The common European mosquitoes Culex pipiens and Aedes albopictus are unable to transmit SARS-CoV-2 after a natural-mimicking challenge with infected blood

Abstract

Background On 11 March 2020, the World Health Organisation (WHO) declared the coronavirus disease 2019 (COVID-19) outbreak to be a pandemic. As the mosquito season progressed, the understandable concern that mosquitoes could transmit the virus began to increase among the general public and public health organisations. We have investigated the vector competence of Culex pipiens and Aedes albopictus, the two most common species of vector mosquitoes in Europe, for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Due to the very unusual feeding behaviour of Ae. albopictus, we also evaluated the role of this mosquito in a potential mechanical transmission of the virus. Methods For the vector competence study, mosquitoes were allowed to take several infectious blood meals. The mosquitoes were then collected and analysed at 0, 3, 7 and 10 days post-feeding. For the mechanical transmission test, Ae. albopictus females were allowed to feed for a short time on a feeder containing infectious blood and then on a feeder containing virus-free blood. Both mosquitoes and blood were tested for viral presence. Results Culex pipiens and Ae. albopictus were found not be competent vectors for SARS-CoV-2, and Ae. albopictus was unable to mechanically transmit the virus. Conclusions This is the first study to show that the most common species of vector mosquitoes in Europe do not transmit SARS-CoV-2 and that Ae. albopictus is unable to mechanically transmit the virus from a positive host to a healthy host through host-feeding.

SARS-CoV-2 and Arthropods: A Review

“…albopictus and Cx. pipiens [ 27 ] that were presented with infected blood meals. Mosquitoes were collected at 0-, 3-, 7-, and 10-days post-feeding and then bodies and legs and wings were tested by RT-qPCR to determine infection and dissemination rates respectively.…”

“…Virus was detected in Ae. albopictus but the low viral load (6.32 × 10 2 to 3.44 × 10 1 plaque forming unit equivalents) limits the possibility of mechanical transmission [ 27 ]. Balaraman et al [ 38 ] exposed house flies, Musca domestica , to milk contaminated with SARS-CoV-2 and demonstrated that flies could remain positive for up to 24 h post-exposure and that viral RNA could be detected on surfaces with which they had come into contact.…”

Impact of COVID-19 Mitigation Measures on Mosquito-Borne Diseases in 2020 in Queensland, Australia

“…The response was that unlike true arboviruses, such as the DENVs, RRV and ZIKV, it was highly unlikely that SARS-CoV-2 would be able to infect or be transmitted by mosquitoes. As experimental evidence supporting this advice accumulated in the scientific literature [ 35 , 36 ], it greatly assisted community messaging. Whilst there remains no scientific evidence to support the suggestion that mosquitoes may be vectors of SARS-CoV-2, public concern and media coverage associated with this unfounded concern has undoubtedly distracted from other health messaging regarding actual mosquito-borne disease risk.…”

Zoonotic and Reverse Zoonotic Transmissibility of SARS-CoV-2

“…Although insects do have ACE2, these are very different from those in humans and are therefore predicted to be unable to bind efficiently with SARS-CoV-2 ( Cashman et al, 2019 ). Recent studies demonstrated that SARS-CoV-2 replication was not supported in biting midges ( Culicoides sonorensis ) and mosquitoes ( Aedes aegypti, Aedes albopictus, Culex pipiens, Culex quinquefasciatus , and Culex tarsalis ), suggesting that these species are unable to be biological vectors of SARS-CoV-2 ( Balaraman et al, 2021a ; Fortuna et al, 2021 ; Huang et al, 2020c ). However, it has been demonstrated that houseflies ( Musca domestica ) can acquire and harbor infectious SARS-CoV-2 for up to 24 hours post-exposure ( Balaraman et al, 2021b ).…”