The presence of HBsAg for HBV was tested in 86.6% of pregnant women (6,939/8,012), being positive the 0.75% (59 patients), with a prevalence in foreigners greater than in Spanish (1.65 as opposed to 0.4%). Antibodies anti-HVI were detected in 22 patients (0.22%), being the prevalence 0.15% among the Spanish and 0.51% among the foreigners.

Measles outbreak in Northern Central African Republic 3 years after the last national immunization campaign

BACKGROUND

Despite huge efforts to promote widespread vaccination, measles remains an important cause of morbidity and mortality worldwide, especially in African children. In March 2011, an abnormally high number of cases were reported from the Ouham Prefecture, Central African Republic to the national measles case-based surveillance system. In response, reactive vaccination activities were implemented. The aims of this study were to investigate this outbreak and describe the response.

METHODS

Measles cases were defined according to WHO recommendations. In the first weeks of the outbreak, blood samples were collected and sent to the Institut Pasteur in Bangui for laboratory confirmation by detection of IgM antibodies against measles virus. In addition, a portion of viral RNA was amplified from 5 IgM positive patient samples and the amplicons were sequenced for phylogenetic analysis.

RESULTS

Between March and September 2011, 723 clinical cases originated from the Ouham Prefecture, including 2 deaths, were reported. Amongst 59 blood samples collected, 49 were positive for the detection of IgM. A high number of self-declared vaccinated subjects (31%) were found amongst the cases. Most of the cases were under 5 years. The causative virus was found to belong to genotype B3.1. In response, 2 sub-national supplementary immunization activities were quickly conducted and limited this outbreak to mainly 2 sub-prefectures.

CONCLUSIONS

This outbreak was the largest epidemic of measles in CAR since 2002. Its occurrence, 3 years after the last national immunization campaign, highlights the necessity to pursue efforts and improve and extend immunization programs in order to reach measles elimination goal in Africa.

[Peculiarity of the laboratory diagnostic of the measles virus infection in previously vaccinated and unvaccinated patients]

119 specimens of blood sera collected from measles cases with different vaccination history (aged 4 months to 48 years) on 5th-6th days after rash onset were Investigated using EIA. The obtained results showed that the primary immune response (PIR) was developed in 59 patients; the secondary immune response (SIR) was developed in 60 patients with a significant increase in the specific high avidity IgG (22.34 IU/ml +/- 3.2). The specific IgM were detected in 100% cases studied with capture ELISA in both previously vaccinated and unvaccinated individuals of different age. The specific IgM were detected by indirect ELISA in 100% cases in unvaccinated patients, while IgM positive sera was defined only in 23.3% of individuals with SIR. It was concluded that measles virus infection in previously vaccinated and unvaccinated adults had clinical differences. The role of patients with SIR in virus transmission was discussed.

Issues and controversies with vitamin A in childhood

Vitamin A deficiency is common in the developing world. Vitamin A supplementation (VAS) has been used to prevent or treat vitamin A deficiency and to decrease mortality and morbidity in children. However, there are still controversial issues in relation to the role of universal VAS in different populations. Thus, studies that look at mortality outcomes reveal that VAS decreases mortality in children >6 months of age; however, there is still controversy on the extent to which reduction in morbidity from diarrhea and respiratory infection, other than measles, decreases mortality. Studies in infants 1-5 months old show no protective effect of VAS on mortality; whether this is secondary to environmental influences (breastfeeding), or interactions with DTP vaccine, needs to be further investigated. Studies with VAS in newborns have resulted in contrasting results in countries in Africa and Asia; trials are underway to better understand this. VAS does not have a universal protective effect on lower respiratory tract infection in children; some studies reveal an increase in respiratory morbidity associated with VAS, especially in well-nourished children; in contrast, VAS may confer some protection to malnourished children. The interaction of VAS with different vaccines is under current debate; some discussions are presented.

Type 1 diabetes and measles, mumps and rubella childhood infections within the Italian Insulin-dependent Diabetes Registry

AIMS

Several studies confirmed the growing rate of Type 1 diabetes mellitus in childhood coinciding with increasing diagnosis of viral infections. A study investigating the incidence of Type 1 diabetes during 1996-1997 showed a higher notification of viral infections in the Pavia District. The aim was to confirm these results.

