Dkf200.fm

Journal of Antimicrobial Chemotherapy (2002) 50, 751–754
DOI: 10.1093/jac/dkf200
Evidence for the efficacy of artesunate in asymptomatic
Plasmodium malariae infections
Steffen Borrmann1,2*, Nicole Szlezák1,3, Ronald K. Binder1, Michel A. Missinou1,2, Bertrand Lell1,2 and
Peter G. Kremsner1,2
1Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, B. P. 118, Gabon; 2Department of Parasitology, Institute of Tropical Medicine, University of Tübingen, Wilhelmstrasse 27, D-72074 Tübingen, Germany; 3John F. Kennedy School of Government, Harvard University, Cambridge, MA 02138, USA Received 10 January 2002; returned 16 May 2002; revised 29 May 2002; accepted 12 August 2002 This study evaluated the efficacy and safety of a 3-day course of artesunate (4 mg/kg/day) for
asymptomatic Plasmodium malariae infections. The parasitological cure rates on days 7 and 56
in the group treated with artesunate were 100% and 83%, respectively, compared with no cure in
the placebo group (P < 0.0001).
Keywords: Plasmodium malariae, artesunate, chemotherapy, malaria, Gabon Introduction
Materials and methods
The resistance of Plasmodium falciparum to chloroquine has The study was carried out from October 2000 to February been documented in all parts of sub-Saharan Africa.1 To a 2001 in the Province Moyen-Ogooué, Gabon, and was part of lesser extent, but still alarmingly, resistance of Plasmodium a double-blind, randomized, placebo-controlled trial includ- vivax has also been reported and raises the gloomy prospect ing 300 schoolchildren in three different villages to investig- that Plasmodium malariae and Plasmodium ovale might also ate the efficacy of artesunate and praziquantel for the develop resistance to chloroquine. Only a few anti-malarial treatment of S. haematobium infections.8 The study area is drugs have been evaluated for their efficacy against P. malar- highly endemic for P. falciparum and S. haematobium.8,9 The iae infections.2,3 Artesunate monotherapy is highly effective study described below was undertaken in a subset of partici- and well tolerated for the treatment of falciparum malaria, and pants of the S. haematobium study in one of the three study combination with standard anti-malarials is strongly advo- villages (Nombakélé) where baseline screening revealed a cated.4 Large WHO-coordinated multi-centre trials to assess high prevalence of infections with P. malariae. Community the efficacy and tolerability of 3-day courses of combinations consent and written informed consent of the parents or guard- of artesunate with chloroquine, amodiaquine and sulpha- ians of the children were obtained. Ethical clearance was doxine/pyrimethamine have been successfully conducted or obtained from the Ethics Committees of the International are still underway in many African countries, including Foundation of the Albert Schweitzer Hospital in Lambaréné, Gabon.5–7 To the best of our knowledge, no published data Gabon, and the Medical Faculty of the University of Tübin- exist on the efficacy of artesunate against P. malariae. There- fore, we studied the efficacy and tolerability of a 3-day course At baseline, children were screened for plasmodial infec- of artesunate for the clearance of asymptomatic P. malariae tions. Giemsa-stained thick blood films were prepared by the infections as part of a double-blind, randomized trial investig- Lambaréné method as described previously,10 and asexual ating the efficacy and safety of artesunate and praziquantel parasitaemia was assessed per microlitre. Briefly, 10 µL of peri- for the treatment of Schistosoma haematobium infections in pheral blood was evenly spread in an area of 18 mm by 10 mm on a clean slide. Slides were subsequently dried and stained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
*Corresponding author. Tel: +49-7071-29-80234; Fax: +49-7071-29-4684; E-mail: steffen.borrmann@uni-tuebingen.de . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2002 The British Society for Antimicrobial Chemotherapy S. Borrmann et al.
with Giemsa (20%, pH 7.2, 20 min). Parasites were counted in Nombakélé. On study day 0, 40 children received artesunate at least 100 high-powered fields (HPFs; 1000× magnifica- (Sanofi, France) 4 mg/kg/day for 3 days and praziquantel tion), and the number of parasites per microlitre was cal- placebo (Medochemie, Cyprus), 35 received artesunate culated by multiplying the mean number of parasites per HPF placebo (Sanofi) and praziquantel (Medochemie), 23 received by 600. This factor was previously determined for the study artesunate (identical dose) combined with praziquantel and microscope and depends on the magnification and the size of 10 received placebo. For our analysis, we pooled all children the HPF of a particular microscope.10 The factor was calculated who received artesunate in one group (n = 63) and the remain- according to the following formula: area of blood on slide/(area ing children in the comparator group (n = 45). To the best of of HPF at 1000× magnification × volume of blood on slide).
