Supervised versus unsupervised primaquine radical cure for the treatment of falciparum and vivax malaria in Papua, Indonesia: a cluster-randomised, controlled, open-label superiority trial

Background There is a high risk of Plasmodium vivax recurrence in patients treated for Plasmodium falciparum malaria in co-endemic areas. Primaquine radical cure has the potential to reduce P vivax recurrences in patients presenting with P falciparum as well as P vivax malaria but is undermined by poor adherence to the currently recommended 14-day regimen. We aimed to assess the efficacy and safety of supervised versus unsupervised primaquine radical cure in patients presenting with uncomplicated malaria. Methods We did a cluster-randomised, controlled, open-label superiority trial in Papua, Indonesia. 21 clusters of village health posts, matched by annual parasite index, were randomly assigned (1:1) to treat patients (age >12 months and body weight >5 kg) presenting with confirmed uncomplicated P falciparum or P vivax malaria with oral dihydroartemisinin–piperaquine plus either a supervised or unsupervised 14-day course of oral primaquine (0·5 mg/kg per day). Patients in the supervised group were supervised taking their primaquine dose on alternate days. Patients were followed-up for 6 months and those who presented again with malaria were retreated with the same drug regimen. Masking was not possible due to the nature of the study. The primary outcome was the incidence risk of P vivax malaria over 6 months, assessed in the modified intention-to-treat population (all patients who were assigned to a treatment group, excluding patients who were lost to follow-up after their first visit). This trial is now complete, and is registered with ClinicalTrials.gov, NCT02787070. Findings Between Sept 14, 2016, and July 31, 2018, 436 patients were screened for eligibility and 419 were enrolled; 223 (53%) patients in 11 clusters were assigned to supervised primaquine treatment and 196 (47%) in ten clusters to unsupervised primaquine treatment. 161 (72%) of 223 patients in the supervised group and 151 (77%) of 196 in the unsupervised group completed 6 months of follow-up. At 6 months, the incidence risk of P vivax recurrence in the supervised group was 29·7% (95% CI 16·4–49·9) versus 55·8% (32·3–81·8) in the unsupervised group (hazard ratio 0·23 [95% CI 0·07–0·76]; p=0·016). The incidence rate for P vivax recurrence was 539 (95% CI 390–747) infections per 1000 person-years in the supervised group versus 859 (673–1096) in the unsupervised group (incidence rate ratio 0·63 [95% CI 0·42–0·94]; p=0·025). The corresponding rates in the 224 patients who presented with P falciparum malaria were 346 (95% CI 213–563) and 660 (446–977; incidence rate ratio 0·52 [95% CI 0·28–0·98]; p=0·043). Seven serious adverse events were reported (three in the supervised group, four in the unsupervised group), none of which were deemed treatment-related, and there were no deaths. Interpretation In this area of moderate malaria transmission, supervision of primaquine radical cure treatment reduced the risk of P vivax recurrence. This finding was apparent for patients presenting with either P falciparum or P vivax malaria. Further studies are warranted to investigate the safety and efficacy of radical cure for patients presenting with uncomplicated falciparum malaria in other co-endemic areas. Funding The Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Foreign Affairs and Trade of the Australian Government. Translation For the Indonesian translation of the abstract see Supplementary Materials section

Intermittent screening and treatment for malaria complementary to routine immunisation in the first year of life in Papua, Indonesia: a cluster randomised superiority trial

