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Find video protocols related to scientific articles indexed in Pubmed.
Glossina palpalis palpalis populations from Equatorial Guinea belong to distinct allopatric clades.
Parasit Vectors
PUBLISHED: 01-14-2014
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Luba is one of the four historical foci of Human African Trypanosomiasis (HAT) on Bioko Island, in Equatorial Guinea. Although no human cases have been detected since 1995, T. b. gambiense was recently observed in the vector Glossina palpalis palpalis. The existence of cryptic species within this vector taxon has been previously suggested, although no data are available regarding the evolutionary history of tsetse flies populations in Bioko.
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Cross-sectional study of malnutrition and associated factors among school aged children in rural and urban settings of Fogera and Libo Kemkem districts, Ethiopia.
PLoS ONE
PUBLISHED: 01-01-2014
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Little information is available on malnutrition-related factors among school-aged children ?5 years in Ethiopia. This study describes the prevalence of stunting and thinness and their related factors in Libo Kemkem and Fogera, Amhara Regional State and assesses differences between urban and rural areas.
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Haemoglobin levels for population from Gambo, a rural area of Ethiopia, and their association with anaemia and malaria.
Malar. J.
PUBLISHED: 07-11-2013
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Knowledge of appropriate reference intervals is critical not only to provide optimal clinical care, but also to enrol populations in medical research. The aim of this study was to generate normal ranges of laboratory values for haemoglobin among healthy Ethiopian adults and children and to determine if anaemia is a possible indicator of malaria in women and children in this area of Ethiopia.
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Artesunate/amodiaquine malaria treatment for Equatorial Guinea (Central Africa).
Am. J. Trop. Med. Hyg.
PUBLISHED: 03-25-2013
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The objectives of this study were: 1) to evaluate the safety and efficacy of combination artesunate (AS)/amodiaquine (AQ) therapy, and 2) to determine the difference between recrudescence and resistance. An in vivo efficacy study was conducted in Equatorial Guinea. A total of 122 children 6-59 months of age from two regional hospitals were randomized and subjected to a 28-day clinical and parasitological follow-up. A blood sample on Whatman paper was taken on Days 0, 7, 14, 21, and 28 or on any day in cases of treatment failure, with the parasite DNA then being extracted for molecular analysis purposes. A total of 4 children were excluded, and 9 cases were lost to follow-up. There were 17 cases of late parasitological failure, 3 cases of late clinical failure, and 89 cases of adequate clinical and parasitological response. The parasitological failure rate was 18.3% (20 of 109) and the success rate 81.70% (95% confidence interval [72.5-87.9%]). After molecular correction, real treatment efficacy stood at 97.3%. Our study showed the good efficacy of combination AS/AQ therapy. This finding enabled this treatment to be recommended to Equatorial Guineas National Malaria Control Program to change the official treatment policy as of March 2008.
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Genetic diversity and signatures of selection of drug resistance in Plasmodium populations from both human and mosquito hosts in continental Equatorial Guinea.
Malar. J.
PUBLISHED: 03-15-2013
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In Plasmodium, the high level of genetic diversity and the interactions established by co-infecting parasite populations within the same host may be a source of selection on pathogen virulence and drug resistance. As different patterns have already been described in humans and mosquitoes, parasite diversity and population structure should be studied in both hosts to properly assess their effects on infection and transmission dynamics. This study aimed to characterize the circulating populations of Plasmodium spp and Plasmodium falciparum from a combined set of human blood and mosquito samples gathered in mainland Equatorial Guinea. Further, the origin and evolution of anti-malarial resistance in this area, where malaria remains a major public health problem were traced.
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Trypanosoma brucei gambiense Adaptation to Different Mammalian Sera Is Associated with VSG Expression Site Plasticity.
PLoS ONE
PUBLISHED: 01-01-2013
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Trypanosoma brucei gambiense infection is widely considered an anthroponosis, although it has also been found in wild and domestic animals. Thus, fauna could act as reservoir, constraining the elimination of the parasite in hypo-endemic foci. To better understand the possible maintenance of T. b. gambiense in local fauna and investigate the molecular mechanisms underlying adaptation, we generated adapted cells lines (ACLs) by in vitro culture of the parasites in different mammalian sera. Using specific antibodies against the Variant Surface Glycoproteins (VSGs) we found that serum ACLs exhibited different VSG variants when maintained in pig, goat or human sera. Although newly detected VSGs were independent of the sera used, the consistent appearance of different VSGs suggested remodelling of the co-transcribed genes at the telomeric Expression Site (VSG-ES). Thus, Expression Site Associated Genes (ESAGs) sequences were analysed to investigate possible polymorphism selection. ESAGs 6 and 7 genotypes, encoding the transferrin receptor (TfR), expressed in different ACLs were characterised. In addition, we quantified the ESAG6/7 mRNA levels and analysed transferrin (Tf) uptake. Interestingly, the best growth occurred in pig and human serum ACLs, which consistently exhibited a predominant ESAG7 genotype and higher Tf uptake than those obtained in calf and goat sera. We also detected an apparent selection of specific ESAG3 genotypes in the pig and human serum ACLs, suggesting that other ESAGs could be involved in the host adaptation processes. Altogether, these results suggest a model whereby VSG-ES remodelling allows the parasite to express a specific set of ESAGs to provide selective advantages in different hosts. Finally, pig serum ACLs display phenotypic adaptation parameters closely related to human serum ACLs but distinct to parasites grown in calf and goat sera. These results suggest a better suitability of swine to maintain T. b. gambiense infection supporting previous epidemiological results.
