Analysis of meningococcal serogroup C-specific antibody levels in British Columbian children and adolescents

Relative importance of complement-mediated bactericidal and opsonic activity for protection against meningococcal disease

Killing of Neisseria meningitidis can result from complement-mediated serum bactericidal activity (SBA) or opsonophagocytosis (OPA), or a combination of the two mechanisms. While SBA titers > or =1:4 confer protection, recent evidence suggests that this threshold titer may not be required. For example, the incidence of meningococcal disease declines between ages 1 and 4 years without evidence of acquisition of SBA titers > or =1:4. Meningococcal polysaccharide vaccination also elicited OPA and lowered the risk of disease in patients with late complement component deficiencies whose sera did not support SBA. Sera from healthy adults immunized with an outer membrane vesicle vaccine showed OPA killing of N. meningitidis with C6-depleted complement, and whole blood from complement-sufficient non-immunized adults with SBA titers <1:4 also frequently had killing activity. Collectively the data indicate that SBA titers <1:4 and/or vaccine-induced OPA can confer protection against meningococcal disease.

Safety and efficacy of meningococcal c vaccination in juvenile idiopathic arthritis

OBJECTIVE

To determine whether vaccinations aggravate the course of autoimmune diseases such as juvenile idiopathic arthritis (JIA) and whether the immune response to vaccinations may be hampered by immunosuppressive therapy for the underlying disease.

METHODS

In this multicenter cohort study, 234 patients with JIA (ages 1-19 years) were vaccinated with meningococcal serogroup C (MenC) conjugate to protect against serogroup C disease (caused by Neisseria meningitidis). Patients were followed up for disease activity for 1 year, from 6 months before until 6 months after vaccination. IgG antibody titers against MenC polysaccharide and the tetanus carrier protein were determined by enzyme-linked immunosorbent assay and toxin binding inhibition assay, respectively. A serum bactericidal assay was performed to determine the function of the anti-MenC antibodies.

RESULTS

No change in values for any of the 6 components of the core set criteria for juvenile arthritis disease activity was seen after MenC vaccination. Moreover, no increase in the frequency of disease relapse was detected. Mean anti-MenC IgG concentrations in JIA patients rose significantly within 6-12 weeks after vaccination. Of 157 patients tested, 153 were able to mount anti-MenC IgG serum levels >2 micro g/ml, including patients receiving highly immunosuppressive medication. The 4 patients with a lower anti-MenC antibody response displayed sufficient bactericidal activity despite receiving highly immunosuppressive medication.

CONCLUSION

The MenC conjugate vaccine does not aggravate JIA disease activity or increase relapse frequency and results in adequate antibody levels, even in patients receiving highly immunosuppressive medication. Therefore, patients with JIA can be vaccinated safely and effectively with the MenC conjugate.

Phase 1 first-in-human studies of the reactogenicity and immunogenicity of a recombinant meningococcal NspA vaccine in healthy adults

BACKGROUND

Neisserial surface protein A (NspA) is a highly conserved, surface-exposed outer membrane protein of Neisseria meningitidis that has been shown to induce a bactericidal immune response in animals against all pathogenic Neisserial serogroups.

METHODS

Healthy 18-50-year-old adults were assigned to receive, in a dose escalating manner, 3 doses of 1 of 5 formulations of an experimental, unfolded, recombinant NspA (rNspA) vaccine or placebo, or 1 dose of commercially available quadravalent (A, C, Y, W-135) meningococcal polysaccharide vaccine (Menomune((R))). Adverse events were collected during the first week post-immunization, prior to the next dose and 1 month after the last dose. Serum for measurement of hematological and biochemical parameters and antibodies by enzyme immunoassay and bactericidal assay were measured before the first dose, prior to the second dose and 1 month after the last dose of vaccine.

