Preliminary studies developing methods for the control of Chrysomya putoria, the African latrine fly, in pit latrines in The Gambia.

OBJECTIVE: To explore ways of controlling Chrysomya putoria, the African latrine fly, in pit latrines. As pit latrines are a major source of these flies, eliminating these important breeding sites is likely to reduce village fly populations, and may reduce the spread of diarrhoeal pathogens. METHODS: We treated 24 latrines in a Gambian village: six each with (i) pyriproxyfen, an insect juvenile hormone mimic formulated as Sumilarv(®) 0.5 G, a 0.5% pyriproxyfen granule, (ii) expanded polystyrene beads (EPB), (iii) local soap or (iv) no treatment as controls. Flies were collected using exit traps placed over the drop holes, weekly for five weeks. In a separate study, we tested whether latrines also function as efficient flytraps using the faecal odours as attractants. We constructed six pit latrines each with a built-in flytrap and tested their catching efficiency compared to six fish-baited box traps positioned 10 m from the latrine. Focus group discussions conducted afterwards assessed the acceptability of the flytrap latrines. RESULTS: Numbers of emerging C. putoria were reduced by 96.0% (95% CIs: 94.5-97.2%) 4-5 weeks after treatment with pyriproxyfen; by 64.2% (95% CIs: 51.8-73.5%) after treatment with local soap; by 41.3% (95% CIs = 24.0-54.7%) after treatment with EPB 3-5 weeks after treatment. Flytraps placed on latrines collected C. putoria and were deemed acceptable to local communities. CONCLUSIONS: Sumilarv 0.5 G shows promise as a chemical control agent, whilst odour-baited latrine traps may prove a useful method of non-chemical fly control. Both methods warrant further development to reduce fly production from pit latrines. A combination of interventions may prove effective for the control of latrine flies and the diseases they transmit.

Boosting antibody responses to Plasmodium falciparum merozoite antigens in children with highly seasonal exposure to infection.

Longitudinal cohort studies are important to describe the dynamics of naturally acquired antibody response profiles to defined Plasmodium falciparum malaria antigens relative to clinical malaria episodes. In children under 7 years of age in The Gambia, serum IgG responses were measured to P. falciparum merozoite antigens AMA1, EBA175, MSP1(19), MSP2 and crude schizont extract, over a 10-month period. Persistence of antibody responses was measured in 152 children during the dry season when there was virtually no malaria transmission, and 103 children were monitored for new episodes of clinical malaria during the subsequent wet season when transmission occurred. Children who experienced clinical malaria had lower antibody levels at the start of the study than those who remained free from malaria. Associations between dry season antibody persistence and subsequent wet season antibody levels suggested robust immunological memory responses. Mean antibody levels to all antigens were elevated by the end of the wet season in children who experienced clinical malaria; each of these children had a boosted antibody response to at least one antigen. In all children, antibody avidities were lower against MSP2 than other antigens, a difference that did not change throughout the study period or in relation to clinical malaria episodes.

Plasmodium falciparum infection of the placenta impacts on the T helper type 1 (Th1)/Th2 balance of neonatal T cells through CD4(+)CD25(+) forkhead box P3(+) regulatory T cells and interleukin-10.

Placental malaria infection affects the T helper type 1 (Th1)/Th2 balance in neonatal children. We investigated a potential role of regulatory T cells in this balance by comparing T cell responses of cord blood mononuclear cells (CBMC) from parasitized and non-parasitized placenta of Gambian women. CBMC were depleted of CD4(+)CD25(+) forkhead box P3 (FoxP3)(+) regulatory T cells and analysed in vitro for their ability to produce interferon (IFN)-gamma, sCD30 and interleukin (IL)-10 in response to phytohaemagglutinin (PHA), live Plasmodium falciparum, schizont extracts and the recombinant P. falciparum blood stage antigen merozoite surface protein 1 (MSP1(19)). As expected, lower IFN-gamma and higher sCD30 responses were observed for the cells from the parasitized group. In addition, higher IL-10 levels were produced by CBMC from the parasitized group. Depletion of regulatory T cells decreased IL-10 production, which resulted in a restoration of IFN-gamma expression in response to all stimuli. The Th2 marker sCD30 remained significantly higher in the parasitized group in response to malaria protein antigens while similar levels were recovered between both groups in response to live P. falciparum. Similar effects were observed by adding an antibody that blocks IL-10 function. These results suggest that the impact of P. falciparum infection on Th1 differentiation of neonatal T cells can be ascribed to regulatory T cells through production of IL-10.