Background In Papua (Indonesia), infants with P. falciparum and/or P. vivax malaria are at risk of severe anaemia and death. We hypothesized that in an area of high malaria transmission, intermittent screening and treatment of infants with malaria (ISTi) will reduce morbidity compared to passive case detection (PCDi). Methods We conducted a cluster randomised, open label, superiority trial. A total of 21 clusters of village health posts (VHP) were randomised 1:1 to either IST for infants coinciding with 4 routine immunisation visits or PCDi. Healthy term infants born to consenting mothers enrolled into a maternal malaria cluster randomised trial were included in the study and followed for 12 months. Point of care malaria rapid diagnostic tests were used to detect peripheral parasitaemia at 2, 3, 4 and 9 months old in all infants in ISTi clusters and when symptomatic in PCDi clusters. Infants with detected peripheral parasitaemia were treated with dihydroartemisinin-piperaquine. The co-primary outcomes were the incidence rate of clinical malaria in the first year of life and the prevalence of parasitaemia at age 12 months. The incidence rate ratio and prevalence ratio between ISTi and PCDi were estimated using mixed-effects Poisson and log-binomial regression modelling (accounting for clustering at VHP level). Results Between May 2014 and February 2017, 757 infants were enrolled into the study, 313 into 10 ISTi clusters, and 444 into 11 PCDi clusters. Overall, 132 episodes of parasitaemia were detected, of whom 17 (12.9%) were in symptomatic infants. Over 12 months, the incidence rate (IR) of clinical malaria was 24 [95% CI, 10–50] per 1000 children-years at risk in the ISTi arm and 19 [95% CI, 8,38] per 1000 children-years in the PCDi arm (adjusted incidence rate ratio [aIRR] 1.77 [95% CI, 0.62–5.01]; p = 0.280). The prevalence of parasitaemia at 12 months was 13% (33/254) in the IST clusters and 15% (57/379) in the PCD clusters (adjusted prevalence ratio (aPR) = 0.92 (95% CI, 0.70–1.21), p = 0.55). There was no difference in the risk of anaemia between treatment arms. Conclusions In high malaria transmission area outside of Africa, our study suggests that compared to PCDi, ISTi offers no significant benefit in reducing the risk of clinical malaria in infants born to women receiving effective protection from malaria during pregnancy. Trial registration ClinicalTrials.gov NCT 02001428, registered on 20 Nov 2013

Preserved dendritic cell HLA-DR expression and reduced regulatory T cell activation in asymptomatic Plasmodium falciparum and P. vivax infection.

Clinical illness with Plasmodium falciparum or Plasmodium vivax compromises the function of dendritic cells (DC) and expands regulatory T (Treg) cells. Individuals with asymptomatic parasitemia have clinical immunity, restricting parasite expansion and preventing clinical disease. The role of DC and Treg cells during asymptomatic Plasmodium infection is unclear. During a cross-sectional household survey in Papua, Indonesia, we examined the number and activation of blood plasmacytoid DC (pDC), CD141(+), and CD1c(+) myeloid DC (mDC) subsets and Treg cells using flow cytometry in 168 afebrile children (of whom 15 had P. falciparum and 36 had P. vivax infections) and 162 afebrile adults (of whom 20 had P. falciparum and 20 had P. vivax infections), alongside samples from 16 patients hospitalized with uncomplicated malaria. Unlike DC from malaria patients, DC from children and adults with asymptomatic, microscopy-positive P. vivax or P. falciparum infection increased or retained HLA-DR expression. Treg cells in asymptomatic adults and children exhibited reduced activation, suggesting increased immune responsiveness. The pDC and mDC subsets varied according to clinical immunity (asymptomatic or symptomatic Plasmodium infection) and, in asymptomatic infection, according to host age and parasite species. In conclusion, active control of asymptomatic infection was associated with and likely contingent upon functional DC and reduced Treg cell activation

Genetic micro-epidemiology of malaria in Papua Indonesia: Extensive P. vivax diversity and a distinct subpopulation of asymptomatic P. falciparum infections

BACKGROUND:Genetic analyses of Plasmodium have potential to inform on transmission dynamics, but few studies have evaluated this on a local spatial scale. We used microsatellite genotyping to characterise the micro-epidemiology of P. vivax and P. falciparum diversity to inform malaria control strategies in Timika, Papua Indonesia. METHODS:Genotyping was undertaken on 713 sympatric P. falciparum and P. vivax isolates from a cross-sectional household survey and clinical studies conducted in Timika. Standard population genetic measures were applied, and the data was compared to published data from Kalimantan, Bangka, Sumba and West Timor. RESULTS:Higher diversity (HE = 0.847 vs 0.625; p = 0.017) and polyclonality (46.2% vs 16.5%, p<0.001) were observed in P. vivax versus P. falciparum. Distinct P. falciparum substructure was observed, with two subpopulations, K1 and K2. K1 was comprised solely of asymptomatic infections and displayed greater relatedness to isolates from Sumba than to K2, possibly reflecting imported infections. CONCLUSIONS:The results demonstrate the greater refractoriness of P. vivax versus P. falciparum to control measures, and risk of distinct parasite subpopulations persisting in the community undetected by passive surveillance. These findings highlight the need for complimentary new surveillance strategies to identify transmission patterns that cannot be detected with traditional malariometric methods

Asymptomatic Vivax and Falciparum Parasitaemia with Helminth Co-Infection: Major Risk Factors for Anaemia in Early Life.