RESULTS

The rNspA vaccine was well tolerated by recipients. Injection-site pain was reported more frequently by recipients of the three highest doses of rNspA compared to placebo but at similar rates to the licensed meningococcal polysaccharide vaccine. Adverse events were reported less frequently after subsequent doses in the three-dose series. An antibody rise measured by enzyme immunoassay was elicited with a dose-related increase that reached a maximum with the 125mug dose. Prolongation of the dosing interval between the second and third dose appeared to be associated with increased antibody levels. No bactericidal antibodies were detected after any of the rNspA formulations.

CONCLUSIONS

The unfolded rNspA meningococcal vaccine was well tolerated and immunogenic in healthy adult volunteers but did not elicit bactericidal antibodies.

Meningococcal conjugate vaccine in adolescents and children

Disease caused by Neisseria meningitidis is associated with high mortality rates and significant sequelae. Quadrivalent (A, C, Y, W-135) polysaccharide meningococcal vaccine has been available for more than 20 years, and although used widely for adolescents entering college, it has a number of limitations, including short duration of immunity and lack of a herd effect. A quadrivalent meningococcal conjugate vaccine has recently been licensed and endorsed for use in adolescents 11 to 12 years of age, at age 15, or at college entry. Among the key features of the new meningococcal conjugate vaccine are stimulation of both B-cell-dependent and T-cell-dependent immune responses, induction of immunologic memory and booster effects, long-term protection, reduction of nasopharyngeal carriage of N. meningitidis, and herd immunity. Large randomized, double-blind studies in adolescents and 2- to 10-year olds have demonstrated the immunogenicity as well as the safety and tolerability of the new meningococcal conjugate vaccine formulation.

Effects of prior polysaccharide vaccination on magnitude, duration, and quality of immune responses to and safety profile of a meningococcal serogroup C tetanus toxoid conjugate vaccination in adults

Extensive use of meningococcal AC polysaccharide (MACP) vaccines has raised concerns about induction of immunologic hyporesponsiveness to C polysaccharide. We investigated the immunogenicity and safety of a meningococcal C-tetanus conjugate (MCC-TT) vaccine in naive adults and prior MACP vaccinees. Laboratory staff (n = 113) were recruited; 73 were naive to meningococcal vaccination, and 40 had previously received > or =1 dose of MACP vaccine. Blood was taken prior to MCC-TT vaccination and 1 week, 1 month, and 6 months later. At each time point, proportions of subjects with serum bactericidal antibody (SBA) titers of > or =8 or > or =128 were similar (P > 0.46); >94% of subjects achieved titers of > or =128 at 1 month. However, the geometric mean titer (GMT) of SBA at 1 month was higher in the naive (1,757; 95% confidence interval [95% CI], 1,102 to 2,803) than in the previously vaccinated (662; 95% CI, 363 to 1,207) group (P = 0.02), and similarly at 6 months (P < 0.001). Conversely, geometric mean concentrations (GMCs) of serogroup C-specific immunoglobulin G (IgG) were significantly higher in the previously vaccinated group pre-MCC-TT and at 1 week; the groups were similar at 1 month, and there was some evidence that the GMC for the previously vaccinated group was higher at 6 months. Qualitative differences in antibodies between groups were demonstrated by using the SBA/IgG ratio, though avidity measures were similar for the two groups throughout the study. MCC-TT was well tolerated, with similar safety profiles in the two groups. Pain in the arm and headache were the most frequently reported events following vaccination. The study shows that MCC-TT is safe and immunogenic in naive and previously MACP-vaccinated adults, though the magnitude and persistence of postvaccination SBA responses in the latter group were lower.

