Development of the BG-Malaria trap as an alternative to human-landing catches for the capture of Anopheles darlingi

Although the human-landing catch (HLC) method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG) and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM). The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines.

Genetics of chloroquine-resistant malaria: a haplotypic view

The development and rapid spread of chloroquine resistance (CQR) in Plasmodium falciparum have triggered the identification of several genetic target(s) in the P. falciparum genome. In particular, mutations in the Pfcrt gene, specifically, K76T and mutations in three other amino acids in the region adjoining K76 (residues 72, 74, 75 and 76), are considered to be highly related to CQR. These various mutations form several different haplotypes and Pfcrt gene polymorphisms and the global distribution of the different CQR- Pfcrt haplotypes in endemic and non-endemic regions of P. falciparum malaria have been the subject of extensive study. Despite the fact that the Pfcrt gene is considered to be the primary CQR gene in P. falciparum , several studies have suggested that this may not be the case. Furthermore, there is a poor correlation between the evolutionary implications of the Pfcrt haplotypes and the inferred migration of CQR P. falciparum based on CQR epidemiological surveillance data. The present paper aims to clarify the existing knowledge on the genetic basis of the different CQR- Pfcrt haplotypes that are prevalent in worldwide populations based on the published literature and to analyse the data to generate hypotheses on the genetics and evolution of CQR malaria.

Evidence of an increased incidence of day 3 parasitaemia in Suriname: an indicator of the emerging resistance of Plasmodium falciparum to artemether

The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.

Aspidosperma (Apocynaceae) plant cytotoxicity and activity towards malaria parasites. Part I: Aspidosperma nitidum (Benth) used as a remedy to treat fever and malaria in the Amazon

Infusions of Aspidosperma nitidum (Apocynaceae) wood bark are used to treat fever and malaria in the Amazon Region. Several species of this family are known to possess indole alkaloids and other classes of secondary metabolites, whereas terpenoids, an inositol and the indole alkaloids harmane-3 acid and braznitidumine have been described in A. nitidum . In the present study, extracts from the wood bark, leaves and branches of this species were prepared for assays against malaria parasites and cytotoxicity testing using human hepatoma and normal monkey kidney cells. The wood bark extracts were active against Plasmodium falciparum and showed a low cytotoxicity in vitro, whereas the leaf and branch extracts and the pure alkaloid braznitidumine were inactive. A crude methanol extract was subjected to acid-base fractionation aimed at obtaining alkaloid-rich fractions, which were active at low concentrations against P. falciparum and in mice infected with and sensitive Plasmodium berghei parasites. Our data validate the antimalarial usefulness of A. nitidum wood bark, a remedy that can most likely help to control malaria. However, the molecules responsible for this antimalarial activity have not yet been identified. Considering their high selectivity index, the alkaloid-rich fractions from the plant bark might be useful in the development of new antimalarials.

First published record of urban malaria in Puerto Gaitan, Meta, Colombia

Patterns of malaria cases were compared between the department of Meta and the municipality of Puerto Gaitán, Colombia, to examine temporal change in malaria from 2005-2010. During this time frame in Meta the mean ratio was 2.53; in contrast, in Puerto Gaitán it was 1.41, meaning that a surprisingly high proportion of Plasmodium falciparum cases were reported from this municipality. A detailed analysis of data from Puerto Gaitán for 2009 and 2010 detected a significant difference (χ2, p < 0.001) in the distribution of plasmodia, with Plasmodium vivax more prevalent in 2009 and P. falciparum in 2010. Males had the highest number of cases but there was no difference in the distribution of cases between sexes and years. In both years, for both sexes, people 16-40 accounted for the majority of cases (58.9% in 2009; 60.4% in 2010). There were significant differences in the distribution of both P. vivax (χ2, p < 0.01) and P. falciparum cases (χ2, p < 0.05) by geographic setting (urban vs. non-urban) between years. Urban cases of both P. vivax and P. falciparum are recorded in this study for the first time in Puerto Gaitán, possibly the result of area wide displacement and migration due to armed conflict.

