Emergence of endemic serogroup W135 meningococcal disease associated with a high mortality rate in South Africa.

BACKGROUND: In the African meningitis belt, Neisseria meningitidis serogroup W135 has emerged as a cause of epidemic disease. The establishment of W135 as the predominant cause of endemic disease has not been described. METHODS: We conducted national laboratory-based surveillance for invasive meningococcal disease during 2000-2005. The system was enhanced in 2003 to include clinical data collection of cases from sentinel sites. Isolates were characterized by pulsed-field gel electrophoresis and multilocus sequence typing. RESULTS: A total of 2135 cases of invasive meningococcal disease were reported, of which 1113 (52%) occurred in Gauteng Province, South Africa. In this province, rates of disease increased from 0.8 cases per 100,000 persons in 2000 to 4.0 cases per 100,000 persons in 2005; the percentage due to serogroup W135 increased from 7% (4 of 54 cases) to 75% (221 of 295 cases). The median age of patients infected with serogroup W135 was 5 years (interquartile range, 2-23 years), compared with 21 years (range, 8-26 years) for those infected with serogroup A (P<.001). The incidence of W135 disease increased in all age groups. Rates were highest among infants (age, <1 year), increasing from 5.1 cases per 100,000 persons in 2003 to 21.5 cases per 100,000 persons in 2005. Overall case-fatality rates doubled, from 11% in 2003 to 22% in 2005. Serogroup W135 was more likely to cause meningococcemia than was serogroup A (82 [28%] of 297 cases vs. 11 [8%] of 141 cases; odds ratio, 8.9, 95% confidence interval, 2.2-36.3). A total of 285 (95%) of 301 serogroup W135 isolates were identified as 1 clone by pulsed-field gel electrophoresis; 7 representative strains belonged to the ST-11/ET-37 complex. CONCLUSIONS: Serogroup W135 has become endemic in Gauteng, South Africa, causing disease of greater severity than did the previous predominant serogroup A strain.     

Meningococcal meningitis outbreak control strategies.

Meningococcal meningitis has been occurring worldwide in both endemic and epidemic forms. Serogroup A accounts for majority of cases of epidemic as well as endemic Meningococcal meningitis in developing nations, whereas group C and group B causes epidemic and endemic meningococcal meningitis in developed countries. Person to person spread of N. meningitides generally occurs through inhalation of droplets of infected nasopharyngeal secretions by direct or indirect oral contact. Incubation period varies from 2 to 10 days. N. meningitides typically causes acute infective illness characterized by sequential development of upper respiratory tract infection, meningococcemia, meningitis and focal neurological deficit. Over 90 per cent cases of adult meningococcal infections have cerebrospinal meningitis, whereas in children prevalence of meningitis is much lower (50 per cent). Acute meningitis manifests with fever, severe headache, vomiting and neck stiffness. Presentations may be non-specific in infants, elderly and in patients with fulminant meningococcemia. Diagnosis is confirmed with cerebrospinal fluid analysis. Overall mortality due to meningitis is usually around 10 per cent. In meningococcal septicemia, the case fatality rate may exceed 50 per cent. Preventive strategies include vaccination, chemoprophylaxis and early detection and treatment. Mass vaccination campaign, if appropriately carried out, has been documented to halt an epidemic of meningococcal disease due to serogroup A or C. In the present review we have discussed the available evidence with regards to prevention at primary, secondary and tertiary level. Public health approach to an outbreak of meningococcal meningitis in a community or an organization is also outlined.     

Epidemiological pattern of meningococcal disease in Valencia, Spain. Impact of a mass immunization campaign with meningococcal C polysaccharide vaccine

The objective of this study was to define the epidemiological pattern of meningococcal disease in the autonomous region of Valencia, Spain, and the impact of a mass immunization campaign against serogroup C meningococcus. Data were obtained from a prospective surveillance program for invasive bacterial diseases in children < 15 y of age that began in the Valencia region on 1 December, 1995. During the period 1996-98, 213 cases of meningococcal disease were detected, representing an annual incidence of 11.3/100,000 children < 15 y. Serogroup C accounted for 31% and 38.5% of cases in 1996 and 1997, respectively (annual incidences of 2.9 and 5.4 cases/100,000 children < 15 y). An immunization campaign with the meningococcal C polysaccharide vaccine, which included all persons between 18 months and 19 y of age, began in late 1997 (vaccination coverage of 86%). In 1998, the annual incidence of meningococcal C disease fell to 1.4 cases per 100,000 children < 15 y of age. These results mirror the increase in the reported incidence of serogroup C meningococcal disease in Spain in the 1990s, a trend that was reversed after the introduction of the mass vaccination campaign. Meningococcal polysaccharide vaccine seems to be an effective public health tool for the management of this serious communicable disease.     