Naturally acquired passive protective activity against Neisseria meningitidis Group C in the absence of serum bactericidal activity

The hallmark of immunity to meningococcal disease is a bactericidal titer in serum of > or =1:4 measured with human complement, but this threshold titer may underestimate the extent of protection. We used the infant rat model of meningococcal bacteremia to measure group C passive protective activity in serum samples from 91 unimmunized adults living in California. A total of 35 sera (38.5%) had passive protective activity. Sera with complement-mediated bactericidal titers of > or =1:4 were 3.4-fold more likely to confer protection (89%) than nonbactericidal sera (26%; P < 0.0001). Thus, bactericidal titers of > or =1:4 are a marker of protection, but this threshold lacks sensitivity for predicting protective activity. We investigated the 73 sera with bactericidal titers of <1:4 to determine the basis of protective activity. The 19 sera with protective activity had a higher geometric mean group C anticapsular antibody concentration (0.72 microg/ml) than the 54 sera that lacked protective activity (0.16 microg/ml; P < 0.001). Thus, protective activity in the absence of bactericidal activity was associated with higher concentrations of anticapsular antibodies, but not all sera with anticapsular antibodies conferred protection. Of 18 nonbactericidal sera with anticapsular antibody concentrations between 0.31 and 0.99 microg/ml, the 11 sera that conferred protection had a higher mean antibody avidity constant (21.9 nM(-1)) than the 7 nonprotective sera (14.6 nM(-1); P < 0.03). Thus, in sera with titers of <1:4, protective activity is associated with higher-avidity group C anticapsular antibodies, which are present in concentrations insufficient to elicit complement-mediated bacteriolysis in vitro but sufficient to confer protection in an in vivo bacteremia model.

Meningococcal serogroup C conjugate vaccine

Meningococcal meningitis and septicaemia are important causes of morbidity and mortality in many parts of the world. More than 90% of the cases are caused by serogroups A, B and C; the remaining 10% are largely caused by the W-135 and Y strains. During the mid-to-late 1990s there was an increase in meningococcal serogroup (MS) C disease in the UK and some parts of Europe. MS C polysaccharide vaccines that were developed in the 1960s are weakly immunogenic and not protective in infants under 2 years of age, but are effective in older recipients. Meningitec (Wyeth-Ayerst) is produced by conjugation of serogroup C oligosaccharide with a mutant diphtheria protein (CRM197), with the aim of inducing T-cell dependent immune responses. It has been found to be immunogenic in infants, toddlers, older children and adults. The vaccine has also been shown to induce immunological memory and therefore is likely to give long-term protection against disease. It received a license for use in the UK in October 1999 and was introduced into the UK immunisation schedule in November 1999. Surveillance studies after introduction of this and similar vaccines have demonstrated a dramatic fall in the incidence of MS C disease. Pre-licensure research studies and post-licensure adverse event data have confirmed that the vaccine is safe.

Evaluation of De-O-acetylated meningococcal C polysaccharide-tetanus toxoid conjugate vaccine in infancy: reactogenicity, immunogenicity, immunologic priming, and bactericidal activity against O-acetylated and De-O-acetylated serogroup C strains

The polysaccharide capsule of serogroup C Neisseria meningitidis (MenC) has been integral to vaccine development. Licensed MenC vaccines contain the O-acetylated (OAc+) form of polysaccharide. Some MenC strains have de-O-acetylated (OAc-) polysaccharide, which may affect antibody specificity and functional activity when used in a vaccine. We evaluated an OAc-MenC conjugate-tetanus toxoid conjugate (MCC-TT) vaccine given concomitantly with whole-cell diphtheria-tetanus-pertussis, Haemophilus influenzae type b, and oral polio immunization in 83 infants at 2, 3, and 4 months of age. Serum bactericidal activities (SBA) against OAc+ and OAc- MenC strains and OAc+ and OAc- polysaccharide-specific immunoglobulin G (IgG) levels were evaluated. MCC-TT vaccine was well tolerated. All infants produced SBA titers of > or = 8 after a single dose at 2 months of age. The SBA geometric mean titer for OAc+ strain C11 increased from 2.7 (95% confidence interval [CI] 2.2 to 3.2) to 320 (95% CI, 237 to 432), 773 (95% CI, 609 to 982), and 1,063 (95% CI, 856 to 1319) after one, two, and three doses of MCC-TT, respectively. OAc- IgG levels were twice as high as OAc+ IgG levels after the primary series of MCC-TT vaccine, and the SBA was significantly higher against the OAc- MenC strain. Antibody responses to booster vaccination with either OAc+ MenC polysaccharide vaccine (MACP) or a fourth dose of MCC-TT at 14 months of age provided evidence of immunologic memory. The acetylation status of the booster vaccine influenced the specificity of the response, with significantly higher OAc- IgG levels and SBA after MCC-TT vaccine compared to MACP vaccine but similar OAc+ antibody levels. MCC-TT vaccine is highly immunogenic and primes for immunologic memory against OAc+ and OAc- MenC strains in infancy.