Variation in the ICAM1 gene is not associated with severe malaria phenotypes.

Evidence from autopsy and in vitro binding studies suggests that adhesion of erythrocytes infected with Plasmodium falciparum to the human host intercellular adhesion molecule (ICAM)-1 receptor is important in the pathogenesis of severe malaria. Previous association studies between polymorphisms in the ICAM1 gene and susceptibility to severe malarial phenotypes have been inconclusive and often contradictory. We performed genetic association studies with 15 single nucleotide polymorphisms (SNPs) around the ICAM1 locus. All SNPs were screened in a family study of 1071 trios from The Gambia, Malawi and Kenya. Two key non-synonymous SNPs with previously reported associations, rs5491 (K56M or 'ICAM-1(Kilifi)') and rs5498 (K469E), were tested in an additional 708 Gambian trios and a case-control study of 4058 individuals. None of the polymorphisms were associated with severe malaria phenotypes. Pooled results across our studies for ICAM-1(Kilifi) were, in severe malaria, odds ratio (OR) 1.02, 95% confidence interval (CI) 0.96-1.09, P=0.54, and cerebral malaria OR 1.07, CI 0.97-1.17, P=0.17. We assess the available epidemiological, population genetic and functional evidence that links ICAM-1(Kilifi) to severe malaria susceptibility.

Medical informatics in medical research - the Severe Malaria in African Children (SMAC) Network's experience.

OBJECTIVES: Computers are widely used for data management in clinical trials in the developed countries, unlike in developing countries. Dependable systems are vital for data management, and medical decision making in clinical research. Monitoring and evaluation of data management is critical. In this paper we describe database structures and procedures of systems used to implement, coordinate, and sustain data management in Africa. We outline major lessons, challenges and successes achieved, and recommendations to improve medical informatics application in biomedical research in sub-Saharan Africa. METHODS: A consortium of experienced research units at five sites in Africa in studying children with disease formed a new clinical trials network, Severe Malaria in African Children. In December 2000, the network introduced an observational study involving these hospital-based sites. After prototyping, relational database management systems were implemented for data entry and verification, data submission and quality assurance monitoring. RESULTS: Between 2000 and 2005, 25,858 patients were enrolled. Failure to meet data submission deadline and data entry errors correlated positively (correlation coefficient, r = 0.82), with more errors occurring when data was submitted late. Data submission lateness correlated inversely with hospital admissions (r = -0.62). CONCLUSIONS: Developing and sustaining dependable DBMS, ongoing modifications to optimize data management is crucial for clinical studies. Monitoring and communication systems are vital in multi-center networks for good data management. Data timeliness is associated with data quality and hospital admissions.

Methods for derivation and detection of anti-parasite monoclonal antibodies.

We describe detailed methods for derivation and cloning of myeloma hybrids which secrete antibodies specific for antigens of protozoan parasites. The methods were designed to enable the derivation of large numbers of specific monoclonal antibodies and to give high cloning efficiencies of desired hybrids. Although special attention is paid to derivation and detection of anti-parasite antibodies, the methods can be applied to many different antibody-antigen systems. Using the described methods we have isolated more than 90 myeloma hybrids which secrete antibodies specific for antigens of African trypanosomes and Theileria parasites, thus illustrating their effectiveness.

Biochemical and immunochemical characterization of surface and excretory-secretory antigens of Loa loa microfilariae.