METHODS

This study evaluated the relationship between new cases of Type 1 diabetes and those of measles, mumps and rubella in 1996-2001, analysing data of newly-diagnosed Type 1 diabetes children, aged 0-14 years and enrolled into the RIDI (Italian Insulin-dependent Diabetes Registry) during the same years. Measles, rubella and mumps rates were calculated using as denominator the estimated 'population at risk', represented by the number of 0- to 14 year-old subjects who did not undergo the MMR (measles, mumps and rubella) vaccination. In order to investigate the association between Type 1 diabetes incidence and measles, rubella and mumps respectively, Spearman's rank correlation was used.

RESULTS

The analysis of the whole Registries data did not at first show any statistical significance between age-standardized Type 1 diabetes incidence density and estimated rates of measles, mumps and rubella notifications. Excluding data from Sardinia Registry, a significant association was observed between Type 1 diabetes incidence and mumps (P = 0.034) and rubella (P = 0.014), respectively, while there was no statistical significance between the incidence of measles cases and diabetes rates (P = 0.269).

CONCLUSIONS

According to our findings, mumps and rubella viral infections are associated with the onset of Type 1 diabetes. The statistical significance observed after exclusion of the Sardinian data suggests that other environmental factors may operate over populations with different genetic susceptibility.

[Monitoring of implementation of international programs of poliomyelitis eradication and measles and rubella elimination in the Republic of Belarus]

AIM

Monitoring of implementation of international programs of poliomyelitis eradication, and measles and rubella elimination in the Republic of Belarus based on results of molecular-epidemiologic studies of 2009 - 2010.

MATERIALS AND METHODS

271 viral agents isolated from children with acute flaccid paralysis syndrome, other diseases, healthy children and from sewage water within the framework of poliomyelitis control implementation were identified by serological and molecular methods. Blood sera of 528 patients with fever and rash were examined for the presence of IgM to measles and rubella virus, 418 - for the presence of IgM to parvovirus B19 and parvovirus DNA. Blood sera of 33 pregnant women and 64 children with signs of intrauterine infection were studied for IgM and IgG antibodies to rubella virus. Measles virus was isolated, N-gene sequence and phylogenetic analysis carried out.

RESULTS

The studies performed confirmed that indigenous wild polioviruses in the country do not circulate, imported wild or vaccine-related polioviruses were also not detected. Measles and rubella morbidity in the Republic of Belarus was less than 1 in 1 000 000. 2 cases of rubella (2009) and 1 case of measles (2010) was detected during adequate control level: the rate of detection of patients with fever and rash, in whom measles and rubella diagnosis was excluded by the results of laboratory examination, was more than 2 in 100 000 of the population. The etiologic agent in more than 20% of diseases with fever and rash was parvovirus B19. A single case of measles was caused by genotype D8 virus imported from India.

CONCLUSION

The data obtained give evidence to conformance of the poliomyelitis, measles, rubella, innate rubella syndrome control implemented in the Republic of Belarus to WHO recommendations; maintenance of status of country as free from poliomyelitis and achievement of main criteria of elimination of both measles and rubella by 2010.

Total blood mercury and serum measles antibodies in US children, NHANES 2003-2004

BACKGROUND

Environmental toxins, pathogens and host susceptibility cofactors may interact to contribute to disease. In vitro mercury exposure inhibited antiviral cytokines in human cells; however, little is known about the relationship between mercury and viruses in children. Children are susceptible to mercury toxicity; lower vitamin B-12 and folate levels and higher homocysteine levels may represent susceptibility cofactors. This study aimed to evaluate associations between total blood mercury (Hg) and measles antibodies in children, and the influence of these susceptibility cofactors.

DESIGN

Cross-sectional data on serum measles antibodies, Hg, homocysteine, methylmalonic acid (MMA, indicator of B-12 deficiency), and folate were obtained from the 2003-2004 NHANES for children aged 6-11 years with measles seropositivity (n=692). We used linear regression to evaluate relationships between measles antibodies and Hg, stratified by sex, MMA ≥, folate <, and homocysteine≥sample medians, adjusted for demographic, nutritional and environmental cofactors.

