Mestan Emek

Seroprevalence of Pertussis Toxin Antibody in Manisa Province of Turkey, After Six Years Implementation of Acellular Pertussis Vaccine

Vaccination is the most effective way of preventing pertussis disease. Turkey commenced a routine infant immunization program using whole cell (wP) pertussis vaccine in 1968. Immunization accelerated in 1985 after participation of Turkey in the Expanded Programme on Immunization initiated by the World Health Organization. Acellular vaccine (aP) replaced wP in 2008 and a booster was added to age 6 in 2010. The immunization programme was successful in reducing the morbidity rate from 20.58 per 100.000 in 1970 to the lowest level of 0.01 per 100.000 in 2009. However, reduction of vaccine-induced protection and reduced natural boosting of circulating Bordetella pertussis are likely to increase the susceptibility of the population. As a result, morbidity rate increased from 0.09 per 100.000 to 0.41 per 100.000 in 2015 compared to the previous year. The aim of this epidemiological study was to determine the seroprevalence of pertussis toxin (PT) antibodies among healthy people and its association with various social determinants in Manisa province in Turkey, 6 years after aP replaced wP vaccine. The study was conducted as a cross-sectional study with a sample of 1250 people that was randomly selected from the over 2 years of age population in Manisa in 2014. Seroprevalence of PT antibody was determined as the dependent variable of the study. Independent variables of the study were; gender, age, migration in the last 5 years, occupational class, perceived income, house ownership, number of people per room, annually per capita equivalent income. The presence of anti-PT IgG was detected by quantitatively using a commercially available ELISA kit. The antibody levels were categorized into groups according to pertussis infection or vaccination immune response status. The groups consisted of undetectable (< 5 IU/ml), mid-range (5-< 62.5 IU/ml: more than one year previously), high (62.5-< 125: with in 12 months) and very high (≥ 125 IU/ml: with in 6 months) antibody levels. The test results with ≥ 5 IU/ml were defined as seropositive. Level > 100 IU/ml detected among adolescent and adult participants indicated acute or recently recovered pertussis infection. Chi-square test was used to evaluate association between social determinants and pertussis seropositivity. The seroprevalence of the whole study population was 58.1% (95% CI 55.32-60.79) and no association was found with any of the social determinants. The highest seroprevalence was found among 2-9 age group (68.3%) followed by 70-79 age group (63.5%). The lowest seroprevalence was found among 20-29 age group (50.9%) followed by 10-19 age group (51.6%). When seropositivity levels according to ages were compared, it was found that there was a decrease one year after the first vaccination at 2nd, 4th and 6th months and the booster at the 6th year, with a lowest rate (19%) in 11 year-old. The highest seropositivity (77.3%) with a level of >100 IU/ml (13.6%) were detected at age 15 among all adolescent and adult participants. Adding an adolescent booster to immunization schedule and recommendation of vaccine to elderly people should be considered to reduce the incidence of pertussis disease in Turkey.

Effect of Blood Cell Subtypes Lysis on Routine Biochemical Tests

Summary Background: The aim of this study is to establish the contribution of blood cells subtypes on hemolysis. Methods: Separated blood cell subtype suspensions prepared with blood from 10 volunteers were serially diluted to obtain different concentrations of cell suspensions. The cells were fully lysed and cell hemolysates were added (1:20) to aliquots of serum pool. Thus, seven serum pools with different concentrations of interferent were obtained for each blood cell subtype. Biochemical parameters and serum indices were measured by an autoanalyzer. As cell lysis markers, free hemoglobin was measured by spectrophotometry while myeloperoxidase and b-thromboglobulin were measured by enzyme immunoassay. The percent changes in analyte levels of the serum pools were evaulated by Wilcoxon Signed Rank Test and compared with clinical thresholds defined for each test. Results: The clinical thresholds were exceeded in lactate dehydrogenase, potassium, aspartate aminotransferase, creatine kinase, magnesium, total protein, total cholesterol, inorganic phosphate, glucose for red blood cells (RBC); lactate dehydrogenase, aspartate aminotransferase, total protein, inorganic phosphate and glucose for platelets (PLT). Free hemoglobin was significantly correlated with RBC (r=0.999; p=0.001), while myeloperoxidase and b thromboglobulin showed no significant correlation to white blood cells (WBC) and PLT, respectively. Conclusion: The effect of RBC hemolysis in serum on the routine biochemical tests are clearly established, yet, additional studies are required in order to verify this kind of effects of PLT and WBC hemolysis.

Seroprevalence and social determinants of varicella in Turkey

Background In Turkey, varicella vaccine was introduced into routine childhood immunization in 2013, with a single dose administered to children aged 12 months. However, there is limited information on the morbidity (incidence and seroprevalence), mortality and burden of disease of varicella in the overall Turkish population. Aim To determine varicella seroprevalence and its social determinants in Manisa Province, Turkey in children aged > 2 years before single-dose varicella vaccination was introduced in 2013. Methods The presence of anti varicella-zoster virus IgG antibodies was determined using enzyme-linked immunosorbent assay in serum samples collected from 1250 participants. Results The overall seroprevalence was 92.8% and the seroprevalence was > 90% among all age groups except 2-9 years (55.7%). Seroprevalence was significantly associated with family size, annual per capita equivalent income, number of people per room and education level. After adjusting by age, only education level remained significantly associated with seroprevalence, reflecting the early age effect. Conclusion High seroprevalance depends on natural exposure to the infectious agent itself and is not associated with social determinants. High vaccine coverage should be maintained for effective varicella control and switching to a 2-dose schedule may also be considered to reduce the number and size of outbreaks in the Turkish population.

Seasonal Influenza Vaccine Effectiveness in Preventing Laboratory Confirmed Influenza in 2014-2015 season in Turkey: A Test-Negative Case Control Study

Background: Influenza has an important public health impact worldwide with its considerable annual morbidity among persons with or without risk factors and its serious complications among persons in high-risk groups. The seasonal influenza vaccine is essential for preventing the burden of influenza in a population. Since the vaccine is reformulated each season according to the virus serotypes in circulation, its effectiveness can vary from season to season. Vaccine effectiveness is defined as the relative risk reduction in vaccinated individuals in observational studies. Aims: To calculate influenza vaccine effectiveness in preventing laboratory-confirmed influenza in the Turkish population for the first time using the national sentinel surveillance data in the 2014-2015 influenza season. Study Design: Test-negative case-control study. Methods: We compared vaccination odds of influenza positive cases to influenza negative controls in the national influenza surveillance in Turkey to estimate influenza vaccine effectiveness. Results: The influenza vaccine effectiveness against influenza A (H1N1) (68.4%, 95% CI: -2.9 to 90.3) and B (44.6%, 95% CI: -27.9 to 66.6) were moderate, and the influenza vaccine effectiveness against influenza A (H3N2) (75.0%, 95% CI: -86.1 to 96.7) was relatively high; all had low precision given the low vaccination coverage. Overall, the influenza vaccination coverage rate was 4.2% (95% CI: 3.5 to 5.0), which is not sufficient to control the burden of influenza. Conclusion: In Turkey, national surveillance for influenza should be strengthened and utilised annually for the assessment of influenza vaccine effectiveness with more precision. Annual influenza vaccine effectiveness in Turkey should continue to be monitored as part of the national sentinel influenza surveillance.