Challenges in the Control and Elimination of Plasmodium vivax Malaria

The human malaria parasite Plasmodium vivax imposes unique challenges to its control and elimination. Primary among those is the hypnozoite reservoir of infection in endemic communities. It is the dominant source of incident malaria and exceedingly difficult to attack due to both inability to diagnose latent carriers and the potentially life-threatening toxicity of primaquine in patients with an inborn deficiency of G6PD, the only therapeutic option against hypnozoites. Large segments of endemic populations are not eligible for primaquine, and alternative strategies for managing the threat of relapse in any group have not been optimized or validated. Association of risk of primaquine failure against latent P. vivax with impaired alleles of P450 2D6 exacerbates the substantial pool of primaquine ineligibles. Resistance to chloroquine against acute P. vivax malaria commonly occurs; alternative therapies like ACTs are effective but seldom evaluated as a partner drug to primaquine in the essential radical cure. Many of the Anopheles mosquito vector of P. vivax in South and Southeast Asia, where >90% of infections occur, thrive in a diversity of habitats and exhibit wide ranges of feeding and breeding behavior. This chapter explores many of these challenges and possible approaches in controlling and eliminating endemic vivax malaria

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

Malaria prevalence in Nias District, North Sumatra Province, Indonesia

BACKGROUND: The Nias district of the North Sumatra Province of Indonesia has long been known to be endemic for malaria. Following the economic crisis at the end of 1998 and the subsequent tsunami and earthquake, in December 2004 and March 2005, respectively, the malaria control programme in the area deteriorated. The present study aims to provide baseline data for the establishment of a suitable malaria control programme in the area and to analyse the frequency distribution of drug resistance alleles associated with resistance to chloroquine and sulphadoxine-pyrimethamine.\ud METHODS: Malariometric and entomology surveys were performed in three subdistricts. Thin and thick blood smears were stained with Giemsa and examined under binocular light microscopy. Blood blots on filter paper were also prepared for isolation of parasite and host DNA to be used for molecular analysis of band 3 (SAO), pfcrt, pfmdr1, dhfr, and dhps. In addition, haemoglobin measurement was performed in the second and third surveys for the subjects less than 10 years old.\ud RESULTS: Results of the three surveys revealed an average slide positivity rate of 8.13%, with a relatively higher rate in certain foci. Host genetic analysis, to identify the Band 3 deletion associated with Southeast Asian Ovalocytosis (SAO), revealed an overall frequency of 1.0% among the 1,484 samples examined. One hundred six Plasmodium falciparum isolates from three sub-districts were successfully analysed. Alleles of the dhfr and dhps genes associated with resistance to sulphadoxine-pyrimethamine, dhfr C59R and S108N, and dhps A437G and K540E, were present at frequencies of 52.2%, 82.5%, 1.18% and 1.18%, respectively. The pfmdr1 alleles N86Y and N1042D, putatively associated with mefloquine resistance, were present at 31.4% and 2%, respectively. All but one sample carried the pfcrt 76T allele associated with chloroquine resistance. Entomologic surveys identified three potential anopheline vectors in the area, Anopheles barbirostris, Anopheles kochi and Anopheles sundaicus.\ud CONCLUSION: The cross sectional surveys in three different sub-districts of Nias District clearly demonstrated the presence of relatively stable endemic foci of malaria in Nias District, North Sumatra Province, Indonesia. Molecular analysis of the malaria parasite isolates collected from this area strongly indicates resistance to chloroquine and a growing threat of resistance to sulphadoxine-pyrimethamine. This situation highlights the need to develop sustainable malaria control measures through regular surveillance and proper antimalarial drug deployment

Detection of 1014F kdr mutation in four major Anopheline malaria vectors in Indonesia