Meningococcal disease in urban south western Sydney, 1990–1994

Background: There has been a sustained increase in incidence of meningococcal disease throughout Australia since 1987. In south western Sydney the incidence is higher than the national rate and a cluster of cases occurred in 1991 resulting in a widespread vaccination programme. Aims: To investigate the clinical demographics of patients with meningococcal disease treated in south western Sydney, and to differentiate meningococcal strains to understand better the epidemiology in this urban setting. In addition, to investigate whether delays in diagnosis of meningococcal disease and institution of appropriate treatment were occurring. Methods: Retrospective classification of notified cases as meningitis, septicaemia, meningitis/septicaemia, and other syndromes. Clinical information recorded to establish patterns of disease, delays in diagnosis and appropriate treatment, and outcome. Microbiological classification of organisms isolated by serogroup, serotype and subtype. Results: Meningococcal disease primarily affects young children in winter months in south western Sydney, with a secondary peak of incidence in the 15–20 year old age group. 20.7% presented with meningitis only, 22.4% with septicaemia only, and 53.4% with meningitis/septicaemia. There was a delay in diagnosis and institution of appropriate treatment of more than two hours in 21/58 (36.2%) patients including three of the six who died. No patient had received a parenteral antibiotic prior to coming to hospital - 18.9% had received an oral antibiotic. The use of antibiotics before diagnostic lumbar puncture decreased the number of positive CSF cultures. However, in all but one patient with negative cultures there was other microbiological evidence of meningococcal disease. The mortality rate was highest (30.8%) in patients with septicaemia only, 6.5% in patients with meningitis/septicaemia and 0% in patients with meningitis only. Serogroup C was the predominant organism in all age groups. The predominant serotype was 2b (80% of serogroup C isolates). Subtypes were more variable but P1.2 occurred in 66.7% of serogroup C strains. Conclusions: There is a need for more education in our Health Area to improve the time taken to diagnose and institute appropriate treatment. The predominance of serogroup C is unusual in urban Australia where national data show serogroup B organisms predominate. Meningococci of phenotype C:2b:Pl.2 have continued to cause disease in our Health Area for the past five years. This phenotype is uncommon in other areas of Australia.     

Secondary immunologically-caused myocarditis, pericarditis and exudative pleuritis due to meningococcal meningitis

Myocarditis, pericarditis and pleural effusion as secondary immunological reactions due to meningococcal meningitis are rare. Meningococcal meningitis is itself uncommon, with a morbidity of approximately 1.25 cases per 100,000 inhabitants per year in Germany. Cardial participation could be observed either primary infectious-toxic in the first week or secondary immunologic in the second week after disease onset. In our patient, six days after the onset of meningococcal meningitis (serogroup B) a distinct swelling of the myocardium appeared together with pericardial effusion in the absence of Waterhouse-Friderichsen syndrome. This case is proving difficult to tackle therapeutically due to repeated relapses.     

Incidence, serogroups and case-fatality rate of invasive meningococcal infections in a Swedish region 1975-1989.

In a retrospective study of invasive meningococcal infections in Greater Gothenburg, Sweden, 213 cases of culture-verified meningitis or septicaemia were identified during the 15-year period 1975-1989. The annual incidence was 2.0/100,000. Cases were seen in all age-groups with the highest rates in the 0-4 and 15-19 year-old groups, 9.5 and 6.2/100,000 respectively. 20% of the patients were less than 2 years. 91% of the patients had no known risk factors. In only 10 cases (5%) was contact with another case of meningococcal infection known. The main clinical manifestations were meningitis (57%), septicaemia with no sign of focal infection (25%) and septic shock (17%). The case-fatality rate for all the patients was 6.6% and did not change during the 15-year period. One-third of the patients who presented with septic shock died. The serogroup was known for strains from 192 patients. 51% of the strains belonged to serogroup B, 10% to group A and 23% to group C. In conclusion, the incidence of meningococcal infection was low but the relatively high case-fatality rate warrants a search for effective prophylaxis. About 30% of the cases were potentially preventable by the currently available tetravalent (A, C, Y and W135) polysaccharide vaccine, which is immunogenic in children greater than 2 years. Widespread use of antibiotic prophylaxis to close contacts of known cases would not lower the incidence markedly.     

