Meningococcal infections in Bolton, 1971-74

Meningitis vaccines in children: what have we achieved and where next?

PURPOSE OF REVIEW

This review highlights the recent impacts of vaccines against the major bacterial causes of meningitis in children, and the challenges for further prevention of bacterial meningitis, with a focus on Streptococcus pneumoniae, Neisseria meningitidis and group B Streptococcus.

RECENT FINDINGS

Conjugate vaccines against S. pneumoniae and N. meningitidis have resulted in dramatic reductions in bacterial meningitis globally where they have been used. Recent licensure and use of capsular group B meningococcal protein vaccines have further reduced meningococcal meningitis in infants, young children and adolescents for countries with endemic disease and during outbreaks.

SUMMARY

Existing vaccines to prevent bacterial meningitis in children should be utilized in countries with significant numbers of cases of pneumococcal and/or meningococcal meningitis. Vaccines, which are able to protect against more than 13 serotypes of S. pneumoniae are in clinical trials and should be able to further reduce pneumococcal meningitis cases. Cost effective meningococcal vaccines against non-A capsular groups are needed for low-resource countries. There remains an urgent need for a vaccine against group B Streptococcus, which is a major cause of neonatal meningitis globally and for which no vaccine currently exists.

Persistence of W135 Neisseria meningitidis carriage in returning Hajj pilgrims: risk for early and late transmission to household contacts

After an outbreak of meningococcal disease caused by Neisseria meningitidis W135, associated with the Hajj pilgrimage in 2001, 15% of returning vaccinated pilgrims carried a single W135 clone, and 55% were still carriers 6 months later. Transmission to 8% of their unvaccinated household contacts occurred within the first few weeks, but no late transmission took place. Public health interventions are needed to protect household contacts.

Maternal cigarette smoking and invasive meningococcal disease: a cohort study among young children in metropolitan Atlanta, 1989-1996

OBJECTIVES

This study assessed the association between maternal cigarette smoking during pregnancy and the risk of invasive meningococcal disease during early childhood.

METHODS

Using a retrospective cohort study design, cases from an active surveillance project monitoring all invasive meningococcal disease in the metropolitan Atlanta area from 1989 to 1995 were merged with linked birth and death certificate data files. Children who had not died or acquired meningococcal disease were assumed to be alive and free of the illness. The Cox proportional hazards analysis was used to assess the independent association between maternal smoking and meningococcal disease.

RESULTS

The crude rate of meningococcal disease was 5 times higher for children whose mothers smoked during pregnancy than for children whose mothers did not smoke (0.05% vs 0.01%). Multivariate analysis revealed that maternal smoking (risk ratio [RR] = 2.9; 95% confidence interval [CI] = 1.5, 5.7) and a mother's having fewer than 12 years of education (RR = 2.1; 95% CI = 1.0, 4.2) were independently associated with invasive meningococcal disease.

CONCLUSIONS

Maternal smoking, a likely surrogate for tobacco smoke exposure following delivery, appears to be a modifiable risk factor for sporadic meningococcal disease in young children.

An outbreak of serogroup B:15:P1.16 meningococcal disease, Frederiksborg County, Denmark, 1987-9

Epidemiological features of an outbreak of group B:15:P1.16 meningococcal disease (MD) in Frederiksborg county, Denmark, 1987-9, were investigated. The study comprised 149 cases notified during the outbreak and the two preceding years; 115 were confirmed by the isolation of Neisseria meningitidis. In 1989 the incidence had increased to 14.1 per 100,000 population. Among group B strains, B:15:P1.16 accounted for 80% (77/97). The overall mortality rate was 10% (15/149). Regarding cases due to group B:15:P1.16 strains a significant time-space clustering, which exclusively occurred within the 10-19 years age group, was demonstrated. The link between cases within clusters was indirect or unknown, except for ten patients with contact to one particular school. The prophylactic measures used included administration of rifampicin to household contacts. During the outbreak the proportion of secondary cases was high (6-15%). All secondary cases occurred outside the household indicating that the household had been protected.

