The importance of serological and molecular analyses for the diagnosis of measles cases and for meeting elimination targets in Turkey from 2007 to 2015

Increase in measles cases in a City hospital, Istanbul, Turkey

OBJECTIVES

Measles cases are increasing remarkably in our country as well as all over the world. In this study, it was aimed to examine the epidemiological and clinical characteristics of measles cases detected in our hospital, as well as the measles seroprevalence in our region.

METHODS

A total of 7,452 individuals whose measles IgG and/or IgM antibodies were studied between December 2021 and March 2023 in the Medical Virology Laboratory in Başakşehir Çam and Sakura City Hospital were included in this retrospective study. Measles IgG and IgM antibodies were analysed by enzyme-linked immunosorbent assay. Demographic information, clinical symptoms and laboratory data of the participants were obtained from the hospital's electronic medical records.

RESULTS

A total of 102 measles cases were identified between December 2021 and March 2023. Of these cases, 77 (75.5%) patients were ≤ 18 years old. Of the 73 measles cases with vaccination information, 90% were unvaccinated. The measles seroprevalence rate was 72.8%. The lowest seroprevalence rate (4.8%) among the age groups was found in 8-11-month-old babies, the highest cases rate (35.7%) was detected in this age group. It was determined that measles immunity increased with age (r = 0.276, p < 0.001) and was over 89.3% over the age of 30.

CONCLUSIONS

Measles immunity is insufficient in our region and measles remains an important public health problem until the age of 18. The recent increase in measles cases in our country and around the world shows that current vaccination programmes need to be implemented more decisively and strictly.

Detection of measles vaccine virus and measles-specific immunoglobulin M in children vaccinated against measles-mumps-rubella during measles outbreak

Information regarding the detection perioid of measles vaccine virus (MeVV) RNA in human nasopharyngeal samples and measles-specific antibodies following measles-mumps-rubella (MMR) vaccination is limited. During contact tracing for a measles outbreak at a hospital in Republic of Korea, 4 out of 206 children vaccinated with MMR underwent real-time RT-PCR assay for measles and measles-specific antibodies test. Measles virus RNA was detected in 2 children, all of which was vaccine virus strain RNA (genotype A). In a healthy 27-month-old boy, MeVV RNA was detected 448 days after MMR vaccination. Measles-specific IgM was positive 1097 days following vaccination in a 4-year-old girl. MeVV RNA and measles-specific IgM were detected for a considerable period following primary MMR vaccination. Physicians should exercise caution when interpreting positive RT-PCR results for MeVV or measles-specific IgM from a child with measles-associated symptoms who has been recently vaccinated against measles.

Laboratory diagnosis of measles infection using molecular and serology during 2019-2020 outbreak in Brazil

INTRODUCTION

Laboratory diagnosis of measles can be challenging, and the reintroduction of the measles virus in Brazil has brought about new issues. The aim of this study was to analyze the qPCR results of swab and urine samples and compare them with those of immunological methods for the diagnosis of measles.

METHODS

This was a cross-sectional study based on a retrospective analysis of 3,451 suspected cases using laboratory test surveillance databases for qPCR (respiratory swabs and urine) and serologic tests for IgM and paired IgG. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and agreement through kappa and adjusted kappa coefficients (PABAK) were calculated using different diagnostic strategies.

RESULTS

The swab and urine samples obtained using real-time qPCR were equivalent. Samples collected simultaneously and the combined samples showed moderate agreement between IgM ELISA and real-time qPCR; however, 48.9 % of the IgM ELISA analyses did not demonstrate detectable qPCR concentrations during simultaneous collections and 43.9 % of combined collections. The paired analysis of IgG showed an accuracy of 67.5 % for IgM and 90.7 % for real-time qPCR.

CONCLUSIONS

Diagnosis based on IgM presents detection delimitation in samples collected early (1-5 days), suggesting that these individuals satisfy at least two criteria. In addition to qPCR, paired analysis of IgG using ELISA can be used to increase the sensitivity and specificity of laboratory diagnoses.

Measles outbreak in the sanitary area of Guadalajara (Spain): difficulty in microbiological diagnosis in the era of its elimination

INTRODUCTION

In Spain, like in other countries where endemic measles has been eliminated, there is a need for available diagnostic tolos for confirming any cases in order to prevent and control its transmission. We describe the different microbiological tests used for the diagnosis of measles during an outbreak that occurred in 2019 in the province of Guadalajara (Spain).

METHODS

Serological and molecular tests were performed at the Microbiology laboratory of the Guadalajara University Hospital and at the National Center for Microbiology of the Carlos III Health Institute (Majadahonda, Spain). Patient data were obtained from the surveillance system.

