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3.
Rev Esp Salud Publica ; 74(4): 419-24, 2000.
Article in Spanish | MEDLINE | ID: mdl-11031852

ABSTRACT

BACKGROUND: A) To ascertain the rate of carriers and the Types of Neisseria Meningitidis circulating in the population resident in the health jurisdiction of Gran Canaria. B) to ascertain the pattern of distribution of such carriers. METHODS: A descriptive transversal design was made, with a random sampling in multiple stages and by conglomerates. A minimum sample size was determined at 707 individuals for an expected prevalence of 8.6%, with a rate of reliability of 95.6% and a precision of 0.02. Assuming that 15% if the individuals would not be willing to co-operate, the sample size was increased to 831 individuals, distributed in each conglomerate in proportion to the existing population. This size was distributed in turn into four groups by age and sex, in proportion to their significance in each basic health care zone selected at random. The individuals in the sample were identified from among those who attended the blood extraction units, and after they had passed the criteria of exclusion, their co-operation was requested as volunteers in the study. If they accepted, a questionnaire was filled out with a number of variables of epidemiological interest and a pharyngeal smear was taken. Since the Primary Care units were selected on a simple random basis, and the same method was used to select the individuals within the units, the estimate of the prevalence was made by means of an unbiased estimator. RESULTS: A total of 828 samples were obtained, that is, 99.6% of the number foreseen. With the exception of three, all of the individuals selected participated voluntarily in the study, a circumstance rendering it highly representative. All of the strains obtained corresponded to N. Meningitidis Serogroup B, except for one identified as N. Meningitidis Serogroup C Sero/Subtype 4:P1.2,5. The strains of N. Meningitidis serogroup B identified corresponded to 25 different sero-subtypes. The prevalence determined after having studied the sample was 6.45%, the variance = 0.0275 and the standard error = 1.66. We can conclude with a 95% degree of reliability that the prevalence of carriers of N. Meningitidis in the Gran Canaria health jurisdiction is estimated to be between 3.2% and 9.7%. CONCLUSIONS: A clear predominance of N. Meningitidis serogroup B strains among carriers has been verified. There are no statistically significant differences in the prevalence observed among the different age groups nor between sexes.


Subject(s)
Carrier State/epidemiology , Neisseria meningitidis/isolation & purification , Adolescent , Adult , Age Distribution , Aged , Carrier State/microbiology , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Neisseria meningitidis/classification , Prevalence , Random Allocation , Reproducibility of Results , Sample Size , Sex Distribution , Spain/epidemiology
4.
Rev Esp Salud Publica ; 74(4): 377-9, 2000.
Article in Spanish | MEDLINE | ID: mdl-11031846

ABSTRACT

Following the use of an extensive immunisation campaign targeting the population between ages 2 and 19 in the majority of the Autonomous Communities (Regions), for the purpose of controlling the "outbreak or epidemic wave" caused by serogroup C in 1996-97, there was great interest in ascertaining the situation of the well-known epidemic strain C:2b:P1.2.5, which had been identified as the cause of the changes brought about in the epidemiological profile of meningococcal disease in Spain, as this would enable us to analyse some of the possible future tendencies of this disease in our country. An analysis of the situation in the first 10 months of 1999 reveals that we have reverted to figures similar to those which, both insofar as the number of cases as well as the frequency of serogroups, were observed in Spain at the beginning of the decade of the nineties, although the epidemic strain C:2b:P1.2.5 represents 56% of the total cases of serogroup C. The strains of serotype 2a, very frequent in serogroup C in European countries, continue to represent a minority in Spain. Finally, it is of interest to mention the appearance of antigen variants which could be the result of processes of intra-specific genetic recombination and which would presumably have been selected in terms of their evolutive advantages.


Subject(s)
Meningococcal Infections/microbiology , Neisseria meningitidis/classification , Adolescent , Adult , Child , Child, Preschool , Disease Outbreaks/prevention & control , Humans , Meningococcal Infections/epidemiology , Spain/epidemiology , Species Specificity , Vaccination
5.
Rev Esp Salud Publica ; 74(4): 433-44, 2000.
Article in Spanish | MEDLINE | ID: mdl-11031854

