Molecular Surveillance for Multidrug-ResistantPlasmodium falciparum, Cambodia

Naman K Shah,Chansuda Wongsrichanalai,Frederic Ariey,Sinuon Muth,Jason D Maguire,Socheat Duong,Steven R Meshnick,Alisa P Alker,Rithy Sem,Agustina Ika Susanti

doi:10.3201/eid1410.080080

Naman K Shah, Chansuda Wongsrichanalai + Show 8 more

Open Access

https://doi.org/10.3201/eid1410.080080

Copy DOI

Abstract

We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective.

Highlights

We have previously shown that elevated P. falciparum multidrug resistance 1 gene copy number is associated with an 8-fold risk for artesunate–mefloquine failure in western Cambodia (6)
Study participants included patients who were seen at health centers with uncomplicated falciparum malaria, including mixed infections
Institutional review board approvals were obtained from the Cambodian National Ethics Committee for Health Research, the US Naval Medical Research Unit No 2, and the University of North Carolina at Chapel Hill (UNC)

Summary

Phnom Penh

Author affiliations: University of North Carolina School of Public Health, Chapel Hill, North Carolina, USA When compared with results at UNC, results of copy number assays performed by the National Malaria Control Program (NMCP) staff in Phnom Penh were slightly lower (mean difference –0.163, 95% confidence interval [CI] –0.277 to –0.049, n = 44), and the 2 groups were in 100% concordance with distinguishing samples with >2 pfmdr[1] copies. The prevalence of parasite samples with amplified pfmdr[1] varied by site and differed in the prevalence of 2 and >3 copies of pfmdr[1] (Figure 1). The prevalence of pfmdr1-184-Phe varied by site, was significantly higher in the West (85.5% vs 17.1%, OR = 27.4, 95% CI 18.1–41.4), but was not more prevalent in samples with pfmdr[1] copy number >1.5 when site was controlled for (OR = 1.5, 95% CI 0.9–28, p = 0.139).

Memut Rattanakiri

Conclusions

Findings

Multivariate linear regression*