Emergence of artemisinin-based combination treatment failure in patients returning from sub-Saharan Africa with P. falciparum malaria

Dihydroartemisinin-piperaquine treatment failure of uncomplicated Plasmodium falciparum malaria infection in a traveller

We report a late dihydroartemisinin–piperaquine treatment failure of uncomplicated Plasmodium falciparum malaria infection in a traveller without evidence of drug resistance. The correct treatment intake was confirmed, isolates drugs susceptibility was confirmed by RSA-PSA and chemosusceptibility. No molecular markers associated with resistance to artemisinin derivatives or piperaquine were identified.

Failure of artemether-lumefantrine therapy in travellers returning to Belgium with Plasmodium falciparum malaria: an observational case series with genomic analysis

BACKGROUND

Failure of artemisinin-based combination therapy is increasingly reported in patients with Plasmodium falciparum malaria in sub-Saharan Africa. We aimed to describe the clinical and genomic characteristics of recent cases of P. falciparum malaria failing artemether-lumefantrine in Belgium.

METHODS

Travel-related cases of malaria confirmed at the national reference laboratory of the Institute of Tropical Medicine, Antwerp, Belgium, were reviewed. All cases for which attending clinicians reported persistence (beyond Day 3 post-treatment initiation, i.e. early failure) or recrudescence (from Day 7 to 42, i.e. late failure) of P. falciparum parasites despite adequate drug intake were analysed. Both initial and persistent/recurrent samples were submitted to next generation sequencing to investigate resistance-conferring mutations.

RESULTS

From July 2022 to June 2023, eight P. falciparum cases of failure with artemether-lumefantrine therapy were reported (early failure = 1; late failure = 7). All travellers were returning from sub-Saharan Africa, most (6/8) after a trip to visit friends and relatives. PfKelch13 (PF3D7_1343700) mutations associated with resistance to artemisinin were found in two travellers returning from East Africa, including the validated marker R561H in the patient with early failure and the candidate marker A675V in a patient with late failure. Additional mutations were detected that could contribute to decreased susceptibility to artemisinin in another three cases, lumefantrine in six cases and proguanil in all eight participants. Various regimens were used to treat the persistent/recrudescent cases, with favourable outcome.

CONCLUSION

Within a 12-month period, we investigated eight travellers returning from sub-Saharan Africa with P. falciparum malaria and in whom artemether-lumefantrine failure was documented. Mutations conferring resistance to antimalarials were found in all analysed blood samples, especially against lumefantrine and proguanil, but also artemisinin. There is a pressing need for systematic genomic surveillance of resistance to antimalarials in international travellers with P. falciparum malaria, especially those experiencing treatment failure.

Absence of association between Pfnfs1 mutation and in vitro susceptibility to lumefantrine in Plasmodium falciparum

Artemether-lumefantrine (AL) is the most widely used antimalarial drug for treating uncomplicated falciparum malaria. This study evaluated whether the K65Q mutation in the Plasmodium falciparum cysteine desulfurase IscS (Pfnfs1) gene was associated with alternated susceptibility to lumefantrine using clinical parasite samples from Ghana and the China-Myanmar border area. Parasite isolates from the China-Myanmar border had significantly higher IC50 values to lumefantrine than parasites from Ghana. In addition, the K65 allele was significantly more prevalent in the Ghanaian parasites (34.5%) than in the China-Myanmar border samples (6.8%). However, no difference was observed in the lumefantrine IC50 value between the Pfnfs1 reference K65 allele and the non reference 65Q allele in parasites from the two regions. These data suggest that the Pfnfs1 K65Q mutation may not be a reliable marker for reduced susceptibility to lumefantrine.

Out of Africa: Increasing reports of artemether-lumefantrine treatment failures of uncomplicated Plasmodium falciparum infection

Studies of travellers returning from Africa with uncomplicated Plasmodium falciparum infection are starting to provide signals of failure of artemether-lumefantrine, a first-line treatment of uncomplicated malaria. Traveller-based reports offer an important adjunct to antimalarial efficacy studies performed in endemic regions.