Background: Malaria is a serious public health problem in Indonesia, particularly in areas outside Java and Bali. The spread of resistance to the currently available anti-malarial drugs or insecticides used for mosquito control would cause an increase in malaria transmission. To better understand patterns of transmission and resistance in Indonesia, an integrated mosquito survey was conducted in three areas with different malaria endemicities, Purworejo in Central Java, South Lampung District in Sumatera and South Halmahera District in North Mollucca.\ud Methods: Mosquitoes were collected from the three areas through indoor and outdoor human landing catches (HLC) and indoor restinging catches. Specimens were identified morphologically by species and kept individually in 1.5 ml Eppendorf microtube. A fragment of the VGSC gene from 95 mosquito samples was sequenced and kdr allelic variation determined.\ud Results: The molecular analysis of these anopheline mosquitoes revealed the existence of the 1014F allele in 4 major malaria vectors from South Lampung. These species include, Anopheles sundaicus, Anopheles aconitus, Anopheles subpictus\ud andAnopheles vagus. The 1014F allele was not found in the other areas.\ud Conclusion: The finding documents the presence of this mutant allele in Indonesia, and implies that selection pressure on the Anopheles population in this area has occurred. Further studies to determine the impact of the resistance allele on the efficacy of pyrethroids in control programmes are neede

The risk of Plasmodium vivax parasitaemia after P. falciparum malaria: An individual patient data meta-analysis from the WorldWide Antimalarial Resistance Network.

BACKGROUND: There is a high risk of Plasmodium vivax parasitaemia following treatment of falciparum malaria. Our study aimed to quantify this risk and the associated determinants using an individual patient data meta-analysis in order to identify populations in which a policy of universal radical cure, combining artemisinin-based combination therapy (ACT) with a hypnozoitocidal antimalarial drug, would be beneficial. METHODS AND FINDINGS: A systematic review of Medline, Embase, Web of Science, and the Cochrane Database of Systematic Reviews identified efficacy studies of uncomplicated falciparum malaria treated with ACT that were undertaken in regions coendemic for P. vivax between 1 January 1960 and 5 January 2018. Data from eligible studies were pooled using standardised methodology. The risk of P. vivax parasitaemia at days 42 and 63 and associated risk factors were investigated by multivariable Cox regression analyses. Study quality was assessed using a tool developed by the Joanna Briggs Institute. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42018097400). In total, 42 studies enrolling 15,341 patients were included in the analysis, including 30 randomised controlled trials and 12 cohort studies. Overall, 14,146 (92.2%) patients had P. falciparum monoinfection and 1,195 (7.8%) mixed infection with P. falciparum and P. vivax. The median age was 17.0 years (interquartile range [IQR] = 9.0-29.0 years; range = 0-80 years), with 1,584 (10.3%) patients younger than 5 years. 2,711 (17.7%) patients were treated with artemether-lumefantrine (AL, 13 studies), 651 (4.2%) with artesunate-amodiaquine (AA, 6 studies), 7,340 (47.8%) with artesunate-mefloquine (AM, 25 studies), and 4,639 (30.2%) with dihydroartemisinin-piperaquine (DP, 16 studies). 14,537 patients (94.8%) were enrolled from the Asia-Pacific region, 684 (4.5%) from the Americas, and 120 (0.8%) from Africa. At day 42, the cumulative risk of vivax parasitaemia following treatment of P. falciparum was 31.1% (95% CI 28.9-33.4) after AL, 14.1% (95% CI 10.8-18.3) after AA, 7.4% (95% CI 6.7-8.1) after AM, and 4.5% (95% CI 3.9-5.3) after DP. By day 63, the risks had risen to 39.9% (95% CI 36.6-43.3), 42.4% (95% CI 34.7-51.2), 22.8% (95% CI 21.2-24.4), and 12.8% (95% CI 11.4-14.5), respectively. In multivariable analyses, the highest rate of P. vivax parasitaemia over 42 days of follow-up was in patients residing in areas of short relapse periodicity (adjusted hazard ratio [AHR] = 6.2, 95% CI 2.0-19.5; p = 0.002); patients treated with AL (AHR = 6.2, 95% CI 4.6-8.5; p < 0.001), AA (AHR = 2.3, 95% CI 1.4-3.7; p = 0.001), or AM (AHR = 1.4, 95% CI 1.0-1.9; p = 0.028) compared with DP; and patients who did not clear their initial parasitaemia within 2 days (AHR = 1.8, 95% CI 1.4-2.3; p < 0.001). The analysis was limited by heterogeneity between study populations and lack of data from very low transmission settings. Study quality was high. CONCLUSIONS: In this meta-analysis, we found a high risk of P. vivax parasitaemia after treatment of P. falciparum malaria that varied significantly between studies. These P. vivax infections are likely attributable to relapses that could be prevented with radical cure including a hypnozoitocidal agent; however, the benefits of such a novel strategy will vary considerably between geographical areas