Dramatic decline of serogroup C meningococcal disease incidence in Catalonia (Spain) 24 months after a mass vaccination programme of children and young people

STUDY OBJECTIVES

The objective of this study was to evaluate the effectiveness of a mass vaccination programme carried out in Catalonia (Spain) in the last quarter of 1997 in response to an upsurge of serogroup C meningococcal disease (SCMD).

DESIGN

Vaccination coverage in the 18 month to 19 years age group was investigated by means of a specific vaccination register. Vaccination effectiveness was calculated using the prospective cohort method. Cases of SCMD were identified on the basis of compulsory reporting and microbiological notification by hospital laboratories. Vaccination histories were investigated in all cases. Unadjusted and age adjusted vaccination effectiveness referred to the time of vaccination and the corresponding 95% confidence intervals (CI) were estimated at 6, 12, 18 and 24 months of follow up.

SETTING

All population aged 18 months to 19 years of Catalonia.

MAIN RESULTS

A total of seven cases of SCMD were detected at six months of follow up (one in the vaccinated cohort), 12 cases at 12 months (one in the vaccinated cohort), 19 cases at 18 months (two in the vaccinated cohort) and 24 at 24 months (two in the vaccinated cohort). The age adjusted effectiveness was 84% (95%CI 30, 97) at six months, 92% (95%CI 63, 98) at 12 months, 92% (95% CI 71, 98) at 18 months and 94% (95%CI 78, 98) at 24 months. In the target population, cases have been reduced by more than two thirds (68%) two years after the vaccination programme. In the total population the reduction was 43%.

CONCLUSION

Vaccination effectiveness has been high in Catalonia, with a dramatic reduction in disease incidence in the vaccinated cohort accompanied by a relevant reduction in the overall population. Given that vaccination coverage was only 54.6%, it may be supposed that this vaccination effectiveness is attributable, in part, to the herd immunity conferred by the vaccine.

Development of natural immunity to Neisseria meningitidis

Although meningococcal disease is rare in industrialized nations, Neisseria meningitidis holds a prominent position amongst pediatric infections because of the dramatic clinical presentation of the disease, high mortality, epidemic potential and the recent disappearance of many other important infectious diseases in developed countries through improvements in public health and vaccination. The precise nature of natural immunity to meningococci remains unknown, although a complex interaction between the organism and nasopharyngeal mucosal barrier, innate immune mechanisms and acquired immunity is involved. Study of the mechanisms of natural immunity may provide the key to development of vaccines that can reduce the burden of disease in early childhood.

Seroconversion and duration of immunity after vaccination against group C meningococcal infection in young children

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.

Safety and immunogenicity of a new Neisseria meningitidis serogroup C-tetanus toxoid conjugate vaccine in healthy adults

We evaluated the safety and immunogenicity of a single dose of a new serogroup C O-deacetylated meningococcal polysaccharide-tetanus toxoid conjugate vaccine in 30 healthy adult volunteers. The vaccine was well tolerated with no serious adverse events and minimal local reactions and systemic symptoms. All subjects developed a fourfold or greater increase in serum bactericidal antibody (SBA) to serogroup C meningococcus. SBA geometric mean titre increased from 11 to 3649 (p<0.001). Serogroup C-specific IgG levels increased postvaccination from 0.65 to 17.02 microg/ml (p<0.001). Bactericidal titres pre- and postimmunisation showed significant correlation with serogroup C-specific IgG (r(2)=0.693). Antibody levels fell by 6 months postvaccination, however, meningococcal C IgG avidity increased indicating the successful induction of a T-cell-dependent antibody response.

