Pediatric Bacterial Meningitis Surveillance in the World Health Organization African Region Using the Invasive Bacterial Vaccine-Preventable Disease Surveillance Network, 2011-2016

Abstract

Background: Bacterial meningitis is a major cause of morbidity and mortality in sub-Saharan Africa. We analyzed data from the World Health Organization's (WHO) Invasive Bacterial Vaccine-preventable Diseases Surveillance Network (2011-2016) to describe the epidemiology of laboratory-confirmed Streptococcus pneumoniae (Spn), Neisseria meningitidis, and Haemophilus influenzae meningitis within the WHO African Region. We also evaluated declines in vaccine-type pneumococcal meningitis following pneumococcal conjugate vaccine (PCV) introduction.

Methods: Reports of meningitis in children <5 years old from sentinel surveillance hospitals in 26 countries were classified as suspected, probable, or confirmed. Confirmed meningitis cases were analyzed by age group and subregion (South-East and West-Central). We described case fatality ratios (CFRs), pathogen distribution, and annual changes in serotype and serogroup, including changes in vaccine-type Spn meningitis following PCV introduction.

Results: Among 49 844 reported meningitis cases, 1670 (3.3%) were laboratory-confirmed. Spn (1007/1670 [60.3%]) was the most commonly detected pathogen; vaccine-type Spn meningitis cases declined over time. CFR was the highest for Spn meningitis: 12.9% (46/357) in the South-East subregion and 30.9% (89/288) in the West-Central subregion. Meningitis caused by N. meningitidis was more common in West-Central than South-East Africa (321/954 [33.6%] vs 110/716 [15.4%]; P < .0001). Haemophilus influenzae (232/1670 [13.9%]) was the least prevalent organism.

Conclusions: Spn was the most common cause of pediatric bacterial meningitis in the African region even after reported cases declined following PCV introduction. Sustaining robust surveillance is essential to monitor changes in pathogen distribution and to inform and guide vaccination policies.

Keywords: PCV; case fatality ratios; pediatric bacterial meningitis; pneumococcal conjugate vaccine; sub-Saharan Africa.

Figure 1.

Bacterial meningitis case classification, 2011–2016. Abbreviation: LP, lumbar puncture. Percentage of cases that did not meet probable criteria due to missing data: ^a1.9%, ^b1.1%, ^c1.3%. ^dNeisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae in addition to other potential pathogens identified by culture or latex agglutination test. ^eDetection of N. meningitidis, S. pneumoniae, and H. influenzae by polymerase chain reaction, culture, or rapid diagnostic tests (latex agglutination or immunochromatographic test).

Figure 2.

Annual number of confirmed Haemophilus influenzae meningitis cases by serotype and African subregion. A, Total number of confirmed cases reported by country in South-East Africa: Ethiopia (n = 10), Lesotho (n = 8), Madagascar (n = 5), Kingdom of Eswatini (formerly Swaziland; n = 3), Uganda (n = 36), Zambia (n = 21), and Zimbabwe (n = 3). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Malawi, Mozambique); did not report any H. influenzae serotype data (Malawi, Rwanda, United Republic of Tanzania). B, Number of confirmed cases reported by country in West-Central Africa: Benin (n = 28), Cameroon (n = 15), Gambia (n = 5), Ghana (n = 2), Niger (n = 8), Nigeria (n = 17), Senegal (n = 7), Togo (n = 14). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Angola, Central African Republic, Cote d’Ivoire, Sierra Leone); did not report any H. influenzae serotype data (Angola, Burkina Faso, Central African Republic, Democratic Republic of Congo). Abbreviations: Hia, Haemophilus influenzae type a; Hib, Haemophilus influenzae type b; Hic, Haemophilus influenzae type c; Hie, Haemophilus influenzae type e.

Figure 3.