Antigenic shift and increased incidence of meningococcal disease

BACKGROUND: The incidence of serogroup C and Y meningococcal disease increased in the United States during the 1990s. The cyclical nature of endemic meningococcal disease remains unexplained. The purpose of this study was to investigate the mechanisms associated with the increase in the incidence of meningococcal disease. METHODS: We characterized an increasing incidence of invasive serogroup C and Y meningococcal disease using population-based surveillance from 1992 through 2001. Isolates were characterized by multilocus sequence typing and antigen sequence typing of 3 outer membrane protein (OMP) genes: porA variable regions (VRs) 1 and 2, porB, and fetA VR. RESULTS: For both serogroups, OMP antigenic shifts were associated with increased incidence of meningococcal disease. For serogroup Y, antigenic shift occurred through amino acid substitutions at all 3 OMPs--PorA VR 1 and 2, PorB, and FetA VR. For serogroup C, antigenic shift involved amino acid substitutions at FetA VR and, in some cases, deletion of the porA gene. On the basis of deduced amino acid sequences, the antigenic changes likely occurred by horizontal gene transfer. CONCLUSIONS: Antigenic shifts were associated with increased incidence of serogroup C and serogroup Y meningococcal disease. For serogroup Y, the changes involved all OMP genes that were studied. Increases in the incidence of meningococcal disease may be caused, in part, by antigenic shift.     

Epidemiology of serogroup B invasive meningococcal disease in Ontario, Canada, 2000 to 2010

ABSTRACT: BACKGROUND: Invasive meningococcal disease (IMD) caused by serogroup B is the last major serogroup in Canada to become vaccine-preventable. The anticipated availability of vaccines targeting this serogroup prompted an assessment of the epidemiology of serogroup B disease in Ontario, Canada. METHODS: We retrieved information on confirmed IMD cases reported to Ontario's reportable disease database between January 1, 2000 and December 31, 2010 and probabilistically-linked these cases to Public Health Ontario Laboratory records. Rates were calculated with denominator data obtained from Statistics Canada. We calculated a crude number needed to vaccinate (NNV) using the inverse of the infant (<1 year) age-specific incidence multiplied by expected vaccine efficacies between 70 % and 80 %, and assuming only direct protection (no herd effects). RESULTS: A total of 259 serogroup B IMD cases were identified in Ontario over the 11-year period. Serogroup B was the most common cause of IMD. Incidence ranged from 0.11 to 0.27/100,000/year, and fluctuated over time. Cases ranged in age from 13 days to 101 years; 21.4 % occurred in infants, of which 72.7 % were <6 months. Infants had the highest incidence (3.70/100,000). Case-fatality ratio was 10.7 % overall. If we assume that all infant cases would be preventable by vaccination, we would need to vaccinate between 33,784 and 38,610 infants to prevent one case of disease. CONCLUSIONS: Although rare, the proportion of IMD caused by serogroup B has increased and currently causes most IMD in Ontario, with infants having the highest risk of disease. Although serogroup B meningococcal vaccines are highly anticipated, our findings suggest that decisions regarding publicly funding serogroup B meningococcal vaccines will be difficult and may not be based on disease burden alone.     

Impact of the meningococcal C conjugate vaccine in Spain: an epidemiological and microbiological decision

The new meningococcal C conjugate vaccine became available in Spain and was included in the infant vaccination schedule in 2000. A catch-up campaign was carried out in children under six years of age. As a consequence, the incidence of meningococcal disease caused by serogroup C has fallen sharply during the last three epidemiological years in Spain. The risk of contracting serogroup C disease in 2002/2003 fell by 58% when compared with the season before the conjugate vaccine was introduced. There was also an important decrease in mortality. Three deaths due to serogroup C occurred in the age groups targeted for vaccination in 2002/2003, compared with 30 deaths in the same age groups in the season before the launch of the vaccine campaign. In the catch-up campaign the vaccine coverage reached values above 92%. For the 2001, 2002 and 2003 routine childhood immunisation programme coverage values ranged from 90% to 95%. During the past three years a total of 111 cases of serogroup C disease have been reported in patients in the vaccine target group. Most of the vaccination failures occurred during the epidemiological year 2002/2003. Eight (53%) vaccine failures occurred in children who had been routinely immunised in infancy, and could be related to a lost of protection with time since vaccination. The isolation of several B:2a:P1.5 strains (ST-11 lineage) is noteworthy. These may have their origin in C:2a:P1.5 strains which, after undergoing genetic recombination at the capsular operon level, express serogroup B. These strains could have relevant epidemic potential.     