our knowledge, praziquantel has never been demonstrated to Thin blood smears were dried, fixed with methanol, stained for be effective against plasmodia, including negative results 30 min with Giemsa (20%, pH 7.2) and then examined micro- from analyses of our own unpublished data, and thus, for the scopically for at least 30 min (1000×). Standard morphological purpose of this study on the efficacy of artesunate in asympto- characteristics were used to distinguish parasite species.
matic P. malariae infections, the comparator group was Specifically, diagnosis of P. malariae infections was made if at considered as the placebo group for artesunate. Efficacy was least one of the following criteria was fulfilled: (i) identi- assessed on days 7 and 56 by means of methodology identical fication of P. malariae schizonts on the thick blood film and to that used for screening. Proportional data were compared (ii) identification of characteristic P. malariae stages (late using Fisher’s exact test, and exact binomial confidence inter- trophozoites with band forms, schizonts or gametocytes) on vals were calculated (Stata v7; Stata Corporation, College the thin blood smear. All blood smears were read by two independent and experienced microscopists. PCR analysis toconfirm the species specificity of microscopic diagnosis was not carried out. Haemoglobin was measured on days 0 and 56 with a portable photometric analyser (DHT Hb 523; Table 1 summarizes the baseline characteristics, including the Developing Health Technologies, UK). Reagent strips (Roche, malarial indices, of the study cohort. All children were Germany) were used for the semi-quantitative assessment of asymptomatic during the whole study period. Positive blood proteinuria. The treatment regimens were allocated sequen- smears were found in 102 children (94%). In particular, the tially according to the randomization code of the trial high prevalence of infections with P. malariae is remarkable evaluating artesunate and praziquantel for the treatment of (60 of 108 children, 56%). Sixty asymptomatic children asymptomatic S. haematobium infections. The details of the with P. malariae infections (including 18 P. malariae mono- randomization procedures have been decribed previously.8 infections) received artesunate (n = 37) or artesunate placebo One hundred and eight eligible children with asympto- (n = 23; Table 1). The urine analysis did not reveal any evid- matic S. haematobium infections were included in the study in ence of glomerulonephritis caused by P. malariae infection as Table 1. Demographic, clinical and laboratory characteristics of asymptomatic children at baseline
[data are given as arithmetic mean (standard deviation), unless otherwise indicated, or number and
percentage of children]
children with >30 mg protein/dL urine (%) geometric mean parasite density/µL (95% CI) geometric mean parasite density/µL (95% CI) mixed infection with P. falciparum and P. malariae geometric mean parasite density/µL (95% CI) mixed infection with P. falciparum, P. malariae and P. ovale Efficacy of artesunate in Plasmodium malariae infections
measured by proteinuria. Only two children infected with S. haematobium infections have been presented previously.8 P. malariae, compared with one uninfected child, had Children with plasmodial or S. haematobium infections at the ∼500 mg protein/dL urine, and no difference in the geometric end of the study received curative treatment.
mean levels of protein in the urine for infected versusuninfected children was detected (data not shown).
Discussion
All participants received the full course of the study regi- men under the direct supervision of the study physicians. Two Our study shows for the first time that a short course of arte- children in the artesunate group were excluded by day 7: one sunate is effective and well tolerated for asymptomatic P. child had not received the full treatment course and the other malariae infections. Treatment with a 3-day course of arte- child was mistakenly given the wrong treatment regimen. All sunate led to a parasitological cure rate of 83% by day 56 in a other children were followed up until day 56. The treatment semi-immune population and an increase in haemoglobin of regimens were well tolerated, and no differences in adverse 0.8 g/dL over the study period. In addition, our results indicate events by day 7 could be detected between the groups (data that praziquantel is not effective against P. malariae nor does it interfere with the efficacy of artesunate against P. malariae.
For all parasitaemic children at baseline, the results com- The reported cure rate has not been corrected for by PCR, paring efficacy of artesunate treatment against placebo are which would have enabled us to distinguish recrudescent given in Table 2. In the artesunate group, all children had from new infections. Assuming the possibility of reinfections cleared P. malariae infections by day 7, and six of 35 children occurring during the 56 day follow-up period, our results are had reappearance of parasites of P. malariae on day 56 (a curerate of 83%) compared with ongoing infections in all children therefore likely to underestimate the exact cure rate. Nonethe- in the placebo group on days 7 and 56 (P < 0.0001 for the com- less, a parasitological cure rate of 83% compares favourably parisons on days 7 and 56; Table 2). There was no difference with findings for P. falciparum where 3-day regimens of in the cure rate between children who received artesunate and artesunate are associated with high recrudescence rates by praziquantel or artesunate and placebo (19 of 23, 83%, versus day 28 in Thailand.11 No studies evaluating the efficacy of the 10 of 12, 83%; P = 0.96). Artesunate cleared P. falciparum 3-day regimen in Africa have been published so far. We parasitaemia in all children except one by day 7 (98%), but the hypothesize that the difference is primarily due to parasite cure rate fell to 38% on day 56 (Table 2). Both treatment species-related drug sensitivities. In addition, the different regimens cleared P. ovale infections (two infections in the levels of initial parasitaemia—P. malariae infections do not artesunate group and one in the placebo group).
