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Abstract：
BACKGROUND: Malaria transmission in Tanzania is driven by mosquitoes of the Anopheles gambiae complex and Anopheles funestus group. The latter includes An. funestus s.s., an anthropophilic vector, which is now strongly resistant to public health insecticides, and several sibling species, which remain largely understudied despite their potential as secondary vectors. This paper provides the initial results of a cross-country study of the species composition, distribution and malaria transmission potential of members of the Anopheles funestus group in Tanzania.
METHODS: Mosquitoes were collected inside homes in 12 regions across Tanzania between 2018 and 2022 using Centres for Disease Control and Prevention (CDC) light traps and Prokopack aspirators. Polymerase chain reaction (PCR) assays targeting the noncoding internal transcribed spacer 2 (ITS2) and 18S ribosomal DNA (18S rDNA) were used to identify sibling species in the An. funestus group and presence of Plasmodium infections, respectively. Where DNA fragments failed to amplify during PCR, we sequenced the ITS2 region to identify any polymorphisms.
RESULTS: The following sibling species of the An. funestus group were found across Tanzania: An. funestus s.s. (50.3%), An. parensis (11.4%), An. rivulorum (1.1%), An. leesoni (0.3%). Sequencing of the ITS2 region in the nonamplified samples showed that polymorphisms at the priming sites of standard species-specific primers obstructed PCR amplification, although the ITS2 sequences closely matched those of An. funestus s.s., barring these polymorphisms. Of the 914 samples tested for Plasmodium infections, 11 An. funestus s.s. (1.2%), and 2 An. parensis (0.2%) individuals were confirmed positive for P. falciparum. The highest malaria transmission intensities [entomological inoculation rate (EIR)] contributed by the Funestus group were in the north-western region [108.3 infectious bites/person/year (ib/p/y)] and the south-eastern region (72.2 ib/p/y).
CONCLUSIONS: Whereas An. funestus s.s. is the dominant malaria vector in the Funestus group in Tanzania, this survey confirms the occurrence of Plasmodium-infected An. parensis, an observation previously made in at least two other occasions in the country. The findings indicate the need to better understand the ecology and vectorial capacity of this and other secondary malaria vectors in the region to improve malaria control.
METHODS: Mosquitoes were collected inside homes in 12 regions across Tanzania between 2018 and 2022 using Centres for Disease Control and Prevention (CDC) light traps and Prokopack aspirators. Polymerase chain reaction (PCR) assays targeting the noncoding internal transcribed spacer 2 (ITS2) and 18S ribosomal DNA (18S rDNA) were used to identify sibling species in the An. funestus group and presence of Plasmodium infections, respectively. Where DNA fragments failed to amplify during PCR, we sequenced the ITS2 region to identify any polymorphisms.
RESULTS: The following sibling species of the An. funestus group were found across Tanzania: An. funestus s.s. (50.3%), An. parensis (11.4%), An. rivulorum (1.1%), An. leesoni (0.3%). Sequencing of the ITS2 region in the nonamplified samples showed that polymorphisms at the priming sites of standard species-specific primers obstructed PCR amplification, although the ITS2 sequences closely matched those of An. funestus s.s., barring these polymorphisms. Of the 914 samples tested for Plasmodium infections, 11 An. funestus s.s. (1.2%), and 2 An. parensis (0.2%) individuals were confirmed positive for P. falciparum. The highest malaria transmission intensities [entomological inoculation rate (EIR)] contributed by the Funestus group were in the north-western region [108.3 infectious bites/person/year (ib/p/y)] and the south-eastern region (72.2 ib/p/y).
CONCLUSIONS: Whereas An. funestus s.s. is the dominant malaria vector in the Funestus group in Tanzania, this survey confirms the occurrence of Plasmodium-infected An. parensis, an observation previously made in at least two other occasions in the country. The findings indicate the need to better understand the ecology and vectorial capacity of this and other secondary malaria vectors in the region to improve malaria control.