Meningococcal carriage in close contacts of cases

Between 1 October 1986 and 31 March 1987, 55 cases of meningococcal disease were identified in the South-West of England, an attack rate of 1.54 per 100,000 during the study period. Antibiotics used in the treatment of the disease successfully eliminated nasopharyngeal carriage of meningococci in 13 out of 14 cases without use of rifampicin. The overall meningococcal carriage rate in 384 close contacts was 18.2% and the carriage rate of strains indistinguishable from the associated case strain was 11.1%. The carriage rate of indistinguishable strains in household contacts (16.0%) was higher than the carriage rate in contacts living at other addresses (7.0%, P less than 0.05). A 2-day course of rifampicin successfully eradicated meningococci from 46 (98%) of 47 colonized contacts. In one third of cases groupable meningococci were isolated from at least one household contact; 92% of these isolates were of the same serogroup as the associated case strain. When a meningococcus is not isolated from a deep site in a clinical case of meningococcal disease, culture of serogroup A or C strains from nasopharyngeal swabs of the case or of household contacts is an indication that the close contact group should be offered meningococcal A + C vaccine in addition to chemoprophylaxis. The failure in this and other studies to isolate meningococci from any household contact in the majority of cases may be due either to the relative insensitivity of nasopharyngeal swabbing in detecting meningococcal carriage or to the acquisition of meningococci by most index cases from sources outside the household.

Endotoxin release from neisseria meningitidis. Relationship between key bacterial characteristics and meningococcal disease

A method was established in order to measure total and filtrable (CF) endotoxin in cultures of Neisseria meningitidis strains. The Limulus lysate (LAL) test gave results which paralleled those of the standard rabbit pyrogen test and of gas chromatography (GLC), concerning detection of different CF endotoxin levels. Meningococci varied in their ability to produce CF endotoxin. Cultures of similar bacterial densities, whether with a high (E+) or a low (E-) release of endotoxin in CF, had both high yields of endotoxin in sonicated culture suspensions determined by the LAL test. GLC demonstrated only small differences in total LPS contents between E+ and E- strains. This suggests that strains with similar cell wall endotoxin contents may vary in CF endotoxin. Electron microscopy revealed that E+ strains presented a high number of free, outer cell wall fragments (blebs, tubuli, membranes and aggregates of such structures) in surroundings. Few such free, small structures were found around E- strains. The amount of CF endotoxin of E+ strains was in part a function of the number of colony forming units (CFU/ml), and generally followed the growth curve. Because of its moment of appearance, and also based on electron microscopy findings, CF endotoxin appeared mainly to be released from living bacteria. The CF level of endotoxin was low or not detected at all in cultures of E- strains although their cultures reached higher mean CFU-levels than the niveaus required for the detection of CF endotoxin in the E+ strains. The E+ property was strain dependent. Meningococci isolated from CSF or blood had a significantly higher proportion of E+ strains (88.2%) and a higher CF endotoxin titre (greater than or equal to 10(3); 34.5%), than isolates from carriers (32.3% and 10.8%, respectively) (p less than 0.001 and p less than 0.001, respectively). A high mean CFU/ml in cultures seemed to be more often associated with isolates from patients than from carriers, more often with the presence than abscence of capsular polysaccharide (p less than 0.05), and more often with the presence than absence of the E+ property (p = 0.002). E+ strains were mostly serogroupable (i.e. encapsulated), regardless of source of the isolate (99% case and 80% carrier isolates). In contrast, serogroupable bacteria were not necessarily E+ when isolated from carriers (54.8%). The serogroup most apt to cause disease tended to have the highest proportion of E+ strains and the highest level of CF endotoxin.(ABSTRACT TRUNCATED AT 400 WORDS)

Epidemiology of meningococcal infections in the Federal Republic of Germany, 1966-1984