ABSTRACT

BACKGROUND: In 1997, 18.5% of the cases of Meningococcal Disease caused b serogroup C in Andalusia were children between 2 and 4 years of age; ages where the initial immune response and the duration of the capsular A + C meningococcal polysaccharide vaccine is less than in older age groups. Research was designed in order to measure the immune response produced by this vaccine in children from 2 to 6 years of age and to compare it with the natural immunity present in unvaccinated children. METHODS: I. Dual monitoring study: a) groups of children vaccinated previously and control groups, b) groups of children who were going to be vaccinated, for pre and post-vaccination (1, 6 and 12 months) analysis and a control group. II. The bactericidal activity was measured according to the standardised protocol of the CDC with regard to the strain of N. meningitidis C-11. The sera with bactericidal activity (TAB) > 1:8 were considered to be protective. RESULTS: 1 and 2 months following vaccination, the proportion of TAB > 1:8 was significantly higher than that of the control group (65.6% and 73% in comparison to 2.2% and 12%). In the pre-vaccine and post-vaccine (after 6, 7, 12 and 13 months) verification, no significant difference between vaccinated individuals and controls was observed. CONCLUSIONS: The differences between vaccinated and unvaccinated individuals 1 and 2 months following vaccination indicate seroconversion in the vaccinated individuals. For the age group of between 2 to 6 years of age, the bactericidal activity acquired decline quickly, as, after 6 months, differences between this group and the control group are no longer observed.


Subject(s)
Antibodies, Bacterial/blood , Meningococcal Vaccines/immunology , Neisseria meningitidis/immunology , Case-Control Studies , Child , Child, Preschool , Female , Humans , Male
6.
Rev Esp Salud Publica ; 74(4): 425-31, 2000.
Article in Spanish | MEDLINE | ID: mdl-11031853

ABSTRACT

BACKGROUND: In 1995 the Community of Madrid detected an increase in the number of cases of meningococcal disease caused by serogroup C. In 1997 a mass vaccination campaign was carried out in relation to the population between 18 months and 19 years of age. The purpose of this study is to ascertain the immune response produced by the vaccine and its relationship to the age of the subjects. METHODS: A sample group of 1,003 children vaccinated during the campaign was selected. A blood sample was extracted prior to vaccination and after one, six (only a under 5 years old) and twelve months had transpired. In order to assess the immune response, the levels of bactericidal and total antibodies were measured. RESULTS: The prevalence of seroconversion measured by bactericidal antibodies is 89.6%. The response is low in children under 3 (34.8%), increases with age and, from 7 years on, surpasses the 90% mark. After 6 months, the prevalence of protective levels in children under 5 years of age drops noticeably (31.3%). After one year, the prevalence drops significantly, particularly in children under 7 years of age. The proportion of individuals with total antibody response after one month is over 90%, and remains high after one year in all of the age groups (97.5%). CONCLUSIONS: The response measured by means of total antibodies contradicts the clinical response to the vaccination and the measurement by means of bactericidal antibodies underestimates the protection if it is compared with the results of vaccinal efficacy, for which reason, we need to search for biological indicators that would correlate adequately with the clinical response following immunisation.


Subject(s)
Antibodies, Bacterial/blood , Meningococcal Vaccines/immunology , Neisseria meningitidis/immunology , Adolescent , Adult , Age Distribution , Child , Child, Preschool , Humans , Infant , Prevalence , Sample Size , Spain
7.
Vaccine ; 18(24): 2656-60, 2000 Jun 01.
Article in English | MEDLINE | ID: mdl-10781851

ABSTRACT

An increase in the incidence of group C meningococcal disease was observed in the Murcia Region (Spain) during 1996-1997. In September 1997, a massive vaccination campaign was implemented among the population aged 18 months to 19 years. The aim of this study was to assess the seroconversion rate of children aged 18-59 months and the persistence of immune response 1 year after vaccination. A total of 296 children were included. Blood samples were obtained before vaccination and 1 month and 1 year after vaccination. Three point seven percent of the children had bactericidal antibody titres of >/=1:8 before vaccination. One month after vaccination seroconversion was 63.7%, with a growing trend related to age at vaccination (p<0.0001). The increase in antibody titres was shown to be quantitatively greater above the age of 36 months (p<0.0001). One year after vaccination only 4.3% of the children who initially seroconverted still had bactericidal activity. Seroconversion in children under 5 increases with age but antibodies decline rapidly in the year following vaccination.


Subject(s)
Antigens, Bacterial/immunology , Bacterial Vaccines/immunology , Meningococcal Infections/prevention & control , Neisseria meningitidis/immunology , Polysaccharides, Bacterial/immunology , Child, Preschool , Female , Humans , Immunization Schedule , Infant , Male , Risk Factors , Spain
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