摘要：
背景：坦桑尼亚的疟疾传播是由冈比亚按蚊和按蚊群的蚊子驱动的。后者包括An。funestuss.s.,一个嗜人媒介,现在对公共卫生杀虫剂有很强的抵抗力，和几个兄弟姐妹物种，尽管它们具有作为次要载体的潜力，但仍未得到充分研究。本文提供了物种组成的跨国研究的初步结果，坦桑尼亚按蚊群体成员的分布和疟疾传播潜力。
方法：在2018年至2022年之间，使用疾病控制和预防中心（CDC）的光诱捕器和Prokopack吸引器在坦桑尼亚12个地区的房屋中收集蚊子。针对非编码内部转录间隔区2（ITS2）和18S核糖体DNA（18SrDNA）的聚合酶链反应（PCR）测定法用于鉴定An中的同胞物种。Funestus组和疟原虫感染的存在，分别。当DNA片段在PCR过程中扩增失败时，我们对ITS2区域进行了测序以鉴定任何多态性。
结果：以下An的同胞物种。在坦桑尼亚各地发现了funestus组：funestuss.s.(50.3%)，A.双亲(11.4%)，A.rivulorum(1.1%),A.leesoni(0.3%)。非扩增样品中ITS2区域的测序表明，标准物种特异性引物引发位点的多态性阻碍了PCR扩增，尽管ITS2序列与An的序列紧密匹配。funestuss.s.,禁止这些多态性。在检测疟原虫感染的914个样本中，11An.funestuss.s.(1.2%)，和2安。双壁（0.2％）个体被确认为恶性疟原虫阳性。Funestus组贡献的最高疟疾传播强度[昆虫接种率（EIR）]在西北地区[108.3传染性叮咬/人/年（ib/p/y）]和东南地区（72.2ib/p/y）。
结论：而An。Funestuss.s.是坦桑尼亚Funestus组中的主要疟疾媒介，这项调查证实了疟原虫感染的发生。肠胃外,先前在该国至少两次其他场合中进行的观察。研究结果表明，需要更好地了解该地区这种和其他继发性疟疾病媒的生态和媒介能力，以改善疟疾控制。
方法：在2018年至2022年之间，使用疾病控制和预防中心（CDC）的光诱捕器和Prokopack吸引器在坦桑尼亚12个地区的房屋中收集蚊子。针对非编码内部转录间隔区2（ITS2）和18S核糖体DNA（18SrDNA）的聚合酶链反应（PCR）测定法用于鉴定An中的同胞物种。Funestus组和疟原虫感染的存在，分别。当DNA片段在PCR过程中扩增失败时，我们对ITS2区域进行了测序以鉴定任何多态性。
结果：以下An的同胞物种。在坦桑尼亚各地发现了funestus组：funestuss.s.(50.3%)，A.双亲(11.4%)，A.rivulorum(1.1%),A.leesoni(0.3%)。非扩增样品中ITS2区域的测序表明，标准物种特异性引物引发位点的多态性阻碍了PCR扩增，尽管ITS2序列与An的序列紧密匹配。funestuss.s.,禁止这些多态性。在检测疟原虫感染的914个样本中，11An.funestuss.s.(1.2%)，和2安。双壁（0.2％）个体被确认为恶性疟原虫阳性。Funestus组贡献的最高疟疾传播强度[昆虫接种率（EIR）]在西北地区[108.3传染性叮咬/人/年（ib/p/y）]和东南地区（72.2ib/p/y）。
结论：而An。Funestuss.s.是坦桑尼亚Funestus组中的主要疟疾媒介，这项调查证实了疟原虫感染的发生。肠胃外,先前在该国至少两次其他场合中进行的观察。研究结果表明，需要更好地了解该地区这种和其他继发性疟疾病媒的生态和媒介能力，以改善疟疾控制。