In the Federal Republic of Germany, the morbidity curve of meningococcal infections from 1966-1984 exhibited two maxima in 1970 and 1979 representing morbidity values of 2.9 and 2.3 per 100,000 of the population, and a small peak in 1974. The average morbidity of the 19 years was 2.1/10(5), the lowest morbidity 1.3/10(5) (1983/84). Meningitis occurred on an epidemic scale in 1970 in Bremen, in 1971 in Schleswig-Holstein and 1971-1977 in the Saarland. Most cases were notified during the first four four-week periods of the year, but in two years (1967, 1969), the late-summer peak exceeded the peak of winter/spring. 17.3% of the cases occurred in infants, 51.7% in the first five years of life. Morbidity was highest during the second quarter of the first year. The sex ratio (m:f) of the infections was 1.6:1, but in the aged, morbidity was about the same in both sexes (0.9:1). The case-fatality ratio varied between 7.1% (1977) and 12.1% (1971, 1982) and averaged at 9.7%. It was highest in the aged (37.1%) and second-highest in infants (18.7%). Differences of lethality due to sex could not be demonstrated. Of 1.685 meningococcal strains isolated from CSF and/or blood, 7.3% were of serogroup A, 74.4% of group B, 15% of group C, 1.5% of group Y and 1.1% of group W135. The proportion of group B infections was highest in infants, of group A infections in children (5-10 years), of group C infections in older children and adolescents (10-20 years). The sensitivity of N. meningitidis to sulfadiazine varied with serogroup and year of isolation. Since 1977, practically all group A strains, but only 13% of group B and 9% of group C strains proved to be resistant. Practically all strains were fully sensitive to rifampicin and minocycline; results of trials with spiramycin were not in support of the use of this compound as a chemoprophylactic agent.

An outbreak of meningococcal disease in Stonehouse: planning and execution of a large-scale survey

In November 1986 a large-scale survey was undertaken in the Gloucestershire town of Stonehouse during an outbreak of meningococcal disease due to group B type 15 subtype P1.16 sulphonamide-resistant strains. There were 15 cases in Stonehouse residents during the 4 years from April 1983, an annual attack rate of 56.5 per 100,000. Four secondary cases occurred despite rifampicin prophylaxis. The objectives of this community survey were to investigate patterns of meningococcal carriage, transmission and immunity and to determine the proportion of non-secretors of blood group antigens in the Stonehouse population and amongst meningococcal carriers. A total of 6237 subjects participated including 75% of the 6635 Stonehouse residents. Over 97% of the participants provided all three of the requested specimens-nasopharyngeal swabs, saliva and blood samples. The co-operation between the many organizations involved in the detailed preliminary planning was instrumental in the success of the survey; in particular the value of effective collaboration between Departments of Community Medicine and Microbiology and of the Public Health Laboratory Service network of laboratories in undertaking investigations of this size and type was clearly demonstrated.

Genetic relationships and clonal population structure of serotype 2 strains of Neisseria meningitidis

Two hundred and thirty-four strains of Neisseria meningitidis, including 94 serotype 2a, 111 serotype 2b, and 19 serotype 2c isolates, together with 10 isolates that were serotyped as 2 with polyvalent antiserum but did not react with monoclonal antibodies, were characterized by the electrophoretic mobilities of 15 metabolic enzymes. Of these enzymes, 14 were polymorphic, and 56 distinctive combinations of alleles at the enzyme loci (electrophoretic types) were identified, among which the mean genetic diversity per locus was 0.413, or about 75% of that recorded for the species N. meningitidis as a whole. Mean genetic diversity among electrophoretic types of the same serotype (2a, 2b, or 2c) was, however, on average, less than half the total species diversity, and no multilocus genotypes were shared between isolates of the different serotypes, which belong to distinctive clonal lineages. Recent temporal changes in the frequencies of recovery of pathogenic strains of serotypes 2a and 2b in South Africa and North America resulted from clone replacement in these populations rather than evolutionary modification of the serotype protein of the initially dominant clones.

Group B meningococcal infection in children during an epidemic in Cape Town, South Africa

One hundred and thirteen children with meningococcal infection were studied during an epidemic caused by N. meningitidis group B. Fifteen per cent presented with only meningeal symptoms, the remainder showed signs of septicaemia or combined septicaemia and meningitis. Sixteen per cent of the children were in shock and 18% required admission to the Intensive Care Unit (ICU). The mortality was 4.4%. More than half the children were younger than 2 years old. There was no statistical association between the age or nutritional state of the children and any of our measures of severity. A short history of symptoms was more common in children who presented with septicaemia and severe illness, who needed admission to the ICU, or who died. Diagnosis was confirmed by routine bacteriological methods and counter-immuno-electrophoresis (CIE) in 104 children. Eighty-six per cent of the isolates were group B type 2. A history of recent antibiotic treatment was associated with fewer positive cultures, but detection of meningococcal antigen by CIE was not affected by this. CIE antigen detection was not reliable because of the high incidence of false-negative results.

