Oxborough Richard M
Richard Oxborough Consultancy, London, UK.
Malar J. 2016 Mar 8;15:146. doi: 10.1186/s12936-016-1201-1.
This article reports the changing pattern of US President's Malaria Initiative-funded IRS in sub-Saharan Africa between 2008 and 2015. IRS coverage in sub-Saharan Africa increased from <2 % of the at-risk population in 2005, to 11 % or 78 million people in 2010, mainly as a result of increased funding from PMI. The scaling up of IRS coverage in sub-Saharan Africa has been successful in several epidemiological settings and contributed to reduced malaria transmission rates. However, the spread and intensification of pyrethroid resistance in malaria vectors led many control programmes to spray alternative insecticides. Between 2009 and 2013, pyrethroid spraying decreased from 87 % (13/15) of PMI-funded countries conducting IRS to 44 % (7/16), while bendiocarb use increased from 7 % (1/15) to 56 % (9/16). Long-lasting pirimiphos-methyl CS received WHOPES recommendation in 2013 and was scheduled to be sprayed in 85 % (11/13) of PMI-funded countries conducting IRS in 2015. The gradual replacement of relatively inexpensive pyrethroids, firstly with bendiocarb (carbamate) and subsequently with pirimiphos methyl CS (organophosphate), has contributed to the downscaling of most PMI-funded IRS programmes. Overall, there was a 53 % decrease in the number of structures sprayed between years of peak coverage and 2015, down from 9.04 million to 4.26 million structures. Sizeable reductions in the number of structures sprayed were reported in Madagascar (56 %, 576,320-254,986), Senegal (64 %, 306,916-111,201), Tanzania (68 %, 1,224,095-389,714) and Zambia (63 %, 1,300,000-482,077), while in Angola, Liberia and Malawi PMI-funded spraying was suspended. The most commonly cited reason was increased cost of pesticides, as vector resistance necessitated switching from pyrethroids to organophosphates. There are worrying preliminary reports of malaria resurgence following IRS withdrawal in parts of Benin, Tanzania and Uganda. The increase in malaria cases following the end of the Global Malaria Eradication Programme in 1969 highlights the fragility of such gains when control efforts are weakened. At present there are several countries reliant on organophosphates and carbamates for IRS, and increasing incipient resistance is a serious threat that could result in IRS no longer being viable. A portfolio of new cost-effective insecticides with different modes of action is urgently needed.
本文报告了2008年至2015年期间美国总统疟疾防治倡议（PMI）资助的撒哈拉以南非洲室内滞留喷洒（IRS）项目模式的变化。撒哈拉以南非洲的IRS覆盖率从2005年占高危人群的不到2%，增加到2010年的11%，即7800万人，这主要是由于PMI增加了资金投入。在撒哈拉以南非洲扩大IRS覆盖率在多个流行病学环境中取得了成功，并有助于降低疟疾传播率。然而，疟蚊对拟除虫菊酯的耐药性不断扩散和增强，导致许多防治项目改用其他杀虫剂。2009年至2013年期间，进行IRS的PMI资助国家中，使用拟除虫菊酯喷洒的国家比例从87%（13/15）降至44%（7/16），而使用残杀威的比例从7%（1/15）增至56%（9/16）。长效甲基嘧啶磷缓释剂于2013年获得世界卫生组织农药评价计划（WHOPES）推荐，并计划在2015年进行IRS的PMI资助国家中85%（11/13）的国家使用。相对便宜的拟除虫菊酯逐渐被取代，首先是被残杀威（氨基甲酸酯类）取代，随后是被甲基嘧啶磷缓释剂（有机磷类）取代，这导致了大多数PMI资助的IRS项目规模缩减。总体而言，从覆盖率峰值年份到2015年，喷洒房屋数量减少了53%，从904万间降至426万间。马达加斯加（56%，从576,320间降至254,986间）、塞内加尔（64%，从306,916间降至111,201间）、坦桑尼亚（68%，从1,224,095间降至389,714间）和赞比亚（63%，从130万间降至482,077间）报告的喷洒房屋数量大幅减少，而在安哥拉、利比里亚和马拉维，PMI资助的喷洒工作已暂停。最常被提及的原因是杀虫剂成本增加，因为病媒耐药性使得必须从拟除虫菊酯转向有机磷类。在贝宁、坦桑尼亚和乌干达部分地区，有令人担忧的初步报告称IRS取消后疟疾有所复发。1969年全球疟疾根除计划结束后疟疾病例增加，凸显了控制措施减弱时此类成果的脆弱性。目前有几个国家在IRS中依赖有机磷类和氨基甲酸酯类杀虫剂，而初现的耐药性不断增加是一个严重威胁，可能导致IRS不再可行。迫切需要一批具有不同作用方式的新的经济高效杀虫剂。