Annual number of confirmed Neisseria meningitidis meningitis cases by serogroup and African subregion. A, Number of confirmed cases reported by country in South-East Africa: Ethiopia (n = 20), Lesotho (n = 3), Rwanda (n = 5), United Republic of Tanzania (n = 1), Uganda (n = 17), Zambia (n = 37), and Zimbabwe (n = 1). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Malawi, Mozambique); did not report any N. meningitidis serogroup data (Malawi, Madagascar, Kingdom of Eswatini [formerly Swaziland]). B, Number of confirmed cases reported by country in West-Central Africa: Benin (n = 35), Gambia (n = 16), Ghana (n = 12), Niger (n = 82), Nigeria (n = 29), Senegal (n = 26). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Angola, Burkina Faso, Central African Republic, Cote d’Ivoire, Sierra Leone); did not report any N. meningitidis serogroup data (Angola, Burundi, Central African Republic, Democratic Republic of Congo, Togo). Abbreviations: NmA, Neisseria meningitidis serogroup A; NmB, Neisseria meningitidis serogroup B; NmW, Neisseria meningitidis serogroup W; NmX, Neisseria meningitidis serogroup X; NmY, Neisseria meningitidis serogroup Y.

Figure 4.

Annual number of confirmed Streptococcus pneumoniae meningitis cases by vaccine-associated serotype and African subregion. A, Number of confirmed cases reported by country in South-East Africa: Ethiopia (n = 42), Madagascar (n = 81), Kingdom of Eswatini (formerly Swaziland, n = 6), United Republic of Tanzania (n = 6), Uganda (n = 134), Zambia (n = 94), Zimbabwe (n = 31). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Malawi, Mozambique); pneumococcal conjugate vaccine (PCV) not introduced during the surveillance period (Rwanda); at least 2 years of data not available following vaccine introduction (Lesotho); did not report any S. pneumoniae serotyping data (Malawi). B, Number of confirmed cases reported by country in West-Central Africa: Benin (n = 67), Cameroon (n = 57), Ghana (n = 19), Senegal (n = 47), Togo (n = 35). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Angola, Central African Republic, Cote d’Ivoire, Sierra Leone); ≤65% PCV coverage for at least 2 consecutive years (Niger, Nigeria); PCV not introduced during the surveillance period (Gambia); did not report any S. pneumoniae serotyping data (Angola, Burkina Faso, Burundi, Central African Republic, Democratic Republic of Congo). Thirteen-valent PCV unique serotypes include 3, 6A, and 19A. Abbreviations: PCV10, 10-valent pneumococcal conjugate vaccine; PCV13, 13-valent pneumococcal conjugate vaccine.

Figure 5.

Annual proportion of confirmed Streptococcus pneumoniae meningitis cases due to vaccine serotypes by pneumococcal conjugate vaccine (PCV) formulation, 2011–2016. A, Proportion of confirmed S. pneumoniae meningitis cases due to 10-valent PCV (PCV10) serotypes in countries that introduced PCV10 (n = 4), by year. Of the 6 countries that introduced PCV10, 4 contributed confirmed cases for this analysis: Ethiopia (n = 22), Madagascar (n = 66), Uganda (n = 106), and Zambia (n = 76). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Mozambique); ≤65% PCV coverage for at least 2 consecutive years (Nigeria). The percentage of PCV10 serotypes was determined by the number of reported PCV10 serotypes/all reported serotype results in a year: 2011 (7/9); 2012 (31/58); 2013 (48/68); 2014 (20/42); 2015 (26/58); 2016 (13/35). B, Proportion of confirmed S. pneumoniae meningitis cases due to 13-valent PCV (PCV13) serotypes in countries that introduced PCV13 (n = 8), by year. Of 20 countries that introduced PCV13, 8 were included in this analysis: Benin (n = 20), Cameroon (n = 17), Ghana (n = 8), Senegal (n = 26), Kingdom of Eswatini (formerly Swaziland, n = 3), Togo (n = 22), United Republic of Tanzania (n = 2), and Zimbabwe (n = 21). Confirmed cases from the following countries were excluded: data unavailable for all surveillance years (Angola, Central African Republic, Cote d’Ivoire, Malawi, Sierra Leone); at least 2 years of data not available following vaccine introduction (Lesotho); ≤65% PCV coverage for at least 2 consecutive years (Niger); PCV not introduced during the surveillance period (Gambia, Rwanda); and/or did not report any S. pneumoniae serotyping data (Angola, Burkina Faso, Burundi, Central African Republic, Democratic Republic of Congo, Malawi). The percentage of PCV13 serotypes was determined by the number of reported PCV13 serotypes/all reported serotype results in a year: 2011(18/20); 2012 (18/28); 2013 (10/16); 2014 (14/32); 2015 (8/12); 2016 (5/11). Dashed blue line indicates the trend line. Abbreviations: PCV10, 10-valent pneumococcal conjugate vaccine; PCV13, 13-valent pneumococcal conjugate vaccine.