A decade of invasive Anopheles stephensi sequence-based identification: toward a global standard

Abstract

Anopheles stephensi is an invasive malaria vector in Africa that has been implicated in malaria outbreaks in the Horn of Africa. In 10 years, it has been detected as far east as Djibouti and as far west as Ghana. Early detections were mostly incidental, but now active surveillance in Africa has been updated to include An. stephensi. Morphological identification of An. stephensi from native vectors can be challenging, thus, sequence-based assays have been used to confirm identification during initial detections. Methods of sequence-based identification of An. stephensi have varied across initial detections to date. Here, we summarize initial detections, make suggestions that could provide a standardized approach, and discuss how sequences can inform additional genomic studies beyond species identification.

Keywords: Anopheles stephensi; genetics; genomics; global health policy; malaria.

Figure 1.. The distribution of percent identities of NCBI BLAST results of An. stephensi sequences of ITS2 (A) and COI (B).

As shown, out of the top 100 BLAST hits with the input sequences, An. stephensi is identified at 86% and above for ITS2 and 98% and above for COI.

Figure 2.. Phylogenetic trees of ITS2 (A) and COI (B) sequences.

Sequences in bold represent novel sequences that may be produced in a study. Bootstrap values are represented on the branches.