Malaria epidemic and drug resistance, Djibouti.Analysis of Plasmodium falciparum Plasmodium fal·cip·a·rum n. A protozoan that causes falciparum malaria. isolates collected before, during, and after a 1999 malaria epidemic in Djibouti shows that, despite a high prevalence of resistance to chloroquine chloroquine /chlo·ro·quine/ (klor´o-kwin) an antiamebic and anti-inflammatory used in the treatment of malaria, giardiasis, extraintestinal amebiasis, lupus erythematosus, and rheumatoid arthritis; used also as the hydrochloride and , the epidemic cannot be attributed to a sudden increase in drug resistance of local parasite populations. ********** From March to June 1999, an epidemic of Plasmodium falciparum malaria affecting all age groups spread in the city of Djibouti, Horn of Africa Horn of Africa, peninsula, NE Africa, opposite the S Arabia Peninsula. Also known as the Somali Peninsula, it encompasses Somalia and E Ethiopia and is the easternmost extension of the continent, separating the Gulf of Aden from the Indian Ocean. , an area with low and irregular transmission. Since the 1970s, autochthonous autochthonous /au·toch·tho·nous/ (aw-tok´thah-nus) 1. originating in the same area in which it is found. 2. denoting a tissue graft to a new site on the same individual. cases of malaria have been reported among the local population, but their incidence is usually low (1). Anopheles Anopheles: see mosquito. arabiensis, the main malaria vector in the city (2,3), has been found since the 1970s, possibly from Ethiopia (1,4). The focused distribution and the specificity of the breeding sites allowed a control strategy based on treatment of the larval larval 1. pertaining to larvae. 2. larvate. larval migrans see cutaneous and visceral larva migrans. sites with a larvivorous autochthonous fish, complemented with pinpoint use of bacterial toxins (3). Unfortunately, malaria control activities were progressively decreased so that, since the mid-1990s, vector control activity has been reduced to irregular insecticide indoor or outdoor spraying. Djiboutians frequently travel, and the Djibouti-Ethiopian railway has been suspected to be an effective route for propagating malaria parasites (5). Although some chloroquine treatment failures were reported in Djibouti in 1990 (6), most persons with P. falciparum were treated by chloroquine or quinine quinine (kwī`nīn', kwĭnēn`), white crystalline alkaloid with a bitter taste. Before the development of more effective synthetic drugs such as quinacrine, chloroquine, and primaquine, quinine was the specific agent in the treatment of at the beginning of the 2000s, including during the 1999 epidemics. To determine whether this epidemic was associated with temporary changes in environmental conditions or to importation of new (virulent) or resistant P. falciparum strains, we investigated P. falciparum population diversity before, during, and after the outbreak and analyzed in vitro in vitro /in vi·tro/ (in ve´tro) [L.] within a glass; observable in a test tube; in an artificial environment. in vi·tro adj. In an artificial environment outside a living organism. susceptibility profiles to a panel of antimalarials during the epidemics. The Study The study was conducted at the Centre Hospitalier des Armees Bouffard, a French military hospital in Djibouti serving military and civilian natives from the entire city, and at other public health facilities of Djibouti. From 1997 to 2002 clinical malaria in the hospital shows the same temporal fluctuations as in dispensaries in the city (Figure). The incidence of patients with P. falciparum malaria fal·cip·a·rum malaria n. Malaria caused by Plasmodium falciparum and characterized by severe malarial paroxysms that recur about every 48 hours and often by acute cerebral, renal, or gastrointestinal manifestations. admitted to the hospital increased >10-fold from March to May 1999 compared with the same period in 1997, 1998, and 2000-2002. In contrast, the number of admissions, consultations at the outpatient clinic, or blood counts performed for other causes than fever did not vary over the same period. The meteorologic me·te·or·ol·o·gy n. The science that deals with the phenomena of the atmosphere, especially weather and weather conditions. [French météorologie, from Greek station of the international airport of Djibouti recorded heavy rainfall the month before the epidemic. However, similar rainfall in 1997 or autumn 1999 was not followed by such a dramatic increase in malaria incidence in the ensuing months (Figure). When annual averages were compared, no particular variations in minimal or maximal mean air temperatures were found to occur during the months preceding the epidemic. [FIGURE OMITTED] Forty-six blood samples were collected from September 14 to December 31, 1998 (period 1), 61 from April 12 to April 30, 1999 (period 2), and 32 from March 15 to May 15, 2002 (period 3), from patients with P. falciparum clinical cases who had not travelled outside the city of Djibouti during the preceding month and declared not having taken any antimalarial drug before the blood sampling. The study was cleared by the Djibouti Ministry of Health. Informed oral consent was obtained from patients before blood collection. Venous blood venous blood n. Abbr. v Blood that has passed through the capillaries of various tissues other than the lungs, is found in the veins, in the right chambers of the heart, and in pulmonary arteries, and is usually dark red as a result of a was collected before treatment administration in Vacutainer EDTA EDTA: see chelating agents. tubes (Becton Dickinson, Rutherford, NJ, USA). Thin blood smears were stained with an RAL 1. RAL - Rutherford Appleton Laboratory (UK). 2. RAL - An expert system. kit (Reactifs RAL, Paris, France). Parasitemia parasitemia /par·a·si·te·mia/ (par?ah-si-te´me-ah) the presence of parasites, especially malarial forms, in the blood. par·a·si·te·mi·a n. The presence of parasites in the blood. was expressed as the proportion of P. falciparum--infected erythrocytes Erythrocytes Red blood cells. Mentioned in: Bartonellosis erythrocytes (ē·rithˑ·rō·sīts), n.pl red blood cells. . Aliquots of freshly collected blood were kept at -20[degrees]C until DNA extraction. P. falciparum genetic diversity was investigated by using msp1 and msp2 encoding highly polymorphic polymorphic - polymorphism loci loci [L.] plural of locus. loci Plural of locus, see there from merozoite surface protein A merozoite surface protein is a protein molecule taken from the skin, or surface, of a merozoite. A merozoite is a "daughter cell" of a protozoan. Merozoite surface proteins, or MSPs, are useful in researching malaria, a disease caused by protozoans. genes. Msp1 and msp2 were genotyped by using nested polymerase chain reaction Nested polymerase chain reaction is a modification of polymerase chain reaction intended to reduce the contaminations in products due to the amplification of unexpected primer binding sites. (PCR PCR polymerase chain reaction. PCR abbr. polymerase chain reaction Polymerase chain reaction (PCR) ), as described (7), except that family-specific fluorescent primers were used in the nested PCR for assignment to the K1-, Mad20-, or Ro33-type msp1 family and to the 3D7- or FC27-type msp2 family. Fragment length was analyzed by the Genescan technology. Approximately 50% of the blood samples contained multiple msp1 or msp2 genotypes. The mean multiplicity of infection The multiplicity of infection or MOI is the ratio of infectious agents (e.g. phage or virus) to infection targets (e.g. cell). For example, when referring to a group of cells inoculated with infectious virus particles, the multiplicity of infection or MOI is the ratio , i.e., the number of genotypes present in the blood sample, was [approximately equal to] concurrent P. falciparum infections per person, with a decreasing tendency over the study period (Table 1). For each locus, multi-infection cases were excluded from analysis of genetic diversity. We identified 9 msp1 alleles in 83 isolates and 17 msp2 alleles in 108 isolates. The genetic diversity estimated by the unbiased expected heterozygocity (8), i.e., the probability that 2 randomly chosen genotypes are different in the sample, before, during, and after the 1999 outbreak was 0.79 (n = 23), 0.37 (n = 39), and 0.64 (n = 21) at the msp1 locus and 0.83 (n = 31), 0.34 (n = 47) and 0.63 (n = 30) at the msp2 locus, respectively. During the epidemic, Ro33-131 accounted for 79% of the msp1 allele allele (əlēl`): see genetics. allele Any one of two or more alternative forms of a gene that may occur alternatively at a given site on a chromosome. and FC27-408 accounted for 81% of the msp2 alleles. Both alleles were present before and after the epidemic but with a much lower prevalence. They accounted for 26% of the msp1 and 35% of the msp2 alleles in 1998 and 14% of the msp1 and 10% of the msp2 alleles in 2002 (Table 2). To look for resistance-associated point mutations and haplotypes, the complete coding region of Pfdhfr (dihydrofolate reductase dihydrofolate reductase enzyme catalyzing the conversion of folate to 5,6,7,8-tetrahydrofolate, which is the key carrier of one-carbon units in purine and pyridime synthesis, the pathway for the breakdown of histidine and the synthesis of S-adenosylmethionine from S ) and Pfdhps (dihydropteroate synthase synthase /syn·thase/ (-thas) a term used in the names of some enzymes, particularly lyases, when the synthetic aspect of the reaction is dominant or emphasized. syn·thase n. ) was amplified and sequenced (ABI Abi (ā`bī) [short for Abijah], in the Bible, King Hezekiah's mother. (Application Binary Interface) A specification for a specific hardware platform combined with the operating system. 3100 Genetic Analyser, Applied Biosystems, Courtaboeuf, France) as described (9). We focused the analysis on point mutations of Pfdhfr codons 16, 51, 59, 108, and 164 and Pfdhps codons 436, 437, 540, 581, and 613, which have been associated with resistance to pyrimethamine pyrimethamine /pyr·i·meth·amine/ (pir?i-meth´ah-men) a folic acid antagonist, used in the treatment of malaria and of toxoplasmosis. py·ri·meth·a·mine n. and proguanil Proguanil (proguanil hydrochloride) is a prophylactic antimalarial drug, which works by stopping the malaria parasite, Plasmodium falciparum and Plasmodium vivax, from reproducing once it is in the red blood cells. metabolite metabolite, organic compound that is a starting material in, an intermediate in, or an end product of metabolism. Starting materials are substances, usually small and of simple structure, absorbed by the organism as food. and to sulfadoxine, respectively (10). The prevalences of the Pfdhfr and Pfdhps mutations are shown in Table 1. No mutant was detected for Pfdhfr codons 16 and 164 and Pfdhps codon codon: see nucleic acid. 581. A single isolate collected in period 2 harbored the Pfdhps A613S mutation. No isolate harbored the quintuple quin·tu·ple adj. 1. Consisting of five parts or members. 2. Five times as much in size, strength, number, or amount. n. A fivefold amount or number. tr. & intr.v. mutant haplotype haplotype /hap·lo·type/ (-tip) the group of alleles of linked genes, e.g., the HLA complex, contributed by either parent; the haploid genetic constitution contributed by either parent. hap·lo·type n. (Pfdhfr S108N, N51I, and C59R and Pfdhps K540E and A437G) or the Pfdhfr C59R and Pfdhps K540E combination that predicts sulfadoxine-pyrimethamine clinical failure (9). One isolate containing at least 2 P. falciparum populations harbored 3 Pfdhfr mutations (S108N, N51I, and C59R) and the Pfdhps K540E mutation. From 1998 to 1999, the frequency of isolates with mutated Pfdhfr codons 51, 59, and 108 decreased (not significantly), and Pfdhps allelic al·lele n. One member of a pair or series of genes that occupy a specific position on a specific chromosome. [German Allel, short for Allelomorph, allelomorph, from English frequency did not differ significantly. The prevalence of isolates harboring the Pfdhfr N51I, Pfdhfr S108N, Pfdhps A437G, and Pfdhps K540E mutations increased from 1998-1999 to 2002 (Fisher exact test, p < 0.001 each). Presence of the chloroquine resistance associated K76T mutation of Pfcrt (chloroquine-resistance transporter) (11) was analyzed by nested allele--specific PCR. Over the study period, 93% of the isolates harbored the Pfcrt K76T mutation (Table 1), without any significant temporal variation. Twenty seven P. falciparum isolates collected during the 1999 epidemic with a 0.05%-5.0% parasitemia were transported at 4[degrees]C to our laboratory in Marseille, France, and analyzed for in vitro drug sensitivity by using an isotopic microtest (12). Among them, 93% were classified as resistant to chloroquine (Table 3). No isolate was resistant to amodiaquine. In vitro resistance was 4% for both pyrimethamine and cycloguanil. Conclusions Before and after the 1999 epidemic, P. falciparum genetic diversity in Djibouti was large, with [approximately equal to] 80% and 63% heterozygocity. This finding is somewhat surprising for an area where disease endemicity is low (13) and probably reflects importation of strains from neighboring areas such as Ethiopia or Somalia (1,5). P. falciparum genetic diversity was diminished during the epidemic, reflecting the circulation of a restricted number of strains during that period. Most of these strains harbored an msp1 and msp2 genotype that was detected before the epidemic. The prevalence of Pfcrt, Pfdhfr, and Pfdhps mutant genotypes did not vary significantly from 1998 to 1999. Thus, our data do not support the hypothesis of a sudden increase in the drug resistance of the local P. falciparum population as causing the epidemic. Our data are also not consistent with massive invasion by a single strain/genotype but rather suggest expansion during the epidemic of a few strains that were already prevalent. Further genotyping is needed to establish how many strains were circulating and their possible origin. What could have caused this sudden amplification? One possibility is a temporary increase in vector density. Unfortunately, no vectors were captured at that time, and this hypothesis is difficult to explore retrospectively. The low prevalence of Pfdhfr and Pfdhps resistance mutations in 1998 and 1999 and of proguanil or pyrimethamine in vitro resistance in 1999 may explain the very low incidence of clinical malaria among the French soldiers stationed in Djibouti who were taking chloroquine-proguanil chemoprophylaxis chemoprophylaxis /che·mo·pro·phy·lax·is/ (-pro?fi-lak´sis) prevention of disease by means of a chemotherapeutic agent. che·mo·pro·phy·lax·is n. Disease prevention by use of chemicals or drugs. . However, the sharp increase of Pfdhfr and Pfdhps resistance mutations observed in 2002 threatens sulfadoxine-pyrimethamine efficacy in the near future, even more so since the limited acquired immunity acquired immunity n. Immunity obtained either from the development of antibodies in response to exposure to an antigen, as from vaccination or an attack of an infectious disease, or from the transmission of antibodies, as from mother to fetus through is unlikely to contribute to sustained drug efficacy (14). Molecular and in vitro assays point to a very high prevalence of chloroquine resistance. This finding calls for an urgent in vivo in vivo /in vi·vo/ (ve´vo) [L.] within the living body. in vi·vo adj. Within a living organism. in vivo adv. assessment of the antimalarials presently used in Djibouti in order to consider a rapid change in first-line treatment policy.
Table 1. Multiplicity of infections deduced from msp1 and msp2
genotyping and frequency (%) of the Pfdhfr (codons 51, 59, and
108), Pfdhps (codons 436, 437, and 540) and Pfcrt (codon 76)
genotypes
Period 1 Period 2
Locus 1998 (n = 46) 1999 (n = 61)
msp1
Mean multiplicity 1.6 1.5
SD * 0.7 0.7
No of multiple infections (%) 23 (50) 22 (36)
msp2 ([dagger])
Mean multiplicity 1.4 1.2
SD 0.7 0.4
No. of multiple infections (%) 14 (31) 12 (20)
msp1 and msp2
Mean multiplicity 1.8 1.6
SD 0.7 0.7
No. of multiple infections (%) 28 (61) 29 (48)
Pf dhfr
Codon 51
(Wildtype) N 38 (83) 60 (98)
N & I 3 (6) 0
I 5 1 (2)
Not genotyped -- --
Codon 59
(Wildtype) C 43 (94) 61 (100)
C & R 1 (2) 0
R 2 (4) 0
Not genotyped -- --
Codon 108
(Wildtype) S 37 (81) 60 (98)
S & N 2 (4) 0
N 7 (15) 1 (2)
Pf dhps
Codon 436
(Wildtype) S 46 (100) 52 (93)
F 0 1 (2)
A 0 3 (5)
Not genotyped -- 5
Codon 437
(Wildtype) A 45 (98) 54 (96)
G 1 (2) 2 (4)
Not genotyped -- 5
Codon 540
(Wildtype) K 44 (96) 60 (98)
K & E 1 (2) 0
E 1 (2) 1 (2)
Pf crt
Codon 76
(Wildtype) K 1 (2) 1 (2)
K & T 3 (7) 2 (3)
T 42 (91) 58 (95)
Period 3 Total
Locus 2002 (n = 32) (N = 139)
msp1
Mean multiplicity 1.3
SD * 0.5
No of multiple infections (%) 11 (34) 56 (40)
msp2 ([dagger])
Mean multiplicity 1.1
SD 0.4
No. of multiple infections (%) 2 (6) 28 (21)
msp1 and msp2
Mean multiplicity 1.4
SD 0.6
No. of multiple infections (%) 12 (38) 69 (50)
Pf dhfr
Codon 51
(Wildtype) N 15 (50) 113 (83)
N & I 0 3 (2)
I 15 (50) 21 (15)
Not genotyped 2 2
Codon 59
(Wildtype) C 29 (97) 133 (97)
C & R 0 1 (1)
R 1 (3) 3 (2)
Not genotyped 2 2
Codon 108
(Wildtype) S 16 (50) 113 (81)
S & N 0 2 (2)
N 16 (50) 24 (17)
Pf dhps
Codon 436
(Wildtype) S 29 (94) 127 (95)
F 0 1 (1)
A 2 (6) 5 (4)
Not genotyped 1 6
Codon 437
(Wildtype) A 19 (61) 118 (89)
G 12 (39) 15 (11)
Not genotyped 1 6
Codon 540
(Wildtype) K 19 (59) 123 (88)
K & E 0 1 (1)
E 13 (41) 15 (11)
Pf crt
Codon 76
(Wildtype) K 1 (3) 7 (5)
K & T 2 (6) 3 (2)
T 29 (91) 129 (93)
* SD, standard deviation; The genotypes at the Pf dhfr, Pf dhps, and
Pf crt locus refer to the one-letter symbolized amino acids coded by
the codons. A, Alanine; C, Cysteine; F, Phenylalanine; G, Glycine; I,
Isoleucine; K, Lysine; N, Asparagine; R, Arginine; S, Serine; T,
Threonine.
([dagger]) msp2 multiplicity estimated on 45 and 59 samples in 1998
and 1999, respectively.
Table 2. Distribution of msp1 and msp2 alleles by allelic families
and fragment size (in base pair) among Djibouti isolates with only
1 ellele detected by locus *
Locus Allelic Allele 1998 (%) 1999 (%) 2002 (%)
families (base pair)
msp1
K1 129 4.3 2.6 14.3
203 0.0 2.6 0.0
Mad 20 166 4.3 0.0 0.0
184 34.8 2.6 57.1
193 0.0 7.7 0.0
202 21.7 5.1 14.3
237 4.3 0.0 0.0
241 4.3 0.0 0.0
Ro 33 131 26.1 79.5 14.3
msp2
3D7 221 9.7 2.1 0.0
226 0.0 2.1 0.0
248 16.1 0.0 60.0
253 0.0 2.1 0.0
261 0.0 2.1 0.0
275 0.0 10.6 0.0
282 3.2 0.0 6.7
284 0.0 0.0 3.3
308 3.2 0.0 0.0
346 0.0 0.0 3.3
366 3.2 0.0 0.0
371 0.0 0.0 3.3
FC27 173 3.2 0.0 0.0
373 6.5 0.0 6.7
408 35.5 80.9 10.0
444 3.2 0.0 0.0
468 16.1 0.0 6.7
* Isolates collected in 1998 (msp1: n = 23; msp2: n = 31), 1999
(msp1: n = 39; msp2: n = 47), and 2002 (msp1: n = 21; msp2: n = 30).
Table 3. In vitro drug sensitivity of 27 Plasmodium falciparum
isolates collected in Djibouti, 1999
Drugs Isolates Mean 95% confidence
studied (n) I[C.sub.50] * interval
Chloroquine 27 326 nmol/L 224-474 nmol/L
Amodiaquine 27 10.0 nmol/L 8.0-12.6 nmol/L
Cycloguanil 24 13 nmol/L 8-21 nmol/L
Pyrimethamine 25 69 nmol/L 41-117 nmol/L
Drugs Cut-off value % resistant
isolates
Chloroquine >100 nmol/L 93
Amodiaquine >80 nmol/L 0
Cycloguanil >500 nmol/L 4
Pyrimethamine >2,000 nmol/L 4
* The 50% inhibitory concentration (I[C.sub.50]) of chloroquine
diphosphate, amodiaquine, pyrimethamine dihydrochloride, and
cycloguanil, i.e., the drug concentration corresponding to 50%
of the uptake of 3H-hypoxanthine by the parasites in drug-free
control wells, was determined by nonlinear regression analysis
of log-dose/response curves. Mean I[C.sub.50] and proportion of
resistant isolates according to cut-off values are indicated.
Data were expressed as the geometric mean I[C.sub.50] and 95%
confidence intervals were calculated.
Acknowledgments We are indebted to E. Garnotel, J.J. DePina, T. Fusai, H. Bouchiba, E. Czarnecki, P. Bigot, J. Mosnier, M. Desbordes, and M. Abakari for their help and technical assistance. This work was supported by the program PAL+ (2002) of the French Ministry for Research, the Delegation Generale pour l'Armement and Impact Malaria (Sanofi-Synthelabo groupe). Dr. Rogier is the chief of the Research Unit in Parasitological parasitological pertaining to or emanating from parasitology. parasitological examination includes examination of feces for protozoa, worm eggs or larvae and for tapeworm segments, skin scrapings for arthropod parasites, blood Biology and Epidemiology of the Institute for Tropical Medicine tropical medicine, study, diagnosis, treatment, and prevention of certain diseases prevalent in the tropics. The warmth and humidity of the tropics and the often unsanitary conditions under which so many people in those areas live contribute to the development and of the French Army, Le Pharo, Marseille, France. His main areas of interest include epidemiology and population genetics Population genetics The study of both experimental and theoretical consequences of mendelian heredity on the population level, in contradistinction to classical genetics which deals with the offspring of specified parents on the familial level. related to malaria. References (1.) Carteron B, Morvan D, Rhodain F. Le probleme de l'endemie palustre dans la Republique de Djibouti. Med Trop (Mars). 1978;38:837-46. (2.) Shidrawi GR. Rapport sur une visite en Republique de Djibouti du 14 janvier au 11 fevrier 1982. OMS/EM/MAL/190. Geneva Geneva, canton and city, Switzerland Geneva (jənē`və), Fr. Genève, canton (1990 pop. 373,019), 109 sq mi (282 sq km), SW Switzerland, surrounding the southwest tip of the Lake of Geneva. : World Health Organization; 1982. (3.) Louis JP, Albert JP. Le paludisme en Republique de Djibouti. Strategie de controle par la lutte antilarvaire biologique: Poissons larvivores autochtones (Aphanius dispar) et toxines bateriennes. Med Trop (Mars). 1988;48:127-31. (4.) Courtois D, Mouchet J. Etude e·tude n. Music 1. A piece composed for the development of a specific point of technique. 2. A composition featuring a point of technique but performed because of its artistic merit. des populations de culicides en TFAI TFAI Trade Fair Authority of India TFAI Table Football Association of Ireland . Med Trop (Mars). 1970;30:837-46. (5.) Fox E, Bouloumie J, Olson JG, Tible D, Lluberas M, Shakib SO, et al. Plasmodium falciparum voyage en train d'Ethiopie a Djibouti. Med Trop (Mars). 