Anthropophilic biting behaviour of Anopheles (Kerteszia) neivai Howard, Dyar & Knab associated with Fishermen’s activities in a malaria-endemic area in the Colombian Pacific

On the southwest Pacific Coast of Colombia, a field study was initiated to determine the human-vector association between Anopheles (Kerteszia) neivai and fishermen, including their nearby houses. Mosquitoes were collected over 24-h periods from mangrove swamps, marshlands and fishing vessels in three locations, as well as in and around the houses of fishermen. A total of 6,382 mosquitoes were collected. An. neivai was most abundant in mangroves and fishing canoes (90.8%), while Anopheles albimanus was found indoors (82%) and outdoors (73%). One An. neivai and one An. albimanus collected during fishing activities in canoes were positive for Plasmodium vivax , whereas one female An. neivai collected in a mangrove was positive for P. vivax . In the mangroves and fishing canoes, An. neivai demonstrated biting activity throughout the day, peaking between 06:00 pm-07:00 pm and there were two minor peaks at dusk and dawn. These peaks coincided with fishing activities in the marshlands and mangroves, a situation that places the fishermen at risk of contracting malaria when they are performing their daily activities. It is recommended that protective measures be implemented to reduce the risk that fishermen will contract malaria.

New records of Mansonella ozzardi: a parasite that is spreading from the state of Amazonas to previously uninfected areas of the state of Acre in the Purus River region

Mansonella ozzardi infections are common in the riverside communities along the Solimões, Negro and Purus Rivers in the state of Amazonas (AM). However, little is known about the presence of this parasite in communities located in regions bordering AM and the state of Acre. The prevalence rate of M. ozzardi infections was determined in blood samples from volunteers according to the Knott method. A total of 355 volunteers from six riverine communities were enrolled in the study and 65 (18.3%) were found to be infected with M. ozzardi. As expected, most of the infections (25%) occurred in individuals involved in agriculture, cattle rearing and fishing and an age/sex group analysis revealed that the prevalence increased beginning in the 40-50-years-of-age group and reached 33% in both sexes in individuals over 50 years of age. Based on the described symptomatology, articular pain and headache were found to be significantly higher among infected individuals (56 and 65% prevalence, respectively, p < 0.05). Sera from volunteers were subjected to ELISA using a cocktail of recombinant proteins from Onchocerca volvulus to evaluate the specificity of the test in an endemic M. ozzardi region. No cross-reactions between M. ozzardi-infected individuals and recombinant O. volvulusproteins were detected, thus providing information on the secure use of this particular cocktail in areas where these parasites are sympatric.

Parasite load and risk factors for poor outcome among children with visceral leishmaniasis. A cohort study in Belo Horizonte, Brazil, 2010-2011

Clinical and laboratory risk factors for death from visceral leishmaniasis (VL) are relatively known, but quantitative real-time polymerase chain reaction (qPCR) might assess the role of parasite load in determining clinical outcome. The aim of this study was to identify risk factors, including parasite load in peripheral blood, for VL poor outcome among children. This prospective cohort study evaluated children aged ≤ 12 years old with VL diagnosis at three times: pre-treatment (T0), during treatment (T1) and post-treatment (T2). Forty-eight patients were included and 16 (33.3%) met the criteria for poor outcome. Age ≤ 12 months [relative risk (RR) 3.51; 95% confidence interval (CI) 1.89-6.52], tachydyspnoea (RR 3.46; 95% CI 2.19-5.47), bacterial infection (RR 3.08; 95% CI 1.27-7.48), liver enlargement (RR 3.00; 95% CI 1.44-6.23) and low serum albumin (RR 7.00; 95% CI 1.80-27.24) were identified as risk factors. qPCR was positive in all patients at T0 and the parasite DNA was undetectable in 76.1% of them at T1 and in 90.7% at T2. There was no statistical association between parasite load at T0 and poor outcome.