Detergent solubilized extracts of 125Iodogen surface-labelled Loa loa microfilariae revealed a relatively simple profile of two strongly labelled molecules of 23 and 67 kDa for blood microfilariae and several strongly labelled molecules of 23, 40, 42-67 kDa for in vitro born microfilariae. In addition, there were other weakly labelled molecules which were resolved after prolonged autoradiographic exposure. Surface molecules of 28, 29, and 33 kDa were unique to blood microfilariae, a 14.4 kDa molecule was unique to in vitro born microfilariae and molecules of 23, 40, and 75-84 kDa were common to both forms of microfilariae. The profile of excretory-secretory products consisted of molecules of 14.4-198 kDa. Human albumin was a predominant component of surface molecules and excretory-secretory products from blood microfilariae. Immunoprecipitation with occult and microfilaremic loaiasis sera demonstrated that the 23 kDa surface molecule and excretory-secretory products of 14.4 and 33 kDa were only recognized by occult loaiasis sera whereas surface molecules of 40 and 75-84 kDa and excretory-secretory products of 28 and 67 kDa were recognised by both sera. Studies with heterologous sera demonstrated that with the exception of the 75-84 kDa antigens, all the L. loa microfilarial surface antigens contained epitopes which were restricted to filarial parasites. Further studies revealed that the 23 kDa antigen was a protein which contained neither asparagine-N-linked oligosaccharides nor interchain disulfide-linkages.

The identification and partial characterization of an immunodominant 29-31 kilodalton surface antigen expressed by adult worms of the human filaria Loa loa.

Detergent solubilized extracts of 125Iodogen surface labelled adult Loa loa revealed a relatively simple profile consisting of a strongly labelled molecule at 29-31 kDa and weakly labelled molecules at 14.5, 17, 21, 23, 34, 58, and 86 kDa. Residents of a L. loa endemic zone were assessed clinically and parasitologically and classified as microfilaremic, amicrofilaremic with documented ocular passage of adult worms, or 'resistant' subjects without any signs of infection. Sera from these subjects were used to identify L. loa adult surface antigens. All 'resistant' sera immunoprecipitated the 29-31 kDa antigen although some were more strongly reactive than others. The amicrofilaremic sera strongly immunoprecipitated the 29-31 kDa antigen, whereas microfilaremic sera reacted weakly or not at all with this antigen. Longer exposures of immunoprecipitates of strongly reactive sera revealed the recognition of additional antigens of 86, 44, 34, 23, 21, 17 and 14.5 kDa. Studies with heterologous sera demonstrated that these antigens contain cross-reactive epitopes which are restricted to filarial parasites. Biochemical characterization of the predominant 29-31 kDa antigen showed that it bound concanavalin A, was sensitive to proteases, and its antigenicity was resistant to heat but sensitive to periodate and endo-beta-N-acetylglucosaminidase H. These observations suggest that it is a glycoprotein containing mannose and N-acetylglucosamine residues and that the carbohydrate moiety is important for antibody binding. The importance of the 29-31 kDa glycoprotein in the immunobiology of loaiasis is suggested by the finding that resistant and infected amicrofilaremic individuals have strongly reactive IgG antibodies to this antigen.

The tyrosine-86 allele of the pfmdr1 gene of Plasmodium falciparum is associated with increased sensitivity to the anti-malarials mefloquine and artemisinin.

