Invasive Meningococcal Meningitis Serogroup C Outbreak in Northwest Nigeria, 2015 – Third Consecutive Outbreak of a New Strain

Abstract

BACKGROUND: In northwest Nigeria in 2013 and 2014, two sequential, localized outbreaks of meningitis were caused by a new strain of Neisseria meningitidis serogroup C (NmC). In 2015, an outbreak caused by the same novel NmC strain occurred over a wider geographical area, displaying different characteristics to the previous outbreaks. We describe cases treated by Médecins Sans Frontières (MSF) in the 2015 outbreak. METHODS: From February 10 to June 8, 2015, data on cerebrospinal meningitis (CSM) cases and deaths were recorded on standardized line-lists from case management sites supported by MSF. Cerebrospinal fluid (CSF) samples from suspected cases at the beginning of the outbreak and throughout from suspected cases from new geographical areas were tested using rapid Pastorex® latex agglutination to determine causative serogroup. A subset of CSF samples was also inoculated into Trans-Isolate medium for testing by the WHO Collaborating Centre for Reference and Research on Meningococci, Oslo. Reactive vaccination campaigns with meningococcal ACWY polysaccharide vaccine targeted affected administrative wards. RESULTS: A total of 6394 (65 confirmed and 6329 probable) cases of CSM including 321 deaths (case fatality rate: 5.0%) were recorded. The cumulative attack rate was 282 cases per 100,000 population in the wards affected. The outbreak lasted 17 weeks, affecting 1039 villages in 21 local government areas in three states (Kebbi, Sokoto, Niger). Pastorex® tests were NmC positive for 65 (58%) of 113 CSF samples. Of 31 Trans-Isolate medium samples, 26 (84%) tested positive for NmC (14 through culture and 12 through PCR); all had the same rare PorA type P1.21-15,16 as isolates from the 2013 and 2014 outbreaks. All 14 culture-positive samples yielded isolates of the same genotype (ST-10217 PorA type P1.21-15,16 and FetA type F1-7). More than 222,000 targeted individuals were vaccinated relatively early in the outbreak (administrative coverage estimates 98% and 89% in Kebbi and Sokoto, respectively). CONCLUSIONS: The outbreak was the largest caused by NmC documented in Nigeria. Reactive vaccination in both states may have helped curtail the epidemic. A vaccination campaign against NmC with a long-lasting conjugate vaccine should be considered in the region.

Evaluation of Pastorex meningitis kit performance for the rapid identification ofNeisseria meningitidisserogroup C in Nigeria

“…This study analyses data collected during three sequential outbreaks of NmC in northern Nigeria in 2013 (9 February to 23 June; 856 clinically suspected patients treated), 2014 (14 March to 3 May; 333 cases), 5 and 2015 (10 February to 8 June; 6394 suspected cases 17 ). During these NmC outbreaks, Médecins Sans Frontières (MSF) managed treatment centres within existing Ministry of Health facilities in areas affected by the outbreaks: three sites in Sokoto state in 2013; one in Kebbi state in 2014; and two in Sokoto and five in Kebbi in 2015 ( Supplementary Table 1 ).…”

Vaccine prevention of meningococcal disease in Africa: Major advances, remaining challenges

“…8 NmC subsequently spread more widely causing endemic cases and epidemics across north Nigeria and neighboring Niger in 2015-2017 ( Figure 3B). 9,35,36,82 Niger and Nigeria each experienced over nine thousand suspected cases and over five hundred deaths due to NmC epidemics in 2015 and 2017, respectively. 9,35,36 NmC epidemics were characterized by very high attack rates in the range of 41.4-673 cases per 100,000 population, comparable to those seen during NmA epidemics.…”

“…9,35,36 NmC epidemics were characterized by very high attack rates in the range of 41.4-673 cases per 100,000 population, comparable to those seen during NmA epidemics. 8,9,82 Since 2013 NmC cases have also been recorded in Burkina Faso, Ghana, Benin and Mali suggesting wide regional spread of an epidemic strain. Molecular epidemiologic and whole genome characterization studies showed that epidemic NmC strains belonged to a newly identified ST-10217 lineage.…”

Outbreak of cerebrospinal meningitis in Kebbi State, Nigeria, April 2017

“…7 Outbreaks due to Neisseria meningitidis serogroup C (NmC) have also occurred but were smaller and less frequent than NmA outbreaks. 2,10 The last NmC outbreak in this region occurred in 1979 in Burkina Faso with 539 cases reported (attack rate (AR) 517/100,000). 7 Outbreaks caused by NmC in northern Nigeria are rare, with the last and only recorded outbreak in 1975 with no detailed report published.…”