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

Declining Incidence of Invasive Meningococcal Disease in South Africa: 2003-2016

BACKGROUND

Invasive meningococcal disease (IMD) is endemic to South Africa, where vaccine use is negligible. We describe the epidemiology of IMD in South Africa.

METHODS

IMD cases were identified through a national, laboratory-based surveillance program, GERMS-SA, from 2003-2016. Clinical data on outcomes and human immunodeficiency virus (HIV) statuses were available from 26 sentinel hospital sites. We conducted space-time analyses to detect clusters of serogroup-specific IMD cases.

RESULTS

Over 14 years, 5249 IMD cases were identified. The incidence was 0.97 cases per 100 000 persons in 2003, peaked at 1.4 cases per 100 000 persons in 2006, and declined to 0.23 cases per 100 000 persons in 2016. Serogroups were confirmed in 3917 (75%) cases: serogroup A was present in 4.7% of cases, B in 23.3%, C in 9.4%; W in 49.5%; Y in 12.3%, X in 0.3%; Z in 0.1% and 0.4% of cases were non-groupable. We identified 8 serogroup-specific, geo-temporal clusters of disease. Isolate susceptibility was 100% to ceftriaxone, 95% to penicillin, and 99.9% to ciprofloxacin. The in-hospital case-fatality rate was 17% (247/1479). Of those tested, 36% (337/947) of IMD cases were HIV-coinfected. The IMD incidence in HIV-infected persons was higher for all age categories, with an age-adjusted relative risk ratio (aRRR) of 2.5 (95% confidence interval [CI] 2.2-2.8; P < .001) from 2012-2016. No patients reported previous meningococcal vaccine exposure. Patients with serogroup W were 3 times more likely to present with severe disease than those with serogroup B (aRRR 2.7, 95% CI 1.1-6.3); HIV coinfection was twice as common with W and Y diseases (aRRR W = 1.8, 95% CI 1.1-2.9; aRRR Y = 1.9, 95% CI 1.0-3.4).

CONCLUSIONS

In the absence of significant vaccine use, IMD in South Africa decreased by 76% from 2003-2016. HIV was associated with an increased risk of IMD, especially for serogroup W and Y diseases.

Population snapshot of invasive serogroup B meningococci in South Africa from 2005 to 2008

In South Africa, serogroup B meningococcal disease is sporadic. The aim of this study was to characterize serogroup B strains causing invasive meningococcal disease (IMD) in South Africa from 2005 to 2008. Isolates, collected through a national, laboratory-based surveillance program for IMD, were characterized by multilocus sequence typing (MLST). Two thousand two hundred thirty-four cases were reported, of which 1,447 had viable isolates. Intermediate resistance to penicillin was observed in 2.8% (41/1,447) of all strains. Serogroup B was the second most common serogroup (17%, 251/1,447) and increased from 14% (58/414) in 2005 to 25% (72/290) in 2008 (P < 0.001); however, incidence remained stable during the study period (average incidence, 0.13/100,000 population) (P = 0.54). Serogroup B was predominantly characterized by three clonal complexes, namely, ST-41/44/lineage 3, ST-32/ET-5, and the new complex ST-4240/6688, which accounted for 27% (65/242), 23% (55/242), and 16% (38/242) of isolates, respectively. ST-4240/6688 was more prevalent among young children (<5 years) than other clonal complexes (27/37 [73%] versus 108/196 [55%]; P = 0.04). In the most densely populated province of South Africa, Gauteng, the prevalence of ST-32/ET-5 increased from 8% (2/24) in 2005 to 38% (9/24) in 2008 (P = 0.04). Capsular switching was observed in 8/242 (3%) strains. The newly assigned clonal complex ST-4240/6688 was more common in young children.

Meningococcal disease in South Africa, 1999-2002

Serogroups and strains differ by location, although hypervirulent strains were identified throughout the country.

We describe the epidemiology of invasive meningococcal disease in South Africa from August 1999 through July 2002, as reported to a laboratory-based surveillance system. Neisseria meningitidis isolates were further characterized. In total, 854 cases of laboratory-confirmed disease were reported, with an annual incidence rate of 0.64/100,000 population. Incidence was highest in infants <1 year of age. Serogroup B caused 41% of cases; serogroup A, 23%; serogroup Y, 21%; serogroup C, 8%; and serogroup W135, 5%. Serogroup B was the predominant serogroup in Western Cape Province, and disease rates remained stable. Serogroup A was most prevalent in Gauteng Province and increased over the 3 years. On pulsed-field gel electrophoresis analysis, serogroup A strains showed clonality, and serogroup B demonstrated considerable diversity. Selected isolates of serogroup A belonged to sequence type (ST)-1 (subgroup I/II) complex, serogroup B to ST-32/electrophoretic type (ET)-5 complex, and serogroup W135 to ST-11/ET-37 complex.

Development of vaccines against meningococcal disease

Neisseria meningitidis is a major cause of bacterial meningitis and sepsis. Polysaccharide-protein conjugate vaccines for prevention of group C disease have been licensed in Europe. Such vaccines for prevention of disease caused by groups A (which is associated with the greatest disease burden worldwide), Y, and W135 are being developed. However, conventional approaches to develop a vaccine for group B strains, which are responsible for most cases in Europe and the USA, have been largely unsuccessful. Capsular polysaccharide-based vaccines can elicit autoantibodies to host polysialic acid, whereas the ability of most non-capsular antigens to elicit broad-based immunity is limited by their antigenic diversity. Many new membrane proteins have been discovered during analyses of genomic sequencing data. These antigens are highly conserved and, in mice, elicit serum bactericidal antibodies, which are the serological hallmark of protective immunity in man. Therefore, there are many promising new vaccine candidates, and improved prospects for development of a broadly protective vaccine for group B disease, and for control of all meningococcal disease.