Haematological consequences of acute uncomplicated falciparum malaria: a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data

Background: Plasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia. Methods: Individual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall ≥ 25% at day 3 and day 7. Results: A total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0–19.7 g/dL) in Africa, 11.6 g/dL (range 5.0–20.0 g/dL) in Asia and 12.3 g/dL (range 6.9–17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to ≥ 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39–3.05], p < 0.001). Conclusions: In patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery

PENGARUH EKSTRAK ETANOL BUNGA CENGKEH (Eugenia caryophylata Thunb) TERHADAP AKTIVITAS ANTIMALARIA ARTEMISININ PADA Plasmodium falciparum Effect of ethanolic extract of clove (Eugenia caryophylata Thunb) as anti-malaria activity on Plasmodium falciparum

ABSTRACTMalaria is still one of the major health problems in Indonesia. The current malaria treatment is using artemisinincombination with other antimalarials drug (Artemisinin-Based Combination Therapy). The main problem of the use of artemisininbecause it is generating free radicals, which are not only toxic to P. falciparum but also toxicto the host. To minimize the effects of free radicals is by takes an antioxidant, that can be derived from clove(Eugenia caryophylata Thunb). This study aims to examine the effects of the ethanol extract of clove (EEBC) asantioxidants in artemisinin treatment. Active component in clove was extracted by reflux using ethanol 96%(v/v). In this study, P. falciparum strain 3D7 was cultured in RPMI 1640 medium containing red blood cells, HEPESbuffer, serum AB and NaHCO3 withTrager and Jensen techniques. The results of the examination on oxidant statusshowed that levels of MDA in the culture of P. falciparum were incubated with combination ofartemisinin andEEBC were significantly decreased (1.778 ± 0.07 nM / ml) ( p &lt; 0.05 ) compared to controls without EEBC (2.026± 0.47 nM / mL). In the other side, GSH levels were significantly increased in the same culture (1.1318 ± 0.07 mg/ml) (p &lt; 0.05) compared to controls without EEBC (0.2496 ± 0.01 mg/mL). It was concluded that ethanol extractof clove can reduce free radicals whis are formed as a result of the artemisinin work but did not affect the activityof artemisinin as antimalarial.Keywords: Eugenia caryophylata Thunb, Plasmodium falciparum, artemisinin, GSH, MDA ABSTRAKMalaria masih merupakan salah satu masalah kesehatan utama di Indonesia. Pengobatan malaria saat inimenggunakan kombinasi artemisinin dengan antimalaria lain (Artemisinin Based Combination Therapy).Masalah utama penggunaan artemisinin adalah radikal bebas yang dihasilkan, yang tidak hanya toksik padaP. falciparum tetapi juga toksik terhadap inang. Untuk mengatasi dampak radikal bebas diperlukan suatuantioksidan, seperti yang dapat diperoleh dari bunga cengkeh (Eugenia caryophylata Thunb). Penelitianini bertujuan menguji efek ekstrak etanol bunga cengkeh (EEBC) sebagai antioksidan dalam terapi denganartemisinin. Komponen aktif dalam bunga cengkeh diekstraksi dengan cara refluk menggunakan etanol 96%(v/v). Dalam penelitian ini P. falciparum galur 3D7 dikultur dalam Medium RPMI 1640 yang mengandung seldarah merah, dapar HEPES, serum AB dan NaHCO3 sesuai teknik Trager dan Jensen. Hasil menunjukan padapemeriksaan status oksidan, kadar MDA pada kultur P. falciparum yang diinkubasi dengan kombinasi EEBC danartemisinin menurun (1,778±0,07 nM/ml) secara bermakna (p&lt;0,05) dibandingkan terhadap kontrol tanpaEEBC (2,026±0,47 nM/ml). Hasil sebaliknya, kadar GSH pada kultur yang sama meningkat (1,1318±0,07 μg/ml) secara bermakna (p&lt;0,05) dibandingkan terhadap kontrol tanpa EEBC (0,2496±0,01 μg/ml). Berdasarkanhasil penelitian ini, ekstrak etanol bunga cengkeh dapat meredam radikal bebas yang terbentuk akibat kerjaartemisinin tetapi tidak mempengaruhi aktivitas antimalaria falciparum artemisinin