Anopheles stephensias an emerging malaria vector in the Horn of Africa with high susceptibility to EthiopianPlasmodium vivaxandPlasmodium falciparumisolates

Abstract

Anopheles stephensi, an efficient Asian malaria vector, recently spread into the Horn of Africa and may increase malaria receptivity in African urban areas. We assessed occurrence, genetic complexity, blood meal source and infection status of An. stephensi in Awash Sebat Kilo town, Ethiopia. We used membrane feeding assays to assess competence of local An. stephensi to P. vivax and P. falciparum isolates from clinical patients. 75.3% of the examined waterbodies were infested with An. stephensi developmental stages that were genetically closely related to isolates from Djibouti and Pakistan. Both P. vivax and P. falciparum were detected in wild-caught adult An. stephensi. Local An. stephensi was more receptive to P. vivax compared to a colony of An. arabiensis. We conclude that An. stephensi is an established vector in this part of Ethiopia, highly permissive for local P. vivax and P. falciparum isolates and presents an important new challenge for malaria control.Summary of the articleAn. stephensi, a metropolitan malaria vector that recently expanded to the Horn of African, was highly susceptible to local P. falciparum and P. vivax isolates from Ethiopia and may increase malariogenic potential of rapidly expanding urban settings in Africa.

Laboratory-based efficacy evaluation of Bacillus thuringiensis subspecies israelensis and temephos larvicides against larvae of Anopheles stephensi in Ethiopia

“…These sites were selected based on the previous reports of the presence of An. stephensi (Ashine et al, 2020;Balkew et al, 2020). The sampling of breeding sites was managed based on the WHO guidelines for laboratory and eld testing of mosquito larvicides (WHO, 2005).…”

“…The recently reported invasive species, An. stephensi in the country has exhibited the potential of transmitting Plasmodium falciparum and P. vivax (Ashine et al, 2020;Balkew et al 2021). The species has also been reported from different Horn of African countries including Djibouti (2012), Sudan (2016), and Somalia (2019) raising concern about appropriate vector control strategies to target this invasive species in those countries (Balkew et al, 2020;WHO, 2019a).…”

“…stephensi is also considered an urban and peri-urban adapted malaria vector, which breeds in man-made habitats such as overhead tanks, ditches and canals (Balkew et al, 2020(Balkew et al, , 2021Thomas et al, 2016). Anopheles stephensi feeds on both humans and animals, with a preference for the latter, and it exhibits more outdoor feeding (Ashine et al, 2020). Anopheles stephensi in Ethiopia is resistant to most insecticides used for bed-nets and indoor residual spraying (IRS) Balkew et al, 2021) so larviciding might be an effective control method (Balkew et al, 2021).…”

The potential impact of Anopheles stephensi establishment on the transmission of Plasmodium falciparum in Ethiopia and prospective control measures

“…stephensi behaviour within Africa was sparse, and so estimates were primarily acquired from studies in Iran, India and Pakistan, with limited data from Ethiopia. A full list of studies and parameter range estimates are in the Additional File Section 2 [5, 29-55]…”

Evaluation of anti-malaria potency of wild and genetically modified Enterobacter cloacae expressing effector proteins in Anopheles stephensi

“…The Plasmodium parasite is the causative agent of malaria, and the female Anopheles mosquito is the vector of the disease. Anopheles stephensi is the main malaria vector throughout its range from Asia to the Horn of Africa [ 2 – 5 ]. Therefore, programs aimed at controlling A. stephensi populations and limiting the ability of these mosquitoes to transmit Plasmodium (refractory mosquitoes) have the potential to reduce the burden of malaria disease [ 6 ].…”