RESULTS

Hg (range: 0.10-19.10μg/L) was inversely associated with measles antibodies (range: 1.00-28.24 units) in non-stratified analysis (n=692), yet positively associated among the subset of boys with higher MMA and lower folate (n=98). Among this subset with higher homocysteine levels (n=61), correlations were positive across all Hg quartiles relative to Q1 (Hg≤0.20μg/L): Q2:β=6.60 (3.02, 10.19); Q3:β=8.49 (6.17, 10.81); Q4 (Hg>0.80μg/L):β=4.90 (2.12, 7.67) (p(trend)=0.077).

CONCLUSION

Stratification by susceptibility cofactors revealed opposing directionality for correlations between Hg and measles antibodies, with positive effect estimates at lowest exposures only among boys with higher MMA, lower folate and higher homocysteine levels.

Seroresponse to the second measles vaccine dose at school entry in Qassim province, Saudi Arabia

In 2001, the measles immunization schedule in Saudi Arabia was changed to 2 measles, mumps and rubella vaccine doses at 12 months and at 6 years. In this follow-up study we evaluated the seroresponse to the second measles dose before school entry. We recruited 138 children randomly from primary health care centres in Qassim; 124 children completed the study. Blood samples were collected before and 1 month after giving the second measles dose, before the age of 6 years. There was a statistically significant increase in the geometric mean titre of measles antibody, from 2205 m IU/mL before vaccination to 4723 mlU/mL after (P = 0.0001). The proportion of children with positive ELISA results increased fro++ 94.2% before vaccination to 99.2% after (P = 0.02), while the proportion with protective level (> or = 200 mlU/mL) increased from 97.1% before vaccination to 99.19% after (P = 0.21). The 2-dose measles immunization schedule can produce optimum protection at school entry if high vaccination coverage is guaranteed.

[Clinical value of CD64 expression in adults with measles complicating bacterial pneumonia]

OBJECTIVE

To study the clinical value of expression of peripheral blood neutrophil CD64 in adults with measles complicating pneumonia.

METHODS

106 patients were divided into two groups by clinical manifestation and bacteria study: measles complicating bacterial pneumonia group and measles complicating viral pneumonia, using flow cytometry determination of CD64, C-reactive protein (CRP) and white blood cell (WBC) count.

RESULTS

The expression of CD64 in the bacterial pneumonia group with eruptive stage was (32.15 +/- 11.07) MFI, which was significantly higher than that in the group of with recovery stage (10.6 +/- 3.23) MFI (P < 0.01) and viral pneumonia (9.55 +/- 3.48) MFI (P < 0.01). These markers were considered positive if CD64 > or = 8.5 MFI, CRP > or = 10 mg/L and WBC > or = 9.05 x 10(9)/L. Their sensitivity was 78.12%, 80.48% and 59.37%. Their specificity was 76.19% ,67.67% and 64.28%. Their accuracy rate was 77.35%, 74.52%, 61.32%; CD64 has a positive relationship with CRP.

CONCLUSION

Compared to CRP, expression of peripheral blood neutrophil CD64 can be a better marker in the early diagnosis of patients with measles complicating bacterial pneumonia and as one of the indicators of disease conditions.

Comparison of three enzyme immunoassays used to detect human parvovirus B19-specific IgM antibodies in sera of people suspected of measles

BACKGROUND

Three commercial EIA tests for the detection of anti-B19V IgM were compared in samples from patients suspected of having measles to identify the best test to perform a differential diagnosis of rash diseases.

MATERIAL/METHODS

A total of 208 serum samples which fulfilled WHO recommendations for clinically suspected measles (fever and maculopapular rash) were investigated according to the WHO program of measles/rubella elimination for the presence of anti-measles virus (MeV) and anti-rubella virus (RUBV) IgM and then were tested by three commercially available EIA kits for anti-B19V IgM (Mikrogen, Biotrin, and DRG).

RESULTS

Of the 208 samples, 21.6% and 28.4% were positive for anti-MeV and anti-RUBV IgM, respectively. Different numbers of positive samples for anti-B19V IgM were observed with the Mikrogen (14.4%), Biotrin (5.8%), and DRG (5.3%) tests. One hundred seventy-eight of the 208 samples had concordant results using all three tests: 6 concordant positive and 172 concordant negative. Samples with discrepant results were tested by PCR. Based on PCR and IgM detection, consensus values were generated and the numbers of true positive (21) and true negative (187) results were assumed. Comparison of the consensus values and the results obtained from the Mikrogen, Biotrin, and DRG tests revealed test sensitivities of 76.2%, 52.4%, and 52.4% and specificities of 92.5%, 99.5%, and 100%, respectively.

