Kulkarni, M. A. | Search bioRxiv

bioRxiv2021

Increasing role of pyrethroid-resistant Anopheles funestus in malaria transmission in the Lake Zone, Tanzania: implications for the evaluation of novel vector control products

Anopheles funestus is playing an increasing role in malaria transmission in parts of sub-Saharan Africa, where An. gambiae s.s. has been effectively controlled by long-lasting insecticidal nets. We investigated vector population bionomics, insecticide resistance and malaria transmission dynamics in 86 study clusters in North-West Tanzania. An. funestus s.l. represented 94.5% (4740/5016) of all vectors and was responsible for the majority of malaria transmission (96.5%), with a sporozoite rate of 3.4% and average monthly entomological inoculation rate (EIR) of 4.57 per house. Micro-geographical heterogeneity in species composition, abundance and transmission was observed across the study district in relation to key ecological differences between northern and southern clusters, with significantly higher densities, proportions and EIR of An. funestus s.l. collected from the south. An. gambiae s.l. (5.5%) density, principally An. arabiensis (81.1%) and An. gambiae s.s. (18.9%), was much lower and closely correlated with seasonal rainfall. Both An. funestus s.l. and An. gambiae s.l. were similarly resistant to alpha-cypermethrin and permethrin. Overexpression of CYP9K1, CYP6P3, CYP6P4 and CYP6M2 and high L1014F-kdr mutation frequency were detected in An. gambiae s.s. populations. Study findings highlight the urgent need for novel vector control tools to tackle persistent malaria transmission in the Lake Region of Tanzania.

zoology↗

bioRxiv2019

Arbovirus Vectors of Epidemiological Concern in the Americas: A Scoping Review of Entomological Studies on Zika, Dengue and Chikungunya Virus Vectors

BackgroundThree arthorpod-borne viruses (arboviruses) causing human disease have been the focus of a large number of studies in the Americas since 2013 due to their global spread and epidemiological impacts: Zika, dengue, and chikungunya viruses. A large proportion of infections by these viruses are asymptomatic. However, all three viruses are associated with moderate to severe health consequences in a small proportion of cases. Two mosquito species, Aedes aegypti and Aedes albopictus, are among the worlds most prominent arboviral vectors, and are known primary vectors for all three viruses in the Americas.\n\nObjectivesThis review summarizes the state of the entomological literature surrounding the biology and ecology of vectors of Zika, dengue and chikungunya viruses and factors affecting virus transmission. The rationale of the review was to elucidate consensus and discord between studies, and guide future research based on identified knowledge gaps.\n\nResultsA total of 196 studies were included in the scoping review after initial screening and subsequent exclusion of out-of-scope studies, secondary data publications, duplicate records, and studies unavailable in English language.\n\nKey findingsTemperature and humidity have the strongest impact on mosquito distribution and dynamics, development of immatures and arborviral infection rates. Low socioeconomic status and related factors, including poor infrastructure, inconsistent access to water, and high household resident density, have been consistently associated with arbovirus vector occurrence. Effects of interspecific competition on arboviral vector species is currently poorly understood. Vector competence for Zika virus is well established for Ae. aegypti and Ae. albopictus. Information on Zika virus vector transmission dynamics is sparse in contrast to the wealth of research available for dengue and chikungunya viruses.\n\nConclusionsBased on the internationally recognized urgency of Zika virus infection as a public health concern, further research on arbovirus vectors and transmission dynamics is of pressing need.

ecology↗