CONCLUSION

meningococcal C-tetanus toxoid conjugate vaccine is immunogenic and well tolerated in healthy adults.

Genetic basis for biosynthesis, structure, and function of meningococcal lipooligosaccharide (endotoxin)

The exclusive human pathogen Neisseria meningitidis expresses lipooligosaccharide (LOS), an endotoxin that is structurally distinct from the lipopolysaccharides (LPS) of enteric Gram-negative bacilli. Differences that appear to be biologically important occur in the composition and attachment of acyl chains to lipid A, phosphorylation patterns of lipid A, and the incorporation and phosphorylation of sugar residues in the LOS inner core. Further, unlike most enteric LPS, only two to five sugar residues are attached to the meningococcal LOS inner core, and there are no multiple repeating units of O-antigens. In contrast to Escherichia coli, where the LPS biosynthesis genes are organized as large operons, the meningococcal LOS biosynthesis genes are organized into small operons or are located individually in the chromosome. Some of these genetic loci in meningococci and gonococci display polymorphisms caused by localized chromosomal rearrangements. One mechanism of antigenic variation of meningococci LOS is the regulation of glycosyltransferase activity by slipped strand mispairing of homopolymeric tracts within the 5' end of the genes encoding these enzymes, resulting in the addition of different sugar residues to the LOS molecule. Meningococcal LOS is a critical virulence factor in N. meningitidis infections and is involved in many aspects of pathogenesis, including the colonization of the human nasopharynx, survival after bloodstream invasion, and the inflammation associated with the morbidity and mortality of meningococcemia and meningitis. Meningococcal LOS, which is a component of serogroup B meningococcal vaccines currently in clinical trials, has been proposed as a candidate for a new generation of meningococcal vaccines. The rapidly expanding knowledge of the genetic basis for biosynthesis, structure, and regulation of meningococcal LOS provides insights into unique endotoxin structures and the precise role of LOS in the pathogenesis of meningococcal disease.

[Meningococcal C disease epidemic in Galicia 1996: the decision making process]

In this article we describe the decision making process used to choose the best alternative for bringing under control an epidemic of meningococcal C disease, which occurred in Galicia in 1996. In the decision making process, we used a methodology which consisted on the identification and definition of a problem, in order to identify alternative solutions and to select one, and finally implement and evaluate it. The health problem was detected studying the data obtained from a survey conducted following an outbreak of meningococcal C disease in february 1995 and from the active epidemiological surveillance system created thereafter. Because this was a new, complex and severe problem, with far-reaching social consequences, critical for our organization, and with long-term implications, and because it was considered important to take the decision as objectively as possible and to clearly explain it, the methodology chosen to solve the problem was a non-programmed, multicriteria making decision process, carried out by a working group using a criterion weighting approach. This working group was created within the General Directorate of Public Health, composed of specialist and of people responsible for the different areas involved. The working group put into practice the different steps of the methodology. The assessment criteria and their respective weights were: effect (efficacy measured by the number of cases we could have prevented if the alternatives were applied in the previous season) 40%; cost (in millions of pesetas) 15%; acceptability (acceptance of and response to each strategy from different groups: general population, health care professionals, other Administrations with competency in Public Health) 30%; and coherence (adherence to the currently accepted strategies for disease control in other countries)15%. When these criteria were applied to the ten alternatives considered, a score was obtained for each one of them. The highest scoring alternative corresponded to the massive vaccination of the total population of Galicia between 18 months and 19 years of age.

Age-related immunogenicity of meningococcal polysaccharide vaccine in aboriginal children and adolescents living in a Northern Manitoba reserve community

OBJECTIVE

To determine the total and functional serogroup C antibody response to a quadrivalent meningococcal polysaccharide vaccine in a group of aboriginal infants, children and adolescents. A secondary objective was to determine their prevalence of meningococcal carriage.