CONCLUSIONS

Although the three EIA tests for anti-B19 IgM detection showed good parameters for the differential diagnosis of measles/rubella, tests with a high specificity should be used.

[The first imported measles case associated with genotype D4 measles virus in China]

This study reported the first imported measles case associated with genotype D4 measles virus in Shanxi province in China. The clinical specimen of throat swab was inoculated into Vero/SLAM culture to isolate the virus. A RT-PCR (Reverse transcription polymerase chain reaction, RT-PCR) was performed to amplify the 676 nucleotides sequence corresponding to the carboxyl terminus of measles virus nucleoprotein. The phylogenetic tree based on the 450 nucleotide acids of carboxyl terminus of N protein was constructed and the homology similarity was analyzed. The Shanxi isolate MVi/Shanxi. CHN/20. 09/1 was clustered within the same genotype group with WHO genotype D4 reference strain, Montreal. CAN/89, and the homology of nucleotide acid between Shanxi isolate and WHO genotype D4 reference strain was 97.3%. The homology of nucleotide acid and amino acid between Shanxi isolate and 2009 genotype D4 representative strain circulating in USA, Canada, India and Russian were 98.0%-100% and 97.3%-100%, respectively. These results showed that the virus isolated from the imported measles case was genotype D4. This is the first report that the genotype D4 measles virus was imported and isolated in China. It is important to accumulate baseline data of China and help to measure transmission pathways and to clarify epidemiological links.

[Safety and immunogenicity of measles attenuated live vaccine prepared by master seed lot vaccine of Shanghai-191 strain]

OBJECTIVE

To evaluate the safety and immunogenicity of a new measles vaccine prepared by master seed lot original vaccine of Shanghai-191 strain.

METHODS

According to selection and exclusion criteria, 8-10-month healthy children, who have no history of measles, measles vaccine inoculation and vaccination contraindication were selected. The children selected were vaccinated 0.5 ml measles attenuate live vaccine prepared by master seed lot vaccine of the Shanghai-191 strain. They were observed the local and systemic response in 30 min and 6h, 24h, 48h, 72h, 7d, 14d, 21d, 28d after inoculation, and immune serum were collected before immunization and after 28 days. Measles virus antibody positive rate and geometric mean titer (GMT) were detected by hemagglutination inhibition.

RESULTS

There were not serious adverse reactions. Measles virus antibodies in serum positive rate was 100% after 28 days of immunization, and measles virus antibody GMT was 1:50.66.

CONCLUSION

New measles vaccine prepared by master seed lot original vaccine of the Shanghai-191 strain at 8-10-month children was safe and immunogenicity.

[Evolution of measles, rubella and mumps from the third seroepidemiological survey in the autonomous region of Madrid, Spain]

In this study results against measles, rubella and mumps obtained in the III Sero-epidemiological Survey of the Autonomous Region of Madrid, performed in 1999-2000, were related to the posterior evolution of these diseases in this Region. The prevalence of antibodies against measles, rubella and mumps was >90%, >95% and <90 %, respectively. Despite of the good results obtained for rubella and measles, in 2005 and 2006 two important outbreaks of these diseases occurred in Madrid. The rubella outbreak in 2005 (450 cases) affected especially to immigrants of both sexes (mainly from Central and South America) and Spanish adults males. The 2006 measles outbreak (174 cases) was imported, a high proportion of cases were adults and most of the patients were unvaccinated. No differences according to sex were observed. In Madrid mumps virus circulation has continued from 1999 to present. Two epidemic waves in the periods 2000-2001 and 2006-2007 have been detected. During 2006-2007, an important proportion of cases showed antecedents of vaccination. Each one of these three diseases has typical characteristics. However, the three has in common the change in the age of apparition, with a growing frequency of cases among young adults.

[Analysis on immune effect of different measles vaccine among 196 infants at age of 8-month in Yunnan Province]

OBJECTIVE

To analyze the effect of different dosage of measles vaccines (0.2 ml or 0.5 ml) to measles antibody level in 8 month-old infants and study the relationship between maternal antibody in infants and the immune response to the vaccine.

METHODS

196 8 month-old infants and their mothers were selected randomly. The measles IgG-antibody in infants before and after vaccination and in their mothers was detected by ELISA.