Surveillance of invasive meningococcal disease in the Czech Republic

Routine notification of invasive meningococcal disease has a long tradition in the Czech Republic: mortality data are available from 1921 and morbidity data from 1943. The collection of Neisseria meningitidis strains kept in the NRL for Meningococcal Infections in Prague dates from 1970 onwards, and represents more than 3500 strains isolated from invasive disease and their contacts, from healthy carriers and from respiratory infection. Analysis of these strains showed that the Czech meningococcal population is different from that seen in western Europe. In 1993, the incidence serogroup C meningococcal disease increased and was associated with the emergence of the hypervirulent complex Neisseria meningitidis C, ST-11, ET-15/37, and caused an increase in the incidence of invasive meningococcal disease which peaked in 1995 (2.2/100,000). A vaccination strategy targeting the part of the population at highest risk of invasive meningococcal disease was adopted in the country.     

Outbreaks of serogroup X meningococcal meningitis in Niger 1995-2000

In the African meningitis belt, the recurrent meningococcal meningitis epidemics are generally caused by serogroup A. In the past 20 years, other serogroups have been detected, such as X or W135, which have caused sporadic cases or clusters. We report here 134 meningitis cases caused by Neisseria meningitidis serogroup X that occurred in Niamey between 1995 and 2000. They represented 3.91% of the meningococcal isolates from all CSF samples, whereas 94.4% were of serogroup A. Meningococcal meningitis cases were detected using the framework of the routine surveillance system for reportable diseases organized by the Ministry of Public Health of Niger. The strains were isolated and determined by the reference laboratory for meningitis in Niamey (CERMES) and further typed at the WHO collaborating center of the Pharo in Marseille and at the National Reference Center for the Meningococci at the Institut Pasteur. Reference laboratories in Marseille and Paris characterized 47 isolates having the antigenic formula (serogroup:serotype:sero-subtype) X:NT:P1.5. Meningitis cases due to meningococcus serogroup X did not present any clinical or epidemiological differences to those due to serogroup A. The seasonal incidence was classical; 93.3% of the cases were recorded during the dry season. The mean age of patients was 9.2 years (+/- 6 years). The sex ratio M/F was 1.3. Case fatality rate was 11.9% without any difference related to age or sex. The increasing incidence of the serogroup X was not related to the decrease of serogroup A, but seemed cyclic, and evolved independently of the recurrence of both serogroups A and C.     

Invasive haemophilus influenzae and meningococcal infections in Finland. A climatic, epidemiologic and clinical approach

A nationwide epidemiological survey on invasive (blood and/or CSF culture positive) Haemophilus influenzae (HI) and meningococcal infections was performed in Finland in 1976-1980. The mean annual incidence of HI infection was 3.4/100,000 inhabitants (813 cases) vs. 2.0/100,000 (469 cases) of meningococcal infection. HI infections showed no geographical predilection, but meningococcal disease, mainly of group B, was more common in northern than in southern Finland (p less than 0.005). Meningitis accounted for 61% of the HI and 91% of the meningococcal infections. The overall fatality rates were 3.1% and 7.9%, respectively. Children accounted for 94% of the HI and 59% of the meningococcal cases. The overall annual incidence of bacterial meningitis in children (less than 15 years) was 19/100,000; in children less than 5 years it was 52/100,000. HI was the most common (62%) causative agent, followed by meningococci (18%) and pneumococci (5%). The fatality rate was 4%. Major neurological sequelae were found in 5%, minor ones in 16%. It was calculated that 42% of the cases of meningitis could have been prevented by vaccines now available on the market. Vaccines now under field investigation may increase the preventability to about 65%.     