An outbreak of meningococcal disease in Gloucestershire

Between October, 1981, and March, 1986, there were 65 cases of meningococcal infection, about five times the expected number, in Gloucester Health District. The cases, mainly in teenagers and young adults, were clustered in the Stroud district and in the southern part of Gloucester City, and most were caused by a sulphonamide-resistant group B type 15 meningococcus. 2 patients died. Only 57% of meningitis cases were formally notified. 7 (11%) patients had septicaemia without meningitis, not a notifiable disease. All meningococcal disease should be made notifiable and meningococci should be serotyped routinely so that the epidemiology of the disease can be monitored before the introduction of suitable vaccines.

Bacterial meningitis in Nottingham

Records of 171 cases of bacterial meningitis admitted to Nottingham hospitals from January 1974 to June 1980 were reviewed. The distribution of organisms producing meningitis and the factors influencing mortality in different age groups were assessed. Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae accounted for 69% of all proven cases. The overall mortality was 26% being lowest in patients with meningococcal meningitis (0%) and highest in those with pneumococcal meningitis (53%). The following factors were associated with a poor prognosis: age more than 40 years, or less than 2 months; state of consciousness on admission; high CSF protein concentration; and a positive blood culture. There was no evidence that antibiotic therapy prior to admission affected prognosis. Although many laboratory findings were altered by prior treatment with antibiotics, this did not prevent the establishment of a diagnosis in the individual patient.

A new serogroup (L) of Neisseria meningitidis

A strain of neisseria meningitidis (LCDC 78189) isolated from the mother of a 3-year-old male with meningococcal meningitis was found to be antigenically distinct from the known serogroups A, B, C, D, H, I, K, X, Y, Z, 29E, and W135; it was designated serogroup L. Anti-78189 serum specifically agglutinated the homologous strain and three other strains which were isolated from the father and two other contacts of the child. Only those strains isolated from the contacts produced immunoprecipitates with the anti-78189 serum by the antiserum-agar method. A structurally unique capsular polysaccharide which was obtained from strain 78189 in a highly purified state was demonstrated to be the antigen responsible for the serological properties of the strain. The polysaccharide formed a precipitin band with the anti-78189 serum but not with the meningococcal grouping sera, and it was also able to absorb both the agglutinating and precipitating activity from the anti-78189 serum.

Longitudinal study of asymptomatic meningococcal carriage in two Belgian populations of schoolchildren

In Brussels, a 15-month longitudinal survey was conducted in two primary schools, from March 1975 to May 1976, in order to analyse the dynamic of asymptomatic meningococcal carriage, during an epidemic mainly caused by serogroup B, serotype 2 Neisseria meningitidis. In the first school, which is situated in a suburban area with upper-middle socio-economic status of residents, a mean prevalence of carriers of 10 per cent, an acquisition rate of eight per 1000 months, and a mean duration of carriage of 12.4 months were observed among 158 schoolchildren aged six to 11 years old. In the second school, which is situated in a densely populated area with low socio-economic status of residents, a mean prevalence of carriers of 33 per cent, an acquisition rate of 28 per 1000 months, and a mean duration of carriage of 11.7 months were observed among 203 schoolchildren aged three to 14 years old. For both schools, the median duration of carriage was estimated at 9.4 months. The differences of prevalence and incidence of acquisition between the two schools cannot be explained by age, sex or ethnic factors and are probably related to socio familial variables. The theoretical relationship between prevalence, incidence and duration of meningococcal carriage was for the first time demonstrated in this study. The results also suggest that populations of low socio-economic status and living in densely populated areas constitute a target population for meningococcal disease prevention.

Prevalence of Neisseria meningitidis in family members of patients with meningococcal infection

The aim of the study was first, to determine the prevalence of Neisseria meningitidis among the family members living with patients suffering from meningococcal infections, and second, to ascertain the distribution among these family members of strains epidemiologically related to those isolated from patients. Forty-two family groups were studied and 135 nasopharyngeal samples were taken from family members living with patients. Twenty family groups were found to contain meningococcal carriers, and of these 20, 13 contained a carrier of the strain that caused the infection (65%). Among the family members who were carriers, the mother and father most frequently yielded the strain which caused the illness. The serotypes most frequently encountered both in patients and carriers were 2 and 8, as well as nontypable strains. The polyacrylamide gel electrophoretic patterns (PAGE) most frequently found were II and IV. A notable feature of the study is the high resistance of the strains to sulphadiazine, since more than 90% of the strains found in patients and more than 75% of those from carriers possessed a minimum inhibitory concentration greater than or equal to 10 micrograms/ml.