RESULTS

Total 101 infants received 0.2 ml MV and 95 infants received 0.5 ml MV. (1) Among all infants who were antibody negative before vaccination, the immune success rate was 88.24% in the Group 1 and 97.3% in Group 2. There were significant differences between the 2 groups (chi2=4.656 P=0.031). (2) Infants who were antibody positive before vaccination the immune success rate was 56.25% in Group 1 and 57.14% in Group 2. There were no significant differences between the 2 groups (chi2=0.003 P=0.957). (3) Before receiving MV, the seronegative rate in total 196 infants was 81.12%, but the seronegative rate in their mothers was 7.65%.

CONCLUSION

For 8 month-old infants, the maternal antibody has limited influence on the immune success rate. Increasing the dosage to 0.5 ml could increase the success rate and decrease the primary immune failure among infants who were antibody negative pre-vaccination. However, for those infants who were antibody positive pre-vaccination, the antibody level was not increase along with the increasing of the vaccine dosage.

Clinical features of measles according to age in a measles epidemic

The purpose of this study was to retrospectively investigate the relationship between age and clinical manifestations and laboratory findings in patients with measles. The study included 216 patients admitted to a hospital in Daejeon, 1 of the largest cities in South Korea, during the 2000-2001 measles outbreak: very young children (<2 y old; 159 patients), school age children (9-11 y old; 34 patients), and young adults (>16 y old; 23 patients). Few of the very young children (9%), but most of the older children (86%) had a history of a prior measles-mumps-rubella vaccination. There were no statistical differences between the 3 groups in terms of the total duration of fever, length of hospitalization, occurrence of complications (defined as hospitalization for more than 7 d) or anti-measles IgM positivity. A reduction in the number of white blood cells and lymphocytes was observed in all age groups. The levels of C-reactive protein were not different between very young children and older children, but hepatic involvement was more prevalent in young adults. In conclusion, the clinical course including the complications experienced was similar in all the measles patients regardless of age.

[Comparison and evaluation of enzyme-linked immunization assay kits with plague reduction neutralization test for detection of measles IgG antibody]

OBJECTIVE

To evaluate and comparison of 2 commercial ELISA kits (Vrion/Serion kit and IBL kit) which ELISA kit will be used in sero-epidemiological survey in China in 2006 by Plaque Reduction Neutralization Test (PRNT).

METHODS

52 serum panel which contain different levels of measles antibody were used.

RESULTS

The results showed that the sensitivity, PPV and accurate of Virion/Serion kit achieved highest score when taking PRNT as "gold standard". Virion/Serion kit showed good relationship with PRNT titer: the correlation coefficients are 0.878 (P<0.01). IBL kit get lower correlation coefficients 0.850 (P<0.01). The test value and mean of unit of serum antibody increased along with neutralizing titers increased.

CONCLUSION

The Virion/Serion kit is good in sensitivity and specificity. It has quantitative for single well. The kit is suitable for sera epidemiology survey to detection of automatic workstation in China.

[Investigation of measles, rubella and varicella IgG antibody levels among migrant and native pupils in Changning District of Shanghai]

OBJECTIVE

To define the measles, rubella and varicella immunoglobulin G (IgG) anti-body levels among migrant and native pupils so as to advise effective measures for measles control and prevention.

METHODS

241 pupils at four or five grade were recruited from 3 primary schools in Changning District. Measles, rubella and varicella IgG antibody levels were tested.

RESULTS

The positive rates of measles, rubella and varicella IgG antibodies of the 241 pupils were 96.68%, 79.67% and 57.68% respectively. The positive rates of IgG antibodies of meales and rubella were not significant difference between the migrant and native groups, but the concentrations of IgG antibodies of measles and rubella in migrant group were higher than those of native group. The positive rate of varicella IgG antibody in migrant group was also higher than that of native group.

CONCLUSION

There was a high potential to outbreak of varicella in primary schools. Surveillance and prevention for infectious diseases and health education should be reinforced in schools. The pupils who have no varicella history are recommended to administer varicella vaccine.

