Seasonal prevalence of malaria in West Sumba district, Indonesia

BACKGROUND: Accurate information about the burden of malaria infection at the district or provincial level is required both to plan and assess local malaria control efforts. Although many studies of malaria epidemiology, immunology, and drug resistance have been conducted at many sites in Indonesia, there is little published literature describing malaria prevalence at the district, provincial, or national level.\ud METHODS: Two stage cluster sampling malaria prevalence surveys were conducted in the wet season and dry season across West Sumba, Nusa Tenggara Province, Indonesia.\ud RESULTS: Eight thousand eight hundred seventy samples were collected from 45 sub-villages in the surveys. The overall prevalence of malaria infection in the West Sumba District was 6.83% (95% CI, 4.40, 9.26) in the wet season and 4.95% (95% CI, 3.01, 6.90) in the dry. In the wet season Plasmodium falciparum accounted for 70% of infections; in the dry season P. falciparum and Plasmodium vivax were present in equal proportion. Malaria prevalence varied substantially across the district; prevalences in individual sub-villages ranged from 0-34%. The greatest malaria prevalence was in children and teenagers; the geometric mean parasitaemia in infected individuals decreased with age. Malaria infection was clearly associated with decreased haemoglobin concentration in children under 10 years of age, but it is not clear whether this association is causal.\ud CONCLUSION: Malaria is hypoendemic to mesoendemic in West Sumba, Indonesia. The age distribution of parasitaemia suggests that transmission has been stable enough to induce some clinical immunity. These prevalence data will aid the design of future malaria control efforts and will serve as a baseline against which the results of current and future control efforts can be assessed

Seasonal distribution of anti-malarial drug resistance alleles on the island of Sumba, Indonesia

Background: Drug resistant malaria poses an increasing public health problem in Indonesia, especially eastern Indonesia, where malaria is highly endemic. Widespread chloroquine (CQ) resistance and increasing sulphadoxine-pyrimethamine (SP) resistance prompted Indonesia to adopt artemisinin-based combination therapy (ACT) as first-line therapy in 2004. To help develop a suitable malaria control programme in the district of West Sumba, the seasonal distribution of alleles known to be\ud associated with resistance to CQ and SP among\ud Plasmodium falciparum isolates from the region was investigated.\ud Methods: Plasmodium falciparum isolates were collected during malariometric surveys in the wet and dry seasons in 2007 using two-stage cluster sampling. Analysis of pfcrt, pfmdr, pfmdr1 gene copy number, dhfr, and dhps genes were done using protocols described previously.\ud Results and Discussion: The 76T allele of the pfcrt gene is nearing fixation in this population. Pfmdr1 mutant alleles occurred in 72.8% and 53.3%, predominantly as 1042D and 86Y alleles that are mutuallyexclusive. The prevalence of amplified\ud pfmdr1 was found 41.9% and 42.8% of isolates in the wet and dryseasons, respectively. The frequency of dhfr mutant alleles was much lower, either as a single 108N mutation or paired with 59R. The 437G allele was the only mutant dhps allele detected and it was only found during dry season.\ud Conclusion: The findings demonstrate a slighly higher distribution of drug-resistant alleles during the wet season and support the policy of replacing CQ with ACT in this area, but suggest that SP might still be effective either alone or in combination with other anti-malarial

Very High Risk of Therapeutic Failure with Chloroquine for Uncomplicated \u3ci\u3ePlasmodium falciparum\u3c/i\u3e and \u3ci\u3eP. vivax\u3c/i\u3e Malaria in Indonesian Papua

Chloroquine remains the first-line therapy for uncomplicated malaria in Indonesia. Among a series of trials of chloroquine for malaria on this archipelago conducted since 1990, we now report the highest risk of therapeutic failure yet observed. A clinical trial of standard chloroquine therapy for uncomplicated malaria at Arso PIR V in northeastern Indonesian Papua was conducted during 1995. We enrolled 104 non-immune subjects infected with Plasmodium falciparum (n=55), P. vivax (n=29), or P. falciparum plus P. vivax (n=20) and administered supervised standard chloroquine therapy (10 + 10 + 5 mg/kg at 24-hour intervals). The 28-day cumulative incidence of therapeutic failure was 95% for P. falciparum, 84% for P. vivax, and 100% for mixed infections. Only one subject each for P. falciparum and P. vivax remained free of parasites at day 28. All recurrent parasitemias occurred with whole blood levels of chloroquine plus desethylchloroquine exceeding 100 ng/ml. These findings document almost complete failure of chloroquine against P. falciparum or P. vivax near the northeastern coast of Indonesian Papua

VERY HIGH RISK OF THERAPEUTIC FAILURE WITH CHLOROQUINE FOR UNCOMPLICATED \u3ci\u3ePLASMODIUM FALCIPARUM\u3c/i\u3e AND \u3ci\u3eP. VIVAX\u3c/i\u3e MALARIA IN INDONESIAN PAPUA

Chloroquine remains the first-line therapy for uncomplicated malaria in Indonesia. Among a series of trials of chloroquine for malaria on this archipelago conducted since 1990, we now report the highest risk of therapeutic failure yet observed. A clinical trial of standard chloroquine therapy for uncomplicated malaria at Arso PIR V in northeastern Indonesian Papua was conducted during 1995. We enrolled 104 non-immune subjects infected with Plasmodium falciparum (n=55), P. vivax (n=29), or P. falciparum plus P. vivax (n=20) and administered supervised standard chloroquine therapy (10 + 10 + 5 mg/kg at 24-hour intervals). The 28-day cumulative incidence of therapeutic failure was 95% for P. falciparum, 84% for P. vivax, and 100% for mixed infections. Only one subject each for P. falciparum and P. vivax remained free of parasites at day 28. All recurrent parasitemias occurred with whole blood levels of chloroquine plus desethylchloroquine exceeding 100 ng/ml. These findings document almost complete failure of chloroquine against P. falciparum or P. vivax near the northeastern coast of Indonesian Papua

DNA prime/Adenovirus boost malaria vaccine encoding P. falciparum CSP and AMA1 induces sterile protection associated with cell-mediated immunity

Contains fulltext : 118242.pdf (publisher's version ) (Open Access)BACKGROUND: Gene-based vaccination using prime/boost regimens protects animals and humans against malaria, inducing cell-mediated responses that in animal models target liver stage malaria parasites. We tested a DNA prime/adenovirus boost malaria vaccine in a Phase 1 clinical trial with controlled human malaria infection. METHODOLOGY/PRINCIPAL FINDINGS: The vaccine regimen was three monthly doses of two DNA plasmids (DNA) followed four months later by a single boost with two non-replicating human serotype 5 adenovirus vectors (Ad). The constructs encoded genes expressing P. falciparum circumsporozoite protein (CSP) and apical membrane antigen-1 (AMA1). The regimen was safe and well-tolerated, with mostly mild adverse events that occurred at the site of injection. Only one AE (diarrhea), possibly related to immunization, was severe (Grade 3), preventing daily activities. Four weeks after the Ad boost, 15 study subjects were challenged with P. falciparum sporozoites by mosquito bite, and four (27%) were sterilely protected. Antibody responses by ELISA rose after Ad boost but were low (CSP geometric mean titer 210, range 44-817; AMA1 geometric mean micrograms/milliliter 11.9, range 1.5-102) and were not associated with protection. Ex vivo IFN-gamma ELISpot responses after Ad boost were modest (CSP geometric mean spot forming cells/million peripheral blood mononuclear cells 86, range 13-408; AMA1 348, range 88-1270) and were highest in three protected subjects. ELISpot responses to AMA1 were significantly associated with protection (p = 0.019). Flow cytometry identified predominant IFN-gamma mono-secreting CD8+ T cell responses in three protected subjects. No subjects with high pre-existing anti-Ad5 neutralizing antibodies were protected but the association was not statistically significant. SIGNIFICANCE: The DNA/Ad regimen provided the highest sterile immunity achieved against malaria following immunization with a gene-based subunit vaccine (27%). Protection was associated with cell-mediated immunity to AMA1, with CSP probably contributing. Substituting a low seroprevalence vector for Ad5 and supplementing CSP/AMA1 with additional antigens may improve protection. TRIAL REGISTRATION: ClinicalTrials.govNCT00870987

Development of parasitemia in the immunized and infectivity control subjects.

<p><b>Panel A</b>: Parasitemia-free survival curves (Kaplan-Meier) for immunized volunteers and infectivity controls based on microscopic examination of peripheral blood smears. <b>Panel B</b>: Quantitative(q)-PCR measurements of parasitemia in immunized and challenge controls (error bars show standard deviation) (see reference 28).</p

Schematic of DNA and Adenovirus CSP and AMA1 vaccines.

<p>Each panel presents the native protein (top of each panel) and the protein expressed by the DNA or Ad construct (middle and bottom of each panel) for the CSP (Panel <b>A</b>) and AMA1 (Panel <b>B</b>) vaccine antigens. N = amino terminus; C = carboxy terminus; TPA = human tissue plasminogen activator signal sequence; TM = transmembrane domain. See text for explanation. Identical colors indicate identical sequences. Not represented is a single amino acid substitution (G → R) in the AMA DNA construct at position 143.</p

Study subjects demographics.

<p>Twenty volunteers were enrolled into the immunization group; five dropped out prior to CHMI (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055571#pone-0055571-g003" target="_blank">Figure 3</a>). Infectivity controls were enrolled later, in time for CHMI on week 28. NAb titers are provided for the 15 study subjects who were challenged (included in the immunogenicity analysis); these were measured just prior to Ad boost.</p

Trial design.

<p>Subjects were immunized week 0, 4, 8 and 24 and challenged week 28 (blue arrows). Samples for measuring cell-mediated immunity (ELISpot assay and flow cytometry) were collected at six time points (black arrows), and for measuring antibody levels (ELISA, IFA and growth inhibition assay) at similar time points plus after the DNA immunizations (gray arrows). See text for details.</p

IFN-γ activities by flow cytometry for CSP and AMA1.

<p>The box plots (see Statistical Analysis section for description) represent IFN-γ -producing CD4+ or CD8+ T cell frequencies as percentage of gated CD4+ or CD8+ T cells, measured by flow cytometry assays after stimulation with a single CSP or AMA1 megapool containing all individual peptide pools for each antigen, for all 15 challenged volunteers. The time points on the x-axis are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055571#pone-0055571-g001" target="_blank">Figure 1</a>. The four protected volunteers are shown as larger, color-coded dots. For the protected volunteers, the CD4+ T cell AMA1 response of v06 at pre-Ad is a box plot outlier, and the CD8+ T cell CSP responses of v11 and v18 post-Ad, and the CD8+ T cell AMA1 responses of v18 post-Ad and post-Ch are box plot suspected outliers. The dotted lines represent positive cutoff (0.03% as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055571#s2" target="_blank">Methods</a>). IFN-γ -producing CD4+ T cell frequencies were significantly higher than baseline (*) post-DNA (p = 0.047), post-Ad (p = 0.0097) and post-Ch (p = 0.004) for AMA1 (mixed linear model). IFN-γ -producing CD8+ T cell frequencies were significantly higher than baseline (*) post-Ad for CSP (p = 0.007) and post-Ad for AMA1 (0.002) (mixed linear model).</p