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. 2023 Jan;29(1):164-169.
doi: 10.3201/eid2901.220036.

Survey of West Nile and Banzi Viruses in Mosquitoes, South Africa, 2011-2018

Caitlin MacIntyre, Milehna Mara Guarido, Megan Amy Riddin, Todd Johnson, Leo Braack, Maarten Schrama, Erin Gorsich, Antonio Paulo Gouveia Almeida, Marietjie Venter

Survey of West Nile and Banzi Viruses in Mosquitoes, South Africa, 2011-2018

Caitlin MacIntyre et al. Emerg Infect Dis. 2023 Jan.

Abstract

We collected >40,000 mosquitoes from 5 provinces in South Africa during 2011-2018 and screened for zoonotic flaviviruses. We detected West Nile virus in mosquitoes from conservation and periurban sites and potential new mosquito vectors; Banzi virus was rare. Our results suggest flavivirus transmission risks are increasing in South Africa.

Keywords: Banzi virus; Culex; Culicidae; South Africa; West Nile virus; disease vectors; flavivirus; vector-borne infections; viruses; zoonoses.

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Figures

Figure 1
Figure 1
Sentinel and ad hoc mosquito collection sites across the northeastern region of South Africa in survey of West Nile and Banzi viruses in mosquitoes, South Africa, 2011–2018. Collection sites were selected according to recent cases of arboviral disease in humans and animals. Asterisks in the color-coded figure legend indicate sites where flaviviruses were identified in mosquitoes.
Figure 2
Figure 2
Phylogenetic analysis of flaviviruses using NS5 gene sequences in survey of West Nile and Banzi viruses in mosquitoes, South Africa, 2011–2018. Maximum likelihood analysis was used to identify flaviviruses found in mosquitoes after partial sequencing of the flavivirus NS5 gene region (226 nt, Kimura 2-parameter model plus gamma distribution plus proportion of invariable sites). Sequence data were edited by using CLC Main Workbench version 8.0.1 (QIAGEN, https://www.qiagen.com). Reference genomes were downloaded from GenBank. Multiple sequence alignments were created by using MAFFT (https://mafft.cbrc.jp/alignment/server/index.html) with default parameters. Phylogenetic analysis was performed by using MEGA X software (MEGA, https://www.megasoftware.net) with bootstrap support for network groupings calculated from 1,000 replicates. Bootstrap values (>70%) are displayed on branches. GenBank accession numbers for newly sequenced virus strains: OL411950 (KYA11MP13 isolate), OL411951 (GAU11MP26 isolate), OL411952 (KYA14MP133 isolate), OL411953 (KYA14MP134 isolate), OL411954 (LAP14MP394 isolate), OL411955 (MAR15MP18 isolate), OL411956 (LAP13MP22 isolate), OL411957 (KNP17MP714 isolate), OL411958 (KNP17MP720 isolate), OL411959 (KNP17MP718 isolate), OL411960 (KYA11MP11 isolate), OL411961 (LAP13MP25 isolate), and OL411962 (LAP13MP26 isolate). Solid black triangles are new viral sequences that were detected in mosquitoes in this study. Scale bar indicates nucleotide substitutions per site.
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