BACKGROUND: Anaemia in children under five years old is associated with poor health, growth and developmental outcomes. In Papua, Indonesia, where the burden of anaemia in infants is high, we conducted a community survey to assess the association between Plasmodium infection, helminth carriage and the risk of anaemia. METHODS: A cross sectional household survey was carried out between April and July 2013 in 16 villages in the District of Mimika using a multistage sampling procedure. A total of 629 children aged 1-59 months from 800 households were included in the study. Demographic, symptom and anthropometry data were recorded using a standardized questionnaire. Blood and stool samples were collected for examination. RESULTS: Of the 533 children with blood film examination, 8.8% (47) had P. vivax parasitaemia and 3.9% (21) had P. falciparum; the majority of children with malaria were asymptomatic (94.4%, 68/72). Soil transmitted helminth (STH) infection was present in 43% (105/269) of children assessed; those with STH were at significantly greater risk of P. vivax parasitaemia compared to those without STH (OR = 3.7 [95%CI 1.5-9.2], p = 0.004). Anaemia (Hb&lt;10 g/dl) was present in 24.5% (122/497) of children and associated with P. vivax parasitaemia (OR = 2.9 [95%CI, 1.7-4.9], p = 0.001), P. falciparum parasitaemia (OR = 4.3 [95%CI, 2.0-9.4], p&lt;0.001), hookworm carriage (OR = 2.6 [95%CI, 1.2-5.8], p = 0.026), Plasmodium-helminth coinfection (OR 4.0 [95%CI, 1.4-11.3], p = 0.008) and severe stunting (OR = 1.9 ([95%CI, 1.1-3.3], p = 0.012). CONCLUSIONS: Asymptomatic P. vivax and P. falciparum infections and hookworm all contribute to risk of paediatric anaemia in coendemic areas and should be targeted with prevention and treatment programs. The relationship between helminth infections and the increased risk of P. vivax parasitaemia should be explored prospectively

Asymptomatic Vivax and Falciparum Parasitaemia with Helminth Co-Infection: Major Risk Factors for Anaemia in Early Life.

BACKGROUND: Anaemia in children under five years old is associated with poor health, growth and developmental outcomes. In Papua, Indonesia, where the burden of anaemia in infants is high, we conducted a community survey to assess the association between Plasmodium infection, helminth carriage and the risk of anaemia. METHODS: A cross sectional household survey was carried out between April and July 2013 in 16 villages in the District of Mimika using a multistage sampling procedure. A total of 629 children aged 1-59 months from 800 households were included in the study. Demographic, symptom and anthropometry data were recorded using a standardized questionnaire. Blood and stool samples were collected for examination. RESULTS: Of the 533 children with blood film examination, 8.8% (47) had P. vivax parasitaemia and 3.9% (21) had P. falciparum; the majority of children with malaria were asymptomatic (94.4%, 68/72). Soil transmitted helminth (STH) infection was present in 43% (105/269) of children assessed; those with STH were at significantly greater risk of P. vivax parasitaemia compared to those without STH (OR = 3.7 [95%CI 1.5-9.2], p = 0.004). Anaemia (Hb<10 g/dl) was present in 24.5% (122/497) of children and associated with P. vivax parasitaemia (OR = 2.9 [95%CI, 1.7-4.9], p = 0.001), P. falciparum parasitaemia (OR = 4.3 [95%CI, 2.0-9.4], p<0.001), hookworm carriage (OR = 2.6 [95%CI, 1.2-5.8], p = 0.026), Plasmodium-helminth coinfection (OR 4.0 [95%CI, 1.4-11.3], p = 0.008) and severe stunting (OR = 1.9 ([95%CI, 1.1-3.3], p = 0.012). CONCLUSIONS: Asymptomatic P. vivax and P. falciparum infections and hookworm all contribute to risk of paediatric anaemia in coendemic areas and should be targeted with prevention and treatment programs. The relationship between helminth infections and the increased risk of P. vivax parasitaemia should be explored prospectively

