Sporadic Cases of Meningococcal Meningitis Serogroup W-135 — Ethiopia, 2013

Abstract

Meningococcal meningitis is a serious bacterial infection of the meninges often caused by N. meningitides. Epidemics occur in 8-12 year cycles, usually in the dry season, across the African meningitis belt. In February 2013, West Arsi zone reported a suspected meningitis outbreak to Regional Public Health Emergency Center. Investigation was done to confirm the etiology, identify risk factors, and establish control measures. A suspected case was defined as any person with sudden onset of fever (>38.5°C rectal or 38.0°C axillary) and one of the following signs: neck stiffness, flaccid neck, bulging fontanel, convulsion or other meningeal sign and confirmed case as identified N. meningitidis from the CSF of a suspected case by culture, PCR or agglutination test. From January 23, 2013 up to April 17, 2013, a case investigation was conducted to identify suspected patients and confirmed meningitis for patients cerebrospinal fluid collected. We also conducted case-control study. Descriptive statistics and odds ratios with 95% confidence intervals were calculated to compare risk factors among cases and controls. A total of 99 cases and 3 deaths were occurred from January 23- April 27, 2013. The median age was 12 years with a range from 3 months to 68 years. Majority (89.9%) of the cases were below 30 years of age and children under five years of age were the most affected (28%) and Attack Rate (AR=4.2/100000). Ten (59%) patients with N. meningitidis were confirmed as serotype “A”, 6 (35.3%) patients were confirmed by latex agglutination test and PCR as serotype W135 and 1 (5.9%) patient was confirmed as mixed serotype. 24 confirmed and suspected Meningococcal meningitis patient cases and 96 community matched by sex, age and place of residence controls were included in the case control study. Recent travel to an area where patients with meningitis were reported (Odds Ratio (OR): 10.0, 95% Confidence Interval (CI): 3.7-27.3), attending in the occasion of gathering of population (OR: 7.7, 95% CI: 2.9-20.6) and a history of upper respiratory tract infection (OR: 7.2, 95% CI: 2.6-19.9) were risk factors. We verified sporadic cases of meningococcal meningitis in the areas. Incidence of disease was highest in children under five years of age. This was the first season that W135 was identified in Ethiopia. Further surveillance for W135 should be conducted in Ethiopia to guide vaccination policy.