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Antimalarial activity of imidazo[2,1-a]isoindol-5-ol derivatives and related compounds.
Eur J Med Chem
PUBLISHED: 06-09-2011
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The synthesis of several series of imidazo[2,1-a]isoindol-5-ol derivatives and the results of their evaluation against Plasmodium falciparum are presented and discussed. The effects of electron-withdrawing or-donating substituents on different parts of the molecule, as well as those produced by the incorporation of an additional fused ring, were analyzed. Several compounds showed significant antimalarial activity in vitro with IC(50) values as low as 60 nM and a certain efficacy in vivo by reducing parasitemia in Plasmodium berghei mouse models.
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Detection of high levels of mutations involved in anti-malarial drug resistance in Plasmodium falciparum and Plasmodium vivax at a rural hospital in southern Ethiopia.
Malar. J.
PUBLISHED: 05-31-2011
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In Ethiopia, malaria is caused by Plasmodium falciparum and Plasmodium vivax, and anti-malarial drug resistance is the most pressing problem confronting control of the disease. Since co-infection by both species of parasite is common and sulphadoxine-pyrimethamine (SP) has been intensively used, resistance to these drugs has appeared in both P. falciparum and P. vivax populations. This study was conducted to assess the prevalence of anti-malarial drug resistance in P. falciparum and P. vivax isolates collected at a rural hospital in southern Ethiopia.
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Duffy negative antigen is no longer a barrier to Plasmodium vivax--molecular evidences from the African West Coast (Angola and Equatorial Guinea).
PLoS Negl Trop Dis
PUBLISHED: 04-17-2011
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Plasmodium vivax shows a small prevalence in West and Central Africa due to the high prevalence of Duffy negative people. However, Duffy negative individuals infected with P. vivax have been reported in areas of high prevalence of Duffy positive people who may serve as supply of P. vivax strains able to invade Duffy negative erythrocytes. We investigated the presence of P. vivax in two West African countries, using blood samples and mosquitoes collected during two on-going studies.
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Different lineages of Chikungunya virus in Equatorial Guinea in 2002 and 2006.
Am. J. Trop. Med. Hyg.
PUBLISHED: 03-09-2010
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Chikungunya virus is a mosquito-borne virus that causes an acute febrile infection and severe arthralgia and is considered a re-emergent pathogen. During a study investigating arboviruses causing febrile infection in infants in Bata, Equatorial Guinea, the genome of this virus was amplified from blood samples during near two rainy seasons (2002-2003). In 2006, this virus was isolated from a traveler returning to Spain from Equatorial Guinea. These results show that chikungunya virus is present in this country and two lineages are circulating. Thus, this virus should be considered in the differential diagnosis of febrile syndromes in inhabitants and in travelers returning from this country.
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Screening of Trypanosoma brucei gambiense in domestic livestock and tsetse flies from an insular endemic focus (Luba, Equatorial Guinea).
PLoS Negl Trop Dis
PUBLISHED: 02-02-2010
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Sleeping sickness is spread over 36 Sub-Saharan African countries. In West and Central Africa, the disease is caused by Trypanosoma brucei gambiense, which produces a chronic clinical manifestation. The Luba focus (Bioko Island, Equatorial Guinea) has not reported autochthonous sleeping sickness cases since 1995, but given the complexity of the epidemiological cycle, the elimination of the parasite in the environment is difficult to categorically ensure.
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Geographic structuring of the Plasmodium falciparum sarco(endo)plasmic reticulum Ca2+ ATPase (PfSERCA) gene diversity.
