Anopheles sundaicus Mosquitoes as Vector for Plasmodium knowlesi, Andaman and Nicobar Islands, India

Abstract

Using PCR and sequencing, we found Plasmodium knowlesi in the malaria vector Anopheles sundaicus mosquito collected from Katchal Island in the Andaman and Nicobar Islands, India. We cannot rule out natural transmission of this parasite to humans through this mosquito species. An in-depth investigation is needed to prevent disease outbreaks.

Keywords: Andaman and Nicobar Islands; Anopheles sundaicus; DNA; India; PCR; Plasmodium knowlesi; macaques; malaria; mosquitoes; parasites; vector-borne infections.

Figure 1

Phylogenetic relationship of Plasmodium knowlesi from the Andaman and Nicobar Islands, India, to other strains from Southeast Asia countries, inferred by using the neighbor-joining method. Isolates are identified by GenBank accession number and location; Plasmodium coatneyi is used as outgroup. Triangle indicates sequence of P. knowlesi isolated in this study (accession no. MK079654) that shares a similar clade with a Myanmar sequence (accession no. GU816246). Isolates from Peninsular Malaysia (accession no. JX870044) and China (accession no. KX007957) are also closer to the Andaman isolate. Scale bar indicates nucleotide substitutions per site.

Figure 2

Agarose gel (2%) electrophoresis of nested PCR products of amplified Plasmodium knowlesi DNA sequences taken from mosquito samples (10 mosquitoes per pool) from Andaman and Nicobar Islands. A) Analysis of PCR products amplified with Pmk8 and Pmk9 primers. Lanes 1–4, pools of Anopheles sundaicus mosquitoes; lane 5, size marker DNA (100-bp DNA ladder); lanes 6 and 7, An. maculatus mosquito pools; lane 8, An. barbirostris mosquito pool (2 mosquitoes); lane 9, positive control; lane 10, negative control. Arrows indicate positive sample from the An. sundaicus mosquito pool in lane 3, 500 bp marker in DNA ladder of lane 5, and positive control in lane 9. B) Analysis of nested PCR products amplified with PKF1140 and PKR1550 primers. Lanes 1–5, An. sundaicus mosquito pools; lanes 6–9, An. maculatus mosquito pools; lane 10, size marker DNA (100-bp DNA ladder); lane 11, An. maculatus mosquito pool; lane 12, An. barbirostris mosquito pool; lane 13, positive control; lane 14, negative control. Arrows indicate An. sundaicus mosquito pool with positive band at 410 bp in lane 3, 600-bp marker in DNA ladder in lane 10, and positive control of 410 bp in lane 13. PC, positive control.