Malaria in Brazil: what happens outside the Amazonian endemic region

Brazil, a country of continental proportions, presents three profiles of malaria transmission. The first and most important numerically, occurs inside the Amazon. The Amazon accounts for approximately 60% of the nation’s territory and approximately 13% of the Brazilian population. This region hosts 99.5% of the nation’s malaria cases, which are predominantly caused by Plasmodium vivax (i.e., 82% of cases in 2013). The second involves imported malaria, which corresponds to malaria cases acquired outside the region where the individuals live or the diagnosis was made. These cases are imported from endemic regions of Brazil (i.e., the Amazon) or from other countries in South and Central America, Africa and Asia. Imported malaria comprised 89% of the cases found outside the area of active transmission in Brazil in 2013. These cases highlight an important question with respect to both therapeutic and epidemiological issues because patients, especially those with falciparum malaria, arriving in a region where the health professionals may not have experience with the clinical manifestations of malaria and its diagnosis could suffer dramatic consequences associated with a potential delay in treatment. Additionally, because the Anopheles vectors exist in most of the country, even a single case of malaria, if not diagnosed and treated immediately, may result in introduced cases, causing outbreaks and even introducing or reintroducing the disease to a non-endemic, receptive region. Cases introduced outside the Amazon usually occur in areas in which malaria was formerly endemic and are transmitted by competent vectors belonging to the subgenus Nyssorhynchus (i.e., Anopheles darlingi, Anopheles aquasalis and species of the Albitarsis complex). The third type of transmission accounts for only 0.05% of all cases and is caused by autochthonous malaria in the Atlantic Forest, located primarily along the southeastern Atlantic Coast. They are caused by parasites that seem to be (or to be very close to) P. vivax and, in a less extent, by Plasmodium malariae and it is transmitted by the bromeliad mosquito Anopheles (Kerteszia) cruzii. This paper deals mainly with the two profiles of malaria found outside the Amazon: the imported and ensuing introduced cases and the autochthonous cases. We also provide an update regarding the situation in Brazil and the Brazilian endemic Amazon.     

How can malaria rapid diagnostic tests achieve their potential? A qualitative study of a trial at health facilities in Ghana

Malaria is still a major public health problem in Brazil, with approximately 306 000 registered cases in 2009, but it is estimated that in the early 1940s, around six million cases of malaria occurred each year. As a result of the fight against the disease, the number of malaria cases decreased over the years and the smallest numbers of cases to-date were recorded in the 1960s. From the mid-1960s onwards, Brazil underwent a rapid and disorganized settlement process in the Amazon and this migratory movement led to a progressive increase in the number of reported cases. Although the main mosquito vector (Anopheles darlingi) is present in about 80% of the country, currently the incidence of malaria in Brazil is almost exclusively (99,8% of the cases) restricted to the region of the Amazon Basin, where a number of combined factors favors disease transmission and impair the use of standard control procedures. Plasmodium vivax accounts for 83,7% of registered cases, while Plasmodium falciparum is responsible for 16,3% and Plasmodium malariae is seldom observed. Although vivax malaria is thought to cause little mortality, compared to falciparum malaria, it accounts for much of the morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with P. vivax have been reported in Brazil and this is a matter of concern for Brazilian malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine in some reports needs to be further investigated. In contrast, asymptomatic infection by P. falciparum and P. vivax has been detected in epidemiological studies in the states of Rondonia and Amazonas, indicating probably a pattern of clinical immunity in both autochthonous and migrant populations. Seropidemiological studies investigating the type of immune responses elicited in naturally-exposed populations to several malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to these antigens are generated in natural infections and their immunogenic potential as vaccine candidates. The present difficulties in reducing economic and social risk factors that determine the incidence of malaria in the Amazon Region render impracticable its elimination in the region. As a result, a malaria-integrated control effort - as a joint action on the part of the government and the population - directed towards the elimination or reduction of the risks of death or illness, is the direction adopted by the Brazilian government in the fight against the disease.     