Although chloroquine-resistance (CQR) in Plasmodium falciparum is increasing and resistance to other blood schizonticidal anti-malarials has been reported, the molecular basis remains unclear. In this study fresh field isolates were obtained from The Gambia, an area of emerging CQR and tested for sensitivity to the anti-malarial drugs mefloquine, halofantrine, artemisinin, dihydroartemisinin, chloroquine and quinine. Sequence polymorphisms in the pfmdr1 gene and size polymorphisms in the cg2 gene were assessed using PCR-based systems. A strong association was observed between the presence of the tyr-86 allele of pfmdr1 and increased sensitivity to mefloquine and halofantrine, as well as the structurally unrelated drugs artemisinin and dihydroartemisinin. A weaker association was found between the presence of tyr-86 and increased resistance to chloroquine and quinine. The cg2 Dd2-like omega repeat size polymorphism was associated with increased resistance to chloroquine and increased sensitivity to mefloquine and halofantrine. An intragenic association was also found between a polymorphism in the polyasparagine linker region of pfmdr1 and the tyr-86 allele, which may be due to genetic hitchhiking, indicative of recent selection by chloroquine. Our data support a hypothesis where the pfmdr1 gene confers a true multidrug resistance phenotype which is lost by mutation.

High-throughput sequence typing of T-cell epitope polymorphisms in Plasmodium falciparum circumsporozoite protein.

We report a method for typing polymorphisms at the T-cell epitopes within the Th2R and Th3R regions of the Plasmodium falciparum circumsporozoite protein (CSP). This method combines the use of PCR and sequence specific oligonucleotide probes (PCR-SSOP), and allows the identification of single nucleotide polymorphisms in these epitope regions. PCR-SSOP is a robust and a high-throughput sequence typing technique which has the same specificity and fidelity as direct sequencing. This method has been developed specifically for the assessment of the protective efficacy of RTS,S/SBAS2 vaccine against the 3D7 strain of P. falciparum (RTS,S/SBAS2 vaccine contains a part of the 3D7 CSP protein) in a phase IIb trial in Gambia which has been completed recently. PCR-SSOP could be used to determine the allelic frequencies of other parasite antigens and their geographical distribution.

Critical care research and pre-emptive informed consent: a practical approach used in Chris Hani Baragwanath ICU.

OBJECTIVES: 1) To establish a protocol within international and local ethical guidelines to obtain informed consent for critical care research, overcoming constraints previously described and 2) To evaluate eventual recruitment using this protocol. DESIGN: Prospective descriptive study. SETTING: Multidisciplinary ICU in a community-based university teaching hospital. PATIENTS AND PARTICIPANTS: Following approval by the University Ethics Committee and Hospital Review Board, patients admitted between January and May 1996 were assessed on weekdays for potential enrollment into existing clinical trials. Discussion with potential candidates and/or next-of-kin occurred at the earliest opportunity and informed consent was obtained preemptively. Next-of-kin was notified if enrollment subsequently occurred. We evaluated the number of patients screened, the number of potential study candidates, the number for whom consent was obtained or refused and the number subsequently enrolled. INTERVENTIONS: None RESULTS: Of 249 patients screened, 149 (60%) did not meet the inclusion criteria. Of 100 potential study candidates (40% of all patients screened), we failed to make contact with the next-of-kin in 29 cases (12% of all patients screened). Thus 71 patients or next-of-kin were counselled (28% of all patients screened). In all, 30 patients (12% of all patients screened) were subsequently enrolled into a study. CONCLUSIONS: A policy of pre-emptive informed consent enabled us to overcome some of the problems previously experienced in our unit with regards to patient enrollment in critical care research. Although overall recruitment remained low, predictions for future enrollment can be made from this study.

Ciprofloxacin pharmacokinetic profiles in paediatric sepsis: how much ciprofloxacin is enough?