Genetic micro-epidemiology of malaria in Papua Indonesia: Extensive <i>P</i>. <i>vivax</i> diversity and a distinct subpopulation of asymptomatic <i>P</i>. <i>falciparum</i> infections

<div><p>Background</p><p>Genetic analyses of <i>Plasmodium</i> have potential to inform on transmission dynamics, but few studies have evaluated this on a local spatial scale. We used microsatellite genotyping to characterise the micro-epidemiology of <i>P</i>. <i>vivax</i> and <i>P</i>. <i>falciparum</i> diversity to inform malaria control strategies in Timika, Papua Indonesia.</p><p>Methods</p><p>Genotyping was undertaken on 713 sympatric <i>P</i>. <i>falciparum</i> and <i>P</i>. <i>vivax</i> isolates from a cross-sectional household survey and clinical studies conducted in Timika. Standard population genetic measures were applied, and the data was compared to published data from Kalimantan, Bangka, Sumba and West Timor.</p><p>Results</p><p>Higher diversity (<i>H</i>_<i>E</i> = 0.847 vs 0.625; <i>p</i> = 0.017) and polyclonality (46.2% vs 16.5%, <i>p</i><0.001) were observed in <i>P</i>. <i>vivax</i> versus <i>P</i>. <i>falciparum</i>. Distinct <i>P</i>. <i>falciparum</i> substructure was observed, with two subpopulations, K1 and K2. K1 was comprised solely of asymptomatic infections and displayed greater relatedness to isolates from Sumba than to K2, possibly reflecting imported infections.</p><p>Conclusions</p><p>The results demonstrate the greater refractoriness of <i>P</i>. <i>vivax</i> versus <i>P</i>. <i>falciparum</i> to control measures, and risk of distinct parasite subpopulations persisting in the community undetected by passive surveillance. These findings highlight the need for complimentary new surveillance strategies to identify transmission patterns that cannot be detected with traditional malariometric methods.</p></div

Characterization of blood dendritic and regulatory T cells in asymptomatic adults with sub-microscopic Plasmodium falciparum or Plasmodium vivax infection.

Background Plasmodium falciparum and Plasmodium vivax infections compromise dendritic cell (DC) function and expand regulatory T (Treg) cells in both clinical disease (malaria) and experimental human sub-microscopic infection. Conversely, in asymptomatic microscopy-positive (patent) P. falciparum or P. vivax infection in endemic areas, blood DC increase or retain HLA-DR expression and Treg cells exhibit reduced activation, suggesting that DC and Treg cells contribute to the control of patent asymptomatic infection. The effect of sub-microscopic (sub-patent) asymptomatic Plasmodium infection on DC and Treg cells in malaria-endemic area residents remains unclear. Methods In a cross-sectional household survey conducted in Papua, Indonesia, 162 asymptomatic adults were prospectively evaluated for DC and Treg cells using field-based flow cytometry. Of these, 161 individuals (99 %) were assessed retrospectively by polymerase chain reaction (PCR), 19 of whom had sub-microscopic infection with P. falciparum and 15 with sub-microscopic P. vivax infection. Flow cytometric data were re-analysed after re-grouping asymptomatic individuals according to PCR results into negative controls, sub-microscopic and microscopic parasitaemia to examine DC and Treg cell phenotype in sub-microscopic infection. Results Asymptomatic adults with sub-microscopic P. falciparum or P. vivax infection had DC HLA-DR expression and Treg cell activation comparable to PCR-negative controls. Sub-microscopic P. falciparum infection was associated with lower peripheral CD4+ T cells and lymphocytes, however sub-microscopic Plasmodium infection had no apparent effect on DC sub-set number or Treg cell frequency. Conclusions In contrast to the impairment of DC maturation/function and the activation of Treg cells seen with sub-microscopic parasitaemia in primary experimental human Plasmodium infection, no phenotypic evidence of dysregulation of DC and Treg cells was observed in asymptomatic sub-microscopic Plasmodium infection in Indonesian adults. This is consistent with DC and Treg cells retaining their functional capacity in sub-microscopic asymptomatic infection with P. falciparum or P. vivax in malaria-endemic areas.</p