1
|
Pang SC, Andolina C, Malleret B, Christensen PR, Lam-Phua SG, Razak MABA, Chong CS, Li D, Chu CS, Russell B, Rénia L, Ng LC, Nosten F. Singapore's Anopheles sinensis Form A is susceptible to Plasmodium vivax isolates from the western Thailand-Myanmar border. Malar J 2017; 16:465. [PMID: 29145859 PMCID: PMC5689142 DOI: 10.1186/s12936-017-2114-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 11/08/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Singapore has been certified malaria-free by the World Health Organization since November 1982. However, sporadic autochthonous malaria outbreaks do occur. In one of the most recent outbreaks of vivax malaria, an entomological investigation identified Anopheles sinensis as the most probable vector. As metaphase karyotype studies divided An. sinensis into two forms, A and B, with different vector competence: the investigation of vector competence of An. sinensis found in Singapore was thus pursued using Plasmodium vivax field isolates from the Thailand-Myanmar border. METHODS Adults and larvae An. sinensis were collected from Singapore from 14 different locations, using various trapping and collection methods between September 2013 and January 2016. Molecular identification of An. sinensis species were conducted by amplifying the ITS2 and CO1 region using PCR. Experimental infections of An. sinensis using blood from seven patients infected with P. vivax from the Thailand-Myanmar border were conducted with Anopheles cracens (An. dirus B) as control. RESULTS Phylogenetic analysis showed that An. sinensis (F22, F2 and collected from outbreak areas) found in Singapore was entirely Form A, and closely related to An. sinensis Form A from Thailand. Artificial infection of these Singapore strain An. sinensis Form A resulted in the development of oocysts in four experiments, with the number of sporozoites produced by one An. sinensis ranging from 4301 to 14,538. CONCLUSIONS Infection experiments showed that An. sinensis Form A from Singapore was susceptible to Thai-Myanmar P. vivax strain, suggesting a potential role as a malaria vector in Singapore.
Collapse
Affiliation(s)
- Sook-Cheng Pang
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543 Singapore
| | - Chiara Andolina
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Benoit Malleret
- Singapore Immunology Network (SIgN), A*STAR, 8A Biomedical Grove, Singapore, 138648 Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, 5 Science Drive 2, Blk MD4, Level 3, Singapore, 117597 Singapore
| | - Peter R. Christensen
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Sai-Gek Lam-Phua
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore
| | | | - Chee-Seng Chong
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543 Singapore
| | - Cindy S. Chu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Bruce Russell
- Department of Microbiology and Immunology, University of Otago, 720 Cumberland St, Dunedin, 9016 New Zealand
| | - Laurent Rénia
- Singapore Immunology Network (SIgN), A*STAR, 8A Biomedical Grove, Singapore, 138648 Singapore
| | - Lee-Ching Ng
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Oxford, UK
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| |
Collapse
|