[The benefit from mumps virus IgG antibody avidity testing in the population with high vaccine coverage in the context of other serological methods for laboratory diagnosis of mumps and the current epidemiological]. / Prínos avidity IgG protilátek u príusnic ve vysoce proockované populaci v kontextu s ostatními sérologickými metodami laboratorní diagnostiky príusnic a soucasnou epidemiologickou situací.

AIM: Regular vaccination against mumps resulted in a significant reduction in epidemic mumps in the Czech Republic. However, mumps cases have recently shown an upward trend, even in the vaccinated population where a considerable proportion of cases have occurred. The aim of this study was to find out, by mumps virus IgG antibody avidity testing, whether the high incidence of mumps in the vaccinated population is a result of primary or secondary vaccine failure and whether the vaccinated differ from the naturally immunised in anamnestic antibody avidity. Given the problematic laboratory diagnosis of mumps in the population with high vaccination coverage, the informative value of the detected IgM, IgA, and IgG antibodies was also considered as well as the potential of antibody avidity testing for improving laboratory diagnosis from a single sample of blood, the most commonly analysed clinical material, in patients with suspected mumps. MATERIAL AND METHODS: Sixty-four patients laboratory confirmed with mumps, whose vaccination status was known, were included in the study (groups 1 and 2). Other study groups were 30 healthy naturally immunised subjects (group 3) and 22 vaccinated children 2-4-years of age with no etiological link to the mumps virus (group 4). The avidity index (AI) was determined using the Siemens Enzygnost Anti-Mumps/IgG kit and 6M urea, able to induce the dissociation of antigen-antibody bonds proportionally to the antibody avidity. IgM, IgG, and IgA antibodies were tested using the Siemens Enzygnost Anti-Mumps/IgM and /IgG, and Mast Diagnostica Mastazyme Mumps IgA kits. The EPIDAT system served as the data source. RESULTS: The results showed that the mumps virus induces antibodies with a low AI after both vaccination, even recent, and natural immunisation. Antibodies with a high AI were only detected in convalescent sera of the vaccinated patients or in re-infected, naturally immunised persons, as a result of recent contact with the mumps virus. The comparison of the results of acute sera testing revealed that in the vaccinated patients, 56% of cases were laboratory confirmed based on IgA positivity, i.e. 20% more cases in comparison with routine detection of IgM antibodies, while of unvaccinated cases, 87% were IgA positive and 74% IgM positive. CONCLUSION: The results of mumps virus IgG antibody avidity testing suggest that the high proportion of cases in the vaccinated patients result from secondary vaccine failure, also known as waning immunity. Diagnostic benefit from antibody avidity testing has been observed in convalescent sera and/or acute sera from both vaccinated and naturally immunised patients collected from day 6 after the onset of the disease when significant increase in AI occurs.The comparison of the serological methods for the detection of IgM, IgG, and IgA antibodies in acute sera revealed that the highest percentage of mumps infection was detected by IgA antibody testing. The addition of this serological method to mumps laboratory diagnosis made the latter considerably more effective, particularly in the vaccinated patients.

[Contribution of the detection of IgA antibodies to the laboratory diagnosis of mumps in the population with a high vaccination coverage]. / Prínos stanovení protilátek IgA pro laboratorní diagnostiku príusnic ve vysoce proockované populaci.

