背景:白纹伊蚊和埃及伊蚊因其作为登革热(DENV)和基孔肯雅(CHIKV)病毒载体的潜力而闻名。然而,昆虫学调查主要在流行病期间进行。在加蓬,两种病毒都爆发了,没有针对这些虫媒病毒的媒介控制程序。因此,我们评估了Lambaréné(加蓬)及其周边地区沿城乡梯度的伊蚊物种的存在,并确定了与其存在相关的生态因素。
方法:在Lambaréné及其周围农村地区进行了昆虫学调查。蚊子是用吸气器在人类住宅周围收集的,并从每个研究区域收集生态和环境数据。形态识别键用于识别伊蚊物种。从雌性蚊子池中提取RNA并通过RT-qPCR扩增以检测DENV和CHIKV的存在。
结果:总体而言,收集到的最常见的媒介是白纹伊蚊(97%,4236/4367个标本),其次是埃及伊蚊(3%,131/4367)。白纹病媒体在农村地区更为丰富(Wilcoxon符号秩检验,Z=627,P=0.043)比市区高。在市区,在经济区(第3区)记录的蚊子数量(45%)高于历史和行政区(第1区和第2区)。在农村地区,与北部农村样带相比,南部农村样带的物种数量比例明显更高(92%)(Wilcoxon符号秩检验,Z=43,P=0.016)。我们还注意到,在以巴西橡胶树(Hevea)和Manihotesculenta(木薯)的单种培养为特征的环境中,载体的丰度很高(Kruskal-WallisH检验,H=25.7,df=2,P<0.001)。最后,没有蚊子池对DENV或CHIKV呈阳性。
结论:白纹伊蚊由于其高侵袭能力而成为研究中心的主要载体。这种存在再次确认了DENV和CHIKV在当地传播的潜力,正如之前在我们研究区域进行的血清学调查所表明的那样,即使在当前研究期间未检测到传播。这些发现强调了在研究区域定期进行虫媒病毒监测的必要性,目的是在疫情爆发时支持病媒控制工作。
BACKGROUND: Aedes albopictus and Aedes aegypti are known for their potential as vectors of dengue (DENV) and chikungunya (CHIKV) viruses. However, entomological surveys are mostly carried out during epidemics. In Gabon where outbreaks of both viruses have occurred, there is no vector control program targeting these arboviruses. Therefore, we assessed the presence of Aedes species along a rural-urban gradient in Lambaréné (Gabon) and its surroundings and determined ecological factors associated to their presence.
METHODS: An entomological survey was conducted in Lambaréné and its surrounding rural areas. Mosquitoes were collected with aspirators around human dwellings, and ecological and environmental data were collected from each study area. Morphological identification keys were used to identify Aedes species. RNA was extracted from pools of female mosquitoes and amplified by RT-qPCR to detect the presence of DENV and CHIKV.
RESULTS: Overall, the most common vector collected was Aedes albopictus (97%, 4236/4367 specimens), followed by Aedes aegypti (3%, 131/4367). Albopictus vectors was more abundant in the rural area (Wilcoxon signed-rank test, Z = 627, P = 0.043) than in the urban area. In the urban area, a higher number of mosquitoes (45%) were recorded in the economic zone (zone 3) than in the historical and administrative zones (zone 1 and 2). In the rural area, the proportions of species numbers were significantly higher along the south rural transect (92%) compared to the north rural transect (Wilcoxon signed-rank test, Z = 43, P ˂ 0.016). We also noted a high abundance of vectors in environments characterized by monocultures of Hevea brasiliensis (Hevea) and Manihot esculenta (cassava) (Kruskal-Wallis H-test, H = 25.7, df = 2, P < 0.001). Finally, no mosquito pools were positive for either DENV or CHIKV.
CONCLUSIONS: Aedes albopictus was the dominant vector across the study sites due to its high invasiveness capacity. This presence re-affirms the potential for local transmission of both DENV and CHIKV, as indicated previously by serological surveys conducted in our study area, even though no transmission was detected during the current study. These findings underscore the need for regular arbovirus surveillance in the study region, with the aim of supporting vector control efforts in the event of outbreaks.