de Chabalier F, Djingarey M H, Hassane A, Chippaux J P
Centre de Recherche sur les Méningites et les Schistosomoses (CERMES), BP 10887, Niamey, Niger.
Trans R Soc Trop Med Hyg. 2000 Nov-Dec;94(6):664-8. doi: 10.1016/s0035-9203(00)90224-4.
Control of epidemic meningitis is still an unresolved problem in Africa. WHO has promoted the use of surveillance and response following alerts based on weekly threshold levels. In order to avoid any waste of resources related to false-positive alerts, it was decided not to choose too sensitive thresholds. This policy, however, leads to delayed response. The seasonal pattern of epidemics provides a solution to this dilemma. We carried out a retrospective survey of district-level surveillance data in Niger from June 1990 to June 1998. We identified an early and late meningitis season. Following this pattern, we studied the performance of the WHO-recommended threshold as compared to alternative thresholds for identifying early, late and non-epidemic district-years (DYs). (ADY was defined as a 52-week period starting in the last week of June, at the district level). We studied 296 DYs, comprising 50 early epidemic, 38 late epidemic, and 208 non-epidemic DYs. Early epidemics were more often large and accounted for almost 75% of total cases. When applied no later than the first week of March, a highly sensitive alternative threshold resulted in initiation of an alert, with a median of 3 weeks earlier than the standard threshold, with no false-positive alerts, i.e., a specificity of 1.
在非洲，控制流行性脑膜炎仍然是一个未解决的问题。世界卫生组织（WHO）推行了基于每周阈值水平发出警报后的监测和应对措施。为了避免因假阳性警报造成资源浪费，决定不选择过于敏感的阈值。然而，这一政策导致应对延迟。疫情的季节性模式为这一困境提供了解决方案。我们对1990年6月至1998年6月期间尼日尔地区一级的监测数据进行了回顾性调查。我们确定了脑膜炎的早季和晚季。按照这种模式，我们研究了WHO推荐的阈值与用于识别早季、晚季和非流行区年份（DYs）的替代阈值相比的性能。（ADY定义为从6月最后一周开始的为期52周的时间段，在地区层面）。我们研究了296个DYs，包括50个早季流行、38个晚季流行和208个非流行DYs。早季疫情往往规模更大，几乎占总病例数的75%。当在不迟于3月的第一周应用时，一个高度敏感的替代阈值导致发出警报，比标准阈值早3周发出警报，且无假阳性警报，即特异性为1。
