Plasmodium falciparum and P. vivax malaria parasites are now resistant, or showing signs of resistance, to most drugs used in therapy. Novel chemical entities that exhibit new mechanisms of antiplasmodial action are needed. New antimalarials that block transmission of Plasmodium spp. from humans to Anopheles mosquito vectors are key to malaria eradication efforts. Although P. vivax causes a considerable number of malaria cases, its importance has for long been neglected. Vivax malaria can cause severe manifestations and death; hence there is a need for P. vivax-directed research. Plants used in traditional medicine, namely Artemisia annua and Cinchona spp. are the sources of the antimalarial natural products artemisinin and quinine, respectively. Based on these compounds, semi-synthetic artemisinin-derivatives and synthetic quinoline antimalarials have been developed and are the most important drugs in the current therapeutic arsenal for combating malaria. In the Amazon region, where P. vivax predominates, there is a local tradition of using plant-derived preparations to treat malaria. Here, we review the current P. falciparum and P. vivax drug-sensitivity assays, focusing on challenges and perspectives of drug discovery for P. vivax, including tests against hypnozoites. We also present the latest findings of our group and others on the antiplasmodial and antimalarial chemical components from Amazonian plants that may be potential drug leads against malaria. © 2013 by the authors; licensee MDPI, Basel, Switzerland.18892199240A research agenda for malaria eradication: Drugs (2011) PLoS Med., 8, pp. e1000402. , malERA Consultative Group on DrugsWhite, N.J., Counter perspective: Artemisinin resistance: Facts, fears, and fables (2012) Am. J. Trop. Med. Hyg., 87, p. 785Phyo, A.P., Nkhoma, S., Stepniewska, K., Ashley, E.A., Nair, S., McGready, R., Ler Moo, C., Lwin, K.M., Emergence of artemisinin-resistant malaria on the western border of Thailand: A longitudinal study (2012) Lancet, 379, pp. 1960-1966Milliken, W., (1997) Plants for Malaria, Plants for Fever: Medicinal Species in Latin America, A Bibliographic Survey, p. 116. , Royal Botanic Gardens, Kew: Richmond, VA, USARuiz, L., Ruiz, L., Maco, M., Cobos, M., Gutierrez-Choquevilca, A.L., Roumy, V., Plants used by native Amazonian groups from the Nanay River (Peru) for the treatment of malaria (2011) J. Ethnopharmacol., 133, pp. 917-921Vigneron, M., Deparis, X., Deharo, E., Bourdy, G., Antimalarial remedies in French Guiana: A knowledge attitudes and practices study (2005) J. Ethnopharmacol., 98, pp. 351-360Bero, J., Quetin-Leclercq, J., Natural products published in 2009 from plants traditionally used to treat malaria (2011) Planta Med., 77, pp. 631-640Deharo, E., Ginsburg, H., Analysis of additivity and synergism in the anti-plasmodial effect of purified compounds from plant extracts (2011) Malar. J., 10 (SUPPL. 1), pp. S5Andrade-Neto, V.F., Brandao, M.G., Nogueira, F., Rosario, V.E., Krettli, A.U., Ampelozyziphus amazonicus Ducke (Rhamnaceae), a medicinal plant used to prevent malaria in the Amazon Region, hampers the development of Plasmodium berghei sporozoites (2008) Int. J. Parasitol., 38, pp. 1505-1511(2010) Global Report on Antimalarial Drug Efficacy and Drug Resistance: 2000-2010, p. 115. , World Health OrganizationWorld Health Organization: Geneva, SwitzerlandYoung, M.D., Moore, D.V., Chloroquine resistance in Plasmodium falciparum (1961) Am. J. Trop. Med. Hyg., 10, pp. 317-320Harinasuta, T., Migasen, S., Boonag, D., (1962) Chloroquine Resistance in Plasmodium Falciparum in Thailand, , UNESCO First Regional Symposium on Scientific Knowledge of Tropical Parasites: Singapore University, SingaporePeters, W., (1987) Chemotherapy and Drug Resistance in Malaria, , 2nd ed.Academic: London, UKRoper, C., Pearce, R., Nair, S., Sharp, B., Nosten, F., Anderson, T., Intercontinental spread of pyrimethamine-resistant malaria (2004) Science, 305, p. 1124Enserink, M., Combating malaria. Malaria treatment: ACT two (2007) Science, 318, pp. 560-563(2006) Guidelines for the Treatment of Malaria, p. 253. , World Health Organization. Roll Back Malaria Dept.World Health Organization: Geneva, SwitzerlandDa Mata, A.A., (2003) Flora Médica Brasiliense, , Valer Editora: Manaus, BrazilElisabetsky, E., Shanley, P., Ethnopharmacology in the Brazilian Amazon (1994) Pharmacol. Therap., 64, pp. 201-214Rodrigues, E., Plants and animals utilized as medicines in the Jau National Park (JNP), Brazilian Amazon (2006) Phytother. Res., 20, pp. 378-391Santos, J.F., Pagani, E., Ramos, J., Rodrigues, E., Observations on the therapeutic practices of riverine communities of the Unini River, AM, Brazil (2012) J. Ethnopharmacol., 142, pp. 503-515Suffredini, I.B., Paciencia, M.L., Varella, A.D., Younes, R.N., Antibacterial activity of Brazilian Amazon plant extracts (2006) Braz. J. Infect. Dis., 10, pp. 400-402Carneiro, A.L., Teixeira, M.F., Oliveira, V.M., Fernandes, O.C., Cauper, G.S., Pohlit, A.M., Screening of Amazonian plants from the Adolpho Ducke forest reserve, Manaus, state of Amazonas, Brazil, for antimicrobial activity (2008) Mem. Inst. Oswaldo Cruz, 103, pp. 31-38Pohlit, A.M., Lopes, N.P., Gama, R.A., Tadei, W.P., Neto, V.F., Patent literature on mosquito repellent inventions which contain plant essential oils-A review (2011) Planta Med., 77, pp. 598-617Pohlit, A.M., Rezende, A.R., Lopes Baldin, E.L., Lopes, N.P., Neto, V.F., Plant extracts, isolated phytochemicals, and plant-derived agents which are lethal to arthropod vectors of human tropical diseases-A review (2011) Planta Med., 77, pp. 618-630Schmidt, T.J., Khalid, S.A., Romanha, A.J., Alves, T.M., Biavatti, M.W., Brun, R., Da Costa, F.B., De Lacerda, M.V., The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases-part I (2012) Curr. Med. Chem., 19, pp. 2128-2175Achan, J., Talisuna, A.O., Erhart, A., Yeka, A., Tibenderana, J.K., Baliraine, F.N., Rosenthal, P.J., D'Alessandro, U., Quinine an old anti-malarial drug in a modern world: Role in the treatment of malaria (2011) Malar. J., 10, p. 144Bray, P.G., Ward, S.A., O'Neill, P.M., Quinolines and artemisinin: Chemistry, biology and history (2005) Curr. Top. Microbiol. Immunol., 295, pp. 3-38Pohlit, A.M., Jabor, V.A.P., Amorim, R.C.N., Costa Silva, E.E.C., Lopes, N.P., LC-ESI-MS determination of quassinoids Isobrucein B and neosergeolide in picrolemma sprucei stem infusions (2009) J. Braz. Chem. Soc., 20, pp. 1065-1070De Andrade-Neto, V.F., Pohlit, A.M., Pinto, A.C., Silva, E.C., Nogueira, K.L., Melo, M.R., Henrique, M.C., Costa, M.R., In vitro inhibition of plasmodium falciparum by substances isolated from Amazonian antimalarial plants (2007) Mem. Inst. Oswaldo Cruz, 102, pp. 359-365Pinto, A.C., Chaves, F.C., Dos Santos, P.A., Nunez, C.V., Tadei, W.P., Pohlit, A.M., Piper peltatum: Biomass and 4-nerolidylcatechol production (2010) Planta Med., 76, pp. 1473-1476Pinto, P.S., (2006) Estudo Químico e Atividade Biológica de Frações Do Extrato Etanólico da Raiz de Cassia Spruceana Benth. (Leguminosae: Caesalpinioideae), , M.Sc. Thesis, Universidade Federal do Amazonas, Manaus, BrazilHenrique, M.C., Nunomura, S.M., Pohlit, A.M., Indole alkaloids from the bark of Aspidosperma vargasii and A desmanthum (2010) Quim. Nova, 33, pp. 284-287Rocha Silva, E.L.F., Montoia, A., Amorim, R.C., Melo, M.R., Henrique, M.C., Nunomura, S.M., Costa, M.R., Dantas, G., Comparative in vitro and in vivo antimalarial activity of the indole alkaloids ellipticine, olivacine, cryptolepine and a synthetic cryptolepine analog (2012) Phytomed. Int. J. Phytother. Phytopharmacol., 20, pp. 71-76Dos Santos Torres, Z.E., Silveira, E.R., Rocha, E.S.L.F., Lima, E.S., De Vasconcellos, M.C., De Andrade Uchoa, D.E., Filho, R.B., Pohlit, A.M., Chemical composition of aspidosperma ulei markgr and antiplasmodial activity of selected indole alkaloids (2013) Molecules, 18, pp. 6281-6297Oliveira, A.B., Dolabela, M.F., Póvoa, M.M., Santos, C.A.M., Varotti, F.P., Antimalarial activity of ulein and proof of its action on the Plasmodium falciparum digestive vacuole (2010) Malar. J., , doi:10.1186/1475-2875-9-S2-O9Tanaka, Y., Sakamoto, A., Inoue, T., Yamada, T., Kikuchi, T., Kajimoto, T., Muraoka, O., Kim, H.-S., Andirolides H-P from the flower of andiroba (Carapa guianensis, Meliaceae) (2012) Tetrahedron, 68, pp. 3669-3677Marti, G., Eparvier, V., Moretti, C., Susplugas, S., Prado, S., Grellier, P., Retailleau, P., Litaudon, M., Antiplasmodial benzophenones from the trunk latex of Moronobea coccinea (Clusiaceae) (2009) Phytochemistry, 70, pp. 75-85Pinto, A.C., Silva, L.F., Cavalcanti, B.C., Melo, M.R., Chaves, F.C., Lotufo, L.V., De Moraes, M.O., Pessoa, C.O., New antimalarial and cytotoxic 4-nerolidylcatechol derivatives (2009) Eur. J. Med. Chem., 44, pp. 2731-2735Bertani, S., Houel, E., Stien, D., Chevolot, L., Jullian, V., Garavito, G., Bourdy, G., Deharo, E., Simalikalactone D is responsible for the antimalarial properties of an Amazonian traditional remedy made with Quassia amara L. (Simaroubaceae) (2006) J. Ethnopharmacol., 108, pp. 155-157Cachet, N., Hoakwie, F., Bertani, S., Bourdy, G., Deharo, E., Stien, D., Houel, E., Chevalley, S., Antimalarial activity of simalikalactone E, a new quassinoid from Quassia amara L. (Simaroubaceae) (2009) Antimicrob. Agents Chemother., 53, pp. 4393-4398Muhammad, I., Bedir, E., Khan, S.I., Tekwani, B.L., Khan, I.A., Takamatsu, S., Pelletier, J., Walker, L.A., A new antimalarial quassinoid from Simaba orinocensis (2004) J. Nat. Prod., 67, pp. 772-777Morais, S.K.R., Silva, S.G., Portela, C.N., Nunomura, S.M., Quignard, E.L.J., Pohlit, A.M., Bioactive dihydroxyfuranonaphthoquinones from the bark of Tabebuia incana A.H. Gentry (Bignoniaceae) and HPLC analysis of commercial pau d'arco and certified T. incana bark infusions (2007) Acta Amaz., 37, pp. 99-102Pérez, H., Diaz, F., Medina, J.D., Chemical investigation and in vitro antimalarial activity of Tabebuia ochracea ssp neochrysantha (1997) Pharm. Biol., 35, pp. 227-235Rocha Silva, E.L.F., Lima, E.S., Vasconcellos, M.C., Aranha, E.S.P., Costa, D.S., Santos, E.V.M., Silva, T.C.M., Alecrim, M.G.C., In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the Amazonian plant Tachia grandiflora (Gentianaceae) (2013) Mem. Inst. Oswaldo Cruz, 108, pp. 501-507Pohlit, A.M., Rocha Silva, E.L.F., Henrique, M.C., Montoia, A., Amorim, R.C., Nunomura, S.M., Andrade-Neto, V.F., Antimalarial activity of ellipticine (2012) Phytom. Int. J. Phytother. Phytopharmacol., 19, p. 1049Roumy, V., Fabre, N., Portet, B., Bourdy, G., Acebey, L., Vigor, C., Valentin, A., Moulis, C., Four anti-protozoal and anti-bacterial compounds from Tapirira guianensis (2009) Phytochem., 70, pp. 305-311Jullian, V., Bourdy, G., Georges, S., Maurel, S., Sauvain, M., Validation of use of a traditional antimalarial remedy from French Guiana, Zanthoxylum rhoifolium Lam (2006) J. Ethnopharmacol., 106, pp. 348-352Saraiva Nunomura, R.C., Pinto, A.C., Nunomura, S.M., Pohlit, A.M., Fernandes Amaral, A.C. Chemical constitutents from stems of Simaba guianensis subesp ecaudata (Cronquist) (2012) Quim. Nova, 35, pp. 2153-2158Montoia, A., (2013) Semi-síntese de Derivados da Elipticina e Atividade Antimalárica de Isolados e Infusões de Aspidosperma Vargasii, , M.Sc. Thesis, Universidade Federal do Amazonas, Manaus, BrazilCamargo, M.R.M., (2011) Avaliação da Atividade Antimalárica e Antimicrobiana de Geissospermum Argenteum e Minquartia Guianensis, Coletadas em Roraima, , M.Sc. Thesis, Universidade Federal de Rondônia, BrazilPinto, P.S., Rocha Silva, E.L.F., Amorim, R.C.N., Melo, M.R.S., Nunomura, S.M., Pohlit, A.M.Q.N., Phenolic constituents from the roots of Cassia spruceana Benth. (Fabaceae) (2013) Quim. Nova, , submitted for publishCavalcanti, B.C., Da Costa, P.M., Carvalho, A.A., Rodrigues, F.A., Amorim, R.C., Silva, E.C., Pohlit, A.M., Pessoa, C., Involvement of intrinsic mitochondrial pathway in neosergeolide-induced apoptosis of human HL-60 leukemia cells: The role of mitochondrial permeability transition pore and DNA damage (2012) Pharm. Biol., 50, pp. 980-993Cabral, J.A., McChesney, J.D., Milhous, W.K., A new antimalarial quassinoid from Simaba guianensis (1993) J. Nat. Prod., 56, pp. 1954-1961Passemar, C., Salery, M., Soh, P.N., Linas, M.D., Ahond, A., Poupat, C., Benoit-Vical, F., Indole and aminoimidazole moieties appear as key structural units in antiplasmodial molecules (2011) Phytomed. Int. J. Phytother. Phytopharmacol., 18, pp. 1118-1125Chong, C.R., Sullivan Jr., D.J., Inhibition of heme crystal growth by antimalarials and other compounds: Implications for drug discovery (2003) Biochem. Pharmacol., 66, pp. 2201-2212Rocha, E.S.L.F., Silva Pinto, A.C., Pohlit, A.M., Quignard, E.L., Vieira, P.P., Tadei, W.P., Chaves, F.C., Costa, M.R., In vivo and in vitro antimalarial activity of 4-nerolidylcatechol (2011) Phytother. Res., 25, pp. 1181-1188Silva Lima, E., Silva Pinto, A.C., Nogueira, K.L., Rocha Silva, E.L.F., Oliveira De Almeida, P.D., Carvalho De Vasconcellos, M., Chaves, F.C., Pohlit, A.M., Stability and antioxidant activity of semi-synthetic derivatives of 4-nerolidylcatechols (2012) Molecules, 18, pp. 178-189Mota, M.L., Lobo, L.T., Costa, J.M., Costa, L.S., Rocha, H.A., Rocha Silva, E.L.F., Pohlit, A.M., Neto, V.F., In vitro and in vivo antimalarial activity of essential oils and chemical components from three medicinal plants found in northeastern Brazil (2012) Planta Med., 78, pp. 658-664Baird, J.K., Eliminating malaria - All of them (2010) Lancet, 376, pp. 1883-1885Schrader, F.C., Barho, M., Steiner, I., Ortmann, R., Schlitzer, M., The antimalarial pipeline-An update (2012) Int. J. Med. Microbiol., 302, pp. 165-171Rieckmann, K.H., McNamara, J.V., Frischer, H., Stockert, T.A., Carson, P.E., Powell, R.D., Effects of chloroquine, quinine, and cycloguanil upon the maturation of asexual erythrocytic forms of two strains of Plasmodium falciparum in vitro (1968) Am. J. Trop. Med. Hyg., 17, pp. 661-671Rieckmann, K.H., Campbell, G.H., Sax, L.J., Mrema, J.E., Drug sensitivity of plasmodium falciparum. An in vitro microtechnique (1978) Lancet, 1, pp. 22-23Noedl, H., Wongsrichanalai, C., Wernsdorfer, W.H., Malaria drug-sensitivity testing: New assays, new perspectives (2003) Trends Parasitol., 19, pp. 175-181Trager, W., Jensen, J.B., Human malaria parasites in continuous culture (1976) Science, 193, pp. 673-675Desjardins, R.E., Canfield, C.J., Haynes, J.D., Chulay, J.D., Quantitative assessment of antimalarial activity in vitro by a semiautomated microdilution technique (1979) Antimicrob. Agents Chemother., 16, pp. 710-718Aguiar, A.C., Rocha, E.M., Souza, N.B., Franca, T.C., Krettli, A.U., New approaches in antimalarial drug discovery and development: A review (2012) Mem. Inst. Oswaldo Cruz, 107, pp. 831-845Makler, M.T., Ries, J.M., Williams, J.A., Bancroft, J.E., Piper, R.C., Gibbins, B.L., Hinrichs, D.J., Parasite lactate dehydrogenase as an assay for Plasmodium falciparum drug sensitivity (1993) Am. J. Trop. Med. Hyg., 48, pp. 739-741Druilhe, P., Moreno, A., Blanc, C., Brasseur, P.H., Jacquier, P., A colorimetric in vitro drug sensitivity assay for Plasmodium falciparum based on a highly sensitive double-site lactate dehydrogenase antigen-capture enzyme-linked immunosorbent assay (2001) Am. J. Trop. Med. Hyg., 64, pp. 233-241Noedl, H., Wernsdorfer, W.H., Miller, R.S., Wongsrichanalai, C., Histidine-rich protein II: A novel approach to malaria drug sensitivity testing. Antimicrob (2002) Agents Chemother., 46, pp. 1658-1664Plouffe, D., Brinker, A., McNamara, C., Henson, K., Kato, N., Kuhen, K., Nagle, A., Anderson, P., In silico activity profiling reveals the mechanism of action of antimalarials discovered in a high-throughput screen (2008) Proc. Natl. Acad. Sci. USA, 105, pp. 9059-9064Cervantes, S., Stout, P.E., Prudhomme, J., Engel, S., Bruton, M., Cervantes, M., Carter, D., Aalbersberg, W., High content live cell imaging for the discovery of new antimalarial marine natural products (2012) BMC Infect. Dis., 12, p. 1Van Vianen, P.H., Thaithong, S., Reinders, P.P., Van Engen, A., Van Der Keur, M., Tanke, H.J., Van Der Kaay, H.J., Mons, B., Automated flow cytometric analysis of drug susceptibility of malaria parasites (1990) Am. J. Trop. Med. Hyg., 43, pp. 602-607Saito-Ito, A., Akai, Y., He, S., Kimura, M., Kawabata, M., A rapid, simple and sensitive flow cytometric system for detection of Plasmodium falciparum (2001) Parasitol. Int., 50, pp. 249-257Wilson, D.W., Crabb, B.S., Beeson, J.G., Development of fluorescent Plasmodium falciparum for in vitro growth inhibition assays (2010) Malar. J., 9, p. 152Che, P., Cui, L., Kutsch, O., Cui, L., Li, Q., Validating a firefly luciferase-based high-throughput screening assay for antimalarial drug discovery (2012) Assay Drug Dev. Technol., 10, pp. 61-68Cui, L., Miao, J., Wang, J., Li, Q., Cui, L., Plasmodium falciparum: Development of a transgenic line for screening antimalarials using firefly luciferase as the reporter (2008) Exp. Parasitol., 120, pp. 80-87Krettli, A.U., Adebayo, J.O., Krettli, L.G., Testing of natural products and synthetic molecules aiming at new antimalarials (2009) Curr. Drug Targets, 10, pp. 261-270Gething, P.W., Elyazar, I.R., Moyes, C.L., Smith, D.L., Battle, K.E., Guerra, C.A., Patil, A.P., Myers, M.F., A long neglected world malaria map: Plasmodium vivax endemicity in 2010 (2012) PLoS Neglect Trop. Dis., 6, pp. e1814Guerra, C.A., Howes, R.E., Patil, A.P., Gething, P.W., Van Boeckel, T.P., Temperley, W.H., Kabaria, C.W., Elyazar, I.R., The international limits and population at risk of Plasmodium vivax transmission in 2009 (2010) PLoS Negl. Trop. Dis., 4, pp. e774Boyd, M.F., Stratman-Thomas, W.K., Muench, H., The occurrence of gametocytes of Plasmodium vivax during the primary attack (1935) Am. J. Trop. Med. Hyg., 16, pp. 133-138Feachem, R.G., Phillips, A.A., Hwang, J., Cotter, C., Wielgosz, B., Greenwood, B.M., Sabot, O., Ghebreyesus, T.A., Shrinking the malaria map: Progress and prospects (2010) Lancet, 376, pp. 1566-1578Rodriguez, J.C., Uribe, G.A., Araujo, R.M., Narvaez, P.C., Valencia, S.H., Epidemiology and control of malaria in Colombia (2011) Mem. Inst. Oswaldo Cruz, 106, pp. 114-122Gama, B.E., Lacerda, M.V., Daniel-Ribeiro, C.T., Ferreira-Da-Cruz Mde, F., Chemoresistance of Plasmodium falciparum and Plasmodium vivax parasites in Brazil: Consequences on disease morbidity and control (2011) Mem. Inst. Oswaldo Cruz, 106, pp. 159-166Oliveira-Ferreira, J., Lacerda, M.V., Brasil, P., Ladislau, J.L., Tauil, P.L., Daniel-Ribeiro, C.T., Malaria in Brazil: An overview (2010) Malar. J., 9, p. 115(2011) World Malaria Report 2011, p. 246. , World Health OrganizationWorld Health Organization: Geneva, SwitzerlandPrice, R.N., Tjitra, E., Guerra, C.A., Yeung, S., White, N.J., Anstey, N.M., Vivax malaria: Neglected and not benign (2007) Am. J. Trop. Med. Hyg., 77, pp. 79-87Baird, J.K., Neglect of Plasmodium vivax malaria (2007) Trends Parasitol., 23, pp. 533-539Tjitra, E., Anstey, N.M., Sugiarto, P., Warikar, N., Kenangalem, E., Karyana, M., Lampah, D.A., Price, R.N., Multidrug-resistant Plasmodium vivax associated with severe and fatal malaria: A prospective study in Papua, Indonesia (2008) PLoS Med., 5, pp. e128Genton, B., D'Acremont, V., Rare, L., Baea, K., Reeder, J.C., Alpers, M.P., Muller, I., Plasmodium vivax and mixed infections are associated with severe malaria in children: A prospective cohort study from Papua New Guinea (2008) PLoS Med., 5, pp. e127Beg, M.A., Sani, N., Mehraj, V., Jafri, W., Khan, M.A., Malik, A., Menezes, E., Smego Jr., R., Comparative features and outcomes of malaria at a tertiary care hospital in Karachi, Pakistan (2008) Int. J. Infect. Dis., 12, pp. 37-42Barcus, M.J., Basri, H., Picarima, H., Manyakori, C., Sekartuti, Elyazar, I., Bangs, M.J., Baird, J.K., Demographic risk factors for severe and fatal vivax and falciparum malaria among hospital admissions in northeastern Indonesian Papua (2007) Am. J. Trop. Med. Hyg., 77, pp. 984-991Lampah, D.A., Yeo, T.W., Hardianto, S.O., Tjitra, E., Kenangalem, E., Sugiarto, P., Price, R.N., Anstey, N.M., Coma associated with microscopy-diagnosed Plasmodium vivax: A prospective study in Papua, Indonesia (2011) PLoS Negl. Trop. Dis., 5, pp. e1032Kochar, D.K., Das, A., Kochar, S.K., Saxena, V., Sirohi, P., Garg, S., Kochar, A., Gupta, V., Severe Plasmodium vivax malaria: A report on serial cases from Bikaner in northwestern India (2009) Am. J. Trop. Med. Hyg., 80, pp. 194-198Kochar, D.K., Saxena, V., Singh, N., Kochar, S.K., Kumar, S.V., Das, A., Plasmodium vivax malaria (2005) Emerg. Infect. Dis., 11, pp. 132-134Tan, L.K., Yacoub, S., Scott, S., Bhagani, S., Jacobs, M., Acute lung injury and other serious complications of Plasmodium vivax malaria (2008) Lancet Infect. Dis., 8, pp. 449-454Bassat, Q., Alonso, P.L., Defying malaria: Fathoming severe Plasmodium vivax disease (2011) Nat. Med., 17, pp. 48-49Anstey, N.M., Russell, B., Yeo, T.W., Price, R.N., The pathophysiology of vivax malaria (2009) Trends Parasitol., 25, pp. 220-227Costa, F.T., Lopes, S.C., Albrecht, L., Ataide, R., Siqueira, A.M., Souza, R.M., Russell, B., Lacerda, M.V., On the pathogenesis of Plasmodium vivax malaria: Perspectives from the Brazilian field (2012) Int. J. Parasitol., 42, pp. 1099-1105Lacerda, M.V., Fragoso, S.C., Alecrim, M.G., Alexandre, M.A., Magalhaes, B.M., Siqueira, A.M., Ferreira, L.C., Ferrer, M., Postmortem characterization of patients with clinical diagnosis of Plasmodium vivax malaria: To what extent does this parasite kill? (2012) Clin. Infect. Dis., 55, pp. e67-e74Alexandre, M.A., Ferreira, C.O., Siqueira, A.M., Magalhaes, B.L., Mourao, M.P., Lacerda, M.V., Alecrim, M., Severe Plasmodium vivax malaria, Brazilian Amazon (2010) Emerg. Infect. Dis., 16, pp. 1611-1614De Lacerda, M.V., Zackiewicz, C., Alecrim, W.D., Alecrim, M., The neglected Plasmodium vivax: Are researchers from endemic areas really concerned about new treatment options? (2007) Rev. Soc. Bras. Med. Trop., 40, pp. 489-490Price, R.N., Douglas, N.M., Anstey, N.M., Von Seidlein, L., Plasmodium vivax treatments: What are we looking for? (2011) Curr. Opin.Infect. Dis., 24, pp. 578-585Carlton, J.M., Sina, B.J., Adams, J.H., Why Is Plasmodium vivax a neglected tropical disease? (2011) PLoS Negl.Trop Dis., 5, pp. e1160Rieckmann, K.H., Davis, D.R., Hutton, D.C., Plasmodium vivax resistance to chloroquine? (1989) Lancet, 2, pp. 1183-1184Harinasuta, T., Suntharasamai, P., Viravan, C., Chloroquine-resistant falciparum malaria in Thailand (1965) Lancet, 2, pp. 657-660Sumawinata, I.W., Bernadeta, Leksana, B., Sutamihardja, A., Purnomo, Subianto, B., Sekartuti, Baird, J.K., Very high risk of therapeutic failure with chloroquine for uncomplicated Plasmodium falciparum and P vivax malaria in Indonesian Papua (2003) Am. J. Trop. Med. Hyg., 68, pp. 416-420Baird, J.K., Wiady, I., Fryauff, D.J., Sutanihardja, M.A., Leksana, B., Widjaya, H., Kysdarmanto, Subianto, B., In vivo resistance to chloroquine by Plasmodium vivax and Plasmodium falciparum at Nabire, Irian Jaya, Indonesia (1997) Am. J. Trop. Med. Hyg., 56, pp. 627-631Sutanto, I., Suprijanto, S., Nurhayati, Manoempil, P., Baird, J.K., Resistance to chloroquine by Plasmodium vivax at Alor in the Lesser Sundas Archipelago in eastern Indonesia (2009) Am. J. Trop. Med. Hyg., 81, pp. 338-342Ratcliff, A., Siswantoro, H., Kenangalem, E., Wuwung, M., Brockman, A., Edstein, M.D., Laihad, F., Tjitra, E., Therapeutic response of multidrugresistant Plasmodium falciparum and P vivax to chloroquine and sulfadoxine-pyrimethamine in southern Papua, Indonesia (2007) Trans. R.oyal Soc. Trop. Med. Hyg., 101, pp. 351-359Young, M.D., Burgess, R.W., Pyrimethamine resistance in Plasmodium vivax malaria (1959) Bull. World Health Org., 20, pp. 27-36Baird, J.K., Resistance to therapies for infection by Plasmodium vivax (2009) Clin. Microbiol. Rev., 22, pp. 508-534Russell, B., Chalfein, F., Prasetyorini, B., Kenangalem, E., Piera, K., Suwanarusk, R., Brockman, A., Cheng, Q., Determinants of in vitro drug susceptibility testing of Plasmodium vivax (2008) Antimicrob. Agents Chemother., 52, pp. 1040-1045Sharrock, W.W., Suwanarusk, R., Lek-Uthai, U., Edstein, M.D., Kosaisavee, V., Travers, T., Jaidee, A., Nosten, F., Plasmodium vivax trophozoites insensitive to chloroquine (2008) Malar. J., 7, p. 94Price, R.N., Auburn, S., Marfurt, J., Cheng, Q., Phenotypic and genotypic