Malaria in the United Kingdom

Over the past decade the United Kingdom had the second highest number of cases of imported malaria among European countries. There has been a substantial rise in recorded cases of malaria during the past three years though some of it may be due to improved notification. Fatal cases of malaria in visitors to Africa have averaged 6.5% of reported infections due to Plasmodium falciparum. Attacks of vivax malaria may occur several months after travellers return from a malarious country.     

Malaria in the whole world and in Romania

Malaria is the world's most important tropical parasitic disease. Malaria is a public health problem today in more than 90 countries. Worldwide prevalence of the disease is estimated to be in the order of 300-500 million clinical cases each year. Malaria is endemic in a total of 101 countries and territories. In Romania, malaria does not represent an important public health problem. In 1999, there were reported a total number of 32 malaria cases in Romanian people. 78% from these recognized as etiological agent Pl. falciparum. The malaria cases imported from Turkey (5) have had as etiological agent Pl. vivax. The most affected age group is between 21-50 years and a distribution by profession shows that sailor personnel accounts for 65.6% of all cases. Africa remains the most important endemic region from where the malaria cases in Romanian people are imported. An adequate chemoprophylaxis is not, yet, easy to obtain for Romanian people who are travelling abroad in endemic countries because of the lack of specific drugs (especially for resistant forms of Pl. falciparum). Even if the Romanian Ministry of Health had elaborated orders regarding malaria and Cloroquine is the usual drug administered, as chemoprophylaxis, to Romanian people who travel abroad, in each year in our country appears around 30-60 imported malaria cases. That is the cause why Romanian Ministry of Health wants to solve this problem which is the major cause of the malaria cases in Romanian people.     

International funding for malaria control in relation to populations at risk of stable Plasmodium falciparum transmission

Background

The international financing of malaria control has increased significantly in the last ten years in parallel with calls to halve the malaria burden by the year 2015. The allocation of funds to countries should reflect the size of the populations at risk of infection, disease, and death. To examine this relationship, we compare an audit of international commitments with an objective assessment of national need: the population at risk of stable Plasmodium falciparum malaria transmission in 2007.

Methods and Findings

The national distributions of populations at risk of stable P. falciparum transmission were projected to the year 2007 for each of 87 P. falciparum–endemic countries. Systematic online- and literature-based searches were conducted to audit the international funding commitments made for malaria control by major donors between 2002 and 2007. These figures were used to generate annual malaria funding allocation (in US dollars) per capita population at risk of stable P. falciparum in 2007. Almost US$1 billion are distributed each year to the 1.4 billion people exposed to stable P. falciparum malaria risk. This is less than US$1 per person at risk per year. Forty percent of this total comes from the Global Fund to Fight AIDS, Tuberculosis and Malaria. Substantial regional and national variations in disbursements exist. While the distribution of funds is found to be broadly appropriate, specific high population density countries receive disproportionately less support to scale up malaria control. Additionally, an inadequacy of current financial commitments by the international community was found: under-funding could be from 50% to 450%, depending on which global assessment of the cost required to scale up malaria control is adopted.

Conclusions

Without further increases in funding and appropriate targeting of global malaria control investment it is unlikely that international goals to halve disease burdens by 2015 will be achieved. Moreover, the additional financing requirements to move from malaria control to malaria elimination have not yet been considered by the scientific or international community.     

Prevention of Malaria Resurgence in Greece through the Association of Mass Drug Administration (MDA) to Immigrants from Malaria-Endemic Regions and Standard Control Measures

Greece was declared malaria-free in 1974 after a long antimalarial fight. In 2011–2012, an outbreak of P. vivax malaria was reported in Evrotas, an agricultural area in Southern Greece, where a large number of immigrants from endemic countries live and work. A total of 46 locally acquired and 38 imported malaria cases were detected. Despite a significant decrease of the number of malaria cases in 2012, a mass drug administration (MDA) program was considered as an additional measure to prevent reestablishment of the disease in the area. During 2013 and 2014, a combination of 3-day chloroquine and 14-day primaquine treatment was administered under direct observation to immigrants living in the epicenter of the 2011 outbreak in Evrotas. Adverse events were managed and recorded on a daily basis. The control measures implemented since 2011 continued during the period of 2013–2014 as a part of a national integrated malaria control program that included active case detection (ACD), vector control measures and community education. The MDA program was started prior to the transmission periods (from May to December). One thousand ninety four (1094) immigrants successfully completed the treatment, corresponding to 87.3% coverage of the target population. A total of 688 adverse events were recorded in 397 (36.2%, 95% C.I.: 33.4–39.1) persons, the vast majority minor, predominantly dizziness and headache for chloroquine (284 events) and abdominal pain (85 events) for primaquine. A single case of primaquine-induced hemolysis was recorded in a person whose initial G6PD test proved incorrect. No malaria cases were recorded in Evrotas, Laconia, in 2013 and 2014, though three locally acquired malaria cases were recorded in other regions of Greece in 2013. Preventive antimalarial MDA to a high-risk population in a low transmission setting appears to have synergized with the usual antimalarial activities to achieve malaria elimination. This study suggests that judicious use of MDA can be a useful addition to the antimalarial armamentarium in areas threatened with the reintroduction of the disease.     

Estimating the Global Clinical Burden of Plasmodium falciparum Malaria in 2007

Background

The epidemiology of malaria makes surveillance-based methods of estimating its disease burden problematic. Cartographic approaches have provided alternative malaria burden estimates, but there remains widespread misunderstanding about their derivation and fidelity. The aims of this study are to present a new cartographic technique and its application for deriving global clinical burden estimates of Plasmodium falciparum malaria for 2007, and to compare these estimates and their likely precision with those derived under existing surveillance-based approaches.

Methods and Findings

In seven of the 87 countries endemic for P. falciparum malaria, the health reporting infrastructure was deemed sufficiently rigorous for case reports to be used verbatim. In the remaining countries, the mapped extent of unstable and stable P. falciparum malaria transmission was first determined. Estimates of the plausible incidence range of clinical cases were then calculated within the spatial limits of unstable transmission. A modelled relationship between clinical incidence and prevalence was used, together with new maps of P. falciparum malaria endemicity, to estimate incidence in areas of stable transmission, and geostatistical joint simulation was used to quantify uncertainty in these estimates at national, regional, and global scales.Combining these estimates for all areas of transmission risk resulted in 451 million (95% credible interval 349–552 million) clinical cases of P. falciparum malaria in 2007. Almost all of this burden of morbidity occurred in areas of stable transmission. More than half of all estimated P. falciparum clinical cases and associated uncertainty occurred in India, Nigeria, the Democratic Republic of the Congo (DRC), and Myanmar (Burma), where 1.405 billion people are at risk.Recent surveillance-based methods of burden estimation were then reviewed and discrepancies in national estimates explored. When these cartographically derived national estimates were ranked according to their relative uncertainty and replaced by surveillance-based estimates in the least certain half, 98% of the global clinical burden continued to be estimated by cartographic techniques.

Conclusions and Significance

Cartographic approaches to burden estimation provide a globally consistent measure of malaria morbidity of known fidelity, and they represent the only plausible method in those malaria-endemic countries with nonfunctional national surveillance. Unacceptable uncertainty in the clinical burden of malaria in only four countries confounds our ability to evaluate needs and monitor progress toward international targets for malaria control at the global scale. National prevalence surveys in each nation would reduce this uncertainty profoundly. Opportunities for further reducing uncertainty in clinical burden estimates by hybridizing alternative burden estimation procedures are also evaluated. Please see later in the article for the Editors'' Summary     

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     

The probability of a sequential Plasmodium vivax infection following asymptomatic Plasmodium falciparum and P. vivax infections in Myanmar,Vietnam, Cambodia,and Laos

