MEASLES VIRUS IMMUNITY LEVEL STUDY IN PARTICULAR POPULATION GROUPS OF THE REPUBLIC OF GUINEA WITHIN THE FRAMEWORK OF GLOBAL MEASLES ELIMINATION PROGRAM. REPORT 2

A goal for measles elimination globally by 2010–2020 was recognized as one of the priorities in the WHO program “Health for All in the 21st Century” (1998). However measles outbreaks occurred in 2010–2016 in countries with high level of measles vaccine coverage including USA and some European countries.Large measles outbreaks were also registered on the African continent and particular in the Republic of Guinea as a result of the decline of measles vaccine coverage due to the Ebola virus epidemic in the Republic of Guinea in 2014–2015. WHO recommends carrying out the routine measles vaccination as well as the supplemental immunization activities after the stop of the Ebola virus transmission. Effectiveness of the activities is definitely connected with the detection of the epidemically significant for the supplemental immunization age groups. The aim of the study was to evaluate the measles immunity level in different age groups of population in the Republic of Guinea. Materials and methods. Twenty five blood serum samples of healthy adult Guineans aged 28–66 and 121 blood serum samples of adolescences and adults admitted to hospital in the town of Kindia (Republic of Guinea) for indoor treatment were tested by ELISA. The specific measles virus antibodies were detected using the following commercial ELISA test-systems produced by Euroimmun Medizinische Labordiagnostika AG Company (Germany): IgM-antibodies — by “Anti-Measles Virus ELISA (IgM)”, IgG-antibodi es — by “Anti-Measles Virus ELISA (IgG)”, IgG-avidity measles virus antibodies — by “Avidity: Anti-Measles Virus ELISA (IgG)”. A part of sera was studied by “Vector-Best IgM-measles” and “Vector-Best IgG-measles” ELISA test-systems (Russia). Results and discussion. The comparative quantitative study of the measles immunity level (i.e. IgG-antibodies titers) of the healthy adult Guineans in 2015 and 2016 revealed the lack of IgGantibodies in serum of only one person aged 30. In 68.7% of cases studied the IgG-antibodies titers didn’t change significantly during the year. In the most part (68.0%) of the 25 tested sera the high levels of the IgG-antibodies titers were detected (≥ 1000 IU/L). In addition the IgG-antibodies of high avidity were revealed in the most part (87.5%) of blood serum samples thus evidencing the history of measles virus infection in the past among the examined adults aged 28+. The ELISA studies of 121 blood serum samples from patients with different clinical diagnosis being on indoor treatment in the hospital of the town of Kindia (Republic of Guinea) revealed 21 anti-measles IgG negative patients. Among patients with the known age (n = 113) IgG-antibodies to measles virus were determined in 78.8% of the samples tested. At the same time in each age group the seronegative patients as well as the patients with low titers of the specific IgG-antibodies to measles virus were revealed. Among patients of 18–40 years of age the part of seronegative patients was equal to 28.5±5.1%. This cohort may be susceptible to measles virus infection and facilitate the support as well as the development of active epidemic process in case of measles outbreaks in the Republic of Guinea.