Immune response to measles vaccine after mass vaccination in Urmia, Islamic Republic of Iran

We investigated the effectiveness of the mass measles vaccination campaign in Urmia, Islamic Republic of Iran, by examining the measles IgG seroprevalence and antibody response from paired data before and after the campaign. The overall seropositive rate of 624 subjects aged 5-25 years increased 1 year after the mass vaccination (from 53.0% to 72.3%). A rise in antibody titre occurred in all age groups except the 21-25 years group, which had the highest titre before mass vaccination. On logistic regression analysis, only immune status prior to vaccination was significantly associated with the seroresponse. It may be cost-effective to check antibody titres before mass vaccinations, especially in high vaccine coverage regions with circulating wild virus.

Endemic measles in Karachi, Pakistan and validation of IMCI criteria for measles

AIM

To estimate the incidence of measles in Karachi, Pakistan and to determine the proportion of children with measles based on the WHO integrated management of childhood illness (IMCI) criteria with a positive IgM for measles or dengue.

METHODS

Patients up to 14 years old were screened for febrile rash illnesses at five Karachi hospitals. Active measles cases were classified as measles, measles with eye and mouth complications, or severe complicated measles using IMCI criteria.

RESULTS

Screening 1,219,061 patients over a 39-month period identified 3503 qualified children. Most (76.8%) measles cases occurred in children under five years of age. The average annual incidence rate was 0.68 per 1000 in year 1; 0.19 in year 2 and 0.08 in year 3 of surveillance. Pneumonia and diarrhoea were the most common complications. Of 18.1% hospitalized, 1.6% died. Of 2286 children tested, 1599 (69.9%) were measles IgM positive. Of 542 measles IgM negative children, 66 (12%) were dengue IgM positive. The predictive positive value for the IMCI case definition was 75%.

CONCLUSION

The IMCI case definitions for measles is reasonable but may overestimate measles incidence. Measles continues to be a public health problem in Pakistan; increased efforts to control measles are urgently needed.

Seroconversion of children following natural measles infection and vaccination

OBJECTIVE

To evaluate the relationship between measles virus (MV) antibodies (abs) in sera and breast milk of nursing mothers, their contributions in seroconversion of children (0-9 months) post vaccination, prevalence of prevaccination measles abs in sera of children brought for measles vaccination and seroconversion rate in vaccinees from nursing and lactating mothers. Also to determine the potency of vaccines available in Nigeria in relation to seroconversion.

METHODS

One hundred and twenty pre- and post-vaccination sera and breast milk samples were collected from each nursing mother while corresponding number of finger prick pre- and post-vaccination sera samples were collected from children on filter papers. These were tested for mv abs using serological techniques.

RESULTS

Eighty (20.0%) mothers had measles haemagglutination inhibition (HI) abs in sera and 88 (27.2%) had mv HI abs in breast milk. Eight (2.0%) children who had prevaccination mv abs in sera came from mv ab negative mothers. Forty-four (37.0%) came back for post vaccination sera, sero-converted while 76 (63.3%) gave low sero-conversion rate of 37.0%. Results showed that mv abs in sera or breast milk of mothers did not interfere with mv vaccination in children. The low sero-conversion rate obtained was due to low vaccine potency with titres ranging between (log10-10 - log10-2.5)TCID/per dose, besides non-specific antiviral substances exhibited virus neutralizing activity.

CONCLUSION

Poor sero-conversion due to loss of passive immunity arose from undernourishment while low ab titres came with natural infection. This suggested mv vaccination did not immunize following natural mv infection or any other previous immune status.

Measles epidemiology and its implications for a vaccination programme in Oman

To describe the epidemiology of measles in Oman and the implications for a vaccination programme, we conducted a retrospective record-based study from 1 January 2000 to 31 December 2003 using data from the national epidemiological surveillance system. All cases notified as suspected measles during the study period were included. Of the 185 notified cases, 19.4% were confirmed measles positive. Blood samples for measles IgM were collected in 97.3% of cases. The mean age of measles cases was 8.0 (SD 10.7) years. The estimated overall incidence rate of measles for the study period was 0.53 per 100,000 person-years. Regression analysis indicated measles was significantly commoner among non-Omanis and children who had not been vaccinated.

[Diagnostic value of enzyme immunoassay test for the detection of specific IgM antibodies to measles virus]

The diagnostic value of enzyme immunoassay systems manufactured by different companies was comparatively studied to detect specific IgM antibodies to measles virus. The assay systems were shown to have a high sensitivity. The specificity was higher in the assay systems designed on the capture principle, a type of solid-phase enzyme immunoassay.