Increasing numbers of aging individuals with chronic co-morbidities travel to regions where falciparum malaria is endemic. Non-communicable diseases are now leading risk factors for death in such countries. Thus, the influence of chronic diseases on the outcome of falciparum malaria is an issue of major importance. Aim of the present study was to assess whether non-communicable diseases increase the risk for severe imported falciparum malaria. A retrospective observational study of all adult cases with imported falciparum malaria hospitalized between 2001 and 2015 in the tertiary care Charité University Hospital, Berlin, was performed. A total of 536 adult patients (median age 37 years; 31.3% female) were enrolled. Of these, 329 (61.4%) originated from endemic countries, 207 patients (38.6%) from non-endemic regions. Criteria for severe malaria were fulfilled in 68 (12.7%) cases. With older age, lack of previous malaria episodes, being a tourist, and delayed presentation, well-characterized risk factors were associated with severe malaria in univariate analysis. After adjustment for these potential confounders hypertension (adjusted odds ratio aOR, 3.06 95% confidence interval, CI 1.34–7.02), cardiovascular diseases (aOR, 8.20 95% CI 2.30–29.22), and dyslipidaemia (aOR, 6.08 95% CI 1.13–32.88) were individual diseases associated with severe disease in multivariable logistic regression. Hypertension proved an independent risk factor among individuals of endemic (aOR, 4.83, 95% CI 1.44–16.22) as well as of non-endemic origin (aOR, 3.60 95% CI 1.05–12.35). In imported falciparum malaria hypertension and its related diseases are risk factors for severe disease.     

Estimating Geographical Variation in the Risk of Zoonotic Plasmodium knowlesi Infection in Countries Eliminating Malaria

BackgroundInfection by the simian malaria parasite, Plasmodium knowlesi, can lead to severe and fatal disease in humans, and is the most common cause of malaria in parts of Malaysia. Despite being a serious public health concern, the geographical distribution of P. knowlesi malaria risk is poorly understood because the parasite is often misidentified as one of the human malarias. Human cases have been confirmed in at least nine Southeast Asian countries, many of which are making progress towards eliminating the human malarias. Understanding the geographical distribution of P. knowlesi is important for identifying areas where malaria transmission will continue after the human malarias have been eliminated.Conclusions/SignificanceWe have produced the first map of P. knowlesi malaria risk, at a fine-scale resolution, to identify priority areas for surveillance based on regions with sparse data and high estimated risk. Our map provides an initial evidence base to better understand the spatial distribution of this disease and its potential wider contribution to malaria incidence. Considering malaria elimination goals, areas for prioritised surveillance are identified.     

Is the Mbita trap a reliable tool for evaluating the density of anopheline vectors in the highlands of Madagascar?

Background

Malaria can be eradicated from islands. To assess the prospects for eradication of malaria from the island of Príncipe in the Gulf of Guinea, we fitted a mathematical model to age-prevalence curves and thus obtained estimates of the vectorial capacity and of the basic reproductive number (R ₀) for malaria.

Methods

A cross-sectional malariological survey was carried out, in mid-1999, in six communities, comprising circa 17% of the total 6,000 population of the island. All houses in these communities were registered and their mode of construction recorded. Thick and thin blood films were prepared from all consenting individuals. Each individual was asked whether they possessed a mosquito net, whether they had slept under a mosquito net the previous night, whether they were allergic to chloroquine, and whether they had visited the main island of São Tomé since the beginning of the year. Outpatient records from March 1999 until the end of December 2000 were also examined and the age and place of residence of diagnosed cases noted.

Results

203 (19.8%) of the 1,026 individuals examined were found to be infected with Plasmodium falciparum. By fitting the mathematical model of the Garki project to the age-prevalence curve we estimate that the basic reproductive number, R ₀, on the island is approximately 1.6. Over a period of one year, a total of 1,792 P. falciparum cases reported to an outpatient facility at the island's hospital. Overall, 54% of the people interviewed slept under mosquito nets and were at reduced risk of infection. Conversely, people living in houses with openings between the top of the wall and the roof had higher risk of infection.

Conclusion

This high incidence suggests that most of the malaria cases on the island attend the hospital and that treatment of these cases is an important factor reducing the effective rate of transmission. Providing that clinical cases are effectively treated, endemic malaria can probably be eliminated from the island mainly by reducing exposure to the vector with simple measures such as insecticide-treated nets and mosquito-proofing of dwellings. In contrast to traditional malaria eradication strategies, this would avoid the risk of malaria epidemics because the reduction in R ₀ should be sustainable.     

Congenital Malaria in China

Abstract

Background

Congenital malaria, in which infants are directly infected with malaria parasites from their mother prior to or during birth, is a potentially life-threatening condition that occurs at relatively low rates in malaria-endemic regions. It is recognized as a serious problem in Plasmodium falciparum–endemic sub-Saharan Africa, where recent data suggests that it is more common than previously believed. In such regions where malaria transmission is high, neonates may be protected from disease caused by congenital malaria through the transfer of maternal antibodies against the parasite. However, in low P. vivax–endemic regions, immunity to vivax malaria is low; thus, there is the likelihood that congenital vivax malaria poses a more significant threat to newborn health. Malaria had previously been a major parasitic disease in China, and congenital malaria case reports in Chinese offer valuable information for understanding the risks posed by congenital malaria to neonatal health. As most of the literature documenting congenital malaria cases in China are written in Chinese and therefore are not easily accessible to the global malaria research community, we have undertaken an extensive review of the Chinese literature on this subject.

Methods/Principal Findings

Here, we reviewed congenital malaria cases from three major searchable Chinese journal databases, concentrating on data from 1915 through 2011. Following extensive screening, a total of 104 cases of congenital malaria were identified. These cases were distributed mainly in the eastern, central, and southern regions of China, as well as in the low-lying region of southwest China. The dominant species was P. vivax (92.50%), reflecting the malaria parasite species distribution in China. The leading clinical presentation was fever, and other clinical presentations were anaemia, jaundice, paleness, diarrhoea, vomiting, and general weakness. With the exception of two cases, all patients were cured with antimalarial drugs such as chloroquine, quinine, artemether, and artesunate.

Conclusions

The symptoms of congenital malaria vary significantly between cases, so clear and early diagnosis is difficult. We suggest that active surveillance might be necessary for neonates born to mothers with a history of malaria.     

Polymorphism and epitope sharing between the alleles of merozoite surface protein-1 of Plasmodium falciparum among Indian isolates

A comparison was made between local malaria transmission and malaria imported by travellers to identify the utility of national and regional annual parasite index (API) in predicting malaria risk and its value in generating recommendations on malaria prophylaxis for travellers. Regional malaria transmission data was correlated with malaria acquired in Latin America and imported into the USA and nine European countries. Between 2000 and 2004, most countries reported declining malaria transmission. Highest API's in 2003/4 were in Surinam (287.4) Guyana (209.2) and French Guiana (147.4). The major source of travel associated malaria was Honduras, French Guiana, Guatemala, Mexico and Ecuador. During 2004 there were 6.3 million visits from the ten study countries and in 2005, 209 cases of malaria of which 22 (11%) were Plasmodium falciparum. The risk of adverse events are high and the benefit of avoided benign vivax malaria is very low under current policy, which may be causing more harm than benefit.     

Malaria in migrants

An increasing proportion of malaria cases in Italy is observed in immigrants revisiting their country of origin, but little specific research work has been carried out in this field. All malaria cases occurring from 1990 to 1998 at the Reference Clinic for Infectious and Tropical Diseases in Brescia were prospectically evaluated to compare clinical outcome in migrant and non-immune cases. No difference was observed between parasitaemia at diagnosis and time to clearance of peripheral parasitaemia. Clinical presentation was milder in migrants than in non-immunes, with an OR for severe malaria of 0.27 (c.i. = 0.09-0.84) (p = 0.01). Fever clearance time was significantly shorter in migrants (3.0 days, SD = 1.2) than in non-immunes (4.3 days, SD = 1.7) (p < 0.001). Among immigrants, the proportion of severe cases was higher in residents since 2 years or less (12.5%) compared to residents since 2 to 5 years (3.3%) and residents since more than 5 years (0.9%) (p = 0.02). The proportion of malaria cases who had used chemoprophylaxis was significantly lower among immigrants (30/272, 11.0%) compared to non-immunes (41/74, 55.4%) (p < 0.001). In a population based malaria KAP analysis among 504 migrants from malaria endemic countries, correct knowledge of malaria risk was reported by 351 (69.5%). Of 170 subjects who reported at least one visit back to the home country, 30 (17.6%) had sought pre-travel advice, 24 (14.1%) had started chemoprophylaxis and 7 (4.1%) had completed it during the last visit. Of 140 migrants who failed to seek pre-travel advice, 73 (52%) were unaware of malaria risk, 56 (40%) did not know how to protect themselves, and 11 (8%) refused to use protective measures. Migrants account for a significant proportion of imported malaria cases in industrialised countries. Clinical presentation is milder compared to non-immune subjects. The proportion of migrants who adopt malaria protective measure while returning home is very low, due to both unawareness of risk and inappropriateness of medical advice.     

Targeting Human Transmission Biology for Malaria Elimination

Malaria remains one of the leading causes of death worldwide, despite decades of public health efforts. The recent commitment by many endemic countries to eliminate malaria marks a shift away from programs aimed at controlling disease burden towards one that emphasizes reducing transmission of the most virulent human malaria parasite, Plasmodium falciparum. Gametocytes, the only developmental stage of malaria parasites able to infect mosquitoes, have remained understudied, as they occur in low numbers, do not cause disease, and are difficult to detect in vivo by conventional methods. Here, we review the transmission biology of P. falciparum gametocytes, featuring important recent discoveries of genes affecting parasite commitment to gametocyte formation, microvesicles enabling parasites to communicate with each other, and the anatomical site where immature gametocytes develop. We propose potential parasite targets for future intervention and highlight remaining knowledge gaps.     

Leishmaniasis in the Middle East: Incidence and Epidemiology

Leishmaniasis is a major health problem worldwide, with several countries reporting cases of leishmaniasis resulting in loss of human life or a lifelong stigma because of bodily scars. The Middle East is endemic for cutaneous leishmaniasis, with countries like Syria reporting very high incidence of the disease. Despite several countries establishing national control programs for containing the sandfly vector and treatment of infection, the disease continues to spread. In addition to the endemicity of the region for leishmaniasis, the Middle East has seen a great deal of human migration either for earning of livelihood or due to political upheaval in the region. These factors contribute to the spread and proliferation of the causative species Leishmania and its sandfly host. This review discusses the current epidemiological scenario in Iraq, Syria, Saudi Arabia, and Jordan, emphasizing the number of cases reported, vector species, Leishmania species, and treatment available. The data is primarily from WHO reports for each country and current and old literature.     

Complexity of Infection and Genetic Diversity in Cambodian Plasmodium vivax

BackgroundPlasmodium vivax is the most widely distributed human malaria parasite with 2.9 billion people living in endemic areas. Despite intensive malaria control efforts, the proportion of cases attributed to P. vivax is increasing in many countries. Genetic analyses of the parasite population and its dynamics could provide an assessment of the efficacy of control efforts, but, unfortunately, these studies are limited in P. vivax by the lack of informative markers and high-throughput genotyping methods.Conclusions/SignificanceOur findings demonstrate that this high-throughput genotyping assay is efficient in characterizing P. vivax diversity and can provide valuable insights to assess the efficacy of malaria elimination programs or to monitor the spread of specific parasites.     

Worldwide incidence of malaria in 2009: estimates, time trends, and a critique of methods

Background

Measuring progress towards Millennium Development Goal 6, including estimates of, and time trends in, the number of malaria cases, has relied on risk maps constructed from surveys of parasite prevalence, and on routine case reports compiled by health ministries. Here we present a critique of both methods, illustrated with national incidence estimates for 2009.

Methods and Findings

We compiled information on the number of cases reported by National Malaria Control Programs in 99 countries with ongoing malaria transmission. For 71 countries we estimated the total incidence of Plasmodium falciparum and P. vivax by adjusting the number of reported cases using data on reporting completeness, the proportion of suspects that are parasite-positive, the proportion of confirmed cases due to each Plasmodium species, and the extent to which patients use public sector health facilities. All four factors varied markedly among countries and regions. For 28 African countries with less reliable routine surveillance data, we estimated the number of cases from model-based methods that link measures of malaria transmission with case incidence. In 2009, 98% of cases were due to P. falciparum in Africa and 65% in other regions. There were an estimated 225 million malaria cases (5th–95th centiles, 146–316 million) worldwide, 176 (110–248) million in the African region, and 49 (36–68) million elsewhere. Our estimates are lower than other published figures, especially survey-based estimates for non-African countries.

Conclusions

Estimates of malaria incidence derived from routine surveillance data were typically lower than those derived from surveys of parasite prevalence. Carefully interpreted surveillance data can be used to monitor malaria trends in response to control efforts, and to highlight areas where malaria programs and health information systems need to be strengthened. As malaria incidence declines around the world, evaluation of control efforts will increasingly rely on robust systems of routine surveillance. Please see later in the article for the Editors'' Summary     

How can the complex epidemiology of malaria in India impact its elimination?

Malaria is a human health hazard in the tropical and subtropical zones of the globe and is poised to be eliminated by the year 2030. Despite a decrease in incidence in the past two decades, many endemic countries, including India, report cases regularly. The epidemiology of malaria in India is unique owing to several features of the Plasmodium parasites, Anopheles vectors, ecoepidemiological situations conducive to disease transmission, and susceptible humans living in rural and forested areas. Limitations in public health reach, and poor health-seeking behaviour of vulnerable populations living in hard-to-reach areas, add to the problem. We bring all of these factors together in a comprehensive framework and opine that, in spite of complexities, targeted elimination of malaria in India is achievable with planned programmatic approaches.     

A sticky situation: the unexpected stability of malaria elimination

Malaria eradication involves eliminating malaria from every country where transmission occurs. Current theory suggests that the post-elimination challenges of remaining malaria-free by stopping transmission from imported malaria will have onerous operational and financial requirements. Although resurgent malaria has occurred in a majority of countries that tried but failed to eliminate malaria, a review of resurgence in countries that successfully eliminated finds only four such failures out of 50 successful programmes. Data documenting malaria importation and onwards transmission in these countries suggests malaria transmission potential has declined by more than 50-fold (i.e. more than 98%) since before elimination. These outcomes suggest that elimination is a surprisingly stable state. Elimination''s ‘stickiness’ must be explained either by eliminating countries starting off qualitatively different from non-eliminating countries or becoming different once elimination was achieved. Countries that successfully eliminated were wealthier and had lower baseline endemicity than those that were unsuccessful, but our analysis shows that those same variables were at best incomplete predictors of the patterns of resurgence. Stability is reinforced by the loss of immunity to disease and by the health system''s increasing capacity to control malaria transmission after elimination through routine treatment of cases with antimalarial drugs supplemented by malaria outbreak control. Human travel patterns reinforce these patterns; as malaria recedes, fewer people carry malaria from remote endemic areas to remote areas where transmission potential remains high. Establishment of an international resource with backup capacity to control large outbreaks can make elimination stickier, increase the incentives for countries to eliminate, and ensure steady progress towards global eradication. Although available evidence supports malaria elimination''s stickiness at moderate-to-low transmission in areas with well-developed health systems, it is not yet clear if such patterns will hold in all areas. The sticky endpoint changes the projected costs of maintaining elimination and makes it substantially more attractive for countries acting alone, and it makes spatially progressive elimination a sensible strategy for a malaria eradication endgame.