Ex vivo drug sensitivity profiles of Plasmodium falciparum field isolates from Cambodia and Thailand, 2005 to 2010, determined by a histidine-rich protein-2 assay.
BACKGROUND
In vitro drug susceptibility assay of Plasmodium falciparum field isolates processed "immediate ex vivo" (IEV), without culture adaption, and tested using histidine-rich protein-2 (HRP-2) detection as an assay, is an expedient way to track drug resistance.


METHODS
From 2005 to 2010, a HRP-2 in vitro assay assessed 451 P. falciparum field isolates obtained from subjects with malaria in western and northern Cambodia, and eastern Thailand, processed IEV, for 50% inhibitory concentrations (IC50) against seven anti-malarial drugs, including artesunate (AS), dihydroartemisinin (DHA), and piperaquine.


RESULTS
In western Cambodia, from 2006 to 2010, geometric mean (GM) IC50 values for chloroquine, mefloquine, quinine, AS, DHA, and lumefantrine increased. In northern Cambodia, from 2009-2010, GM IC50 values for most drugs approximated the highest western Cambodia GM IC50 values in 2009 or 2010.


CONCLUSIONS
Western Cambodia is associated with sustained reductions in anti-malarial drug susceptibility, including the artemisinins, with possible emergence, or spread, to northern Cambodia. This potential public health crisis supports continued in vitro drug IC50 monitoring of P. falciparum isolates at key locations in the region.
Department of Immunology and Medicine, US Army Medical Corps, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
Stuart D
SD
Tyner
Chanthap
C
Lon
Youry
Y
Se
Delia
D
Bethell
Doung
D
Socheat
Harald
H
Noedl
Darapiseth
D
Sea
Wichai
W
Satimai
Kurt
K
Schaecher
Wiriya
W
Rutvisuttinunt
Mark M
MM
Fukuda
Suwanna
S
Chaorattanakawee
Kritsanai
K
Yingyuen
Siratchana
S
Sundrakes
Panjaporn
P
Chaichana
Piyaporn
P
Saingam
Nillawan
N
Buathong
Sabaithip
S
Sriwichai
Soklyda
S
Chann
Ans
A
Timmermans
David L
DL
Saunders
Douglas S
DS
Walsh
D000293:Adolescent; D000328:Adult; D000368:Aged; D000953:Antigens, Protozoan / Q000096:biosynthesis*; D000962:Antimalarials / Q000494:pharmacology*; D002160:Cambodia; D002648:Child; D002675:Child, Preschool; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D021261:Parasitic Sensitivity Tests / Q000379:methods; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000302:isolation & purification; D015800:Protozoan Proteins / Q000096:biosynthesis*; D013785:Thailand; D055815:Young Adult
D000953:Antigens, Protozoan; D000962:Antimalarials; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins