EHP LIBRARY MALARIA BULLETIN 47: OCT 16-27, 2002

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Lancet Infect Dis  2002 Oct;2(10):618

Eradication of Anopheles gambiae from Brazil: lessons for malaria control in Africa?

Killeen G, Fillinger U, Kiche I, Gouagna L, Knols B.

GFK is an ecological epidemiologist at the Department of Public Health and Epidemiology, Swiss Topical Institute, Basel, Switzerland

Current malaria-control strategies emphasise domestic protection against adult mosquitoes with insecticides, and improved access to medical services. Malaria prevention by killing adult mosquitoes is generally favoured because moderately reducing their longevity can radically suppress community-level transmission. By comparison, controlling larvae has a less dramatic effect at any given level of coverage and is often more difficult to implement. Nevertheless, the historically most effective campaign against African vectors is the eradication of accidentally introduced Anopheles gambiae from 54000 km(2) of largely ideal habitat in northeast Brazil in the 1930s and early 1940s. This outstanding success was achieved through an integrated programme but relied overwhelmingly upon larval control. This experience was soon repeated in Egypt and another larval control programme successfully suppressed malaria for over 20 years around a Zambian copper mine. These affordable approaches were neglected after the advent of dichlorodiphenyl trichloroethane (DDT) and global malaria-control policy shifted toward domestic adulticide methods. Larval-control methods should now be re-prioritised for research, development, and implementation as an additional way to roll back malaria. 

Health Place 2002 Dec;8(4):227-36 

The use of a GIS-based malaria information system for malaria research and control in South Africa.

Martin C, Curtis B, Fraser C, Sharp B.

Malaria Research Programme, Medical Research Council, Durban, P.O. Box 17120, Congella, 4013, Durban, South Africa

The paper aims to outline the innovative development and application of a Geographical Information System based Malaria Information System for malaria research and control in South Africa. This system is a product of collaboration between the Malaria Control Programmes and the Malaria Research Programmeof the Medical Research Council of South Africa. The ability of such a system to process data timeously into a usable format is discussed, as well as its relevance to malaria research, appropriate malaria control measures, tourism, and social and economic development.

Ann Trop Med Parasitol 2002 Sep;96(6):575-86 

Water-related disease patterns before and after the construction of the Diama dam in northern Senegal.

Sow S, De Vlas SJ, Engels D, Gryseels B.

Helminthology Unit, Department of Parasitology, Prince Leopold Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium and Programme ESPOIR, Region Medicale de St Louis, B.P. 394, St Louis, Senegal.

The ecological changes caused by projects for the development of water resources are known to affect the epidemiology of water-related diseases. The effects of the construction of the Diama dam (completed#10; in 1986) in the Senegal River on the epidemiology of malaria, urinary and intestinal schistosomiasis, diarrhoea and dysentery were investigated in four districts in northern Senegal.

To make allowance for#10; any general trend in reported morbidity (caused by changes in demography or the healthcare system), the numbers of cases of these illnesses reported by the basic healthcare facilities before and after the#10; completion of the dam were compared with those of respiratory disease. Prior to the construction of the dam, malaria was the most encountered water-related disease in the medical records of all districts,#10; followed by diarrhoea, dysentery and urinary schistosomiasis. This order remained the same after the completion of the dam. Despite the optimism of health-assessment reports prepared prior to the construction#10; of the Diama dam, the unexpected appearance and spread of intestinal schistosomiasis as well as an increase in the incidence of urinary schistosomiasis have aggravated public health in the Senegal River#10; basin. It remains to be judged whether the economic benefits of the dam will counterbalance its adverse effects. #10;

Ann Trop Med Parasitol 2002 Sep;96(6):559-73 

The chemotherapy of rodent malaria. LX. The importance of formulation in evaluating the blood schizontocidal activity of some endoperoxide antimalarials.

Peters W, Fleck SL, Robinson BL, Stewart LB, Jefford CW.

Centre for Tropical Antiprotozoal Chemotherapy, Y Block, Northwick Park Institute for Medical Research, Harrow HA1 3UJ, U.K.

The activities of artemisinin (QHS) and a number of its semi-synthetic analogues, as well as Fenozan B07 (B07), a synthetic 1,2,4-trioxane, and arteflene (ATF), a synthetic surrogate of yingzhaosu, were#10; compared in mice infected with drug-sensitive Plasmodium berghei or chloroquine-resistant P. yoelii ssp. NS. The studies were stimulated by the observation that B07, in certain aqueous preparations,#10; appears to be equipotent by the subcutaneous (sc) or oral (po) routes in the rodent model but not in a simian model. In the rodent model, B07 was found to undergo rapid alteration (with a half-life of <24h)#10; in an aqueous stock solution prepared using dimethyl sulphoxide (DMSO) to pre-dissolve the drug. Therefore, for all later experiments with aqueous preparations, the test material was newly formulated each#10; day. In a carboxymethylcellulose formulation used as a ‘standard suspending vehicle’ (SSV), B07 and dihydroartemisinin (DIHYD) were found to be, respectively, one sixth and one 10th as active po as when#10; the drugs were pre-dissolved in DMSO and then diluted with water. ATF in DMSO given po was less than one 20th as active as when used sc in the rodent model, and this drug in SSV was almost inactive po.#10; The relatively low oral activity of these three compounds (especially DIHYD and ATF) may be attributable to extensive first-pass metabolism in the mouse. Oral beta-artemether (AM) and beta-arteether#10; (AE) were highly active when used in SSV. ATF has been found to have low activity in simian models and clinical trials because of its poor absolute bio-availability. In in-vivo studies of the blood schizontocidal#10; action of anti-malarials, in rodent malaria models, the data collected on the structure-activity relationships (SAR) of the drugs must be viewed critically when selecting specific compounds from a chemical#10; series for further development. A study of the influence of drug formulation on the activity of other, novel antimalarials is crucial to the evaluation of the drugs, and merits high priority. #10;

Ann Trop Med Parasitol  2002 Sep;96(6):553-7 

The efficacy of chloroquine for the treatment of acute, uncomplicated, Plasmodium falciparum malaria in Laos.

Guthmann JP, Kasparian S, Phetsouvanh R, Nathan N, Garcia M, Phompida S, Brockman A, Gastellu M, Legros D.

Epicentre, 8 rue Saint Sabin, 75011 Paris, France.

To assess the local efficacy of chloroquine for the treatment of acute, uncomplicated, Plasmodium falciparum malaria, children and adults from Sekong province (an area of Laos with a low intensity#10; of transmission) were tested in a 28-day, in-vivo study. Complete data were collected from 88 of the 102 subjects enrolled between October 1999 and September 2000. After genotypic analysis to distinguish#10; recrudescing infections from re-infections, 35 (39.7%, with a 95% confidence interval of 29.5%-50.7%) of these 88 patients were considered treatment failures. These results seriously question the use of#10; chloroquine as the first-line treatment for P. falciparum malaria in the study area. #10;

Ann Trop Med Parasitol  2002 Sep;96(6):543-51 

The effects of chloroquine, amodiaquine and chloroquine plus chlorpheniramine  on the disposition kinetics of the hepatomegaly associated with acute, uncomplicated, Plasmodium falciparum malaria in#10; children #10;.

Sowunmi A, Adedeji AA.

Department of Pharmacology and Therapeutics and Postgraduate Institute for Medical Research and Training, University of Ibadan, Ibadan, Nigeria.

The effects of chloroquine (CQ), amodiaquine (AQ) and CQ plus chlorpheniramine (a histamine H(1) antagonist that reverses CQ resistance in vitro and in vivo) on the disposition of#10; the enlarged liver associated with acute, symptomatic, uncomplicated, Plasmodium falciparum malaria were evaluated. The subjects, 131 children aged 0.6-12 years who lived in an endemic area of Nigeria,#10; were randomly allotted to the three treatment groups. The cumulative proportions of the children with complete resolution of their enlarged livers at 48, 96, 168 or 336 and 504 h after commencement of treatment#10; were significantly higher in those treated with CQ plus chlorpheniramine (CQCP) than in the other two treatment groups (with P-values of 0.02, 0.001, 0.00000 and 0.00002, respectively). Among those with#10; complete resolution, however, the times to resolution of 50% (HR50) or 90% (HR90) of the liver enlargement were similar in all the treatment groups. Complete resolution of the enlarged liver within 168#10; h was associated with a sensitive response to each treatment. Overall, in children with complete or partial resolution of their enlarged livers, the area produced by plotting liver size against time#10; (i.e. the area under the curve of hepatomegaly v. time, or AUC(hp)) and the half-life of the hepatomegaly (t(1/2hp)) were significantly lower in the CQCP group than in the#10; other two groups. The volume of blood completely cleared of the ‘hepatic pathological processes’ which led to the hepatomegaly (CL(Bhp)) and the fractional reduction of AUC(hp) at 48 and#10; 96 h (i.e. AUC(hpFr148) and AUC(hpFr96)) were significantly higher in the CQCP group than in the other treatment groups. When the children with complete resolution of their liver enlargement#10; were considered separately, t(1/2hp) (P=0.0008) but not AUC(hp) was found to be significantly lower, and AUC(hpFr196) (P=0.01) and CL(Bhl) (P=0.002) were found#10; to be significantly higher in the CQCP group than in the other groups. Among the children with only partial resolution of their enlarged livers, the indices of resolution and the kinetic parameters of disposition#10; were similar in all three groups. The data indicate that the addition of chlorpheniramine to chloroquine had a beneficial effect on both the early and late stages of the resolution of the liver enlargement#10; associated with acute, symptomatic, uncomplicated, P. falciparum malaria. #10;

J Dev Behav Pediatr 2002 Oct;23(5):353-64 

Effects of early cerebral malaria on cognitive ability in senegalese children.

Boivin MJ.

Department of Psychology, Indiana Wesleyan University, Marion, Indiana 46953, USA. Email: [email protected]

Twenty-nine Senegalese children with a history of cerebral malaria (CM) performed more poorly on the Kaufman Assessment Battery for Children (K-ABC) Simultaneous Processing domain and on the Test of Variables of Attention (TOVA) attention capacity indicators in comparison with a matched control group. Thus, CM can disrupt neuropsychological integration during critical developmental periods, impacting on global neurological integrity, attentional vigilance, perceptual acuity, and subsequent development of visual-spatial processing and memory foundational to global cognitive ability. A subsequent structural equation model confirmed that rural children are at greater risk for CM, subsequent attention deficits, and other developmental risk factors in addition to the CM impact on K-ABC performance. We document CM as one of a host of developmental risk factors within the complex web of poverty in sub-Saharan Africa, which limit children’s ability to achieve their full intellectual potential and, thus, extend the human cost of the disease beyond general measures of mortality and morbidity.

Blood 2002 Aug 29; [epub ahead of print] 

Malaria-parasitized erythrocytes and hemozoin nonenzymatically generate  large amounts of hydroxy-fatty acids that inhibit monocyte functions.

Schwarzer E, Kuehn H, Valente E, Arese P.

Plasmodium falciparum digests up to 75% of RBC hemoglobin and forms hemozoin. Phagocytosed hemozoin and trophozoites inhibit important monocyte functions. Delipidized trophozoites and hemozoin were remarkably less toxic to monocytes. Parasitized RBC and hemozoin contained large amounts of mostly esterified monohydroxy derivatives (OH-PUFA), the stable end products of peroxidation of polyenoic fatty acids. The levels of OH-PUFA were (micromol/L RBC): 1.8 in nonparasitized RBC; 11.1 in rings; 35 in trophozoites; and approx. 90/L RBC equivalents in hemozoin. In parasitized RBC and hemozoin a complex mixture of monohydroxy derivatives of arachidonic (HETEs) and linoleic (HODEs) acid was determined. 13- and 9-HODE, and 9- and 12-HETE were predominant in hemozoin and parasitized RBC, respectively. The estimated concentrations of all HETE isomers were 33 and 39 micromol/L RBC or RBC equivalents in trophozoites and hemozoin, respectively. No evidence of lipoxygenase activity was found in parasitized RBC while the large number of positional and optical isomers, the racemic structure and their generation by incubation of arachidonic acid with hemozoin indicated non-enzymatic origin via heme-catalysis. Sub/low-micromolar concentrations of 12- and 15-HETE were toxic to monocytes, while HODE isomers were ineffective. Low micromolar concentrations of HETE isomers were estimated to be similarly present in monocytes after phagocytosis of trophozoites or hemozoin. Thus, specific products of heme-catalyzed lipid peroxidation appear to contribute to hemozoin toxicity to phagocytes and may thus play a role in increased cytoadherence, vascular permeability and chemotaxis, as well as in immunodepression in malaria.

Blood 2002 Jul 25; [epub ahead of print] 

Malarial anemia leads to adequately increased erythropoiesis in asymptomatic Kenyan children.

Verhoef H, West CE, Kraaijenhagen R, Nzyuko SM, King R, Mbandi MM, Van Laatum S, Hogervorst R, Schep C, Kok FJ.

Rationale: Malarial anemia is associated with a shift in iron distribution from functional to storage compartments. This suggests a relative deficit in erythropoietin production or action similar to that observed in other infections. Objectives: Our study in Kenyan children with asymptomatic malaria aimed at investigating whether malaria causes increased erythropoiesis, and whether the erythropoietic response appeared appropriate for the degree of resulting anemia. Methods: Longitudinal and baseline data were used from a trial with a 2×2 factorial design, in which 328 anemic Kenyan children were randomly assigned to receive either iron or placebo, and sulfadoxine-pyrimethamine or placebo. Erythropoiesis was evaluated by serum concentrations of erythropoietin and soluble transferrin receptor. Findings: Prospectively collected data showed that malarial infection resulted in decreased hemoglobin concentrations, and increased serum concentrations of erythropoietin and transferrin receptor. Conversely, disappearance of malarial antigenemia resulted in increased hemoglobin concentrations, and decreased concentrations of these serum indicators. Additionally, our baseline data showed that current or recent malarial infection is associated with increased serum concentrations of erythropoietin and transferrin receptor, and that these were as high as or perhaps even higher than values of children without malarial infection and without inflammation. Conclusions: Our findings indicate that in asymptomatic malaria, the erythropoietic response is adequate for the degree of anemia, and that inflammation probably plays no or only a minor role in the pathogenesis of the resulting anemia. Further research is needed to demonstrate the role of deficient erythropoietin production or action in the pathogenesis of the anemia of acute malaria.

Trop Med Int Health 2002 Nov;7(11):931-934 

Renal dysfunction in falciparum- malaria is detected more often when  assessed by serum concentration of cystatin C instead of creatinine.

Gunther A, Burchard GD, Slevogt H, Abel W, Grobusch MP.

Institut fur Tropenmedizin, Berlin, Germany Medizinische Klinik mit Schwerpunkt Infektiologie, Charite Campus Virchow, Berlin, Germany Abteilung fur Laboratoriumsmedizin am Unfallkrankenhaus Berlin, Germany Institut fur Tropenmedizin, Eberhard-Karls-Universitat, Tubingen, Germany.

OBJECTIVES: To estimate the frequency of renal dysfunction in falciparum malaria by serum concentration of cystatin C, a new sensitive indicator of the glomerular filtration rate (GFR). METHODS: Retrospective study of stored sera and patient files. Assessment of renal function by serum concentration of creatinine and cystatin C and comparison of the results from both indicators of GFR. RESULTS: A total of 108 adult patients with falciparum malaria were included in the study. Concentration of creatinine and cystatin C correlated well (r = 0.706; P < 0.001). Elevated cystatin C was more frequent than elevated creatinine (54.6%vs. 20.4%; P < 0.001). Patients older than 50 years developed renal dysfunction more often (P < 0.05) than younger ones. Results from cystatin C and creatinine were concordant in 63 (58.3%) and contradictory in 45 (41.6%) cases. Four (3.7%) patients had elevated creatinine but normal cystatin C levels, hence 63 patients (58.3%) showed elevation of at least one indicator of GFR. The frequency of elevated cystatin C and elevated creatinine was unrelated to body weight, gender or bilirubin level. CONCLUSIONS: The prevalence of impaired renal function in patients with falciparum malaria seems to have been underestimated in the past. Using a sensitive marker, 55% of the patients have a reduced GFR.

Trop Med Int Health 2002 Nov;7(11):925-30 

Chloroquine and sulphadoxine-pyrimethamine efficacy for uncomplicated malaria treatment and haematological recovery in children in Bobo-Dioulasso, Burkina Faso during a 3-year period 1998-2000.

Tinto H, Zoungrana EB, Coulibaly SO, Ouedraogo JB, Traore M, Guiguemde TR, Van Marck E, D’Alessandro U.

Centre Muraz, Bobo-Dioulasso, Burkina Faso, Africa Institut de Recherche en Sciences de la Sante, Bobo-Dioulasso, Burkina Faso, Africa University of Antwerp, Antwerp, Belgium Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium.

We determined the parasitological resistance and the clinical failure to chloroquine (CQ) and sulphadoxine-pyrimethamine (SP) by the WHO 14-day in vivo test over three consecutive years in 948 children aged 6-59 months with uncomplicated malaria attending four health centres in the province of Houet, Burkina Faso. Children were alternatively allocated to either CQ or SP. Packed cell volume (PCV) was measured at days 0 and 14. Parasitological resistance (RI, RII and RIII) to CQ was 18% (83 of 455) and to SP <1% (two of 308). Clinical failure with CQ was 12% (53 of 455) with no evidence of increase over time. Only one case of clinical failure was detected among the children treated with SP. The prevalence of anaemia (PCV <25%) was about 40% at day 0 and had decreased substantially by day 14 in both groups. However, in children treated with SP the prevalence of anaemia at day 14 was significantly lower than in those treated with CQ:RR = 3.15 (95% CI: 1.33-7.42, P = 0.008). CQ and SP are still efficacious for the treatment of uncomplicated malaria in children, at least in this area of Burkina Faso. However, the prevalences of CQ resistance reported from other areas of the country are worrying because of its potential spread. Regular surveillance of resistance to commonly used antimalarial drugs should

continue.

Trop Med Int Health 2002 Nov;7(11):919-24 

Tolerability of doxycycline monohydrate salt vs. chloroquine-proguanil in malaria chemoprophylaxis.

Pages F, Boutin JP, Meynard JB, Keundjian A, Ryfer S, Giurato L, Baudon D.

Institut de Medecine Tropicale du Service de Sante des Armees (IMTSSA), le Pharo Marseille, France.

The resistance of Plasmodium falciparum to the chloroquine-proguanil association (C/P) as antimalarial chemoprophylaxis is becoming increasingly common in Africa. Daily oral doxycycline hyclate 100 mg is effective as malaria prophylaxis. But the hyclate salt’s adverse effects combined with the capsule’s galenic form are incompatible with good chemoprophylaxis compliance. We conducted a randomized group study of 522 French soldiers deployed in Gabon and Chad for 4 months to determine the tolerability of short-term malaria chemoprophylaxis with a 100-mg daily tablet of a monohydrate doxycycline salt compared with a daily C/P capsule. At days 7 and 120, compliance was better in the doxycycline group [respectively 98.5%vs. 73.9% (P < 0.001) and 90.5%vs. 74% (P < 0.001)]. No major event (evacuation, hospitalization) was related to the medications. Epigastralgia, diarrhoea, urticaria, mouth ulcers, sun sensitization and desquamation were significantly more frequent in the C/P group (P < 0.05). There was no statistical difference for malaria incidence, vertigo, nausea and hair loss. These results suggest that doxycycline monohydrate may be safely used in short-term malaria chemoprophylaxis. With the same efficacy as a hyclate doxycycline, doxycycline monohydrate could be a good chemoprophylaxis for short-term travellers at particular risk of C/P resistant P. falciparum malaria.

Trop Med Int Health 2002 Nov;7(11):911-918 

Alanine metabolism in acute falciparum malaria.

Pukrittayakamee S, Krishna S, Ter Kuile F, Wilaiwan O, Williamson DH, White NJ.

Department of Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. Department of Infectious Diseases, St George’s Hospital Medical School, London, UK. Division of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical Centre, University of Amsterdam, The Netherlands. Paholpolpayuhasena Hospital, Kanchanaburi, Thailand. Metabolic Research Laboratory, Nuffield Department of Clinical Medicine, University of Oxford, UK. Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Oxford University, UK.

We investigated the integrity of the gluconeogenic pathway in severe malaria using alanine metabolism as a measure. Alanine disposition and liver blood flow, assessed by indocyanine green (ICG) clearance, were measured simultaneously in 10 patients with falciparum malaria (six severe and four moderately severe malaria). After intravenous infusion of alanine (0.3 g/kg), glucose increments (AUC0-55 min) were lower in patients with severe malaria than in those with moderately severe malaria (median = 508 vs. 808 mmol/min/l; P = 0.055). There were no significant differences in the other metabolite increments (alanine, lactate and pyruvate; P >/= 0.27). The two fatal cases had markedly delayed alanine removal (larger AUC0-55 min), prolonged T(1/2) and slower clearance (P </= 0.007). Overall the increments in blood alanine correlated directly with lactate increments (rs = 0.84; P = 0.002) and inversely with glucose (rs = -0.70; P = 0.025). Between acute and convalescent studies, the increments (AUC0-55 min) of alanine and glucose were not significantly different (P >/= 0.07) but the increments of lactate and pyruvate were lower in convalescence.

Thus, the ratio of the increments of alanine to those of lactate and pyruvate were significantly higher in the convalescent study (P </= 0.017). The mean (SD) ICG clearance during acute malaria was not significantly different to that in convalescence (21.6 +/- 9.3 vs. 34.1 +/- 15.5 ml/min/kg; P = 0.25). During the acute study, there was a significant inverse correlation between ICG clearance and the post-infusion increments of lactate (rs = -0.63, P = 0.049) and pyruvate (rs = -0.74, P = 0.014). These data indicate that alanine clearance is impaired in acute falciparum malaria in proportion to the severity of illness and suggest an important role for anaerobic glycolysis in the pathogenesis of hypoglycaemia in severe malaria.

Clin Exp Immunol 2002 Nov;130(2):300-6 

Fcgamma receptor-mediated phagocytosis of Plasmodium falciparum-infected erythrocytes in vitro.

Tebo AE, Kremsner PG, Luty AJ.

Department of Parasitology, Institute of Tropical Medicine, University of Tubingen,Tubingen, Germany and Medical Research Unit, Albert Schweitzer Hospital, Lambarene, Gabon.

Although convincing evidence exists for the role of immunoglobulin G (IgG) antibodies in immunity to malaria, antibody titres do not usually predict protection. In this study we have assessed the interaction between Plasmodium falciparum-infected erythrocytes (PE), opsonized with immune serum containing different amounts of IgG antibody isotypes, with either THP-1 cells, ex-vivo human monocytes or IIAI.6 transfectant cells expressing FcgammaRIIa-Arg/Arg131 or -His/His131 allotypes. Our results show that PMA-treated THP-1 cells were capable of phagocytosing serum-opsonized PE by FcgammaRI (CD64) and FcgammaRIIa (CD32), acting synergistically. The known FcgammaRIIa polymorphism motivated us to examine its influence on IgG isotype-mediated phagocytosis of opsonized PE with human monocytes and the IIAI.6 transfectant cells expressing either allelic forms. Regardless  of the cell type, PE phagocytosis with FcgammaRIIa-His/His131 was highest following  opsonization with a predominantly IgG3-containing immune serum pool. In contrast,  PE phagocytosis with FcgammaRIIa-Arg/Arg131 tended to be higher with an IgG1-containing pool. These results suggest a genetically determined influence of effector cell phenotype on IgG antibody-pathogen interaction in P. falciparum malaria.

East Afr Med J 2002 Mar;79(3):115-9 

Resistance patterns of Plasmodium falciparum malaria to chloroquine in  Kampala, Uganda.

Mulindwa HC, Mayanja-Kizza H, Freers J.

Makerere University Hospital, Kampala, Uganda.

BACKGROUND: Chloroquine is a first line drug for the treatment of uncomplicated Plasmodium falciparum malaria in Uganda. Recently, there have been increasing reports of resistance of Plasmodium falciparum malaria to chloroquine, as well as an increase in malaria morbidity and mortality among adults and children.

OBJECTIVES: To assess the current effectiveness (clinical and parasitological response) of chloroquine in the treatment of uncomplicated Plasmodium falciparum malaria, and to define the magnitude of chloroquine resistant Plasmodium falciparum malaria in Kampala. DESIGN: A descriptive cross-sectional study among adults and children. SETTING: Mulago hospital complex (the national referral and teaching hospital in Kampala, Uganda) between September 1998 and March 1999.

RESULTS: Ninety six patients with Plasmodiumfalciparum parasitaemia of 1000 to 100,000/microl of blood were treated with oral chloroquine phosphate, and followed up for 14 days. Sixty three (65.6%) patients showed clinical improvement, 29 (30.2%) deteriorated and four (4.2%) had no change. Adequate parasitogical response was seen in 71(74 %), moderate in four (4.2%) and poor in 21(21.8%) patients. Treatment failures were highest among children below five years, with eleven (57.9%) children not responding to chloroquine. 

CONCLUSION: Although chloroquine was found to be effective in two thirds of all patients, the high treatment failure, especially seen in children below five years is of concern. This necessitates further countrywide studies, and possibly a need to review the use of chloroquine as single first line drug for the treatment of uncomplicated malaria in Uganda, especially in children below five years of age.

Am J Trop Med Hyg  2002 Aug;67(2):191-5 

Repellency of live potted plants against Anopheles gambiae from human baits in semi-field experimental huts.

Seyoum A, Kabiru EW, Lwande W, Killeen GF, Hassanali A, Knols BG.

International Centre of Insect Physiology and Ecology, Nairobi, Kenya. Email: [email protected]

The repellency of potted plants against the malaria vector Anopheles gambiae sensu stricto Giles was quantified in experimental huts under semi-field conditions inside a screen-walled greenhouse. Ocimum americanum Linnaeus (Labiatae), Lantana camara L. (Verbenaceae), and Lippia uckambensis Spreng (Verbenaceae) repelled at an average of 39.7% (95% confidence interval [CI] 29.6-48.4%), 32.4% (95% CI = 19.7-43.1%), and 33.3% (95% CI = 21.5-43.3%) of the mosquitoes, respectively (P < 0.0001 for all treatments). This was determined by logistic regression, allowing for variations associated with different bait hosts, sampling huts, and replicate test nights. In contrast, Ocimum kilimandscharicum Guerke (Labiatae), Ocimum suave Willd. (Labiatae), Corymbia citriodora Hook (Myrtaceae), Azadirachta indica A. Juss (Meliaceae), Tagetes minuta L. (Asteraceae), and Hyptis suaveolens Poit. (Lamiaceae) did not significantly repel mosquitoes. The combination of O. americanum with either L. camara or L. uckambensis repelled 31.6% (95% CI = 19.7-41.7%) and 45.2%  (95% CI = 34.7-54.0%) of the mosquitoes, respectively (P < 0.0001 for both treatments). This study is the first to show that live intact plants can reduce domestic exposure to malaria vector mosquitoes. As such, they may represent a new, sustainable and readily applicable malaria vector control tool for incorporation into integrated vector management programs.

Am J Trop Med Hyg 2002 Aug;67(2):141-4 

Comparison of field and expert laboratory microscopy for active surveillance for asymptomatic Plasmodium falciparum and Plasmodium vivax in western Thailand.

Coleman RE, Maneechai N, Rachaphaew N, Kumpitak C, Miller RS, Soyseng V, Thimasarn K, Sattabongkot J.

Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.

Microscopy of Giemsa-stained thick and thin films by a skilled microscopist has remained the standard laboratory method for the diagnosis of malaria. However, diagnosis of malaria with this method is problematic since interpretation of results requires considerable expertise, particularly at low parasite levels. We compared the efficacy of “field” and “expert laboratory” microscopy for active surveillance of Plasmodium falciparum and P. vivax in western Thailand. Field microscopy consisted of an approximately five-minute read (50-100 fields) of a thick film at x700 using a natural light source, whereas expert laboratory microscopy consisted of a 20-minute read (number of parasites per 500 leukocytes) at x1,000 using a high-quality, well-maintained microscope with an artificial light source. All discordant and 20% of concordant results were cross-checked blindly. A total of 3,004 blood films collected between May and November 2000 were included in the study, of which 156 (5.2%) were positive for P. falciparum, 177 (5.9%) for P. vivax, and 4 (0.1%) for both P. falciparum and P. vivax by expert microscopy. A total of 84.4% (135 of 160) of the P. falciparum-positive slides and 93.9% of the P. vivax-positive slides had a parasitemia of less than 500/microL. Field microscopy was specific (99.3%) but not sensitive (10.0%) for the diagnosis of P. falciparum malaria, with a positive predictive value (PPV) of 43.2% and a negative predictive value (NPV) of 95.1%. The corresponding specificity and sensitivity for the diagnosis of P. vivax malaria were 99.2% and 7.1%, respectively, with a PPV of 38.7% and an NPV of 93.9%. Field microscopy, as defined in this study, is not an effective method for active malaria surveillance in western Thailand, where prevalence and parasitemia rates are low.

Am J Trop Med Hyg 2002 Aug;67(2):137-40 

Relationship between parasite density and fever risk in a community exposed to a low level of malaria transmission in Madagascar highlands.

Boisier P, Jambou R, Raharimalala L, Roux J.

Malaria Unit, Institut Pasteur de Madagascar, Antananarivo. Email: [email protected]

To establish a simple definition of a malaria attack based on blood parasite density and other explanatory covariates, a cohort study was conducted from 1993 to 1996 in the Madagascar highlands undergoing a low seasonal transmission of falciparum malaria. Using logistic regression, the explanatory variables found to be significantly related to the risk of fever are parasite density, age, season, and year. However, and in contrast with other studies, we found no evidence of a clear cutoff in parasite density values consistent with the concept of “pyrogenic threshold” despite a gradual increase of the risk of fever with increasing parasite density. Furthermore, the model evidenced an individual-dependent relationship at a given age. This point was in accordance with the immunological data recorded from the participants. The investigators conclude that the parasite density to distinguish malaria attacks from other causes of fever is not reliable in a context of low falciparum transmission.

Lancet 2002 Oct 12;360(9340):1136-43 

Chlorproguanil-dapsone versus sulfadoxine-pyrimethamine for sequential episodes of uncomplicated falciparum malaria in Kenya and Malawi: a randomised clinical trial.

Sulo J, Chimpeni P, Hatcher J, Kublin JG, Plowe CV, Molyneux ME, Marsh K, Taylor TE, Watkins WM, Winstanley PA.

Centre for Geographical Medicine, Kenya Medical Research Institute, Kilifi, Kenya.

BACKGROUND: Chlorproguanil-dapsone exerts lower resistance pressure on Plasmodium falciparum than does sulfadoxine-pyrimethamine, but is rapidly eliminated. We aimed to find out whether chlorproguanil-dapsone results in a higher retreatment rate for malaria than sulfadoxine-pyrimethamine. METHODS: In a randomised trial of paediatric outpatients with uncomplicated falciparum malaria, patients received either chlorproguanil-dapsone or sulfadoxine-pyrimethamine and were followed up for up to 1 year. Sites were in Kenya (n=410) and Malawi (n=500). We used per-protocol analysis to assess the primary outcome of annual malaria incidence. 

FINDINGS: Drop-outs were 117 of 410 (28.5%) in Kenya, and 342 of 500 (68.4%) in Malawi. Follow-up was for a median of 338 days (IQR 128-360) and 342 days (152-359) in Kilifi (chlorproguanil-dapsone and sulfadoxine-pyrimethamine, respectively), and for 120 days (33-281) and 84 days (26-224) in Blantyre. Mean annual malaria incidence was 2.5 versus 2.1 in Kenya (relative risk 1.16, 95% CI 0.98-1.37), and 2.2 versus 2.8 in Malawi (0.77, 0.63-0.94). 4.3% versus 12.8%, and 5.4% versus 20.1%, of patients were withdrawn for treatment failure in Kenya and Malawi, respectively. In Kenya haemoglobin concentration of 50 g/L or less caused exit in 6.9% of chlorproguanil-dapsone patients and 1.5% of sulfadoxine-pyrimethamine patients, but most anaemia occurred before re-treatment. In Malawi only one patient exited because of anaemia.

INTERPRETATION: Despite the rapid elimination of chlorproguanil-dapsone, children treated with this drug did not have a higher incidence of malaria episodes than those treated with sulfadoxine-pyrimethamine. Treatment failure was more common with sulfadoxine-pyrimethamine. Cause of anaemia in Kenya was probably not adverse reaction to chlorproguanil-dapsone, but this observation requires further study.

J Infect 2002 Oct;45(3):165 

Usefulness of an Inexpensive, Paracheck(R) Test in Detecting Asymptomatic Infectious Reservoir of Plasmodium falciparum During Dry Season in an Inaccessible Terrain in Central India.

Singh N, Saxena A, Sharma VP.

Malaria Research Centre, Field Station, Medical College Building, Jabalpur, 482 003, India

OBJECTIVES: The performance of a new indigenous rapid diagnostic test, Paracheck Pf(R) was evaluated in detection of Plasmodium falciparum in asymptomatic children in remote forest villages of Mandla district, central India to determine the lower limits of sensitivity and specificity of rapid test.METHODS: A finger prick blood sample was collected to prepare blood smear and for testing with the Paracheck test. The blood smears were read by an experienced technician blinded to the Paracheck results. The figures for specificity, sensitivity, accuracy and predictive values were calculated using microscopy as gold standard.

RESULTS: The new diagnostic test had a sensitivity of 94% and a specificity of 89%. The positive and negative predictive values were 71% and 98%, respectively. TheJ -index was 0.83%.CONCLUSION: The rapid test was found  to be very easy to perform and the result could be read reliably by field workers. The field evaluation with this new inexpensive test, ($0.65/test) indicates that it could be used as an epidemiological tool in the management of malaria particularly in areas where microscopy is not operationally feasible to attain the goal of the roll back malaria initiative. 

J Infect 2002 Oct;45(3):160 

Consensual Treatment of Plasmodium falciparum Malaria Does not Lead to Adequate Quinine Blood Concentrations.

Roger PM, Marty P, Prestifilippo L, Garaffo R, Hyvernat H, Dunais B, Chaillou S, Delaunay P, Bernardin G, Mattei M, Le Fichoux Y, Dellamonica P.

Service des Maladies Infectieuses et Tropicales, Centre Hospitalier Universitaire, Nice, France

Since 1996, we have a common protocol in the Infectious Diseases Department and the Intensive Care Unit for the administration of quinine in case of Plasmodium falciparum malaria. Patients were classified as uncomplicated form of malaria (UFM) or severe form of malaria (SFM) according to WHO criteria, adding parasitemia >5% as a criteria of SFM. Treatment of SFM should consist of a 4 infusion of 16 mg/kg quinine-base loading dose, followed by 8 mg/kg every 8 h. Patients with UFM receive quinine-base, 8 mg/kg every 8 h. A therapeutic index of 10-15 mg/l was considered adequate. Hypoglycemia and cardiotoxicity were the two main adverse effects of quinine to be investigated. In order to verify that these modalities for quinine administration are associated with adequate quinine blood concentrations, we have reviewed the pharmacological data and the occurrence of adverse effects. Between April 1996 and December 2000, 95 patients were hospitalised: 25 with SFM and 70 with UFM: 78/95 patients (82%) received adequate treatment and 26/95 (28%) of the patients presented an overdosage of quinine. Six severe adverse effects were observed, even in case of adequate quinine administration. Consensual treatment of malaria does not confer adequate quinine blood concentrations, and toxic effects are still common.

Mem Inst Oswaldo Cruz 2002 Sep;97(6):901-3 

Time course of in vitro maturation of intra-erythrocytic malaria parasite: a comparison between Plasmodium falciparum and Plasmodium knowlesi.

Srinivas SD, Puri SK.

Division of Parasitology, Central Drug Research Institute, Lucknow, India. Email: [email protected]

The schizont maturation assay for in vitro drug sensitivity tests has been a standard method employed in the global baseline assessment and monitoring of drug response in Plasmodium falciparum. This test is limited in its application to synchronous plasmodial infections because it evaluates the effect of drug on the maturation of parasite especially from ring to schizont stage and therefore synchronized P. falciparum cultures are required. On the other hand, P. knowlesi, a simian malaria parasite has a unique 24-h periodicity and maintains high natural synchronicity in monkeys. The present report presents the results of a comparative study on the course of in vitro maturation of sorbitol synchronized P. falciparum and naturally synchronous P. knowlesi. Ring stage parasites were incubated in RPMI medium supplemented with 10-15% pooled homologous serum in flat-bottomed 96-well micro plates using a candle jar at 37 degrees C. The results suggest that the ideal time for harvesting the micro-assay plates for in vitro drug sensitivity test for sorbitol-synchronized P. falciparum and naturally synchronous P. knowlesi are from 26 to 30 h and from 22 to 25 h, respectively. The advantages of using P. knowlesi in chemotherapeutic studies are discussed.

Clin Infect Dis 2002 Nov 1;35(9):E92-5 

Atovaquone/Proguanil Therapy for Plasmodium falciparum and Plasmodium vivax Malaria in Indonesians Who Lack Clinical Immunity.

Lacy MD, Maguire JD, Barcus MJ, Ling J, Bangs MJ, Gramzinski R, Basri H, Sismadi P, Miller GB, Chulay JD, Fryauff DJ, Hoffman SL, Baird JK.

Parasitic Diseases Program, US Naval Medical Research Unit 2, Jakarta, Indonesia.

Thirty-eight of 295 subjects participating in a randomized, double-blind, placebo-controlled trial of the efficacy of daily administration of atovaquone/proguanil for malaria prevention developed malaria at some time during the 20-week prophylaxis period. These subjects (3 atovaquone/proguanil recipients and 35 placebo recipients) were treated with 4 tablets of atovaquone/proguanil per day for 3 days. Atovaquone/proguanil provided safe, well-tolerated, and effective therapy for uncomplicated malaria in nonimmune Indonesians.

Life Sci 2002 Oct 25;71(23):2773 

1H-NMR structures of the Plasmodium falciparum 1758 erythrocyte binding peptide analogues and protection against malaria.

Guzman F, Jaramillo K, Salazar L, Torres A, Rivera A, Patarroyo M.

Fundacion Instituto de Inmunologi;a de Colombia (FIDIC), Carrera 50 No. 26-00, Bogota, Colombia

A conserved high activity erythrocyte binding peptide (HAEBP) derived from the 175-erythrocyte binding antigen (EBA-175), coded 1758, was synthesized and analyzed for antigenic and protective activities in Aotus monkeys, together with several of its analogues. Conformational analysis by 1H Nuclear Magnetic Resonance in TFE-solution was done for some of them, as well as the 1758 parent peptide. We show that the conserved 1758 HAEBP (being neither immunogenic nor protective) has an alpha helical structure, whilst its analogues contain beta-turn structures. The 13790 peptide (highly immunogenic and protective for some monkeys) shows a type I beta-turn structure distorted in psi(i + 1) psi(i +2) angles, whilst immunogenic and non-protective (as well as the non-immunogenic and non-protective peptides) have type III’ beta-turns. An understanding of native peptide’s correlation with altered peptide three-dimensional structure and resulting immunogenicity and protective activity may lead to a more rational design of multi-antigenic, multi-stage P. falciparum subunit based malaria vaccines.

J Biol Chem 2002 Oct 14; [epub ahead of print] 

Phage display peptides bind to the malarial protein apical membrane antigen-1 and inhibit the invasion of merozoites into host erythrocytes.