OBJECTIVE: To determine the pharmacokinetic profile of ciprofloxacin 20 mg/kg per day (10 mg/kg administered intravenously 12 hourly) in paediatric patients with severe sepsis. DESIGN: Open and prospective. SETTING: Tertiary referral multi-disciplinary ICU. PATIENTS: Twenty patients (two groups - group A: 3 months-1 year; group B 1-5 years). INTERVENTIONS: Timed blood samples were taken for pharmacokinetics after the first dose (D(0)), as well as day 2 (D(2)) and then between days 6-8. MEASUREMENTS AND RESULTS: Ciprofloxacin serum levels were measured by high performance liquid chromatography. Demographic and clinical data and all adverse events were noted. Standard pharmacokinetic variables were calculated by non-compartmental methods. Peak concentrations (C(max)) for group A were D(0) 6.1+/-1.2 mg/l, D(2) 9.0+/-1.8 mg/l and D(7) 5.8+/-1.3 mg/l and, for group B, 7.4+/-1.3 mg/l, 7.8+/-1.6 mg/l and 6.4+/-1.3 mg/l, respectively, for the study periods. Concentration 12 h after the start of infusion (C(min)) for all periods were 0.2 mg/l or less. Areas under the curve (AUC, 12 h) were group A: 15.6+/-1.3, 19.2+/-1.63 and 14.1+/-1.4 mg/h per l, and group B: 15.9+/-1.3, 18.0+/-1.7 and 13.2+/-1.26 mg/h per l. One patient presenting with seizures, initially controlled, had another convulsion and a further patient developed seizures whilst on ciprofloxacin. C(max) in these patients were higher than the average C(max). The convulsions of both patients were easily controlled. No other drug-related serious adverse events occurred. No arthropathy was noted. Three patients died of their underlying disease. CONCLUSIONS: There was no accumulation of drug even after 7 days of administration. Our C(max) and AUC were lower than that achieved in a similar adult pharmacokinetic study. To achieve end points of area under the inhibitory curve (AUIC) of 100-150 mg/h per l, 10 mg/kg ciprofloxacin eight hourly would be required for some resistant ICU organisms.

Differential recognition of Loa loa antigens by sera of human subjects from a loiasis endemic zone.

Somatic antigens of Loa loa adult worms with molecular weights of 15-180 kDa were identified by Western blot analysis using sera from 3 categories of parasitologically and clinically defined subjects from a loiasis endemic zone. Sera of occult, amicrofilaremic (OL), and 'resistant' individuals with no clinical signs of infection (R) reacted with an antigen of 160 kDa; sera of highly microfilaremic individuals (ML) did not. ML sera strongly reacted with an antigen of 18 kDa which was recognized only weakly or not at all by OL and R sera. At higher dilutions, OL sera only reacted with antigens at 23 and 160 kDa and ML sera reacted with antigens at 18 and 23 kDa, whereas R sera reacted with antigens at 23, 42, 54, 70, 100, and 160 kDa. These data suggested that R sera contained a higher concentration of antibodies which reacted with denatured, nitrocellulose-bound antigens. The IgG4 isotype predominated for all groups of sera, while IgG3 antibody responses were observed only with R sera. IgG1 antibodies were seen in all groups but reacted with fewer antigens than IgG4 antibodies, and no IgG2 antibody responses were detected. Sera against Brugia malayi, Wuchereria bancrofti, Onchocerca volvulus, and Dirofilaria immitis cross-reacted with somatic antigens greater than 70 kDa, whereas none reacted with Loa loa antigens less than 23 kDa.

Tolerance and efficacy of single high-dose ivermectin for the treatment of loiasis.

A study was carried out in southeastern Gabon to evaluate the tolerance and efficacy of single high doses of ivermectin in 31 Loa loa-infected subjects with low-to-moderate parasitemia (7-7,700 microfilaria/ml). The first group of 16 subjects received 300 micrograms/kg of ivermectin and, seven days later, a second group of 15 received 400 micrograms/kg. Complete clinical and biological monitoring was carried out during the first 10 days post-treatment and again after one and three months. All subjects continued with their usual activities during the study. The clinical tolerance of treatment was very good, and except in one case, only mild adverse reactions were observed, with pruritus being the most common symptom. There were no significant changes in blood or urine function test results or in hematologic results, except for a pronounced eosinophil reaction. The 400 micrograms/kg dose of ivermectin equaled or surpassed in tolerance that of 300 micrograms/kg dose. After treatment, L. loa microfilaremia decreased rapidly to less than 9% of the pretreatment value by day 10. This decrease was enhanced with the 400 micrograms/kg dose, although differences between the two groups diminished slightly with time. At 100 days post-treatment, the microfilaremia was still at less than 10% of the initial values in the two groups, which may indicate an effect of ivermectin on the adult worms.

