Novel pfdhps haplotypes among imported cases of Plasmodium falciparum malaria in the United Kingdom.
Treatment of acute malaria caused by Plasmodium falciparum may include long-half-life drugs, such as the antifolate combination sulfadoxine-pyrimethamine (SP), to provide posttreatment chemoprophylaxis against parasite recrudescence or delayed emergence from the liver. An unusual case of P. falciparum recrudescence in a returned British traveler who received such a regimen, as well as a series of 44 parasite isolates from the same hospital, was analyzed by PCR and direct DNA sequencing for the presence of markers of parasite resistance to chloroquine and antifolates. The index patient harbored a mixture of wild-type and resistant pfdhfr and pfdhps alleles upon initial presentation. During his second malaria episode, he harbored only resistant parasites, with the haplotypes IRNI (codons 51, 59, 108, and 164) and SGEAA (codons 436, 437, 540, 581, and 613) at these two loci, respectively. Analysis of isolates from 44 other patients showed that the pfdhfr haplotype IRNI was common (found in 81% of cases). The SGEAA haplotype of pfdhps was uncommon (found only in eight cases of East African origin [17%]). A previously undescribed mutation, I431V, was observed for seven cases of Nigerian origin, occurring as one of two haplotypes, VAGKGS or VAGKAA. The presence of this mutation was also confirmed in isolates of Nigerian origin from the United Kingdom Malaria Reference Laboratory. The presence of the pfdhps haplotype SGEAA in P. falciparum parasites of East African origin appears to compromise the efficacy of treatment regimens that include SP as a means to prevent recrudescence. Parasites with novel pfdhps haplotypes are circulating in West Africa. The response of these parasites to chemotherapy needs to be evaluated.
HPA Parasite Reference Laboratory, Department of Clinical Parasitology, Hospital for Tropical Diseases, Mortimer Market Centre, Capper St., London WC1E 6JB, United Kingdom. colin.sutherland@lshtm.ac.uk
Colin J
CJ
Sutherland
Helen
H
Fifer
Richard J
RJ
Pearce
Faisal
F
bin Reza
Meredydd
M
Nicholas
Thomas
T
Haustein
Njah E
NE
Njimgye-Tekumafor
Justin F
JF
Doherty
Philip
P
Gothard
Spencer D
SD
Polley
Peter L
PL
Chiodini
D000328:Adult; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use; D053626:Atovaquone / Q000627:therapeutic use; D002738:Chloroquine / Q000494:pharmacology / Q000627:therapeutic use; D004094:Dihydropteroate Synthase / Q000235:genetics*; D004338:Drug Combinations; D004351:Drug Resistance / Q000235:genetics; D005493:Folic Acid Antagonists / Q000627:therapeutic use; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000469:parasitology*; D008297:Male; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D002727:Proguanil / Q000627:therapeutic use; D011739:Pyrimethamine / Q000627:therapeutic use; D017422:Sequence Analysis, DNA; D013413:Sulfadoxine / Q000627:therapeutic use; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics; D006113:United Kingdom
D000962:Antimalarials; D004338:Drug Combinations; D005493:Folic Acid Antagonists; C109496:atovaquone, proguanil drug combination; C001205:fanasil, pyrimethamine drug combination; D013413:Sulfadoxine; D002738:Chloroquine; D013762:Tetrahydrofolate Dehydrogenase; D004094:Dihydropteroate Synthase; D002727:Proguanil; D053626:Atovaquone; D011739:Pyrimethamine