[Comparative assessment of determination of measles virus IgG antibodies in blood serum and dried whole blood]

Enzyme immunoassay (Dade Behring Enzygnost diagnostic kit, Germany) was used to estimate the levels of measles virus IgG antibodies in 72 samples of blood serum and eluates of the whole blood dried on the Whatman 3M filter paper. The sensitivity of the dried blood test was 98.4%. The regression analysis showed a high correlation of the results (r2 = 0.89; regression coefficient 0.89). Measles virus IgG antibodies were ascertained to be retained in the dried blood at room temperature long (for at least 2 years). After 2-year storage at +4 degrees C, there was a reduction in the concentration of antibodies; however, they were still detectable in 62 (96.9%) out of 64 positive samples. The dried blood test is recommended for wide use to study immunity to measles virus.

[Enhancement of measles-mumps divaccine using myelopeptide 2 in experiment]

Combined application of mumps and measles vaccine strains in equal doses results in significant decrease of immune response to the former component in humans. It is possible that this phenomenon is related with well-known immunodepressive effect of measles virus, which was demonstrated both in vivo and in vitro. It was previously shown that myelopeptide-2 (MP-2) partially neutralizes suppressive effect of measles vaccine on blast transformation of activated human lymphocytes in vitro. Partial supression of immune response to mumps vaccine by live measles vaccine was reproduced in laboratory animals. It was shown that in experiment MP-2 partially neutralized suppressive effect of measles vaccine.

Oxidant and non-enzymatic antioxidant status in measles

Measles is a highly contagious viral disease of childhood associated with serious complications and significant morbidity and mortality. In the present study, antioxidant and oxidant status was investigated in children with measles. Our aim was to evaluate the possible changes in non-enzymatic antioxidant levels and their relationship to the oxidative stress in measles. According to our knowledge, there are no data about the blood levels of malondialdehyde (MDA), reduced glutathione (GSH) and vitamin C in measles. We measured the whole blood MDA (as a marker of lipid peroxidation) and GSH, and serum beta-carotene, retinol, alpha-tocopherol and ascorbic acid levels in all subjects. There was a statistically significant difference between the groups for all parameters (p < 0.05). Non-enzymatic antioxidant status was found to be decreased but, lipid peroxidation was increased in the study group. As a conclusion, these findings suggested that oxidant and antioxidant defence system were altered in children with measles.

Prevalence of antibodies against measles, mumps, and rubella before and after vaccination of school-age children with three different triple combined viral vaccines, Rio Grande do Sul, Brazil, 1996

OBJECTIVE

We evaluated the seroprevalence for measles, mumps, and rubella in school-age children (6-12 years old) before and after the administration of three triple combined viral vaccines.

METHODS

In two municipal schools of Rio Grande do Sul, Brazil, 692 blood samples were collected before vaccination and 636 samples 21 to 30 days after vaccination during 1996. IgG antibody seropositivity was investigated by enzyme-linked immunosorbent assay (measles and mumps with Enzygnost [Behring, Marburg, Germany]; rubella with Rubenostika [Organon Teknica, Boxtel, the Netherlands]). The vaccines compared were: A: E-Zagreb, L-Zagreb, and Wistar RA 27/3 (Tresivac); B: Moraten, J-Lynn, and Wistar RA 27/3 (M-M-R II); and C: Schwarz, Urabe AM-9, and Wistar RA 27/3 (Trimovax).

RESULTS

Before vaccination, 79.2% [95% confidence interval (CI)=76.0%-82.2%] of the samples were positive for measles, 69.4% (95% CI=65.8%-72.8%) for mumps, and 55.4% (95% CI=51.6%-59.2%) for rubella. After vaccination with the A, B, and C vaccines, seropositivity was 100.0%, 99.5%, and 100.0%, respectively for measles; 99.5%, 94.5%, and 92.0% for mumps; and 92.6%, 91.3%, and 88.6% for rubella.

CONCLUSIONS

About one-fifth (20.8%) of the schoolchildren who could have been vaccinated against measles at age 9 months had levels of antibodies insufficient for protection. In the sample of schoolchildren without previous vaccination against mumps and rubella, high proportions of susceptible levels were found. All vaccines were immunogenic, but vaccine A yielded a seroconversion rate of 99.5% for the mumps component, which was significantly higher than the other two vaccines (P<0.01).