Outcome of meningococcal group B meningitis

Sixty children who survived meningitis during the outbreak of meningococcal group B infection in Bolton 1971-74 were assessed between 5 and 9 years later. Each case, together with a matched control, has been examined clinically and subjected to a number of psychological tests and to routine audiology. The results, unlike those from other series, did not demonstrate any incoordination, ataxia, or other physical abnormality, nor was there any statistically significant impairment on psychological testing. The incidence of sensorineural deafness (5%), although marginally lower, was comparable with the best of other series. When compared with the incidence in controls (3%) it is not statistically significant. A 'mattress test', suggestive of vestibular damage, was positive in those with more severe degrees of sensorineural deafness. The high mortality in the Bolton series (17%) has been reconsidered and it is concluded that unless a potent meningococcus type B vaccine is developed, mortality would still be high in a similar outbreak today.

Strains of Neisseria meningitidis isolated from patients and their close contacts

Neisseria meningitidis isolates from contacts, mostly family members, of 27 unrelated meningococcal disease patients were examined by serogrouping, serotyping, and a recently described sodium dodecyl sulfate-polyacrylamide gel electrophoresis typing procedure. Most of the isolates were serogroup B or C. Serotyping and sodium dodecyl sulfate-polyacrylamide gel electrophoresis typing now provide a more precise means than serogrouping for determining the epidemiological relationships among patient isolates and those of related carriers. In 70% of the families studied, all contact carriers had strains indistinguishable from that of the patient. In the other 30%, more than one meningococcal strain was recovered from the family. Sixty percent of the carrier isolates were recovered from adults. It was found that, among household contacts, the mother was most likely and the father was least likely to carry the disease isolate. Nonhousehold contacts were least likely to carry the disease isolate.

Meningococcal disease in Scandinavia

Scandinavia (Denmark, Finland, Iceland, Norway, and Sweden) comprises with mutual borders and 22.3 million inhabitants an area where the socioeconomic and cultural conditions are similar. Epidemic diseases, such as meningococcal infection, might therefore be expected to be uniformly distributed. An epidemiological study in the 10-year period 1970-9 shows, however, remarkable differences in the incidence, age, and serogroup and type distribution, as well as in the general dynamics of the disease. Three epidemics, two caused by different serotypes of group B (Norway and Iceland) and one by group A (Finland) occurred within the observation period. The annual overall incidence was generally around 3/100 000 but increased from fivefold (Finland) to eightfold (northern Norway) during epidemics. The epidemic strains caused infection in over 3000 patients and the loss of at least 250 lives. The overall case fatality rate was 8.6% (range 4.1-13.7%). Men were more susceptible and had a worse prognosis than women of the same age group. The group A epidemic in Finland was influenced by a large vaccination campaign, but this possibility was not feasible in the two other epidemics.

An epidemic of meningococcal infection at Zaria, Northern Nigeria. 3. Meningococcal carriage

Meningococcal carriage was studied in household contacts of patients with group A meningococcal disease and in controls. The carriage rate of group A meningococci among 1,098 household contacts was low (3.8%) and only slightly higher than the carriage rate found among 416 controls (2.6%). However, higher carrier rates were found among those in close contact with a patient. Carriage was found most frequently among children and young adults and was commoner in adult females than in adult males. Sulphonamides had no effect on carriage and all 60 strains tested in vitro were resistant to sodium sulphadiazine at a concentration of 10 micrograms/ml.

Serotypes of group B meningococci

Strains of group B meningococci isolated from cases of sporadic infection, epidemic infection, and from patients unassociated with clinical meningococcal infection have been examined by a serological typing technique. The majority of group B meningococci from clinical infections in the UK have serotype 2 antigen. Such strains were relatively uncommon among carriers who had no association with meningococcal disease.