Publications

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[demonstration of chloroquine diphosphate resistance in plasmodium falciparum strains naturally infecting man in an area of the bolivar state, venezuela]. 19751091958
use of the polymerase chain reaction to directly detect malaria parasites in blood samples from the venezuelan amazon.we have examined the reproducibility, sensitivity, and specificity of detecting plasmodium falciparum using the polymerase chain reaction (pcr) and the species-specific probe ppf14 under field conditions in the venezuelan amazon. up to eight samples were field collected from each of 48 consenting amerindians presenting with symptoms of malaria. sample processing and analysis was performed at the centro amazonico para la investigacion y control de enfermedades tropicales simon bolivar. a total of ...19948116809
evaluation of dna recombinant methodologies for the diagnosis of plasmodium falciparum and their comparison with the microscopy assay.since 1984, dna tests based on the highly repeated subtelomeric sequences of plasmodium falciparum (rep 20) have been frequently used in malaria diagnosis. rep 20 is very specific for this parasite, and is made of 21 bp units, organized in repeated blocks with direct and inverted orientation. based in this particular organization, we selected a unique consensus oligonucleotide (pf-21) to drive a pcr reaction coupled to hybridization to non-radioactive labeled probes. the pf-21 unique oligo pcr ( ...19989830531
point mutations in dihydrofolate reductase and dihydropteroate synthase genes of plasmodium falciparum isolates from venezuela.the present study was designed to characterize mutations in dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes of plasmodium falciparum in the bolivar region of venezuela, where high levels of clinical resistance to sulfadoxine-pyrimethamine (sp, fansidar; f. hoffman-la roche, basel, switzerland) has been documented. we used a nested mutation-specific polymerase chain reaction and restriction digestion methods to measure 1) the prevalence of dhfr mutations at 16, 50, 51, 59 ...199910497990
[malaria and pregnancy. san isidro parish, municipality sifontes, state of bolívar, venezuela, 2005-2006].malaria in pregnancy constitutes a world-wide public health problem. with the objective of studying malaria in pregnancy, a cross-sectional, descriptive epidemiological study was carried out on 449 women, in mining areas of the san isidro parish, municipality sifontes, state of bolívar, venezuela, during 2005-2006. the malaria incidence in pregnant women was 27.4%: 87% for plasmodium vivax, 12.2% plasmodium falciparum and 0.8% mixed infections. these infections appeared mainly during the second ...200920306719
malaria seroprevalence in blood bank donors from endemic and non-endemic areas of venezuela.in venezuela, a total of 363,466 malaria cases were reported between 1999-2009. several states are experiencing malaria epidemics, increasing the risk of vector and possibly transfusion transmission. we investigated the risk of transfusion transmission in blood banks from endemic and non-endemic areas of venezuela by examining blood donations for evidence of malaria infection. for this, commercial kits were used to detect both malaria-specific antibodies (all species) and malaria antigen (plasmo ...201121537669
common origin and fixation of plasmodium falciparum dhfr and dhps mutations associated with sulfadoxine-pyrimethamine resistance in a low-transmission area in south america.recent studies indicated that sensitive parasites could increase in frequency in a population when drugs are removed, suggesting that the life span of affordable antimalarial drugs could be expanded. we studied 97 samples from bolivar state, venezuela, an area where sulfadoxine-pyrimethamine (sp) has not been used for 8 years due to its ineffectiveness. we characterized point mutations in two genes that have been implicated in resistance to sp, dihydrofolate reductase (dhfr) and dihydropteroate ...200717283199
genetic diversity of merozoite surface protein-1 gene of plasmodium vivax isolates in mining villages of venezuela (bolivar state).the merozoite surface protein-1 gene of plasmodium vivax is highly polymorphic and so, currently used in epidemiological studies of p. vivax malaria. we sequenced the variable block 5 of the gene from 39 venezuelan isolates, 18 of which were co-infected with plasmodium falciparum. we observed a limited variability with 34 isolates belonging to the type salvador i, none belem type and only five recombinants. among the recombinants, only two types of sequences were observed with, respectively, 18 ...200515862584
genetics of drug-resistant plasmodium falciparum malaria in the venezuelan state of bolivar.the state of bolivar in venezuela experiences episodic outbreaks of multidrug-resistant plasmodium falciparum malaria. we obtained p. falciparum-infected blood samples in bolivar in 1998-2000, and performed molecular assays for mutations conferring resistance to the antifolate combination of sulfadoxine-pyrimethamine (sp) and to chloroquine. all infections carried the dihydrofolate reductase (dhfr) s108a and n51i mutations, and 45% of the infections had the dhfr c50r mutation, which has been imp ...200212452494
chemotherapy of malaria and resistance to antimalarial drugs in guayana area, venezuela.resistance to antimalarial chemotherapy is one of the greatest difficulties for the control of malaria transmission. seventy patients with plasmodium falciparum malaria were included in a study of resistance to chloroquine and sulfadoxine-pyrimethamine therapy. resistance levels ri, rii, and riii were established. eighteen infections (51%) cleared after chloroquine treatment and did not recur within 28 days of follow-up; these were classified as sensitive. ten infections (29%) were resistant at ...199910432068
detection of specific antibodies to plasmodium falciparum in blood bank donors from malaria-endemic and non-endemic areas of venezuela.malaria antibody detection is valuable in providing retrospective confirmation of an attack of malaria. blood bank screening is another area were malaria serology is potentially useful. in the present study, we tested the presence of antibodies to plasmodium falciparum in sera from blood bank donors of non-endemic and malaria-endemic areas of venezuela. sera from 1,000 blood donors were tested by an indirect immunofluorescent antibody (ifa) assay and an igg-elisa for the presence of malaria anti ...199910403326
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