Morphological identification and genetic characterization of Anopheles stephensi in Somaliland

Ali, Said M.; Samake, Jeanne N; Spear, Joseph; Carter, Tamar E.

doi:10.1186/s13071-022-05339-y

Cited by 29 publications

(30 citation statements)

References 26 publications

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“…The An. stephensi detected showed similar breeding sites to those documented in the Horn of Africa [4,9,10,12], and highlights the importance of integrating WaSH measures with larval control, given a reliance on open water containers. Further detection and genomic analyses are required to reveal the pattern and direction of spread to inform integrated vector control programmes aiming to control An.…”

Section: Discussionsupporting

confidence: 62%

“…stephensi was from Djibouti in 2012 [4], where it has since been associated with significant urban outbreaks of malaria in 2013 and 2014, and continuously increasing annual urban malaria case numbers through to 2017 [5,6]. Subsequent discoveries in four countries, three of which host > 10.5 million conflict and disaster displaced people in camps and urban settings [7,8]; Ethiopia [9], Sudan [10] in 2019 in Somalia [11] and in 2020 in Somaliland [12] (since confirmed in multiple sites in each country [13][14][15]), suggest An. stephensi is becoming established in the region and could spread further, with potentially serious consequences for malaria control and elimination [3,15].…”

Section: Introductionmentioning

confidence: 99%

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Confirmation of the presence of Anopheles stephensi among internally displaced people’s camps and host communities in Aden city, Yemen

Allan

Weetman

Sauskojus

et al. 2023

Malar J

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Background Declines in global malaria cases and deaths since the millennium are currently challenged by multiple factors including funding limitations, limits of, and resistance to vector control tools, and also recent spread of the invasive vector species, Anopheles stephensi—especially into novel urban settings where malaria rates are typically low. Coupled with general increases in urbanization and escalations in the number of conflicts creating rapid and unplanned population displacement into temporary shelter camps within host urban areas, particularly in the Middle East and sub-Saharan Africa, increased urban malaria is a major threat to control and elimination. Methods Entomological monitoring surveys (targeting Aedes aegypti) of water containers across urban areas hosting internally displaced people (IDP) communities in Aden city, Yemen, were performed by The MENTOR Initiative, a non-governmental organisation. As part of these surveys in 2021 23 larvae collected and raised to adults were morphologically identified as An. stephensi. Twelve of the samples were sent to Liverpool School of Tropical Medicine for independent morphological assessment and genetic analysis by sequencing the ribosomal ITS2 region and the mitochondrial COI gene. Results All twelve samples were confirmed morphologically and by sequence comparison of the single ITS2 and COI haplotype detected to the NCBI BLAST database as An. stephensi. Phylogenetic analysis with comparable COI sequences indicated close relationship to haplotypes found in Djibouti and Ethiopia. Conclusion The study results confirm the presence of An. stephensi in Yemen. Confirmation of the species in multiple urban communities hosting thousands of IDPs living in temporary shelters with widescale dependency on open water containers is of particular concern due to the vulnerability of the population and abundance of favourable breeding sites for the vector. Proactive monitoring and targeted integrated vector management are required to limit impacts in this area of typically low malaria transmission, and to prevent further the spread of An. stephensi within the region.

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Section: Discussionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Confirmation of the presence of Anopheles stephensi among internally displaced people’s camps and host communities in Aden city, Yemen

Allan

Weetman

Sauskojus

et al. 2023

Malar J

View full text Add to dashboard Cite

show abstract

“…stephensi was from Djibouti in 2012, 4 where it has been associated with an over 30-fold increase in malaria since 2013. 5,6 Subsequent discoveries in Ethiopia 7 and Sudan, 8 in 2019 in Somalia 9 and in 2020 in Somaliland 9 (since con rmed in multiple sites in each country [10][11][12] ), suggest An. stephensi is becoming established in the region and could spread further, with potentially serious consequences for malaria control and elimination.…”

Section: Introductionmentioning

confidence: 99%

“…4,7,8,10 and highlights the importance of integrating WaSH measures with larval control, given a reliance on open water containers. Further detection and genomic analyses are required to reveal the pattern and direction of spread to inform integrated vector control programmes aiming to control An.…”

mentioning

confidence: 99%

Confirmation of the presence of Anopheles stephensi among a conflict-affected host community in Aden City, Yemen