RESULTS

A total of 43 patients had a laboratory diagnosis of measles: 29 cases by PCR (pharyngeal exudate or urine) and positive specific IgM, 11 cases by PCR, and 3 cases only by a positive IgM. Genotype D8 was identified in 35 confirmed cases and genotype A in two that were discarded as post-vaccination cases. PCR was positive in the acute sera of 11 out of 14 patients with a negative IgM. Eleven confirmed cases had recieved one or two vaccine doses. Twelve adult patients were hospitalizated, all of them with a diagnostic of hepatitis.

CONCLUSIONS

The combination of molecular tests and the presence of specific IgM is necessary for a correct diagnosis of measles and also to classify patients with a breakthrough infection or vaccine failures (primary or secondary). Genotyping is essential for the correct classification of the patients in the context of a measles elimination program.

Comparative evaluation of assays for IgM detection of rubella and measles infections

BACKGROUND

Serological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence.

METHODS

Seven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays.

RESULTS

The ranges of sensitivity, specificity and agreement for rubella were 94.8-100%, 52.4-100% and 75.5-98.1%, respectively. The corresponding ranges for measles assays were 87.0-100%, 53.3-100%, and 73.0-99.4%.

CONCLUSION

The best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).

Measles outbreak in the sanitary area of Guadalajara (Spain): Difficulty in microbiological diagnosis in the era of its elimination

INTRODUCTION

In Spain, like in other countries where endemic measles has been eliminated, there is a need for available diagnostic tools for confirming any cases in order to prevent and control its transmission. We describe the different microbiological tests used for the diagnosis of measles during an outbreak that occurred in 2019 in the province of Guadalajara (Spain).

METHODS

Serological and molecular tests were performed at the Microbiology laboratory of the Guadalajara University Hospital and at the National Center for Microbiology of the Carlos III Health Institute (Majadahonda, Spain). Patient data were obtained from the surveillance system.

RESULTS

A total of 43 patients had a laboratory diagnosis of measles: 29 cases by PCR (pharyngeal exudate or urine) and positive specific IgM, 11 cases by PCR, and 3 cases only by a positive IgM. Genotype D8 was identified in 35 confirmed cases and genotype A in 2 that were discarded as post-vaccination cases. PCR was positive in the acute sera of 11 out of 14 patients with a negative IgM. Eleven confirmed cases had recieved one or 2 vaccine doses. Twelve adult patients were hospitalizated, all of them with a diagnostic of hepatitis.

CONCLUSIONS

The combination of molecular tests and the presence of specific IgG and IgM are necessary for a correct diagnosis of measles and also to classify patients with a breakthrough infection or vaccine failures (primary or secondary). Genotyping is essential for the correct classification of the patients in the context of a measles elimination program.

Comparative evaluation of assays for IgM detection of rubella and measles infections

BACKGROUND

Serological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence.

METHODS

Seven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays.

RESULTS

The ranges of sensitivity, specificity and agreement for rubella were 94.8-100%, 52.4-100% and 75.5-98.1%, respectively. The corresponding ranges for measles assays were 87.0-100%, 53.3-100%, and 73.0-99.4%.

CONCLUSION

The best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).

Prevalence of Protective Measles Virus Antibody Levels in Umbilical Cord Blood Samples and Sera of Mothers and Transplacental Transport Ratio in Turkey

In Turkey, the Measles Elimination Program has been implemented since 2002. The aim of this study was to evaluate the measles-specific antibody levels of mothers admitted to a hospital for birth and their infants, to determine the factors influencing the antibody levels of both, and to evaluate the transplacental transport ratio. We selected healthy women who came to the hospital for birth and their healthy newborns. We collected blood samples from 1,547 mothers and 1,529 infants. The protective prevalence of measles antibody levels of mothers was 80% (95% confidence interval [CI]: 78-82%) and that of newborns was 85% (95% CI: 83-86%). The antibody levels of mothers and newborns were positively linearly correlated (R: 0.922, p < 0.001) and were associated with parity (p < 0.001). The ratio of neonatal to maternal antibody levels increased with gestational age. The protective levels were 1.6 times higher (95% CI: 1.1-2.4) in mothers ≥ 32 years of age and 2.1 times higher (95% CI: 1.4-3.3) in naturally immune mothers. Two factors affecting the antibody levels of newborns were the mothers' antibody levels and their immunization status. The antibody level of mother was the most significant factor that influenced the infant's antibody level. Vaccination of women before pregnancy could enhance passive antibody protection by increasing the level of transplacental transmission.