High Complexity of Plasmodium vivax Infections in Symptomatic Patients from a Rural Community in Central Vietnam Detected by Microsatellite Genotyping

Fourteen published and three newly identified polymorphic microsatellites were used to genotype 69 Plasmodium vivax samples obtained from 39 patients detected over a period of two years who lived in a rural community of central Vietnam. All samples were polyclonal with an average expected heterozygosity of 0.86. Among the 39 patients, 16 experienced 1–5 recurrent episodes of P. vivax malaria, most of them (83%) with a different genotype profile compared with previous infections. The minimal set of microsatellites required for differentiating the genotype profiles of the recurrent infections compared with the full set of 17 microsatellites was explored. A combination of five markers was sufficient to identify all recurrent infections with an unrelated or different genotype profile compared with all previous episodes

Extended high efficacy of the combination sulphadoxine-pyrimethamine with artesunate in children with uncomplicated falciparum malaria on the Benin coast, West Africa

<p>Abstract</p> <p>Background</p> <p>A study carried out in 2003–2005 in Southern Benin showed a day-28 sulphadoxine-pyrimethamine (SP) monotherapy failure rate greater than 40%, while for SP combined with artesunate (SP-AS) the failure rate was 5.3%. Such a large difference could be explained by the relatively short 28-day follow-up period, with a substantial number of recurrent infections possibly occurring after day 28. This paper reports the treatment outcome observed in the same study cohort beyond the initial 28-day follow-up.</p> <p>Methods</p> <p>After the 28-day follow-up, children treated with either chloroquine alone (CQ), SP or SP-AS, were visited at home twice a week until day 90 after treatment. A blood sample was collected if the child had fever (axillary temperature ≥37.5°C). Total clinical failure for each treatment group was estimated by combining all the early treatment failures and late clinical failures that occurred over the whole follow-up period, i.e. from day 0 up to day 90. Pre-treatment randomly selected blood samples were genotyped for the <it>dhfr </it>gene (59) and the <it>dhps </it>gene (437 and 540) point mutations related to SP resistance.</p> <p>Results</p> <p>The PCR-corrected clinical failure at day 90 was significantly lower in the SP-AS group (SP-AS: 2.7%, SP alone: 38.2%; CQ: 41.1%) (Log-Rank p < 0,001). The most prevalent haplotype was <it>dhfr </it>Arg-59 with the <it>dhps </it>Gly-437 mutant and the <it>dhps </it>540 wild type (85.5%). The <it>dhps </it>540 mutation could be found in only three (8.3%) samples.</p> <p>Conclusion</p> <p>Combining artesunate to SP dramatically increased the treatment efficacy, even when extending the follow-up to day 90 post-treatment, and despite the high percentage of failures following treatment with SP alone. Such a good performance may be explained by the low prevalence of the <it>dhps </it>540 mutation, by the rapid parasite clearance with artesunate and by the level of acquired immunity.</p

Adding artesunate to sulphadoxine-pyrimethamine greatly improves the treatment efficacy in children with uncomplicated falciparum malaria on the coast of Benin, West Africa

<p>Abstract</p> <p>Background</p> <p>Benin has recently shifted its national antimalarial drug policy from monotherapies to combinations containing artemisinin derivatives. When this decision was taken, the available information on alternatives to chloroquine and sulphadoxine-pyrimethamine, the first- and second-line treatment, was sparse.</p> <p>Methods</p> <p>In 2003 – 2005, before the drug policy change, a randomized, open-label, clinical trial was carried out on the efficacy of chloroquine, and sulphadoxine-pyrimethamine alone or combined with artesunate, with the aim of providing policy makers with the information needed to formulate a new antimalarial drug policy. Children between six and 59 months of age, with uncomplicated malaria and living in the lagoon costal area in southern Benin, were randomly allocated to one of the three study arms and followed up for 28 days.</p> <p>Results</p> <p>Treatment failure (PCR corrected) was significantly lower in the artesunate + sulphadoxine-pyrimethamine group (4/77, 5.3%) than in chloroquine group(51/71, 71.8%) or the sulphadoxine-pyrimethamine alone group (30/70, 44.1%) (p < 0.001). Despite high sulphadoxine-pyrimethamine failure, its combination with artesunate greatly improved treatment efficacy.</p> <p>Conclusion</p> <p>In Benin, artesunate + sulphadoxine-pyrimethamine is efficacious and could be used when the recommended artemisinin-based combinations (artemether-lumefantrine and amodiaquine-artesunate) are not available. However, because sulphadoxine-pyrimethamine is also used in pregnant women as intermittent preventive treatment, its combination with artesunate should not be widely employed in malaria patients as this may compromise the efficacy of intermittent preventive treatment.</p

Epidemiology of forest malaria in central Vietnam: a large scale cross-sectional survey

In Vietnam, a large proportion of all malaria cases and deaths occurs in the central mountainous and forested part of the country. Indeed, forest malaria, despite intensive control activities, is still a major problem which raises several questions about its dynamics. A large-scale malaria morbidity survey to measure malaria endemicity and identify important risk factors was carried out in 43 villages situated in a forested area of Ninh Thuan province, south central Vietnam. Four thousand three hundred and six randomly selected individuals, aged 10–60 years, participated in the survey. Rag Lays (86%), traditionally living in the forest and practising "slash and burn" cultivation represented the most common ethnic group. The overall parasite rate was 13.3% (range [0–42.3] while Plasmodium falciparum seroprevalence was 25.5% (range [2.1–75.6]). Mapping of these two variables showed a patchy distribution, suggesting that risk factors other than remoteness and forest proximity modulated the human-vector interactions. This was confirmed by the results of the multivariate-adjusted analysis, showing that forest work was a significant risk factor for malaria infection, further increased by staying in the forest overnight (OR= 2.86; 95%CI [1.62; 5.07]). Rag Lays had a higher risk of malaria infection, which inversely related to education level and socio-economic status. Women were less at risk than men (OR = 0.71; 95%CI [0.59; 0.86]), a possible consequence of different behaviour. This study confirms that malaria endemicity is still relatively high in this area and that the dynamics of transmission is constantly modulated by the behaviour of both humans and vectors. A well-targeted intervention reducing the "vector/forest worker" interaction, based on long-lasting insecticidal material, could be appropriate in this environment

A comparison of fluoroquinolones versus other antibiotics for treating enteric fever: meta-analysis

Objectives To review evidence supporting use of fluoroquinolones as first line agents over other antibiotics for treating typhoid and paratyphoid fever (enteric fever)

Human Plasmodium knowlesi infections in young children in central Vietnam.

BACKGROUND: Considering increasing reports on human infections by Plasmodium knowlesi in Southeast Asian countries, blood samples collected during two large cross-sectional malariometric surveys carried out in a forested area of central Vietnam in 2004 and 2005 were screened for this parasite. METHODS: Blood samples collected at the 2004 survey and positive for Plasmodium malariae were randomly selected for PCR analysis detecting P. knowlesi. Blood samples collected in 2005 from the same individuals were screened again for P. knowlesi. Positive samples were confirmed by sequencing. Family members of positive cases who participated in both surveys were also screened. RESULTS: Ninety-five samples with P. malariae mono- or mixed infections identified by species-specific PCR were screened for P. knowlesi. Among the five (5.2%) positive samples by PCR, three were confirmed to be P. knowlesi infections by sequencing, two young children (<5 years old) and a young man, all asymptomatic at the time of the survey and for the next six months after the survey. One of the two children was still positive one year later. No infection was found among the family members. CONCLUSION: Plasmodium knowlesi infections in humans can be found in central Vietnam. A small child was positive for P. knowlesi in both surveys at one year interval, though it is unclear whether it was the same or a new infection

Safety and efficacy of lumefantrine-artemether (Coartem) for the treatment of uncomplicated Plasmodium falciparum malaria in Zambian adults.

BACKGROUND: In Zambia, unacceptably high resistance to commonly used antimalarial drugs prompted the choice of artemether-lumefantrine (AL) as first line treatment for uncomplicated Plasmodium falciparum malaria. Although the safety and efficacy of AL have been extensively documented, no clinical trials had been carried out in Zambia. METHODS: Nine hundred seventy one adult patients with uncomplicated malaria were randomized to either sulfadoxine-pyrimethamine (SP)(486) or AL (485) and followed up for 45 days. Outcome of treatment was defined according to the standard WHO classification. Recurrent parasitaemia were genotyped to distinguish between recrudescence and new infection. RESULTS: Fever at day 3 was significantly lower (AL: 0.9%; 4/455; SP: 3,5%; 15/433; p = 0.007) and the mean haemoglobin at day 45 significantly higher (AL: 134 g/l; SP 130 g/l; p = 0.02) in the AL group. Almost all clinical symptoms cleared faster with AL. Early treatment failure was significantly higher in the SP (25/464) than in the AL (2/463) (OR: 13.1 95% CI: 3.08-55.50; P < 0.001). The rate of new infections was similar in both groups (18 with SP and 19 with AL). Late clinical failure (OR: 2.55; 95% CI: 1.34-4.84; P = 0.004) and late parasitological failure (OR:3.18; 95% CI: 1.25-8.09; P = 0.02) were significantly higher in the SP group. Total treatment failure was significantly higher in the SP group (96/393; 19.3%) as compared to the AL (22/403; 5.4%) group (OR: 4.15; 95% CI: 2.52-6.83; P < 0.001). CONCLUSION: In Zambia, the new first line regimen AL is far more efficacious than SP in treating uncomplicated P. falciparum malaria in adults. Data on safety and efficacy of AL in pregnant women are urgently needed

Varying efficacy of artesunate+amodiaquine and artesunate+sulphadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria in the Democratic Republic of Congo: a report of two in-vivo studies

BACKGROUND: Very few data on anti-malarial efficacy are available from the Democratic Republic of Congo (DRC). DRC changed its anti-malarial treatment policy to amodiaquine (AQ) and artesunate (AS) in 2005. METHODS: The results of two in vivo efficacy studies, which tested AQ and sulphadoxine-pyrimethamine (SP) monotherapies and AS+SP and AS+AQ combinations in Boende (Equatorial province), and AS+SP, AS+AQ and SP in Kabalo (Katanga province), between 2003 and 2004 are presented. The methodology followed the WHO 2003 protocol for assessing the efficacy of anti-malarials in areas of high transmission. RESULTS: Out of 394 included patients in Boende, the failure rates on day 28 after PCR-genotyping adjustment of AS+SP and AS+AQ were estimated as 24.6% [95% CI: 16.6-35.5] and 15.1% [95% CI: 8.6-25.7], respectively. For the monotherapies, failure rates were 35.9% [95% CI: 27.0-46.7] for SP and 18.3% [95% CI: 11.6-28.1] for AQ. Out of 207 patients enrolled in Kabalo, the failure rate on day 28 after PCR-genotyping adjustment was 0 [1-sided 95% CI: 5.8] for AS+SP and AS+AQ [1-sided 95% CI: 6.2]. It was 19.6% [95% CI: 11.4-32.7] for SP monotherapy. CONCLUSION: The finding of varying efficacy of the same combinations at two sites in one country highlights one difficulty of implementing a uniform national treatment policy in a large country. The poor efficacy of AS+AQ in Boende should alert the national programme to foci of resistance and emphasizes the need for systems for the prospective monitoring of treatment efficacy at sentinel sites in the country

Real-time PCR/MCA assay using fluorescence resonance energy transfer for the genotyping of resistance related DHPS-540 mutations in Plasmodium falciparum

BACKGROUND: Sulphadoxine-pyrimethamine has been abandoned as first- or second-line treatment by most African malaria endemic countries in favour of artemisinin-based combination treatments, but the drug is still used as intermittent preventive treatment during pregnancy. However, resistance to sulphadoxine-pyrimethamine has been increasing in the past few years and, although the link between molecular markers and treatment failure has not been firmly established, at least for pregnant women, it is important to monitor such markers. METHODS: This paper reports a novel sensitive, semi-quantitative and specific real-time PCR and melting curve analysis (MCA) assay using fluorescence resonance energy transfer (FRET) for the detection of DHPS-540, an important predictor for SP resistance. FRET/MCA was evaluated using 78 clinical samples from malaria patients and compared to PCR-RFLP. RESULTS: Sixty-two samples were in perfect agreement between both assays. One sample showed a small wild type signal with FRET/MCA that indicates a polyclonal infection. Four samples were not able to generate enough material in both assays to distinguish mutant from wild-type infection, six samples gave no signal in PCR-RFLP and five samples gave no amplification in FRET/MCA. CONCLUSION: FRET/MCA is an effective tool for the identification of SNPs in drug studies and epidemiological surveys on resistance markers in general and DHPS-540 mutation in particular

A modified semi-nested multiplex malaria PCR (SnM-PCR) for the identification of the five human Plasmodium species occurring in Southeast Asia.

We have modified an existing semi-nested multiplex polymerase chain reaction (PCR) by adding one Plasmodium knowlesi-specific nested PCR, and validated the latter against laboratory and clinical samples. This new method has the advantage of being relatively affordable in low resource settings while identifying the five human Plasmodium species with a three-step PCR