1991;51:185-9. (6.) Rodier GR, Parra JP, Kamil M, Chakib SO, Cope SE. Recurrence and emergence of infectious diseases in Djibouti city. Bull World Health Organ. 1995;73:755-9. (7.) Zwetyenga J, Rogier C, Tall A, Fontenille D, Snounou G, Trape Jf, et al. No influence of age on infection complexity and allelic distribution in Plasmodium falciparum infections in Ndiop, a Senegalese village with seasonal, mesoendemic malaria. Am J Trop Med Hyg. 1998;59:726-35. (8.) Nei M. Estimation of average heterozygosity heterozygosity /het·ero·zy·gos·i·ty/ (het?er-o-zi-gos´i-te) the state of possessing different alleles at a given locus in regard to a given character.heterozy´gous het·er·o·zy·gos·i·ty n. and genetic distance from small number of individuals, Genetics. 1978;89:583-90. (9.) Kublin JG, Dzinjalamala FK, Kamwendo DD, Malkin EM, Cortese JF, Martino LM, et al. Molecular markers for failure of sulfadoxine-pyrimethamine and chlorproguanil-dapsone treatment of Plasmodium falciparum malaria. J Infect Dis. 2002;185:380-8. (10.) Reeder JC, Rieckmann KH, Genton B, Lorry K, Wines B, Cowman AF. Point mutations in the dihydrofolate reductase and dihydropteroate synthetase genes and in vitro susceptibility to pyrimethamine and cycloguanil of Plasmodium falciparum isolates from Papua New Guinea Papua New Guinea (păp`  ə, –y . Am
J Trop Med Hyg. 1996;55:209-13.(11.) Djimde A, Doumbo OK, Cortese JF, Kayentao K, Doumbo S, Diourte Y, et al. A molecular marker for chloroquine-resistant falciparum malaria. N Engl J Med. 2001;344:257-63. (12.) Pradines B, Rogier C, Fusai T, Tall A, Trape JF, Doury JC. In vitro activity of artemether and its relationship to other standard antimalarial drugs Antimalarial Drugs Definition Antimalarial drugs are medicines that prevent or treat malaria. Purpose Antimalarial drugs treat or prevent malaria, a disease that occurs in tropical, subtropical, and some temperate regions of the world. against West African isolates. Am J Trop Med Hyg. 1998;58:354-7. (13.) Anderson TJ, Haubold B, Williams JT, Estrada-Franco JG, Richardson L, Mollinedo R, et al. Microsatellite See miniaturized satellite. markers reveal a spectrum of population structures in the malaria parasite Plasmodium falciparum. Mol Biol Evol. 2000;17:1467-82. (14.) Plowe CV, Kublin JG, Dzinjalamala FK, Kamwendo DS, Mukadam RA, Chimpeni P, et al. Sustained clinical efficacy of sulfadoxine-pyrimethamine for uncomplicated falciparum malaria in Malawi after 10 years as first line treatment: five year prospective study. BMJ BMJ n abbr (= British Medical Journal) → vom BMA herausgegebene Zeitschrift . 2004;328:545-8. Address for correspondence: Christophe Rogier, IMTSSA, BP46, Pare du Pharo, 13998 Marseille-Armees, France; fax: 33 4 91 15 01 64; email: christophe.rogier@wanadoo.fr Christophe Rogier, * Bruno Pradines, * H. Bogreau, * Jean-Louis Koeck, ([dagger]) ([double dagger]) Mohamed-Ali Kamil, ([section]) and Odile Mercereau-Puijalon ([paragraph]) * IMTSSA-IFR48, Marseille, France; ([dagger]) Centre Hospitalier des Armees Bouffard, Djibouti; ([double dagger]) HIA HIA Høgskolen I Agder HIA Health Impact Assessment HIA Hot Ion Analyzer HIA Housing Industry Association (Australia) HIA Herzberg Institute of Astrophysics (Canada) HIA Hemp Industries Association R. Piquet piquet or picquet (both: pēkā`), card game played by two persons with a deck of 32 cards—7 (low) up to ace (high) in each suit. Each player receives 12 cards, and eight cards are left on the table face down. , Bordeaux, France; ([section]) Ministry of Health, Djibouti; and ([paragraph]) Institut Pasteur, Paris, France |
|
||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion