Portugal’s prominence in malaria research: How a small country became a key player in European research on one of the world’s deadliest diseases

Despite its limited resources, Portugal has gained a prominent position in research on malaria. Several historical and personal factors have contributed to this achievement. Subject Categories: S&S: Economics & Business, S&S: History & Philosophy of Science, Microbiology, Virology & Host Pathogen Interaction

Despite a significant increase that started during the 1990s, Portugal’s scientific production remains rather modest compared with the overall research output in the European Union (EU). However, the country’s achievements in malaria research are truly remarkable and, in relative terms, far above its EU neighbors in most relevant accounts. The factors to explain this accomplishment include the fact that malaria was autochthonous in Portugal until 1973; the country’s colonial history and its close ties with its former colonies; and several outstanding scientists who each inspired generations of malariologists.For most of the 20th century, research in Portugal was underfunded, and the country’s overall contribution to science was modest at best. This started to change when Portugal joined the European Union (then the European Economic Community) in 1985 and gained further momentum in the 1990s with the creation of a dedicated Ministry of Science. As a consequence, the Portuguese scientific production increased significantly in terms of the number of scientific articles published. Nevertheless, public funding for research has remained well below that of many other EU countries, and far from the target of 3% of the country’s GDP, which limits Portugal’s overall scientific output. Yet, there is one field of research where Portugal has been making significant contributions, even long before 1985: malaria.

… there is one field of research where Portugal has been making significant contributions, even long before 1985: malaria.

Among many other achievements, Portuguese laboratories have delivered important contributions to malaria research in areas as diverse as drug development, discovery and repurposing, genetic diversity of Plasmodium parasites, mechanisms of drug resistance, co‐infection between Plasmodium and other parasites, host–Plasmodium interactions, nutrient sensing and acquisition by malaria parasites, modulation of Plasmodium liver infection, immune and inflammatory responses to Plasmodium infection, diagnosis, vaccines, the role of microbiota on malaria transmission, pathogenesis of placental and cerebral malaria and acute lung injury, mechanisms of tolerance to malaria, malaria epidemiology, and vector genetics (see Further Reading for examples). Portugal’s percentage of scientific papers published in the field of malaria during the past decade relative to the total number of published articles is the highest in the EU (Fig 1A). Naturally, Portugal cannot compete with larger or more affluent countries in terms of the absolute numbers of articles published on malaria. Yet, the country ranks 5^th in this regard, closely following the Netherlands, Belgium, Sweden, and Denmark, four countries that have been investing much more and much longer in scientific research (Fig 1B). In fact, if one takes into account the funding for R&D in the EU nations, Portugal ranks ahead of every other country in terms of the number of malaria papers published relative to the investment made in science at the national level (Fig 1C).Open in a separate windowFigure 1Malaria research in Portugal and in the EU(A) Percentage of papers on the subject of malaria relative to the total number of papers from each of the indicated countries from 2009 to present. (B) Number of malaria research articles per 1,000 researchers in each of the indicated countries. (C) Number of malaria research articles per 100,000 Euros of gross domestic expenditure on R&D in each of the indicated countries. Total R&D personnel and intramural R&D expenditure data are from 2017. Papers were quantified through searches of PubMed for articles with affiliation to each of the indicated countries, published from 2009 to present, by use of the terms “malaria” or “Plasmodium”. Data on R&D investments from Eurostat.This raises the question of why Portugal, a rather small country with only a few decades of research history and an overall moderate scientific performance, fares relatively so well when it comes to research on malaria. I argue that there are three independent, albeit interrelated factors to explain this feat.A lasting reality demanding an appropriate responseThe first factor was the presence of autochthonous malaria in Portugal until the second half of the 20th century and the establishment of research institutions largely dedicated to studying and fighting the disease. Until the end of the World War II, malaria was endemic throughout much of Southern Europe; Italy, Greece, and Portugal were particularly affected. From 1955 to 1969, the WHO conducted its Global Malaria Eradication Programme, which successfully eliminated malaria in several regions of the world, including Southern Europe. The specific history of malaria eradication in Portugal is described in great detail by Bruce‐Chwatt (Bruce‐Chwatt, 1977) and highlights the intense efforts by multiple state‐sponsored institutions dedicated to studying and combating the disease.Even before the war, in 1931, the Malaria Research Station (Estação Experimental de Combate ao Sezonismo, EECS) was created in Benavente, the goals of which included the collection and analysis of blood samples from infected individuals, treatment of malaria patients, identification of mosquito populations, and malaria prophylaxis. In 1938, the Malaria Institute (Instituto de Malariologia, iMal) was founded in Águas de Moura to investigate the epidemiology of the disease, promoting adequate treatment and implementing vector control measures (Saavedra, 2010). Nonetheless, it was not until 1973 that malaria was eventually eliminated in Portugal, three years after Italy, and only one year before Greece.

… it was not until 1973 that malaria was eventually eliminated in Portugal, three years after Italy, and only one year before Greece.

Yet, the threat of malaria reemergence meant ongoing vigilance, and iMal paved the way for the creation of the Centre for the Study of Malaria and Parasitology (Centro de Estudos de Malária e Parasitologia), in 1973, later to become the Centre for the Study of Zoonoses (Centro de Estudos de Zoonoses) in 1987, and the Centre for Vector and Infectious Disease Studies (Centro de Estudos de Vetores e Doenças Infeciosas) in 1993. In addition, the Portuguese School of Tropical Medicine (later called National School of Public Health and Tropical Medicine, ENSPMT, now the Institute of Tropical Medicine and Hygiene, IHMT), founded in 1902, was one of only four institution of its kind in the world (Amaral, 2008). Since its inception, its mission has been the teaching and research in tropical medicine, biomedical sciences, and international health and, to this day, a significant part of its research continues to focus on malaria.A close bond with AfricaAnother major factor for Portugal’s prominent position in malaria research is its colonial past and the country’s close ties with its former colonies. During its period of maritime expansion in the 15^th and 16^th centuries, Portugal colonized many territories from Asia to the Americas and Africa. Most, if not all, of these territories were, and for a large part still are, endemic for malaria. Former colonies, such as Brazil or the Portuguese territories in India, gained their independence during the 19^th century, but maintained close ties with Portugal.However, several African countries, specifically Angola, Cape Verde, Guinea‐Bissau, Mozambique, and S. Tomé & Príncipe, remained under Portuguese rule until well into the second half of the 20^th century (Miller, 1975). In fact, while most African nations gained their independence from European countries during the 1950s and 1960s, Portugal’s dictatorship held on to and suppressed its African overseas territories, which led to armed uprisings in Angola and Guinea‐Bissau in 1961, and in Mozambique in 1964 (Miller, 1975). During the ensuing colonial wars, thousands of Portuguese soldiers were sent to these countries, where they were exposed not only to the horrors of war, but also to malaria (Campos, 2017). The Portuguese military actions in Africa finally came to an end in 1974 after the peaceful Carnation Revolution, which established democracy in Portugal and ended the colonization of all Portuguese‐held African territories.Over the next few years, hundreds of thousands of military personnel and former residents of the ex‐colonies, known as “retornados”, moved back to Portugal, leading to an increase in the number of imported malaria cases (Bruce‐Chwatt, 1977). Since then, these numbers have subsided, but the close ties that Portugal maintains with its former colonies mean that travel to and from malaria‐endemic regions remains high, contributing to the prevalence of imported malaria cases (Piperaki, 2018). It also means that malaria is not such a distant threat for most Portuguese; even today, many younger people have direct contact with family members or friends who have experienced malaria, bringing the reality of this scourge closer to home than in many other EU countries.

… even today, many younger people have direct contact with family members or friends who have experienced malaria, bringing the reality of this scourge closer to home than in many other EU countries.

Remarkable and inspiring figuresThe third and final factor is the enormous and lasting influence of various uniquely inspiring figures from several generations of malaria researchers. Indeed, the history of Portuguese malaria research is rich in prominent scientists who shaped the national research landscape. Attempting to highlight specific names among the many doctors, epidemiologists, and scientists from the past and present is a naturally risky exercise that runs the risk of overlooking important figures. Nevertheless, the crucial contribution of a few representatives of four generations of Portuguese scientists is beyond dispute.Ricardo Jorge (1858–1939) was a renowned epidemiologist responsible for the 1899–1901 National Sanitary Plan, which marked the introduction of modern sanitary concepts in Portugal and changed national public health. In 1903, Jorge was the first to collect reliable and extensive data on the incidence of malaria and its seasonal distribution (JORGE, 1903). He was Portugal’s Health Inspector‐General from 1899 to 1926, succeeded by José Alberto de Faria (1888–1958), another key figure who, with the support of the Rockefeller Foundation (Saavedra, 2014), created the EECS in Benavente, the first step for advancing knowledge about malaria in Portugal (Bruce‐Chwatt, 1977).Well within the 20^th century, Francisco Cambournac (1903–1994) and Fausto Landeiro (1896–1949) were arguably the most important contributors to Portuguese malariology during that period. Following extensive training in some of the most reputed parasitology schools in Europe, Cambournac became Director of Benavente’s EECS in 1933, and Landeiro occupied that position from 1938 to 1949. Cambournac founded the iMal in Águas de Moura, serving as its Director from 1939 to 1954, and became Director of the WHO’s African region from 1954 to 1964 (Lobo, 2012).Cambournac and Landeiro published extensively on the epidemiology, entomology, and control of malaria during the 1930s and 1940s, and gave a comprehensive account of the status of the disease in Portugal during that period. Cambournac’s 237‐page long review (Cambournac, 1942) provided all the epidemiological and other data needed for future planning of control and eradication of malaria in the country, the success of which is widely acknowledged to his immense work (Bruce‐Chwatt, 1977).During the 1960s and early 1970s, the National School of Public Health and Tropical Medicine, ENSPMT, now the Institute of Tropical Medicine and Hygiene, IHMT, played an important role not only in Portuguese research on malaria and other tropical diseases, but also in the cooperation with Portugal’s overseas territories at the time. The 1974 revolution and the decolonization in Africa led to a reshaping of this cooperation, which became increasingly centered on reinforcing the newly independent countries’ health systems, on their capacity to carry out research on endemic diseases, and on training programs in tropical and preventive medicine (Havik, 2015). Virgílio do Rosário, professor at the IHMT and, later, head of the Institute’s Centre for Malaria and Other Tropical Diseases (CMDT), played a pivotal role in this process. Do Rosário was the founder of several national and international networks for studying malaria and neglected diseases in various regions around the world. He inspired a whole generation of future malaria researchers, making him an inescapable figure among Portuguese malariologists in the second half of the 20^th century.At the dawn of the 21^st century, many Portuguese scientists, who had benefitted from the country’s investment in science in the 1980s and 1990s to acquire international training, came back home to set up their own research groups. Among them was Maria Mota, who returned from New York University to Portugal in 2002 to become a group leader, initially at the Instituto Gulbenkian de Ciência (IGC), and subsequently at the Instituto de Medicina Molecular (iMM). Mota’s research on the liver stage of infection by Plasmodium parasites has had an enormous impact and yielded a plethora of outstanding publications. She became Director of iMM in 2014, and commonly features among the most influential women in Portugal. Mota is also a gifted and engaging communicator, who has helped to garner public attention to malaria research and to the fight against the disease. As a great scientist and public advocate for malaria research, Mota has inspired numerous scientists, several of whom have become independent malaria researchers themselves, both in Portugal and internationally.

As a great scientist and public advocate for malaria research, Mota has inspired numerous scientists, several of whom have become independent malaria researchers themselves…

These historical, epidemiological, and humane factors have made Portugal an important player in malaria research, from the basic science of the parasite to the pathology of the disease, and from epidemiology to clinical research and drug development. However, these great achievements, and the role played by individual inspiring scientists, should not be taken for granted, but rather serve as an argument for nurturing and supporting research on malaria by future generations of scientists and political decision‐makers. A small country with fairly limited financial and human resources cannot reasonably aspire to excel in every area of research, but it can efficiently direct and focus its investment on those that are more likely to generate success. The history of Portuguese malaria research clearly demonstrates this and warrants its continued support as a top priority for national science policies.Further ReadingImportant contributions to malaria research by Portuguese laboratories during the past decade Drug development, discovery and repurposing Oliveira R, Guedes RC, Meireles P, Albuquerque IS, Goncalves LM, Pires E, Bronze MR, Gut J, Rosenthal PJ, Prudencio M, Moreira R, O''Neill PM, Lopes F (2014) Tetraoxane‐pyrimidine nitrile hybrids as dual stage antimalarials. J Med Chem 57: 4916–4923da Cruz FP, Martin C, Buchholz K, Lafuente‐Monasterio MJ, Rodrigues T, Sonnichsen B, Moreira R, Gamo FJ, Marti M, Mota MM, Hannus M, Prudencio M (2012) Drug screen targeted at Plasmodium liver stages identifies a potent multistage antimalarial drug. J Infect Dis 205: 1278–1286Hanson KK, Ressurreicao AS, Buchholz K, Prudencio M, Herman‐Ornelas JD, Rebelo M, Beatty WL, Wirth DF, Hanscheid T, Moreira R, Marti M, Mota MM (2013) Torins are potent antimalarials that block replenishment of Plasmodium liver stage parasitophorous vacuole membrane proteins. Proc Natl Acad Sci USA 110: E2838–E2847Machado M, Sanches‐Vaz M, Cruz JP, Mendes AM, Prudencio M (2017) Inhibition of Plasmodium Hepatic Infection by Antiretroviral Compounds. Front Cell Infect Microbiol 7: 329 Genetic diversity of Plasmodium parasites Guerra M, Neres R, Salgueiro P, Mendes C, Ndong‐Mabale N, Berzosa P, de Sousa B, Arez AP (2017) Plasmodium falciparum Genetic Diversity in Continental Equatorial Guinea before and after Introduction of Artemisinin‐Based Combination Therapy. Antimicrob Agents Chemother 61Mendes C, Salgueiro P, Gonzalez V, Berzosa P, Benito A, do Rosario VE, de Sousa B, Cano J, Arez AP (2013) Genetic diversity and signatures of selection of drug resistance in Plasmodium populations from both human and mosquito hosts in continental Equatorial Guinea. Malar J 12: 114 Mechanisms of drug resistance Escobar C, Pateira S, Lobo E, Lobo L, Teodosio R, Dias F, Fernandes N, Arez AP, Varandas L, Nogueira F (2015) Polymorphisms in Plasmodium falciparum K13‐propeller in Angola and Mozambique after the introduction of the ACTs. PLoS One 10: e0119215Ferreira A, Marguti I, Bechmann I, Jeney V, Chora A, Palha NR, Rebelo S, Henri A, Beuzard Y, Soares MP (2011) Sickle hemoglobin confers tolerance to Plasmodium infection. Cell 145: 398–409Veiga MI, Osorio NS, Ferreira PE, Franzen O, Dahlstrom S, Lum JK, Nosten F, Gil JP (2014) Complex polymorphisms in the Plasmodium falciparum multidrug resistance protein 2 gene and its contribution to antimalarial response. Antimicrob Agents Chemother 58: 7390–7397 Host‐Plasmodium interactions Portugal S, Carret C, Recker M, Armitage AE, Goncalves LA, Epiphanio S, Sullivan D, Roy C, Newbold CI, Drakesmith H, Mota MM (2011) Host‐mediated regulation of superinfection in malaria. Nat Med 17: 732–737Real E, Rodrigues L, Cabal GG, Enguita FJ, Mancio‐Silva L, Mello‐Vieira J, Beatty W, Vera IM, Zuzarte‐Luis V, Figueira TN, Mair GR, Mota MM (2018) Plasmodium UIS3 sequesters host LC3 to avoid elimination by autophagy in hepatocytes. Nat Microbiol 3: 17–25Sa ECC, Nyboer B, Heiss K, Sanches‐Vaz M, Fontinha D, Wiedtke E, Grimm D, Przyborski JM, Mota MM, Prudencio M, Mueller AK (2017) Plasmodium berghei EXP‐1 interacts with host Apolipoprotein H during Plasmodium liver‐stage development. Proc Natl Acad Sci USA 114: E1138–E1147 Nutrient sensing and acquisition Itoe MA, Sampaio JL, Cabal GG, Real E, Zuzarte‐Luis V, March S, Bhatia SN, Frischknecht F, Thiele C, Shevchenko A, Mota MM (2014) Host cell phosphatidylcholine is a key mediator of malaria parasite survival during liver stage infection. Cell Host Microbe 16: 778–786Mancio‐Silva L, Slavic K, Grilo Ruivo MT, Grosso AR, Modrzynska KK, Vera IM, Sales‐Dias J, Gomes AR, MacPherson CR, Crozet P, Adamo M, Baena‐Gonzalez E, Tewari R, Llinas M, Billker O, Mota MM (2017) Nutrient sensing modulates malaria parasite virulence. Nature 547: 213–216Meireles P, Mendes AM, Aroeira RI, Mounce BC, Vignuzzi M, Staines HM, Prudencio M (2017) Uptake and metabolism of arginine impact Plasmodium development in the liver. Sci Rep 7: 4072 Modulation of Plasmodium liver infection Ruivo MTG, Vera IM, Sales‐Dias J, Meireles P, Gural N, Bhatia SN, Mota MM, Mancio‐Silva L (2016) Host AMPK Is a Modulator of Plasmodium Liver Infection. Cell Rep 16: 2539–2545Zuzarte‐Luis V, Mello‐Vieira J, Marreiros IM, Liehl P, Chora AF, Carret CK, Carvalho T, Mota MM (2017) Dietary alterations modulate susceptibility to Plasmodium infection. Nat Microbiol 2: 1600–1607 Immune and inflammatory responses to Plasmodium infection Liehl P, Zuzarte‐Luis V, Chan J, Zillinger T, Baptista F, Carapau D, Konert M, Hanson KK, Carret C, Lassnig C, Muller M, Kalinke U, Saeed M, Chora AF, Golenbock DT, Strobl B, Prudencio M, Coelho LP, Kappe SH, Superti‐Furga G et al (2014) Host‐cell sensors for Plasmodium activate innate immunity against liver‐stage infection. Nat Med 20: 47–53Munoz‐Ruiz M, Ribot JC, Grosso AR, Goncalves‐Sousa N, Pamplona A, Pennington DJ, Regueiro JR, Fernandez‐Malave E, Silva‐Santos B (2016) TCR signal strength controls thymic differentiation of discrete proinflammatory gammadelta T cell subsets. Nat Immunol 17: 721–727Seixas E, Gozzelino R, Chora A, Ferreira A, Silva G, Larsen R, Rebelo S, Penido C, Smith NR, Coutinho A, Soares MP (2009) Heme oxygenase‐1 affords protection against noncerebral forms of severe malaria. Proc Natl Acad Sci USA 106: 15837–15842 Diagnosis Frita R, Rebelo M, Pamplona A, Vigario AM, Mota MM, Grobusch MP, Hanscheid T (2011) Simple flow cytometric detection of haemozoin containing leukocytes and erythrocytes for research on diagnosis, immunology and drug sensitivity testing. Malar J 10: 74 Vaccines Reuling IJ, Mendes AM, de Jong GM, Fabra‐Garcia A, Nunes‐Cabaco H, van Gemert GJ, Graumans W, Coffeng LE, de Vlas SJ, Yang ASP, Lee C, Wu Y, Birkett AJ, Ockenhouse CF, Koelewijn R, van Hellemond JJ, van Genderen PJJ, Sauerwein RW, Prudencio M (2020) An open‐label phase 1/2a trial of a genetically modified rodent malaria parasite for immunization against Plasmodium falciparum malaria. Sci Transl Med 12 Pathogenesis of placental and cerebral malaria de Moraes LV, Tadokoro CE, Gomez‐Conde I, Olivieri DN, Penha‐Goncalves C (2013) Intravital placenta imaging reveals microcirculatory dynamics impact on sequestration and phagocytosis of Plasmodium‐infected erythrocytes. PLoS Pathog 9: e1003154Ribot JC, Neres R, Zuzarte‐Luis V, Gomes AQ, Mancio‐Silva L, Mensurado S, Pinto‐Neves D, Santos MM, Carvalho T, Landry JJM, Rolo EA, Malik A, Silva DV, Mota MM, Silva‐Santos B, Pamplona A (2019) gammadelta‐T cells promote IFN‐gamma‐dependent Plasmodium pathogenesis upon liver‐stage infection. Proc Natl Acad Sci USA 116: 9979–9988 Mechanisms of tolerance to malaria Gozzelino R, Andrade BB, Larsen R, Luz NF, Vanoaica L, Seixas E, Coutinho A, Cardoso S, Rebelo S, Poli M, Barral‐Netto M, Darshan D, Kuhn LC, Soares MP (2012) Metabolic adaptation to tissue iron overload confers tolerance to malaria. Cell Host Microbe 12: 693–704Jeney V, Ramos S, Bergman ML, Bechmann I, Tischer J, Ferreira A, Oliveira‐Marques V, Janse CJ, Rebelo S, Cardoso S, Soares MP (2014) Control of disease tolerance to malaria by nitric oxide and carbon monoxide. Cell Rep 8: 126–136 Epidemiology Corder RM, Ferreira MU, Gomes MGM (2020) Modelling the epidemiology of residual Plasmodium vivax malaria in a heterogeneous host population: A case study in the Amazon Basin. PLoS Comput Biol 16: e1007377 Vector genetics Salgueiro P, Moreno M, Simard F, O''Brochta D, Pinto J (2013) New insights into the population structure of Anopheles gambiae s.s. in the Gulf of Guinea Islands revealed by Herves transposable elements. PLoS One 8: e62964Vicente JL, Sousa CA, Alten B, Caglar SS, Falcuta E, Latorre JM, Toty C, Barre H, Demirci B, Di Luca M, Toma L, Alves R, Salgueiro P, Silva TL, Bargues MD, Mas‐Coma S, Boccolini D, Romi R, Nicolescu G, do Rosario VE et al (2011) Genetic and phenotypic variation of the malaria vector Anopheles atroparvus in southern Europe. Malar J 10: 5Early Portuguese institutions dedicated to malaria investigation and researchLandeiro F (1932) Relatório do primeiro ano de luta antisezonática na estação de BenaventeLandeiro F (1934) Organização do Serviço Antisezonático em Portugal