Evaluation of a multi-component early warning system for pastoralist populations in Doolo zone, Ethiopia: mixed-methods study.

BACKGROUND: This study evaluated an early warning, alert and response system for a crisis-affected population in Doolo zone, Somali Region, Ethiopia, in 2019-2021, with a history of epidemics of outbreak-prone diseases. To adequately cover an area populated by a semi-nomadic pastoralist, or livestock herding, population with sparse access to healthcare facilities, the surveillance system included four components: health facility indicator-based surveillance, community indicator- and event-based surveillance, and alerts from other actors in the area. This evaluation described the usefulness, acceptability, completeness, timeliness, positive predictive value, and representativeness of these components. METHODS: We carried out a mixed-methods study retrospectively analysing data from the surveillance system February 2019-January 2021 along with key informant interviews with system implementers, and focus group discussions with local communities. Transcripts were analyzed using a mixed deductive and inductive approach. Surveillance quality indicators assessed included completeness, timeliness, and positive predictive value, among others. RESULTS: 1010 signals were analysed; these resulted in 168 verified events, 58 alerts, and 29 responses. Most of the alerts (46/58) and responses (22/29) were initiated through the community event-based branch of the surveillance system. In comparison, one alert and one response was initiated via the community indicator-based branch. Positive predictive value of signals received was about 6%. About 80% of signals were verified within 24 h of reports, and 40% were risk assessed within 48 h. System responses included new mobile clinic sites, measles vaccination catch-ups, and water and sanitation-related interventions. Focus group discussions emphasized that responses generated were an expected return by participant communities for their role in data collection and reporting. Participant communities found the system acceptable when it led to the responses they expected. Some event types, such as those around animal health, led to the community's response expectations not being met. CONCLUSIONS: Event-based surveillance can produce useful data for localized public health action for pastoralist populations. Improvements could include greater community involvement in the system design and potentially incorporating One Health approaches.

Evaluation of Pastorex meningitis kit performance for the rapid identification of Neisseria meningitidis serogroup C in Nigeria.

BACKGROUND: Neisseria meningitidis serogroup C (NmC) has caused outbreaks in Nigeria of increasing size in three consecutive years since 2013. Rapid diagnostic tests (RDTs) for meningitis can facilitate quick identification of the causative pathogen; Pastorex can detect N. meningitidis serogroups A, C (NmC), Y/W135, N. meningitidis serogroup B/Escherichia coli K1, Haemophilus influenzae type b (Hib), Streptococcus pneumoniae, and group B Streptococcus. There is no published field evaluation of Pastorex in the identification of NmC. We report our experience with Pastorex in detecting NmC in field conditions. METHODS: During sequential outbreaks of NmC in Nigeria in 2013, 2014 and 2015, cerebrospinal fluid (CSF) was collected from suspected cases of meningitis that met the case definition. Pastorex latex agglutination rapid test was done in the field and trans-isolate media were inoculated with CSF for culture and/or PCR, which was used as the reference standard for 63 paired samples. RESULTS: The sensitivity of Pastorex for NmC was 80.0% (95% CI 65.4-90.4%) and the specificity was 94.4% (95% CI 72.7-99.9%). The positive likelihood ratio (LR) was 14.4 (95% CI 2.1-97.3) and negative LR was 0.2 (95% CI 0.1-0.4). The positive and negative predictive values (PPV and NPV) were 97.3% (95% CI 85.8-99.9) and 65.4% (95% CI 44.3-82.8), respectively, with a prevalence estimate of 71.4% (95% CI 58.6-82.1). CONCLUSION: Pastorex showed good performance in detecting NmC under field conditions. Prepositioning Pastorex at peripheral health facilities during non-epidemic periods is constrained by a short shelf-life of 1 month after the kit is opened. There is need for development of RDTs that are cheaper and with less challenging requirements for storage and usage.

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

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.