DESIGN

Open prospective, before and after intervention study.

SUBJECTS

Aboriginal children ages 0.5 to 19.9 years, living in a single Northern community and eligible for a public health immunization campaign conducted in all Manitoba native reserve communities to control a meningococcal serogroup C, electrophoretic type (ET) 15 outbreak. No outbreak cases had occurred in the community at the time of the study.

METHODS

Total serogroup C capsular polysaccharide antibody (CPA) and functional bactericidal antibody (BA) responses were measured by enzyme-linked immunosorbent assay and bactericidal assay, respectively.

RESULTS

Neisseria meningitidis was recovered from the oropharynx of 13 (5.2%) of 249 aboriginal children including 4 (1.6%) serogroup C isolates, all with the designation C:2a:P1.2,5 ET15. Paired sera from 152 children were available for assay. For CPA the geometric mean concentrations and proportions with > or =2 microg/ml before and after immunization were 0.69, 18% and 12.3, 96%, respectively. A significant increase in serum CPA was achieved by children of all ages, with the greatest response occurring after age 11 years. Among infants < lyear old 89% achieved concentrations of > or =2 microg/ml. For BA the pre- and post-vaccine geometric mean titers were 1.02 and 45.9. The response was significantly associated with age. BA titers > or =1:8 were present, before and after immunization, respectively, in 0 and 0% of infants <1 year old, 0 and 20% of 1- to 1.4-year-olds, 0 and 50% of 1.5- to 1.9-year-olds and 1 and 100% of > or =2-year-olds.

CONCLUSION

The age-related total and functional group C meningococcal antibody response after quadrivalent polysaccharide vaccine among aboriginals is similar to that reported for Caucasian children. After age 2 all children made excellent CPA and BA responses. In the younger age groups the BA response was blunted but 82 to 95% achieved CPA titers of > or =2 microg/ml.

Age-dependent Neisseria meningitidis serogroup C class-specific antibody concentrations and bactericidal titers in sera from young children from Montana immunized with a licensed polysaccharide vaccine

Neisseria meningitidis serogroup C bactericidal titers and class-specific enzyme-linked immunosorbent assay (ELISA) antibody concentrations were measured in sera from 173 children (1 to 5 years old) before and 6 weeks and 7 months following vaccination with a quadrivalent (A/C/Y/W-135) polysaccharide vaccine. The immune responses of the children were compared with those of 40 adults 6 weeks postvaccination. Both bactericidal titers and ELISA antibody concentrations were significantly higher in the adults than in the children (P < 0.05). In addition, the ratio of immunoglobulin G (IgG) to IgM was higher in the children than in the adults. With an ELISA total antibody concentration of >/=2 microg/ml used as a measure of seroconversion, >/=84% of the individuals from each age group responded to the serogroup C polysaccharide. However, with a >/=4-fold-increase in bactericidal titer used, only 18% of 1-year-olds, 32% of 2-year-olds, and 50 to 60% of 3-, 4-, and 5-year-olds seroconverted. The ELISA results suggest that >50% of all children retained >/=2 microg of total antibody per ml at 7 months postimmunization. However, the bactericidal titers suggest that <10% of children <4 years old retained a >/=4-fold increase at 7 months following vaccination. Of particular note, 59 of 79 sera (75%) from the 1- and 2-year-olds had high ELISA antibody concentrations (2 to 20 microg/ml) with no associated bactericidal titer (<1:8). Discordant results between bactericidal titers and ELISA antibody concentrations were not explained by the presence of IgA blocking antibody or relative levels of IgG and IgM. The bactericidal results show age-dependent differences in the production and retention of antibody in young children immunized with serogroup C polysaccharide; these differences are not evident with the ELISA data.