PLoS ONE
PUBLISHED: 01-22-2010
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Artemisinin, a thapsigargin-like sesquiterpene has been shown to inhibit the Plasmodium falciparum sarco/endoplasmic reticulum calcium-ATPase PfSERCA. To collect baseline pfserca sequence information before field deployment of Artemisinin-based Combination therapies that may select mutant parasites, we conducted a sequence analysis of 100 isolates from multiple sites in Africa, Asia and South America. Coding sequence diversity was large, with 29 mutated codons, including 32 SNPs (average of one SNP/115 bp), of which 19 were novel mutations. Most SNP detected in this study were clustered within a region in the cytosolic head of the protein. The PfSERCA functional domains were very well conserved, with non synonymous mutations located outside the functional domains, except for the S769N mutation associated in French Guiana with elevated IC(50) for artemether. The S769N mutation is located close to the hinge of the headpiece, which in other species modulates calcium affinity and in consequence efficacy of inhibitors, possibly linking calcium homeostasis to drug resistance. Genetic diversity was highest in Senegal, Brazil and French Guiana, and few mutations were identified in Asia. Population genetic analysis was conducted for a partial fragment of the gene encompassing nucleotide coordinates 87-2862 (unambiguous sequence available for 96 isolates). This supported a geographic clustering, with a separation between Old and New World samples and one dominant ancestral haplotype. Genetic drift alone cannot explain the observed polymorphism, suggesting that other evolutionary mechanisms are operating. One possible contributor could be the frequency of haemoglobinopathies that are associated with calcium dysregulation in the erythrocyte.
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Nutritional and socio-economic factors associated with Plasmodium falciparum infection in children from Equatorial Guinea: results from a nationally representative survey.
Malar. J.
PUBLISHED: 07-16-2009
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Malaria has traditionally been a major endemic disease in Equatorial Guinea. Although parasitaemia prevalence on the insular region has been substantially reduced by vector control in the past few years, the prevalence in the mainland remains over 50% in children younger than five years. The aim of this study is to investigate the risk factors for parasitaemia and treatment seeking behaviour for febrile illness at country level, in order to provide evidence that will reinforce the EG National Malaria Control Programme.
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[Detection of antimalarial activity for new compounds by isotopic microtest].
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi
PUBLISHED: 05-23-2009
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Two clone lines (Dd2 and 3D7) of Plasmodium falciparum were cultivated continuously in human erythrocytes at 37 degrees C in RPMI 1640 medium with human serum and subjected to 6% sorbitol treatment 2 times in order to obtain highly synchronized cultures. The second generation parasites after the treatment were diluted with human RBC to be a suspension of P. falciparum-human RBC at 2.5% hematocrit and 0.5% parasitemia, and 2 microCi/ml of 8-3H-hypoxanthine was added. Isotopic microtest was employed to detect the antimalarial activity for 20 new compounds. Results revealed that the 20 compounds showed no anti-malarial activity, while the control drugs, chloroquine and quinine, exhibited high efficacy, indicating that the isotopic microtest is a stable and reproducible assay for screening new antimalarials.
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Molecular cloning and characterisation of the RESA gene, a marker of genetic diversity of Plasmodium falciparum.
Mol. Biol. Rep.
PUBLISHED: 03-23-2009
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To identity immunodiagnostic antigen genes, a Plasmodium falciparum (Dd2 clone) expression library was screened using human immune sera. The ring-infected erythrocyte surface antigen (RESA) was isolated: this antigen of the resistant clone presents repeat tandem sequences like the 3D7 clone, albeit in different numbers. RESA has been studied as a marker of genetic diversity, with different sizes being observed in different isolates and clones of Plasmodium falciparum. The native protein was localised in cultures by western-blot and immuno-transmission electron microscopy. The antigenicity of RESA was evaluated by ELISA, using the carboxy-terminal repeat region as antigen. The assays sensitivity and specificity were 78.2 and 94% respectively.
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Efficacy of Artesunate + Sulphadoxine-Pyrimethamine (AS + SP) and Amodiaquine + Sulphadoxine-Pyrimethamine (AQ + SP) for Uncomplicated falciparum Malaria in Equatorial Guinea (Central Africa).
J Trop Med
PUBLISHED: 02-11-2009
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Objectives. The objectives of the study were (i) to evaluate the efficacy of combination drugs, such as artesunate + sulphadoxine-pyrimethamine (AS + SP) and amodiaquine + sulphadoxine-pyripethamine (AQ + SP) in treatment of uncomplicated falciparum malaria (ii) to differentiate recrudescence from reinfection by analysing msp-1 and msp-2 genes of Plasmodium falciparum in treatment failure cases. Methods. We carried out an in vivo study in the year 2005 in 206 children between 6 to 59 months age groups. Of the 206, 120 received AQ + SP, and 86 received AS + SP. A clinical and parasitological followup during 14 days was undertaken. Finger-prick blood sample from each patient was taken on Whatman filter paper (no. 3) on days 0, 7, 14 and also the day when the parasite and symptoms reappeared for PCR analysis. Results. Late treatment failure was observed in 3.5% (4/114) with AQ + SP, and 2.5% (2/79) with AS + SP. The success rate was 96.5% with AQ + SP and 97.5% with AS + SP. No deaths and severe reactions were recorded. Out of the 6 treatment failure cases, one was reinfection as observed by PCR analysis of msp-1 and msp-2 genes on day 14. Discussion. Both the combinations found to be efficacious and safe and could be used as a first-line treatment for uncomplicated falciparum malaria in Equatorial Guinea.