Meningococcal disease in Italy

In 1985, nationwide surveillance of meningococcal disease aimed at establishing appropriate guidelines for prophylaxis started in Italy. The incidence of disease was 1.1/100,000 in 1985 and 0.6/100,000 in 1987. This decreasing trend was particularly evident among military recruits (from 17.3/100,000 in 1985 to 5/100,000 in 1987), reflecting the use of bivalent serogroup (A + C) meningococcal polysaccharide vaccine in all new recruits since January 1987. The age distribution of cases was statistically different from that observed during the 1970s (P less than 0.001), with a shift towards older age groups. Men have been in the majority (516 vs. 358, P less than 0.0000001). Group C has been the most common serogroup encountered (72.2%), while only 18% of the isolates belonged to serogroup B. Among military recruits, serogroup C accounted for 92% (81/88) of the cases. The proportion of strains resistant to sulphonamides was 67%, while only 3% strains were resistant to rifampicin and to minocycline. Reduced susceptibility to ampicillin and to penicillin was observed in 3 and 4% strains respectively. Nine secondary cases were all due to failure in the administration of chemoprophylaxis (sulphonamide given in seven cases, prophylaxis not attempted in two cases). Immunisation of all new military recruits and effective chemoprophylaxis of close contacts of cases are the major guidelines provided by the National Meningitis Surveillance Programme.     

Genetic and antigenic analysis of invasive serogroup C Neisseria meningitidis in Canada: A decrease in the electrophoretic type (ET)-15 clonal type and an increase in the proportion of isolates belonging to the ET-37 (but not ET-15) clonal type during the period from 2002 to 2009

BACKGROUND:

Serogroup C meningococcal disease has been endemic in Canada since the early 1990s, with periods of hyperendemic disease documented in the past two decades. The present study characterized invasive serogroup C meningococci in Canada during the period from 2002 to 2009.

METHODS:

Serogroup C meningococci were serotyped using monoclonal antibodies. Their clonal types were identified by either multilocus enzyme electrophoresis or multilocus sequence typing.

RESULTS:

The number of invasive serogroup C Neisseria meningitidis isolates received at the National Microbiology Laboratory (Winnipeg, Manitoba) for characterization has dropped from a high of 173 isolates in 2001 to just 17 in 2009, possibly related to the introduction of the serogroup C meningococcal conjugate vaccine. Before 2006, 80% to 95% of all invasive serogroup C meningococci belonged to the electrophoreic type (ET)-15 clonal type, and the ET-37 (but not ET-15) type only accounted for up to 5% of all isolates. However, beginning in 2006, the percentage of the ET-15 clonal type decreased while the ET-37 (but not ET-15) type increased from 27% in 2006 to 52% in 2009. The percentage of invasive serogroup C isolates not belonging to either ET-15 or ET-37 also increased. Most ET-15 isolates expressed the antigenic formula of C:2a:P1.7,1 or C:2a:P1.5. In contrast, the ET-37 (but not ET-15) isolates mostly expressed the antigens of C:2a:P1.5,2 or C:2a:P1.2.

CONCLUSION:

A shift in the antigenic and clonal type of invasive serogroup C meningococi was noted. This finding suggests vigilance in the surveillance of meningoccocal disease is warranted.     

Nasopharyngeal carriage of Neisseria meningitidis in general population and meningococcal disease

Nasopharyngeal carriage of Neisseria meningitidis was determined in the normal healthy population in Delhi at monthly intervals for a period of 2 years from January, 1986 to December, 1987. Of a total of 6513 individuals screened only 107 (1.64 per cent) were found to carry Neisseria meningitidis serogroup A. There was no age and sex difference in carriage. During the same period, data of laboratory confirmed cases of meningitis due to N. meningitidis serogroup A was obtained from 6 hospitals of Delhi which acted as sentinel centres. Of the total 11,870 pyogenic C.S.F. samples processed, only 557 (4.69 per cent) were due to N. meningitidis serogroup A. There was no correlation observed between the nasopharyngeal meningococcal carriage in the healthy population with the disease prevalence. There was no seasonal variation in nasopharyngeal carriage though upsurge in the number of meningococcal meningitis cases was noticed from January to April.     

Meningitis caused by a serogroup W135 clone of the ET-37 complex of Neisseria meningitidis in West Africa

Summary Meningococci belonging to serogroup W135 caused several cases of meningococcal meningitis in The Gambia in 1995 and were isolated during a serogroup A epidemic in Mali in 1994. The eight isolates tested belonged to the same clone of the ET-37 complex and differed in several bands from the pulsed-field gel electrophoresis restriction pattern of serogroup C meningococci of the ET-37 complex isolated in Mali. Three of 6 patients infected in The Gambia died, indicating that this W135 clone is virulent. Vaccines that protect only against infections with meningococci belonging to serogroups A and C are usually used to control outbreaks in Africa, although vaccines containing the W135 polysaccharide are available. The findings of this study indicate that outbreaks of meningococcal meningitis in Africa can be associated with serogroup W135 infections and that serogrouping is essential before vaccination campaigns are started.     