STUDY OBJECTIVE: Serological diagnosis of epidemic mumps can be difficult in vaccinated persons, particularly due to the absence of specific IgM antibodies. The aim was to find whether adding the detection of IgA antibodies to the currently used routine serological diagnosis of mumps (detection of IgM and IgG antibodies in an acute serum sample) would make the serological diagnosis of mumps more effective in a population with a high vaccination coverage. At the same time, ELISA kits for the detection of early IgA and IgM antibodies against the mumps virus were compared and statistical analysis of the results was performed. MATERIAL AND METHODS: Sixty-four acute sera from patients with laboratory confirmed diagnosis of mumps were included in the study. Clinical specimens were collected at the onset of clinical symptoms. To test the sera, the MASTAZYME ELISA Mumps IgA kit (MAST DIAGNOSTICA, Germany) with the MASTSORB sorbent (RF and IgG) and Enzygnost Anti-Parotitis-Virus/IgM kit (Siemens, Germany) were used. A panel of 121 acute sera with no epidemiological link to mumps virus served as specificity controls for the IgA assay. The epidemiological data were derived from the EPIDAT system. The level of agreement was assessed using the McNemara test and Cohen's coefficient kappa. The Stata 9.2 software (Stata Corp LP, College Station, USA) was used for statistical analysis. RESULTS: The detection of IgA and IgM antibodies against the mumps virus yielded concordant results in 50/64 acute sera, 32 positive and 18 negative, i.e. an agreement of 78.12 %. Of the remaining 14 samples, 13 were only IgA positive and one was only IgM positive. The controls showed non-specific IgA positivity in 5/121 samples which indicates a 96% specificity. CONCLUSION: The absence of specific IgM antibodies against mumps virus is relatively often seen in vaccinated indivi-duals; nevertheless, the test is routinely used in patients with suspected active infection. The test for IgA antibodies, which is not routinely performed, significantly increased the detection rate of the disease. Based on the results of the present study, it can be concluded that the combination of the anti-mumps IgM and IgA assays increased the effectiveness of the serological diagnosis at the onset of clinical symptoms from less than 52% to nearly 72%.

[Genotyping results, laboratory diagnosis, and epidemiology of the mumps virus circulating in the Czech Republic in 2012]. / Výsledky genotypizace, laboratorní diagnostika a epidemiologie viru príusnic cirkulujícího v Ceské republice v roce 2012.

GOAL: To extend the present routine serological diagnosis of mumps with the methods of direct detection of the pathogen and subsequent genotyping of the isolated viruses in an attempt to obtain more detailed data on recent mumps viruses circulating in the Czech Republic. Sub-goals were to point out the particularities of the laboratory examination in the population with a high vaccine coverage and to evaluate the current epidemiological situation. MATERIAL AND METHODS: Altogether 47 buccal swabs from patients with suspected mumps were included in the study. Clinical specimens collected at the onset of clinical symptoms were obtained from five administrative regions of the Czech Republic from February 2012 to December 2012. Vero cell cultures were used for virus isolation and isolates were identified using real-time quantitative polymerase chain reaction (RT-qPCR). Genotyping was performed by the WHO Regional Reference Laboratory for Measles, Mumps, and Rubella (RRL MMR), Robert Koch Institute, Berlin. The EPIDAT system was used as a source of epidemiological data. RESULTS: From 47 buccal swabs, 20 mumps viruses were isolated on Vero cells and in seven other specimens, the presence of viral RNA without positive isolation was only detected by RT-qPCR. Nineteen isolates were referred for genotyping. The phylogenetic analysis of the SH gene classified them into genotype G, as four variants. In both 2011 and 2012, most cases occurred in vaccinated patients (80%), with 15-19-year-olds being the most affected age group. The leading complication was orchitis, followed by meningitis. More complications were reported in non-vaccinated individuals. CONCLUSIONS: The increased incidence of mumps cases in the Czech Republic in 2012 was due primarily to genotype G, the leading cause of mumps in most European countries since 2005. The presence of genotype G was first reported in the Czech Republic in 2006. In the context of the unfavourable epidemiological trend, molecular epidemiological studies including genotyping of recent mumps virus strains appear to be necessary. A detailed monitoring could be helpful in elucidating the pattern of virus circulation and in designing strategies to control emerging outbreaks. The vaccination efficacy in relation to the causative genotype and possible role of waning immunity in mumps outbreaks are the issues that need to be addressed.

Increased incidence of mumps in the Czech Republic in the years 2011 and 2012.

A nation-wide vaccination against mumps that had been launched in the Czech Republic in 1987 eliminated great outbreaks (up to 100,000 cases per year) of this disease in 1955-1988, but did not prevent small outbreaks (a few thousand cases per year) in 1995-1996, 2005-2007, and 2010-2012. The extent of these small outbreaks shows an increasing trend. The article describes mumps outbreaks in the Czech Republic in 2011 and 2012 with the aim to bring additional data contributing to the clarification of repeated outbreak triggers. In the years 2011 and 2012 there have been reported 2885 and 3902 mumps cases, respectively, in the Czech Republic. Similarly to other countries, a shift in the age-specific incidence of the disease towards higher age has been found, with the highest occurrence seen in the age group of 15-19 years. Men were slightly more affected than women. Clinical complications and vaccination status of patients were also observed.