Kamgang Basile, Acântara João, Tedjou Armel, Keumeni Christophe, Yougang Aurelie, Ancia Anne, Bigirimana Françoise, Clarke Sian E, Gil Vilfrido Santana, Wondji Charles
Centre for Research in Infectious Diseases, Department of Medical Entomology, Yaoundé, Cameroon.
Centro Nacional de Endemias, Ministério da Saúde de São Tomé e Príncipe, Agua Grande, São Tomé e Príncipe.
PLoS Negl Trop Dis. 2024 Jun 3;18(6):e0011903. doi: 10.1371/journal.pntd.0011903. eCollection 2024 Jun.
The first dengue outbreak in Sao Tome and Principe was reported in 2022. Entomological investigations were undertaken to establish the typology of Aedes larval habitats, the distribution of Ae. aegypti and Ae. albopictus, the related entomological risk and the susceptibility profile of Ae. aegypti to insecticides, to provide evidence to inform the outbreak response.
METHODOLOGY/PRINCIPAL FINDINGS: Entomological surveys were performed in all seven health districts of Sao Tome and Principe during the dry and rainy seasons in 2022. WHO tube and synergist assays using piperonyl butoxide (PBO) and diethyl maleate (DEM) were carried out, together with genotyping of F1534C/V1016I/V410L mutations in Ae. aegypti. Aedes aegypti and Ae. albopictus were found in all seven health districts of the country with high abundance of Ae. aegypti in the most urbanised district, Agua Grande. Both Aedes species bred mainly in used tyres, discarded tanks and water storage containers. In both survey periods, the Breteau (BI > 50), house (HI > 35%) and container (CI > 20%) indices were higher than the thresholds established by WHO to indicate high potential risk of dengue transmission. The Ae. aegypti sampled were susceptible to all insecticides tested except dichlorodiphenyltrichloroethane (DDT) (9.2% mortality, resistant), bendiocarb (61.4% mortality, resistant) and alpha-cypermethrin (97% mortality, probable resistant). A full recovery was observed in Ae. aegypti resistant to bendiocarb after pre-exposure to synergist PBO. Only one Ae. aegypti specimen was found carrying F1534C mutation.
CONCLUSIONS/SIGNIFICANCE: These findings revealed a high potential risk for dengue transmission throughout the year, with the bulk of larval breeding occurring in used tyres, water storage and discarded containers. Most of the insecticides tested remain effective to control Aedes vectors in Sao Tome, except DDT and bendiocarb. These data underline the importance of raising community awareness and implementing routine dengue vector control strategies to prevent further outbreaks in Sao Tome and Principe, and elsewhere in the subregion.
圣多美和普林西比2022年首次报告登革热疫情。开展了昆虫学调查，以确定埃及伊蚊幼虫栖息地类型、埃及伊蚊和白纹伊蚊的分布、相关昆虫学风险以及埃及伊蚊对杀虫剂的敏感性概况，为疫情应对提供依据。
方法/主要发现：2022年旱季和雨季期间，在圣多美和普林西比的所有七个卫生区进行了昆虫学调查。使用胡椒基丁醚（PBO）和马来酸二乙酯（DEM）进行了世卫组织试管和增效剂试验，并对埃及伊蚊的F1534C/V1016I/V410L突变进行了基因分型。在该国所有七个卫生区均发现了埃及伊蚊和白纹伊蚊，在城市化程度最高的阿瓜格兰德区，埃及伊蚊数量众多。两种伊蚊主要在废旧轮胎、废弃水箱和储水容器中繁殖。在两个调查期间，布雷托指数（BI>50）、房屋指数（HI>35%）和容器指数（CI>20%）均高于世卫组织确定的表明登革热传播高潜在风险的阈值。所采集的埃及伊蚊对除滴滴涕（死亡率9.2%，抗性）、残杀威（死亡率61.4%，抗性）和高效氯氰菊酯（死亡率97%，可能抗性）之外的所有测试杀虫剂敏感。预先接触增效剂PBO后，对残杀威有抗性的埃及伊蚊出现了完全恢复。仅发现一只埃及伊蚊标本携带F1534C突变。
结论/意义：这些发现揭示了全年登革热传播的高潜在风险，大部分幼虫滋生发生在废旧轮胎、储水处和废弃容器中。除滴滴涕和残杀威外，大多数测试杀虫剂对圣多美控制伊蚊媒介仍然有效。这些数据强调了提高社区意识和实施常规登革热媒介控制策略对于预防圣多美和普林西比以及该次区域其他地方进一步疫情爆发的重要性。
