Relapses in Plasmodium Ovale and Efficacy of Artemether-lumefantrine for Mixed Species and Non-falciparum Malaria
Relapses in Plasmodium Ovale and Efficacy of Artemether-lumefantrine for Mixed Species and Non-falciparum Malaria
Malaria is a protozoan infection transmitted by anopheline mosquitoes. The most severe forms
 are caused by Plasmodium (P) falciparum and to a much lesser extent by P. vivax.

 Although the interest in research on malaria has increased during the last years, yet little
 research is conducted on the "neglected" malaria species P. ovale and P. malariae. P. ovale
 being first described in 1922, it still remains unclear whether it displays dormant
 pre-erythrocytic liver stages, so called hypnozoites, or not. Primaquine, the only marketed
 drug with liver stage activity at present, can cause severe hemolysis in glucose-6-phosphate
 dehydrogenase (G6PD) deficient persons and methemoglobinemia. Because G6PD is widely spread
 in Central Africa, it is important to explore whether additional intake of liver-active
 medication is really needed and on this account further research to investigating new
 treatment options with liver stage activity should be conducted.

 While, due to widespread resistance, treatment recommendations for P. falciparum and mixed
 infections have switched from chloroquine to the safer applicable artemisinin-based
 combination therapies (ACTs), World Health Organization (WHO) guidelines still suggest
 chloroquine as first line treatment for P. malariae and P. ovale mono infections. Further
 studies assessing alternative treatment options are largely missing.

 Summing up the current situation for both topics shows the need for further research.
 Therefore this study aims to assess the evidence and characterize the frequency of relapses
 in P. ovale infections with respect to differences between its subspecies as well as the
 effectiveness of the ACT artemether-lumefantrine in P. malariae and P. ovale mono- and mixed
 infections.
Although P. ovale hypnozoites have never been demonstrated by biological experiments and
 findings in the literature about relapses are controversial, a 14 days primaquine standard
 therapy is recommended for every patient suffering from P. ovale infection. As there is no
 clear evidence of relapses of P. ovale it is of importance to conclusively analyze clinical
 evidence for its relapse potential to evaluate the necessity for further anti-relapse
 treatment options.

 Moreover, summarizing the actual situation shows the need for further evaluation of the
 clinical use of ACTs in non-falciparum infections:

 -  Firstly, molecular diagnostic methods indicate that P. malariae and P. ovale are more
 prevalent than previously thought. In many settings malaria is treated on clinical
 suspicion. Diagnosis by microscopy is difficult if parasitemia is low and
 differentiation of species requires experience. This leads to the assumption that P.
 malariae and P. ovale infections are already blindly treated with the common ACTs
 recommended for P. falciparum malaria. The evaluation of artemisinin based combination
 therapies for non-falciparum malaria is therefore essential.

 -  Secondly, combination therapies have proven to be protective for the emergence of
 resistant parasites and in Asia combination therapy could even reduce resistance. As
 chloroquine-resistant P. malariae parasites have been reported, a combination therapy
 should be implemented in order to stop the emergence and spread of further resistance.
 Additionally, artemisinins can, in contrast to chloroquine, reduce transmissibility by
 their gametocytocidal activity.

 A uniform treatment algorithm for all four Plasmodium species would simplify and facilitate
 treatment of malaria. With the reduction of chloroquine use in settings of poor quality
 diagnosis, the risk of fatal treatment failure due to wrongly administered chloroquine to
 chloroquine-resistant P. falciparum would be decreased. Finally, if no 8-aminoquinoline
 treatment was necessary for P. ovale infections, this could improve the safety and compliance
 of treatment.

 The study is designed as an open label prospective study with a within group design. Patients
 enrolled will receive oral artemether-lumefantrine tablets as a 6 dose regimen over 3
 consecutive days (Day 0, 1 and 2). Dosage depends on the patient's weight is according to the
 manufacturers recommendations. Patients will be followed for 42 days. If P. ovale is
 diagnosed at baseline, a one-year follow-up will be conducted every second week.

 Parasite density, expressed as the number of parasites per microliter (µl) of blood, will be
 measured regularly to determine parasite clearance time (PCT).

 Blood smears preparation, staining, examination and interpretation will be done according to
 the Lambaréné method. Thick and thin blood films for parasite count and species diagnosis
 should be obtained and examined at screening on D0 to confirm inclusion/exclusion criteria.
 Thick blood films will be examined every 24h following first dose administration and until
 the parasites have cleared. Thick and thin blood films will be also examined on Days 7, 14,
 21, 28, 35 and 42 or on any other day if the patient spontaneously returns. For participants
 with P. ovale infection at baseline, reading of thick and thin blood films will be continued
 every second week for up to one year. In case of reappearance of parasites, Coartem will be
 administered again and Follow-up will be continued as scheduled.

 Diagnosis of P. ovale will be effected by PCR. Furthermore, genotyping studies will be used
 to differentiate a new infection from relapse or recrudescence and to confirm microscopic
 diagnosis of species. Plasma samples will be collected and stored for further pharmacokinetic
 analysis 7 days after treatment initiation.

 To determine the efficacy clinically, body temperature and clinical signs and symptoms of
 malaria will be assessed. Safety assessments include physical examination, vital signs and
 hematology.

 Adverse Events and Serious Adverse Events will be ascertained. The investigator or his / her
 staff will notify the Independent Ethics Committee of all Serious Adverse Events as soon as
 possible and in accordance with local regulations.
Inclusion Criteria:

 -  Male or female patients older than 1 year

 -  Presence of uncomplicated malaria infection confirmed by: fever or history of fever in
 the previous 3 days, and positive microscopy of P. malariae, P. ovale or mixed
 infection with parasite density > 10 - 200000/µl of blood

 -  Residence in vicinity and no travel plans for the next 6 months

 -  Written informed consent by the patient or the legal representative and where
 possible, patient assent will be sought. If the patient/parent/guardian is unable to
 write, witnessed consent is permitted according to local ethical considerations.

 Exclusion Criteria:

 -  Presence of P. falciparum monoinfection

 -  Presence of severe malaria (clinical WHO criteria)

 -  Presence of other febrile conditions

 -  Known history of hypersensitivity, allergic or adverse reactions to artemether or
 lumefantrine

 -  Intake of any antimalarials or antibiotics with known antimalarial activity in the
 past 72 hours

 -  Intake of an 8-aminoquinoline antimalarial or atovaquone-proguanil in preceding 28
 days

 -  Pregnant women in first trimenon