Getting ready for malaria elimination: a check list of critical issues to consider

In recent years, a renewed interest in malaria elimination and eradication has emerged and seems to be rooting in the minds of the scientific community, public health specialists, funding bodies, policy makers and politicians. Malaria eradication will certainly benefit from improved and innovative tools; notwithstanding novel knowledge in fields ranging from basic science to mathematical modelling and health systems research. However, the elimination of malaria also encompasses a broad range of essential aspects that countries and other actors need to consider when thinking of embarking on such an adventure, including the implementation of innovative strategies, the ability to incorporate the most up-to-date evidence into policy, the integration of malaria into the broader health agenda, the strengthening of surveillance and health systems, capacity building, funding, advocacy and, very importantly, research. While in some cases this enthusiasm is clearly justified, some countries are still a long way from realistically advancing towards elimination. This paper attempts to provide guidance on all the necessary issues that should be considered when initiating a malaria elimination program.

Plasmodium vivax malaria elimination: should innovative ideas from the past be revisited?

In the 1950s, the strategy of adding chloroquine to food salt as a prophylaxis against malaria was considered to be a successful tool. However, with the development of Plasmodium resistance in the Brazilian Amazon, this control strategy was abandoned. More than 50 years later, asexual stage resistance can be avoided by screening for antimalarial drugs that have a selective action against gametocytes, thus old prophylactic measures can be revisited. The efficacy of the old methods should be tested as complementary tools for the elimination of malaria.

Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity.

Influence of age on the haemoglobin concentration of malaria-infected patients in a reference centre in the Brazilian Amazon

Anaemia is amongst the major complications of malaria, a major public health problem in the Amazon Region in Latin America. We examined the haemoglobin (Hb) concentrations of malaria-infected patients and compared it to that of malaria-negative febrile patients and afebrile controls. The haematological parameters of febrile patients who had a thick-blood-smear performed at an infectious diseases reference centre of the Brazilian Amazon between December 2009-January 2012 were retrieved together with clinical data. An afebrile community control group was composed from a survey performed in a malaria-endemic area. Hb concentrations and anaemia prevalence were analysed according to clinical-epidemiological status and demographic characteristics. In total, 7,831 observations were included. Patients with Plasmodium falciparum infection had lower mean Hb concentrations (10.5 g/dL) followed by P. vivax-infected individuals (12.4 g/dL), community controls (12.8 g/dL) and malaria-negative febrile patients (13.1 g/dL) (p < 0.001). Age, gender and clinical-epidemiological status were strong independent predictors for both outcomes. Amongst malaria-infected individuals, women in the reproductive age had considerably lower Hb concentrations. In this moderate transmission intensity setting, both vivax and falciparum malaria are associated with reduced Hb concentrations and risk of anaemia throughout a wide age range.

Vascular dysfunction as a target for adjuvant therapy in cerebral malaria

Cerebral malaria (CM) is a life-threatening complication of Plasmodium falciparum malaria that continues to be a major global health problem. Brain vascular dysfunction is a main factor underlying the pathogenesis of CM and can be a target for the development of adjuvant therapies for the disease. Vascular occlusion by parasitised red blood cells and vasoconstriction/vascular dysfunction results in impaired cerebral blood flow, ischaemia, hypoxia, acidosis and death. In this review, we discuss the mechanisms of vascular dysfunction in CM and the roles of low nitric oxide bioavailability, high levels of endothelin-1 and dysfunction of the angiopoietin-Tie2 axis. We also discuss the usefulness and relevance of the murine experimental model of CM by Plasmodium berghei ANKA to identify mechanisms of disease and to screen potential therapeutic interventions.

The Duffy binding protein as a key target for a Plasmodium vivax vaccine: lessons from the Brazilian Amazon

Plasmodium vivax infects human erythrocytes through a major pathway that requires interaction between an apical parasite protein, the Duffy binding protein (PvDBP) and its receptor on reticulocytes, the Duffy antigen/receptor for chemokines (DARC). The importance of the interaction between PvDBP (region II, DBPII) and DARC to P. vivax infection has motivated our malaria research group at Oswaldo Cruz Foundation (state of Minas Gerais, Brazil) to conduct a number of immunoepidemiological studies to characterise the naturally acquired immunity to PvDBP in populations living in the Amazon rainforest. In this review, we provide an update on the immunology and molecular epidemiology of PvDBP in the Brazilian Amazon - an area of markedly unstable malaria transmission - and compare it with data from other parts of Latin America, as well as Asia and Oceania.