Allan

Weetman

Sauskojus

et al. 2022

Preprint

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Background Declines in global malaria cases and deaths since the millennium are currently challenged by multiple factors including funding limitations, limits of, and resistance to vector control tools, and also recent spread of the invasive vector species, Anopheles stephensi – especially into novel urban settings where malaria rates are typically low. Coupled with general increases in urbanisation and escalations in the number of conflicts creating rapid and unplanned population displacement into urban areas, particularly in the Middle East and sub-Saharan Africa, increased urban malaria is a major threat to control and elimination. MethodsEntomological monitoring surveys (targeting Aedes aegypti) of water containers across urban areas hosting internally displaced people (IDP) communities in Aden city, Yemen, were performed by The MENTOR Initiative, a non-governmental organisation. As part of these surveys, in 2021 In 23 larvae collected and raised to adults were morphologically identified as An. stephensi. Twelve of the samples were sent to Liverpool School of Tropical Medicine for independent morphological assessment and genetic analysis by sequencing the ribosomal ITS2 region and the mitochondrial COI gene. ResultsAll twelve samples were confirmed morphologically and by sequence comparisons to the NCBI BLAST database as An. stephensi, with phylogenetic analysis of the COI sequences identifying a single haplotype with closest relationship to a haplotype found in Djibouti and Ethiopia. ConclusionOur results confirm the presence of An. stephensi in Yemen. Discovery of the species in an urban community hosting thousands of IDPs living in temporary shelters with widescale dependency on open water containers is of particular concern due to the vulnerability of the population and abundance of favourable breeding sites for the vector. Proactive monitoring and targeted integrated vector management are required to limit impacts in this area of typically low malaria transmission, and to prevent further the spread of An. stephensi within the region.

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“…The African invasion by An. stephensi was first reported from Djibouti City in 2012 24 and has since been recorded in Ethiopia 18,25 , Sudan 26,27 , Somalia 28 and Somaliland 29 , with recent work highlighting suitability of the continent's largest population centres (where >100 million individuals live) as a habitat for this species 16 . Whilst causality has yet to be established, emergence of An.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Dynamics of Anopheles stephensi and its Implications for Mosquito Detection and Emergent Malaria Control in the Horn of Africa

Whittaker

Hamlet

Sherrard-Smith

et al. 2022

Preprint

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Invasion of the malaria vector Anopheles stephensi across the Horn of Africa threatens control efforts across the continent, particularly in urban settings where the vector is able to proliferate. Malaria transmission across Africa is primarily determined by the abundance of dominant vectors, which often varies seasonally with rainfall. However, it remains unclear how An.stephensi abundance changes throughout the year, despite this being a crucial input to surveillance and control activities. We collate longitudinal catch-data from across its endemic range to better understand the vector's seasonal dynamics and explore the implications of this seasonality for malaria surveillance and control across the Horn of Africa. Our analyses reveal pronounced variation in seasonal dynamics, the timing and nature of which are poorly predicted by rainfall patterns. Instead, they are associated with temperature and patterns of land-use, with seasonality frequently differing between rural and urban settings. Our results show that timing entomological surveys to coincide with rainy periods is unlikely to improve the likelihood of detecting An.stephensi. Integrating these results into a model of malaria transmission, we show that timing indoor residual spraying campaigns to coincide with peak rainfall offers little improvement in reducing disease burden compared to starting in a random month. Our results suggest that unlike other major malaria vectors in Africa, rainfall may be a poor guide to predicting the timing of peaks in An.stephensi-driven malaria transmission. This highlights the urgent need for longitudinal entomological monitoring of the vector in its new environments given recent invasion and potential spread across the continent.

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Morphological identification and genetic characterization of Anopheles stephensi in Somaliland

Cited by 29 publications

References 26 publications

Confirmation of the presence of Anopheles stephensi among internally displaced people’s camps and host communities in Aden city, Yemen

Confirmation of the presence of Anopheles stephensi among internally displaced people’s camps and host communities in Aden city, Yemen

Confirmation of the presence of Anopheles stephensi among a conflict-affected host community in Aden City, Yemen

Seasonal Dynamics of Anopheles stephensi and its Implications for Mosquito Detection and Emergent Malaria Control in the Horn of Africa

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