Comparison of a parasite lactate dehydrogenase-based immunochromatographic antigen detection assay (OptiMAL) with microscopy for the detection of malaria parasites in human blood samples.

Microscopic examination of blood smears remains the gold standard for malaria diagnosis, but is labor-intensive and requires skilled operators. Rapid dipstick technology provides a potential alternative. A study was conducted in The Gambia to compare the performance of OptiMAL, an immunochromatographic antigen detection assay for the diagnosis of malaria using parasite lactate dehydrogenase, against standard microscopy in patients with suspected malaria. For initial diagnosis of Plasmodium falciparum, irrespective of stage, this assay had a sensitivity of 91.3%, a specificity of 92%, a positive predictive value of 87.2%, and a negative predictive value of 94.7%. The sensitivity of the test decreased markedly at parasitemias < 0.01%. This assay can be used for the diagnosis of malaria in areas where microscopy is not available and for urgent malaria diagnosis at night and at weekends, when routine laboratories are closed and when relatively inexperienced microscopists may be on duty.

Identification of frequently recognized dimorphic T-cell epitopes in plasmodium falciparum merozoite surface protein-1 in West and East Africans: lack of correlation of immune recognition and allelic prevalence.

The merozoite surface protein-1 (MSP1) is the most studied malaria blood-stage vaccine candidate. Lymphokines such as interferon gamma (IFN-gamma) and interleukin 4 (IL-4) may mediate blood-stage specific protection. Here we identify Plasmodiumfalciparum MSP1 T-cell epitopes capable of rapid induction of IFN-gamma and/or IL-4 from peripheral blood mononuclear cells of East and West African donors. Both allelic forms of these novel MSP1 T-cell epitopes were stimulatory. An unusually high numbers of Gambian responders (> 80%) to these epitopes were observed, suggesting that MSPI reactivity may have been underestimated previously in this population. Surprisingly, IFN-gamma responses to allelic T-cell epitopes failed to correlate with differential antigenic exposure in The Gambia compared to Kenya. These results suggest an unexpected level of immunoregulation of IFN-gamma response with variable allelic T-cell reactivity independent of the level of antigenic exposure. Further analysis of the mechanisms determining this response pattern may be required if vaccines are to overcome this allelic reactivity bias in malaria-exposed populations.

A randomized controlled trial of artemether/benflumetol, a new antimalarial and pyrimethamine/sulfadoxine in the treatment of uncomplicated falciparum malaria in African children.

We report here the results of a randomized double blind trial comparing coartemether (CGP56697), a combination of artemether and benflumetol, with pyrimethamine/sulfadoxine (P/S). Two hundred eighty-seven children 1-5 years of age with uncomplicated falciparum malaria were enrolled at two centers in The Gambia between July 1996 and December 1996. Following treatment, children were visited at home every 24 hr until a blood film free of asexual parasites was obtained. Genotyping of parasites was used to distinguish recrudescence from new infections. Three days after the start of treatment, 133 (100%) of the CGP56697-treated children compared with 128 (93.4%) of children treated with P/S had cleared their parasites (P = 0.003). The day 15 cure rate was 93.3% for CGP56697 and 97.7% for P/S (P = 0.13). Within the third and fourth week after initiation of therapy, 20 children treated with CGP56697 and one of the P/S-treated children returned with second malaria episodes (P < 0.0001). Genotyping suggested that the majority (19 of 23 [82.6%]) of these second episodes were due to new infections, supporting the World Health Organization recommendation that longer follow-up is not relevant for the assessment of drug efficacy. At the two-week follow-up, 28.9% of the P/S treated children but none of the CGP56697-treated children carried gametocytes (P < 0.0001). This study showed that CGP56697 is safe in African children with acute uncomplicated falciparum malaria, clears parasites more rapidly than P/S, and results in fewer gametocyte carriers. More frequent new infections within the third and fourth week following treatment with CGP56697 than treatment with P/S are likely to be due to the short prophylactic effect of CGP56697.

A phase I safety and immunogenicity trial with the candidate malaria vaccine RTS,S/SBAS2 in semi-immune adults in The Gambia.

RTS,S is a novel pre-erythrocytic malaria vaccine based on the circumsporozoite surface protein (CSP) of Plasmodium falciparum linked to hepatitis B surface antigen (HBs) and combined with a novel adjuvant system (SBAS2). We have conducted a Phase I trial with three doses of this vaccine given at 0, 1, and 6 months to 20 semi-immune, adult, male volunteers in The Gambia to assess its safety and immunogenicity. Eighteen of the 20 volunteers completed the study. There were no clinically significant local or systemic adverse events following each vaccination. Hematologic and biochemical indices before and two weeks after each vaccination showed no evidence of toxicity. Antibody titers to both CSP and HBs showed a significant increase after vaccination; these were the largest after the third dose. We conclude that the RTS,S/SBAS2 vaccine induces no significant toxicity in this semi-immune population and produces significant increases in antibody titers to CSP.

An epidemiological study of a Schistosoma intercalatum focus in south-east Gabon.

A Schistosoma intercalatum focus in south-east Gabon was studied between July 1989 and July 1990. Among the 356 permanent residents in the village, 354 provided stool specimens and 101 (28.5%) were excreting eggs (geometric mean of egg density = 101.4 eggs/g, with a range of 1-3200). The pattern of prevalence and intensity of infection with age showed the curve usually found in schistosomiasis, i.e. increasing during the first 2 decades of life and then gradually decreasing. The analysis by stepwise logistic regression of factors shown to be important in determining infection in other schistosomiasis clearly demonstrated the significant and independent effects of both age and water contact on infection by S. intercalatum. These similarities with other schistosomal infections could indicate that similar immune mechanisms were operating. Urine from 284 subjects, of whom 90 were egg excreters, was tested for circulating antigen by enzyme-linked immunosorbent assay using a Schistosoma genus-specific monoclonal antibody (Sm 10.27.12). The test was positive for 90 subjects but only 35 of these were egg excreters. Although S. intercalatum is usually considered of low pathogenicity in man, this study showed a relationship between egg excretion and both splenomegaly and lower haemoglobin levels, even after taking into account the confounding presence of Plasmodium falciparum.

The safety of the combination artesunate and pyrimethamine-sulfadoxine given during pregnancy.

Malaria during pregnancy is associated with an increased risk of severe anaemia and low-birthweight babies. Effective intermittent therapy with pyrimethamine-sulfadoxine (PSD) decreases parasitaemia and severe anaemia and improves birthweight in areas where Plasmodium falciparum is sensitive to this drug. Increasing resistance to PSD is a concern and alternative antimalarial regimens during pregnancy are needed. Artesunate with PSD is a promising antimalarial combination but few data are available on the safety of artemisinins when taken during pregnancy. Outcome of pregnancy was evaluated for 287 women in The Gambia who were exposed in June 1999 to a single dose of the combination artesunate and PSD during a mass drug administration and 172 women who were not exposed. Women who received placebo (40) and those who did not participate in the mass drug administration (132) comprised the non-exposed group. There was no difference in the proportion of abortions, stillbirths, or infant deaths among those exposed or not exposed to the drugs. The mean weight of 18 infants born to mothers who had received artesunate and PSD during the third trimester was 3.10 kg compared to a mean weight of 2.62 kg of the 10 infants of untreated mothers (adjusted P value = 0.05). We found no evidence of a teratogenic or otherwise harmful effect of gestational exposure to artesunate and PSD. Treatment of a self-selected group of pregnant women with PSD and artesunate during pregnancy was associated with a greater birthweight, which may have resulted from clearance of malaria parasites. However, the influence of confounding factors cannot be excluded.