Probable contribution of Culex quinquefasciatus mosquitoes to the circulation of chikungunya virus during an outbreak in Mombasa County, Kenya, 2017–2018

Abstract

Background Chikungunya virus is an alphavirus, primarily transmitted by Aedes aegypti and Ae. albopictus. In late 2017–2018, an outbreak of chikungunya occurred in Mombasa county, Kenya, and investigations were conducted to establish associated entomological risk factors. Methods Homes were stratified and water-filled containers inspected for immature Ae. aegypti, and larval indices were calculated. Adult mosquitoes were collected in the same homesteads using BG-Sentinel and CDC light traps and screened for chikungunya virus. Experiments were also conducted to determine the ability of Culex quinquefasciatus to transmit chikungunya virus. Results One hundred thirty-one houses and 1637 containers were inspected; 48 and 128 of them, respectively, were positive for immature Ae. aegypti, with the house index (36.60), container index (7.82) and Breteau index (97.71) recorded. Jerry cans (n = 1232; 72.26%) and clay pots (n = 2; 0.12%) were the most and least inspected containers, respectively, while drums, the second most commonly sampled (n = 249; 15.21%), were highly positive (65.63%) and productive (60%). Tires and jerry cans demonstrated the highest and lowest breeding preference ratios, 11.36 and 0.2, respectively. Over 6900 adult mosquitoes were collected and identified into 15 species comprising Cx. quinquefasciatus (n = 4492; 65.04%), Aedes vittatus (n = 1137; 16.46%) and Ae. aegypti (n = 911; 13.19%) and 2 species groups. Simpson’s dominance and Shannon-Wiener diversity indices of 0.4388 and 1.1942 were recorded, respectively. Chikungunya virus was isolated from pools of Ae. aegypti (1) and Cx. quinquefasciatus (4), two of which were males. Minimum infection rates of 3.0 and 0.8 were observed for female Ae. aegypti and Cx. quinquefasciatus, respectively. Between 25 and 31.3% of exposed mosquitoes became infected with CHIKV 7, 14 and 21 days post-exposure. For the experimentally infected Cx. quinquefasciatus mosquitoes, between 13 and 40% had the virus disseminated, with 100% transmission being observed among those with disseminated infection. Conclusions These results demonstrated high risk of chikungunya transmission for residents in the sampled areas of Mombasa. Transmission data confirmed the probable role played by Cx. quinquefasciatus in the outbreak while the role of Ae. vittatus in the transmission of chikungunya virus remains unknown.

Potential Nosocomial Infections by the Zika and Chikungunya Viruses in Public Health Facilities in the Metropolitan Area of Recife, Brazil

“…Since evidence shows that this species is not able to transmit CHIKV [20], this result can only highlight the hyperendemicity found in that area. Similar findings were reported by Cruz et al (2020) [6] in Brazil and Lutomiah et al (2021) [34] in Kenya, who reported CHIKV-positive when analyzing whole-body C. quinquefasciatus derived from field collections.…”

Spread of a Novel Indian Ocean Lineage Carrying E1-K211E/E2-V264A of Chikungunya Virus East/Central/South African Genotype across the Indian Subcontinent, Southeast Asia, and Eastern Africa

“…In addition, in the large-scale outbreak of IOL sub-lineage E1-K211E/E2-V264A carrying E1-I317V in Thailand during 2018-2020, Aedes aegypti was identified as the primary vector, and viral RNA was also found in another mosquito species, Culex quinquefasciatus [50,51]. In Mombasa, Kenya, these two mosquito species might have played a role in the outbreak of IOL sub-lineage E1-K211E/E2-V264A/E1-I317V [41,52]. Whether this mutation has a functional role in viral adaptation to Aedes aegypti or other mosquito species needs to be clarified by further studies in the future.…”

Instagram Helped to Reveal That Aedes aegypti (Diptera: Culicidae) Was the Main Vector of Chikungunya Virus (ECSA-Genotype) and Presented High Frequencies of kdr Mutations during an Explosive Outbreak in Minas Gerais, Brazil, 2023

“…quinquefasciatus pool positive for CHIKV RNA suggests the potential for transovarian or sexual transmission, as previously suggested [13,14]. In Kenya, Lutomiah et al [15] proposed the involvement of Cx. quinquefasciatus in CHIKV transmission based on the discovery of naturally infected mosquitoes and evidence of high vector competency in laboratory assays.…”

“…albopictus are highly competent for transmitting CHIKV [8,9] and have spread widely since their introduction in 1986 [10][11][12]. Additionally, urban areas in Brazil are infested with Culex quinquefasciatus, which has been found naturally infected by CHIKV [6,13,14], although its vector competence is controversial [15,16].…”