produce the high parasite load seen with P. falciparum—and The level of haemoglobin in children infected with P. differences in the level of host immune responses may also malariae at baseline increased from day 0 to day 56 in the play an important role. Additional studies are now needed to group receiving artesunate, compared with the group who confirm the efficacy of a short course of artesunate alone, or did not receive artesunate, but this difference did not reach preferably in combination, for curing clinical episodes of significance (0.8 versus 0.1 g/dL; P = 0.1 with paired t-test).
P. malariae infections in non-immune and semi-immune Results on the efficacy of praziquantel and artesunate in Table 2. Efficacy of artesunate versus placebo for asymptomatic P. malariae infections in children
geometric mean parasite density/µL (95% CI) geometric mean parasite density/µL (95% CI) aP < 0.0001 for the comparison with placebo.
bP = 0.0001 for the comparison with placebo.
S. Borrmann et al.
The importance of P. malariae for the development of com- 3. Ringwald, P., Bickii, J., Same-Ekobo, A. & Basco, L. K. (1997).
plications of falciparum malaria (e.g. severe anaemia) remains Pyronaridine for treatment of Plasmodium ovale and Plasmodium
malariae infections. Antimicrobial Agents and Chemotherapy 41,
so far unknown. However, morbidity from P. malariae infec- tions contributes to the excessive but preventable diseaseburden in sub-Saharan African countries. Co-infections of 4. White, N. J. & Olliaro, P. (1998). Artemisinin and derivatives in
the treatment of uncomplicated malaria. Médecine Tropicale 58,
P. malariae with P. falciparum are common, and the diag- nostic repertoire to differentiate between the species islimited. Treatment decisions in sub-Saharan Africa are over- 5. Adjuik, M., Agnamey, P., Babiker, A., Borrmann, S., Brasseur,
P., Cisse, M. et al. (2002). Amodiaquine-artesunate versus amodi- whelmingly based on clinical criteria, and light microscopy aquine for uncomplicated Plasmodium falciparum malaria in African plays a negligible role. An ideal anti-malarial will thus be cheap children: a randomised, multicentre trial. Lancet 359, 1365–72.
and well tolerated as well as highly effective not only againstP. falciparum but also against P. malariae and P. ovale. Pend- 6. Olliaro, P., Taylor, W. R. & Rigal, J. (2001). Controlling malaria:
challenges and solutions. Tropical Medicine and International ing the confirmation of our results in symptomatic P. malariae Health 6, 922–7.
infections, our study adds support to the use of a 3-day courseof artesunate in combination with other anti-malarials in future 7. von Seidlein, L., Milligan, P., Pinder, M., Bojang, K., Anyale-
bechi, C., Gosling, R. et al. (2000). Efficacy of artesunate plus pyrimethamine-sulphadoxine for uncomplicated malaria in Gambian
children: a double-blind, randomised, controlled trial. Lancet 355,
Acknowledgements
8. Borrmann, S., Szlezák, N., Faucher, J. F., Matsiegui, P. B.,
We would like to acknowledge the crucial support of Mr Neubauer, R., Binder, R. K. et al. (2001). Artesunate and prazi- Phaedon Ellinas, Medochemie, and Dr Jean-Pascal Ducret, quantel for the treatment of Schistosoma haematobium infections: a Sanofi, for providing the study medication. We are indebted double-blind, randomized, placebo-controlled study. Journal of
Infectious Diseases 184, 1363–6.
to the study children, their parents and schoolteachers. Wethank Dr Adrian Luty for carefully reviewing the manuscript.
9. Wildling, E., Winkler, S., Kremsner, P. G., Brandts, C., Jenne, L.
We also thank the local health workers Brigitte Migombet and & Wernsdorfer, W. H. (1995). Malaria epidemiology in the province
of Moyen Ogoov, Gabon. Tropical Medicine and Parasitology 46,
Jean-Roger Avera. In addition, we thank Swissair for the 10. Planche, T., Krishna, S., Kombila, M., Engel, K., Faucher, J. F.,
Ngou-Milama, E. et al. (2001). Comparison of methods for the rapid
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