The changing epidemiology of meningococcal disease in the United States, 1992-1996

New meningococcal vaccines are undergoing clinical trials, and changes in the epidemiologic features of meningococcal disease will affect their use. Active laboratory-based, population-based US surveillance for meningococcal disease during 1992-1996 was used to project that 2400 cases of meningococcal disease occurred annually. Incidence was highest in infants; however, 32% of cases occurred in persons >/=30 years of age. Serogroup C caused 35% of cases; serogroup B, 32%; and serogroup Y, 26%. Increasing age (relative risk [RR], 1.01 per year), having an isolate obtained from blood (RR, 4.5), and serogroup C (RR, 1.6) were associated with increased case fatality. Among serogroup B isolates, the most commonly expressed serosubtype was P1.15; 68% of isolates expressed 1 of the 6 most common serosubtypes. Compared with cases occurring in previous years, recent cases are more likely to be caused by serogroup Y and to occur among older age groups. Ongoing surveillance is necessary to determine the stability of serogroup and serosubtype distribution.     

Epidemiological patterns of meningococcal meningitis in Niger in 2003 and 2004: under the threat of N. meningitidis serogroup W135

Since the Neisseria meningitidis serogroup W135 epidemic in Burkina Faso in 2002, the neighbouring countries dread undergoing outbreaks. Niger has strongly enhanced the microbiological surveillance, especially by adding the polymerase chain reaction (PCR) assay to the national framework of the surveillance system. During the 2003 epidemic season, 8113 clinically suspected cases of meningitis were notified and nine districts of the 42 crossed the epidemic threshold, while during the 2004 season, the number of cases was 3521 and four districts notified epidemics. In 2003 and 2004, serogroup A was identified in most N. meningitidis from cerebrospinal fluid (CSF) specimens (89.7% of 759 and 87.2% of 406, respectively). Although serogroup W135 represented only 8.3% of the meningococcal meningitis in 2003 and 7.9% in 2004, and was not involved in outbreaks, it was widespread in various areas of the country. In the regions that notified epidemics, the proportion of serogroup W135 was tiny while it exceeded 40% in several non-epidemic regions. Despite the wide distribution of W135 serogroup in Niger and the fears expressed in 2001, the threat of a large epidemic caused by N. meningitidis W135 seems to have been averted in Niger so far. There is no clear indication whether this serogroup will play a lasting role in the epidemiology of meningococcal meningitis or not. As early as in the 1990s, a significant but transient increase in the incidence of N. meningitidis serogroup X was observed. Close microbiological surveillance is crucial for monitoring the threat and for identifying at the earliest the serogroups involved in epidemics.     

Prevention of bacterial meningitis: an overview of Cochrane systematic reviews

Acute bacterial meningitis (ABM) is an acute inflammation of leptomeninges caused by bacteria, and has a case fatality rate of 10-30%. Prevention strategies, such as vaccination and prophylactic antibiotics, can prevent ABM and have substantial public health impact by reducing the disease burden associated with it. The aim of this paper is to summarize the main findings from Cochrane systematic reviews that have considered the evidence for measures to prevent ABM. We assessed the evidence available in the Cochrane Library. We found five Cochrane reviews focused on the prevention of ABM; three with use of vaccination and two with prophylactic antibiotics. Polysaccharide serogroup A vaccine is strongly protective for the first year, against serogroup A meningococcal meningitis in adults and children over 5 years of age. Meningococcal serogroup C conjugate (MCC) vaccine is safe and effective in infants. Haemophilus influenzae type b (Hib) vaccine is safe and effective against Hib-invasive disease at all ages. Ceftriaxone, rifampicin and ciprofloxacin are the most effective prophylactic antibiotics against Neisseria meningitidis. There is sufficient evidence to use polysaccharide serogroup A vaccine to prevent serogroup A meningococcal meningitis, MCC conjugate vaccines to prevent meningococcal C meningitis and Hib conjugate vaccine to prevent Hib infections. More studies are needed to evaluate the effects of Hib conjugate vaccine on mortality. Further, studies are required to compare the relative effectiveness of ceftriaxone, ciprofloxacin and rifampicin in chemoprophylaxis against meningococcal infection.