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Initial characterization of Pf62, a novel protein of Plasmodium falciparum identified by immunoscreening.
Parasitol. Res.
PUBLISHED: 01-08-2009
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In order to find new antigens from Plasmodium falciparum, a complementary DNA (cDNA) library was constructed and screened. The study of expression library of P. falciparum was performed in an attempt to identify new antigens that could have potential relevance for the falciparum-malaria diagnosis and/or protection. Between the positive clones detected (ring erythrocyte surface antigen, merozoite erythrocyte surface antigen, RHOP H3, CSP, LSA), a new gene that correspond to a new protein (Pf62) was isolated and characterized. This antigen was useful for the diagnosis of malaria in enzyme-linked immunosorbent assay tests. The cDNA corresponding to this antigen and structure of the gene were characterized. Pf62 is a single copy gene that contains one exon. The Pf62 cDNA has an open reading frame of 1,599 nucleotides that code for a putative protein of 532 amino acids with a predicted molecular mass of 62 kDa. The polypeptide contains in the central section two regions of repeats of 21 and 19 amino acids, respectively. The localization of the Pf62 protein was performed by immunoblot, indirect immunofluorescence assay and immunoelectron microscopy. Pf62 is localized in the cytoplasm of the parasite and also on the surface of the infected erythrocyte. Serologic assays by using synthetic peptides designed from different antigenic regions of the Pf62 protein resulted in acceptable data of sensitivity and specificity in symptomatic malaria patients.
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Characterization of the Plasmodium falciparum sarcoplasmic/endoplasmic reticulum Ca2+-ATPase gene in samples from Equatorial Guinea before implementation of artemisinin-based combination therapy.
Am. J. Trop. Med. Hyg.
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Plasmodium falciparum resistance to the primary drugs used for treatment of malaria has become the main obstacle to malaria control. Artemisinin combination therapies are the current treatment strategy, and it has been suggested that resistance to artemisinin derivatives may be related to mutations in the Plasmodium falciparum sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase ortholog of the mammalian sarco-endoplasmic reticulum Ca(2+) ATPase gene, known as the pfatp6 gene. Thus, the purpose of this study was to determine the prevalence of single-nucleotide polymorphisms (SNPs) in pfatp6. The presence of different SNPs was detected by polymerase chain reaction amplification of the pfatp6 gene, and then sequencing to identify all possible alleles of the gene. A total of 20 SNPs were detected, including eight SNPs that have not been previously described: K481R in Malabo; R801H on Annobon Island; and the synonymous SNPs a141t, c1788t, a2211g, t2739g, a2760c, and g2836a. The genotypic profile of pfatp6 in samples from Equatorial Guinea, may be a useful epidemiologic tool for monitoring local efficacy of artemisinin combination therapies.
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Microscopy and molecular biology for the diagnosis and evaluation of malaria in a hospital in a rural area of Ethiopia.
Malar. J.
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Malaria is a leading public health problem in Ethiopia. Accurate diagnosis of Plasmodium infections is crucial for the reduction of malaria in tropical areas and for epidemiological studies. The role of light microscopy (LM) as gold standard has been questioned and, therefore, new molecular methods have been developed for the detection of Plasmodium species. The aim of the present work was to compare different malaria diagnostic methods in order to detect the most common species of Plasmodium and to broaden the knowledge of malaria prevalence in a hospital in a rural area in Ethiopia.
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Molecular markers in plasmodium falciparum linked to resistance to anti-malarial drugs in samples imported from Africa over an eight-year period (2002-2010): impact of the introduction of artemisinin combination therapy.
Malar. J.
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Drug resistance is a major problem to control Plasmodium falciparum infection in endemic countries. During last decade, African countries have changed first-line treatment to artemisinin-based combinations therapy (ACT); sulphadoxine-pyrimethamine (SP) is recommended for Intermittent Preventive Therapy (IPT). Molecular markers related to P falciparum resistance were analysed for the period of transition from SP to ACT, in isolates imported from Africa.
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