Li F, Dluzewski A, Coley AM, Thomas AW, Tilley L, Anders RF, Foley M.

Biochemistry, La Trobe University, Melbourne, Victoria 3083.

AMA1 is a transmembrane protein present on the surface of merozoites that is thought to be involved in the process of parasite invasion into the host erythrocytes. Although it is the target of a natural immune response that can inhibit invasion, little is known about the molecular mechanisms by which AMA1 could facilitate the invasion process. In an attempt to identify peptides that specifically interact with, and block the function of AMA1, a random peptide library displayed on the surface of filamentous phage was panned on recombinant AMA1 from Plasmodium falciparum. Three peptides with affinity for AMA1 were isolated and a characterisation of their fine binding specificities indicated that they bind to a similar region on the surface of AMA1. One of these peptides was found to be a potent inhibitor of the invasion of P. falciparum merozoites into human erythrocytes. It is proposed that this peptide blocks an interaction between AMA1 and a ligand on the erythrocyte surface that is involved in a critical step in malaria invasion. The identification and characterisation of these peptide inhibitors now permit an evaluation of the essential requirements that are necessary for efficient neutralisation of merozoite invasion by blocking AMA1 function.

Nat Med 2002 Oct 15; [epub ahead of print] 

Migration through host cells activates Plasmodium sporozoites for infection.

Mota MM, Hafalla JC, Rodriguez A.

Department of Pathology, New York University School of Medicine, New York, New York, USA.

Plasmodium sporozoites, the infective stage of the malaria parasite transmitted by mosquitoes, migrate through several hepatocytes before infecting a final one. Migration through hepatocytes occurs by breaching their plasma membranes, and final infection takes place with the formation of a vacuole around the sporozoite. Once in the liver, sporozoites have already reached their target cells, making migration through hepatocytes prior to infection seem unnecessary. Here we show that this migration is required for infection of hepatocytes. Migration through host cells, but not passive contact with hepatocytes, induces the exocytosis of sporozoite apical organelles, a prerequisite for infection with formation of a vacuole. Sporozoite activation induced by migration through host cells is an essential step of Plasmodium life cycle.

Infect Immun 2002 Nov;70(11):6075-82 

Merozoite surface protein 1-specific immune response is protective against exoerythrocytic forms of Plasmodium yoelii.

Kawabata Y, Udono H, Honma K, Ueda M, Mukae H, Kadota J, Kohno S, Yui K.

Division of Immunology, Department of Molecular Medicine, Nagasaki University School of Medicine, Sakamoto, Nagasaki 852-8523, Japan.

One of the difficulties in developing an effective malaria vaccine is the antigenic change of the parasite during the life cycle. It is desirable that vaccine-induced protective immunity be effective at different stages of parasite development. Merozoite surface protein 1 (MSP1) is a candidate vaccine antigen against blood-stage malaria, but it is also expressed in the exoerythrocytic forms. It was not known, however, whether the anti-MSP1 immune response is effective against the liver-stage malaria parasite. We generated a recombinant protein of MSP1 fused to heat-shock cognate protein 70 (hsc70) and studied its vaccination effect. When C57BL/6 mice were immunized with the fusion protein prior to challenge infection with Plasmodium yoelii sporozoites, the onset of parasitemia was delayed or no parasitemia was observed. To determine whether this was due to the protective immunity against liver-stage parasites, P. yoelii-specific rRNA in the infected liver was quantitated by real-time reverse transcription-PCR analysis. The level of parasite-specific rRNA was reduced in mice immunized with the fusion protein of MSP1 and hsc70 but not with hsc70 alone, indicating that MSP1-specific immunity can be protective against the exoerythrocytic form of the parasite. Furthermore, the adoptive transfer experiments of immune lymphocytes and serum into naive mice suggested that the protective immunity was dependent on cellular and not humoral immunity. Finally, the vaccine-induced protection was also observed in A/J, C3H, and BALB/c mice, suggesting that MSP1-specific protective immunity at the exoerythrocytic stage can be induced in animals over a wide range of genetic backgrounds.

Bull World Health Organ 2002;80(9):704-8 

Therapeutic efficacy of chloroquine and sulfadoxine/pyrimethamine against Plasmodium falciparum infection in Somalia.

Warsame M, Abdillahi A, Duale ON, Ismail AN, Hassan AM, Mohamed A, Warsame A.

Division of International Health Care Research, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden. Email: [email protected]

OBJECTIVE: To assess the efficacy of chloroquine and sulfadoxine/pyrimethamine in the treatment of uncomplicated Plasmodium falciparum infections in Somalia.

METHODS: Patients with clinical malaria in Merca, an area of high transmission of the disease, were treated with the standard regimens of chloroquine (25 mg/kg) or sulfadoxine/pyrimethamine (25 mg sulfadoxine and 1.25 mg pyrimethamine per kg). Similar patients in Gabiley, an area of low transmission, received the standard regimen of  chloroquine. The clinical and parasitological responses were monitored for 14 days. 

FINDINGS: Chloroquine treatment resulted in clinical failure in 33% (n = 60) and 51% (n = 49) of the patients in Merca and Gabiley respectively. There were corresponding parasitological failures of 77% RII/RIII and 35% RII/RIII. Patients who experienced clinical failure had significantly higher initial parasitaemia than those in whom there was an adequate clinical response, both in Merca (t = 2.2; P t = 2.8; P n = 50) of the patients achieved an adequate clinical response despite a parasitological failure rate of 76% RII/RIII. 

CONCLUSION: Chloroquine should no longer be considered adequate for treating clinical falciparum malaria in vulnerable groups in the areas studied. Doubts about the therapeutic life of sulfadoxine/pyrimethamine in relation to malaria are raised by the high levels of resistance in the Merca area and underline the need to identify suitable alternatives.

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