characterisation of drug-resistant Plasmodium vivax (2012) Trends Parasitol., 28, pp. 522-529Chotivanich, K., Udomsangpetch, R., Chierakul, W., Newton, P.N., Ruangveerayuth, R., Pukrittayakamee, S., Looareesuwan, S., White, N.J., In vitro efficacy of antimalarial drugs against Plasmodium vivax on the western border of Thailand (2004) Am. J. Trop. Med. Hyg., 70, pp. 395-397Kerlin, D.H., Boyce, K., Marfurt, J., Simpson, J.A., Kenangalem, E., Cheng, Q., Price, R.N., Gatton, M.L., An analytical method for assessing stage-specific drug activity in Plasmodium vivax malaria: Implications for ex vivo drug susceptibility testing (2012) PLoS Negl. Trop. Dis., 6, pp. e1772Marfurt, J., Chalfein, F., Prayoga, P., Wabiser, F., Kenangalem, E., Piera, K.A., Fairlie, D.P., Andrews, K.T., Ex vivo activity of histone deacetylase inhibitors against multidrug-resistant clinical isolates of Plasmodium falciparum and P vivax (2011) Antimicrob. Agents Chemother., 55, pp. 961-966Tasanor, O., Noedl, H., Na-Bangchang, K., Congpuong, K., Sirichaisinthop, J., Wernsdorfer, W.H., An in vitro system for assessing the sensitivity of Plasmodium vivax to chloroquine (2002) Acta Trop., 83, pp. 49-61Mazier, D., Renia, L., Snounou, G., A pre-emptive strike against malaria's stealthy hepatic forms (2009) Nat. Rev. Drug Discov., 8, pp. 854-864Hollingdale, M.R., Collins, W.E., Campbell, C.C., In vitro culture of exoerythrocytic parasites of the North Korean strain of Plasmodium vivax in hepatoma cells (1986) Am. J. Trop. Med. Hyg., 35, pp. 275-276Hollingdale, M.R., Collins, W.E., Campbell, C.C., Schwartz, A.L., In vitro culture of two populations (dividing and nondividing) of exoerythrocytic parasites of Plasmodium vivax (1985) Am. J. Trop. Med. Hyg., 34, pp. 216-222Mazier, D., Collins, W.E., Mellouk, S., Procell, P.M., Berbiguier, N., Campbell, G.H., Miltgen, F., Gentilini, M., Plasmodium ovale: In vitro development of hepatic stages (1987) Exp. Parasitol., 64, pp. 393-400Mazier, D., Landau, I., Druilhe, P., Miltgen, F., Guguen-Guillouzo, C., Baccam, D., Baxter, J., Gentilini, M., Cultivation of the liver forms of Plasmodium vivax in human hepatocytes (1984) Nature, 307, pp. 367-369Hastings, M.D., Porter, K.M., Maguire, J.D., Susanti, I., Kania, W., Bangs, M.J., Sibley, C.H., Baird, J.K., Dihydrofolate reductase mutations in Plasmodium vivax from Indonesia and therapeutic response to sulfadoxine plus pyrimethamine (2004) J. Infect. Dis., 189, pp. 744-750Krudsood, S., Tangpukdee, N., Wilairatana, P., Phophak, N., Baird, J.K., Brittenham, G.M., Looareesuwan, S., High-dose primaquine regimens against relapse of Plasmodium vivax malaria (2008) Am. J. Trop. Med. Hyg., 78, pp. 736-740Ku, M.J., Dossin, F.M., Choi, Y., Moraes, C.B., Ryu, J., Song, R., Freitas Jr., L.H., Quantum dots: A new tool for anti-malarial drug assays (2011) Malar. J., 10, p. 118Karl, S., Wong, R.P., St Pierre, T.G., Davis, T.M., A comparative study of a flow-cytometrybased assessment of in vitro Plasmodium falciparum drug sensitivity (2009) Malar. J., 8, p. 294Malleret, B., Claser, C., Ong, A.S., Suwanarusk, R., Sriprawat, K., Howland, S.W., Russell, B., Renia, L., A rapid and robust tri-color flow cytometry assay for monitoring malaria parasite development (2011) Sci. Rep., 1, p. 118Meister, S., Plouffe, D.M., Kuhen, K.L., Bonamy, G.M., Wu, T., Barnes, S.W., Bopp, S.E., Che, J., Imaging of Plasmodium liver stages to drive next-generation antimalarial drug discovery (2011) Science, 334, pp. 1372-1377