Childhood hearing loss in sub-Saharan Africa: a review and recommendations

Nearly 10% of the world's population lives in sub-Saharan Africa, a region comprised of many countries with least developed nation status. The region has a predominantly young population and many children in the region are at risk of pathologies associated with hearing loss. Despite the constraints associated with low socioeconomic levels, a number of valuable studies have been carried out into the prevalence and etiology of childhood hearing loss in the sub-Saharan region. A review of the published literature related to childhood hearing loss in sub-Saharan Africa is presented and recommendations made on possible future research directions that could assist hearing loss prevention and management.

Fatal meningococcal disease in childhood: an autopsy study of 86 cases

A retrospective study of the pathology in 86 consecutive autopsies of fatal meningococcal infection in children, performed at the Red Cross War Memorial Children's Hospital during the 19-year period from 1973 to 1991, was undertaken. The most prominent pathological changes found at autopsy were those of an overwhelming bacterial infection with evidence of disseminated intravascular coagulopathy in many organs of the body. The skin, adrenal glands and central nervous system were most commonly involved. Acute myocarditis occurred in 23 cases (27%) and was diagnosed almost exclusively histologically. In only one case was it diagnosed clinically. In addition, the nutritional status and the morphological expression of immune reactivity of our hospital population was better than expected.

Endemic bacterial meningitis in Sudanese children: aetiology, clinical findings, treatment and short-term outcome

During the period April 1985 to November 1986 (18 months), 196 children (of age greater than 1 month) admitted to the Children's Emergency Hospital in Khartoum, Sudan, with clinical suspicion of meningitis/meningoencephalitis were followed up prospectively. Bacterial meningitis was diagnosed by culture, direct microscopy and/or antigen-detecting assays (co-agglutination and enzyme immunoassay) in 44 infants (25 Haemophilus influenzae type b, 8 Neisseria meningitidis, 7 Streptococcus pneumoniae, 3 enterobacteria and one mixed infection), aseptic meningitis in 52, cerebral malaria in 4 and febrile convulsions in 96. The majority of cases of bacterial meningitis were boys and 57% of those in whom H. influenzae was the commonest isolate were less than 1 year old. The presenting signs and symptoms are described as well as the transient and permanent short-term sequelae. The total mortality from bacterial meningitis was 19%, permanent neurological sequelae were seen in 26% of survivors. Prospective follow-up, including audiometry, of 35 children 1-2 months after discharge showed that 11% had hemiplegia and 20% had hearing impairment. The potential impact of vaccination against invasive H. influenzae infections is discussed.

Childhood acute bacterial meningitis in the Sudan: an epidemiological, clinical and laboratory study

The aims of the present study were to document the epidemiology, clinical features and complications of childhood acute bacterial meningitis (ABM) in The Sudan during both an inter-epidemic (endemic) period (1985-1986), and the 1988 serogroup A epidemic; and to examine the phenotypic and genetic similarities and differences of Neisseria meningitidis strains isolated in The Sudan and Sweden. A new enzyme immunoassay test (Pharmacia Meningitis EIA-Test) was evaluated as a potential rapid diagnostic method for the detection of Haemophilus influenzae (HI) type b, Neisseria meningitidis (MC) and Streptococcus pneumoniae (PNC). The test was found to have good sensitivity (0.86) and specificity (0.95) in the inter-epidemic period; and to be adaptable to the field work in The Sudan during the 1988 MC epidemic. During inter-epidemic (endemic) situations in The Sudan, greater than 90% of childhood ABM was caused by one of the three organisms, HI type b, MC and PNC. HI accounted for 57% of the cases. The peak incidence (76%) of HI cases was in infants (less than 12 months) similar to the situation in other African countries. The overall case fatality ratio was 18.6%. Prospective follow-up of survivors for 3-4 years revealed that an additional 43% either died or had permanent neurological complications, the most prevalent and persistent of which was sensorineural hearing loss recorded in 22% of long term survivors. Post-meningitic children were found to have significantly lower intelligence quotients (92.3 +/- 13.9) than their sibling controls (100.7 +/- 10.2, P = 0.029). Features of the large serogroup A sulphonamide resistant MC epidemic (February-August 1988) in Khartoum are described. An estimated annual incidence of 1,679/100,000 was recorded at the peak of the epidemic. The highest attack rate was in young children less than 5 years, as in many other African countries; nevertheless, a high morbidity was observed in adults (31% of the cases greater than or equal to 20 years). The clinical features, mortality (6.3%) and short term sequelae in Sudanese children were generally within the framework described for MC disease elsewhere. Detailed analysis of MC isolates from Sudan and Sweden by characterizing their electrophoretic enzyme types, DNA restriction endonuclease pattern and outer membrane proteins, revealed that serogroup A MC clone III-1 was responsible of The Sudan epidemic in 1988 and has been the dominant serogroup A organism in Sweden since 1973. The Sudanese strains isolated prior to the epidemic (1985) were clone IV-1.(ABSTRACT TRUNCATED AT 250 WORDS)