Multiple causes of an unexpected malaria outbreak in a high-transmission area in Madagascar
Multiple causes of an unexpected malaria outbreak in a high-transmission area in Madagascar
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DOI：
10.1186/s12936-016-1113-0
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发表时间：
2016-02-02
期刊：
影响因子：
3
通讯作者：
Randrianarivelojosia, Milijaona
中科院分区：
文献类型：
--
作者：
Kesteman, Thomas;Rafalimanantsoa, Solofoniaina A.;Randrianarivelojosia, Milijaona
背景：马达加斯加的疟疾负担在过去十年中有所下降，这主要是由于控制措施的扩大。尽管如此，2011-2012年，在多雨的马达加斯加东南部的两个地区，疟疾病例显著增加，那里的疟疾被认为是中度流行病，人们应该受到对疟原虫的后天免疫力的保护。进行了多学科调查，以确定爆发的原因。方法：2012年3月，在20个随机选择的集群进行了横断面研究，涉及所有>= 6个月大的家庭成员的快速诊断检测和问卷调查的社会人口数据和接触疟疾控制干预措施。通过对地方当局的定性访谈评价了环境条件的变化，通过遥感评价了气候条件，通过定量手段评价了保健设施中疟疾用品的缺货情况。在每个集群中对两种长效驱虫蚊帐进行取样，以评估其状况及其杀虫活性的残留。昆虫学调查还包括收集媒介按蚊在两个网站，并测量其对溴氰菊酯。结果：横断面调查包括440户1615名成员。调查前一天的平均蚊帐使用率为71.1%。6-14岁儿童的疟原虫感染率较高（比值比（OR）7.73 [95% CI 3.58-16.68]），农村地区（OR 6.25 [4.46-8.76]），在最贫穷的社会经济阶层（OR 1.54 [1.13-2.08]），而经常在蚊帐下睡觉的个体的OR值较低（OR 0.51 [0.32-0.82]）。据报告，在过去6个月里，三分之二的保健设施的抗疟疾药物缺货。与前三个雨季相比，降雨量有所增加。收集的媒介对拟除虫菊酯敏感。分发两年后，几乎所有收集的长效驱虫蚊帐都显示出身体完整性和杀虫剂活性的丧失，结论：降雨量增加、使用量减少和长效驱虫蚊帐的杀虫剂活性降低以及药物短缺可能是造成或促成2011-2012年马达加斯加东南部疫情的原因。消除疟疾的控制干预措施必须持续下去，冒着引发有害流行病的风险，即使在高传播区也是如此。
Background: The malaria burden in Madagascar dropped down last decade, largely due to scale-up of control measures. Nevertheless, a significant rise of malaria cases occurred in 2011-2012 in two regions of the rainy South-Eastern Madagascar, where malaria is considered as mesoendemic and the population is supposed to be protected by its acquired immunity against Plasmodium. A multidisciplinary investigation was conducted in order to identify the causes of the outbreak.Methods: In March 2012, a cross-sectional study was conducted in 20 randomly selected clusters, involving the rapid diagnostic testing of all >= 6 month-old members of households and a questionnaire about socio-demographic data and exposure to malaria control interventions. Changes in environmental conditions were evaluated by qualitative interview of local authorities, climatic conditions were evaluated by remote-sensing, and stock outs of malaria supplies in health facilities were evaluated by quantitative means. Two long-lasting insecticidal nets (LLINs) were sampled in each cluster in order to evaluate their condition and the remanence of their insecticidal activity. The entomological investigation also encompassed the collection Anopheles vectors in two sites, and the measure of their sensitivity to deltamethrin.Results: The cross-sectional survey included 1615 members of 440 households. The mean Plasmodium infection rate was 25.6 % and the mean bed net use on the day before survey was 71.1 %. The prevalence of Plasmodium infections was higher in 6-14 year-old children (odds ratio (OR) 7.73 [95 % CI 3.58-16.68]), in rural areas (OR 6.25 [4.46-8.76]), in poorest socio-economic tercile (OR 1.54 [1.13-2.08]), and it was lower in individuals sleeping regularly under the bed net (OR 0.51 [0.32-0.82]). Stock outs of anti-malarial drugs in the last 6 months have been reported in two third of health facilities. Rainfalls were increased as compared with the three previous rainy seasons. Vectors collected were sensitive to pyrethroids. Two years after distribution, nearly all LLINs collected showed a loss of physical integrity and insecticide activity,Conclusions: Increased rainfall, decreasing use and reduced insecticide activity of long-lasting insecticide-treated nets, and drug shortages may have been responsible for, or contributed to, the outbreak observed in South-Eastern Madagascar in 2011-2012. Control interventions for malaria elimination must be sustained at the risk of triggering harmful epidemics, even in zones of high transmission.