Novel Mutation in Cytochrome B of Plasmodium falciparum in One of Two Atovaquone-Proguanil Treatment Failures in Travelers Returning From Same Site in Nigeria.
BACKGROUND
Atovaquone-proguanil (AP) is the most commonly used treatment for uncomplicated Plasmodium falciparum malaria in the United States. Apparent AP treatment failures were reported 7 months apart in 2 American travelers who stayed in the same compound for foreign workers in Rivers State, Nigeria.


METHODS
We analyzed pretreatment (day 0) and day of failure samples from both travelers for mutations in the P falciparum cytochrome B (pfcytb) and dihydrofolate reductase (pfdhfr) genes associated with resistance to atovaquone and cycloguanil, the active metabolite of proguanil, respectively. We genotyped the parasites and sequenced their mitochondrial genomes.


RESULTS
On day 0, both travelers had proguanil-resistant genotypes but atovaquone-sensitive cytb sequences. Day of failure samples exhibited mutations in cytb for both travelers. One traveler had the common Y268S mutation, whereas the other traveler had a previously unreported mutation, I258M. The travelers had unrelated parasite genotypes and different mitochondrial genomes.


CONCLUSIONS
Despite the infections likely having been contracted in the same site, there is no evidence that the cases were related. The mutations likely arose independently during the acute infection or treatment. Our results highlight the importance of genotyping parasites and sequencing the full cytb and dhfr genes in AP failures to rule out transmission of AP-resistant strains and identify novel mechanisms of AP resistance.
Division of Parasitic Diseases and Malaria, Center for Global Health ; Epidemic Intelligence Service , Centers for Disease Control and Prevention , Atlanta, Georgia.
Mateusz M
MM
Plucinski
Division of Parasitic Diseases and Malaria, Center for Global Health.
Curtis S
CS
Huber
Division of Parasitic Diseases and Malaria, Center for Global Health.
Sheila
S
Akinyi
Terrebonne General Medical Center, Houma, Louisiana.
Willard
W
Dalton
Terrebonne General Medical Center, Houma, Louisiana.
Mary
M
Eschete
Division of Parasitic Diseases and Malaria, Center for Global Health.
Katharine
K
Grady
Division of Parasitic Diseases and Malaria, Center for Global Health.
Luciana
L
Silva-Flannery
Division of Parasitic Diseases and Malaria, Center for Global Health.
Blaine A
BA
Mathison
Division of Parasitic Diseases and Malaria, Center for Global Health.
Venkatachalam
V
Udhayakumar
Division of Parasitic Diseases and Malaria, Center for Global Health.
Paul M
PM
Arguin
Division of Parasitic Diseases and Malaria, Center for Global Health.
John W
JW
Barnwell
Malarone; Plasmodium falciparum; dihydrofolate reductase; drug resistance; malaria