[Meningococcal disease: epidemiology and control of secondary cases]

Epidemiological features of meningococcal disease described as from the second half of the 80's inclusive, have motivated a revision of current guidelines for sporadic disease and outbreak control. The increase of disease among teenagers and linked cases involving schools are the two most significant aspects that have prompted the revision of control measures. Vaccination routines and advice for the disease management of clusters are also relevant features recently revised. This present paper describes the management and some epidemiological features of secondary cases.

Standardization and a multilaboratory comparison of Neisseria meningitidis serogroup A and C serum bactericidal assays. The Multilaboratory Study Group

A standardized serum bactericidal assay (SBA) is required to evaluate the functional activity of antibody produced in response to Neisseria meningitidis serogroup A and C vaccines. We evaluated assay parameters (assay buffer, target strains, growth of target cells, target cell number, complement source and concentration, and methods for growth of surviving bacteria) which may affect the reproducibility of SBA titers. The various assay parameters and specificity of anticapsular antibody to five serogroup A strains (A1, ATCC 13077, F8238, F9205, and F7485) and four serogroup C strains (C11, G7880, G8050, and 1002-90) were evaluated with Centers for Disease Control and Prevention meningococcal quality control sera. The critical assay parameters for the reproducible measurement of SBA titers were found to include the target strain, assay incubation time, and complement. The resulting standardized SBA was used by 10 laboratories to measure functional anticapsular antibody against serogroup A strains F8238 and serogroup C strain C11. In the multilaboratory study, SBA titers were measured in duplicate for 14 pairs of sera (seven adults and seven children) before and after immunization with a quadrivalent polysaccharide (A, C, Y, and W-135) vaccine. The standardized SBA was reliable in all laboratories regardless of experience in performing SBAs. For most sera, intralaboratory reproducibility was +/- 1 dilution; interlaboratory reproducibility was +/- 2 dilutions. The correlation between median titers (interlaboratory) and enzyme-linked immunosorbent assay total antibody concentrations was high for both serogroup A (r = 0.86; P < 0.001; slope = 0.5) and serogroup C (n = 0.86; P < 0.001; slope = 0.7). The specified assay, which includes the critical parameters of target strain, incubation time, and complement source, will facilitate interlaboratory comparisons of the functional antibody produced in response to current or developing serogroup A and C meningococcal vaccines.

Meningococcal disease in Los Angeles County, California, and among men in the county jails

BACKGROUND

From January through March 1993, there were 54 cases of meningococcal disease in Los Angeles County, California, of which 9 occurred among men incarcerated in the county's jail system, which was 40 percent above capacity at the time. Several of the 45 patients from the community had had contact with men recently released from a county jail.

METHODS

We interviewed patients from the community (n=42) and neighborhood controls matched with the patients for age, race, and ethnic group (n=84) about potential exposures. We collected and cultured pharyngeal swabs for Neisseria meningitidis from men entering the central jail (n=162), men leaving the central jail (n=379), members of the jail staff (n=121), and patients at a community health center (n=214). Meningococcal isolates were identified by serotyping and multilocus enzyme electrophoresis.

RESULTS

The presence of community-acquired meningococcal disease was strongly associated with exposure to a person who had been in or worked at one of the county jails (multivariate matched odds ratio, 18.5; 95 percent confidence interval, 3.8 to 90.8; P<0.001). Pharyngeal carriage of meningococcus was significantly more frequent among men released from jail (19 percent) or entering jail (17 percent) than among workers at the jails (3 percent) or community residents seen at the clinic (1 percent). Among men entering jail, those who had previously been incarcerated were more often carriers than those who had not (21 percent vs. 7 percent, P=0.03). Of the isolates from nine community residents with serogroup C meningococcal disease, eight were the same strain as that isolated from the eight inmates with serogroup C disease.

CONCLUSIONS

In this outbreak of meningococcal disease in Los Angeles County, nearly half of community residents with the disease had contact with persons who had been in a county jail. The high rates of carriage among recidivists and released inmates suggests that the men became meningococcal carriers while in jail.