Evolução da resistencia in vitro do Plasmodium falciparum a antimaláricos em área de prospecção de ouro no Estado do Amapá, entre 1983 e 1990

Couto, Álvaro Augusto Ribeiro D'Almeida; Calvosa, Vanja Suely Pachiano; Lima, Joana Esteves de; Souza, José Maria de

doi:10.1590/s0037-86821993000400003

Cited by 10 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Two previous surveillance studies of drug-resistant malaria in the Amazon region demonstrated a high level of chloroquine resistance. 5,30 Thus, in this case the in vitro data correlates with the in vivo clinical resistance. An attempt to treat malaria in the Amazon region using a high-dose regimen of chloroquine may have delayed the development of clinical resistance, but it did not prevent it.…”

Section: Resultsmentioning

confidence: 80%

“…Several factors are associated with the emergence of drug resistance, but certainly a major contributing factor is the drug pressure in the region. 5 Today, in many malaria-endemic areas of Brazil clinical failures of chloroquine are reaching 100% and the drug is no longer recommended for treatment of uncomplicated P. falciparum malaria (Pang L, Walter Reed Army Institute of Research [WRAIR], unpublished data). With the advent of chloroquine resistance, other antimalarials were introduced.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Characterization of Plasmodium falciparum isolated from the Amazon region of Brazil: evidence for quinine resistance.

Zalis¹,

Pang²,

Silveira³

et al. 1998

Am J Trop Med Hyg

116

View full text Add to dashboard Cite

The prevalence and severity of drug-resistant malaria is emerging rapidly in the Amazon basin of Brazil. In support of clinical trials using the new antimalarial drug combination of atovaquone and proguanil, we performed in vitro drug sensitivities, molecular characterization of parasite populations using the circumsporozoite protein, merozoite surface antigen-1 (MSA-1), and MSA-2 markers, and an analysis of the Plasmodium falciparum multidrug resistance (pfmdr1) gene sequence and copy number in 26 isolates of P. falciparum obtained in a gold-mining endemic area in Peixoto de Azevedo, Mato Grosso State. All 26 isolates were found to be resistant to chloroquine (50% inhibitory concentration [IC 50 ] ϭ 100-620 nM) and sensitive to mefloquine (IC 50 Ͻ 23 nM) and halofantrine (IC 50 Ͻ 6 nM). The isolates also show reduced susceptibility to quinine (IC 50 ϭ 48-280 nM). Sequence analysis of the pfmdr1 gene revealed Asn, Phe, Cys, Asp, and Tyr in positions 86, 184, 1034, 1042, and 1246, respectively. These point mutations were similar to that previously described in other Brazilian isolates. Southern blot analysis revealed no amplification of the pfmdr1 gene. These results suggest that three different mechanisms for drug resistance exist for chloroquine, mefloquine, and quinine.

show abstract

Section: Resultsmentioning

confidence: 80%

mentioning

confidence: 99%

Characterization of Plasmodium falciparum isolated from the Amazon region of Brazil: evidence for quinine resistance.

Zalis¹,

Pang²,

Silveira³

et al. 1998

Am J Trop Med Hyg

116

View full text Add to dashboard Cite

show abstract

“…Similar results have been showed by many authors. 13,[15][16][17][18][19] Our results indicate a direct correlation between the geographical dispersion and the different resistance rates. Similar observations have been pointed out in Brazilian Amazonia.…”

Section: Resultsmentioning

confidence: 87%

“…As is known, self-medication and subcurative doses favor the selection of resistant parasite populations, which are frequent in areas of high malarial transmission. [8][9][10][11][12][13][14] Another factor that may influence the development of high resistance of P. falciparum to chloroquine (although no studies have been performed) could be the uncontrolled population migration movements within and into and out of the municipality of Domingo Sifontes and surrounding areas, as proposed above. Similar results have been showed by many authors.…”

Section: Resultsmentioning

confidence: 99%

Chemotherapy of malaria and resistance to antimalarial drugs in Guayana area, Venezuela.

Caraballo¹,

Rodrı́guez-Acosta²

1999

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

Abstract. 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 the RI level. Resistance at level RII was observed in 5 (14%) cases, and RIII resistance was demonstrated in 2 infections (6%). With sulfadoxine-pyrimethamine, 28 (80%) infections were classified as sensitive. Six infections (17%) showed resistance at level RII, and 1 (3%) infection was resistant at the RI level. Resistance at level RIII was not observed. In a microtest for chloroquine and sulfadoxinepyrimethamine sensitivity in vitro, schizont development was accomplished successfully in 70 blood samples. In vitro resistance to chloroquine was demonstrated in 15 of 70 (21%) of all isolates. Eight of 70 (11%) of all isolates showed resistance to sulfadoxine-pyrimethamine. Diversity of response of P. falciparum to the studied antimalarial drugs in the Guayana area of Venezuela is considered a problem restricting the control of malaria in this geographical area. A constant evaluation program monitoring P. falciparum drug sensitivity is necessary for preserving the efficacy of the established treatment.After a successful eradication program implemented over several decades, malaria is now endemic in Venezuela in patchy forest areas where activities associated with gold mining are limiting control efforts. From 1992 to 1995, Plasmodium falciparum infections and outbreaks were registered only in remote areas in southern Venezuela, in 11 municipalities that are located in Bolívar State and Amazonas and Delta Amacuro territories. Bolívar State has contributed more than 60% of all malaria cases in Venezuela; of these, 20% correspond to P. falciparum infections. On average, the infection rates of the parasite reach 2 cases per 1,000 inhabitants among a population composed mainly of gold and diamond miners and indigenous groups.Resistance to antimalarial chemotherapy is one of the obstacles for the control of malaria transmission in various regions of the world. The adequate use of antimalarial drugs is essential for reducing the high morbidity and mortality associated with P. falciparum malaria in nonimmune hosts. Therefore, knowledge of the geographical distribution of P. falciparum strains that are resistant and the identification of the severity of this resistance are important in the choice of an effective therapeutic regimen.Chloroquine resistance was first reported in Venezuela, 1 and soon after was confirmed in several countries. Since 1975, very few studies on resistant P. falciparum strains have been carried out in Venezuela; some of them have shown different resistance levels in vivo for chloroquine 2 (Navarret...

show abstract

Mefloquine resistance in Plasmodium falciparum

Mockenhaupt¹

1995

Parasitology Today

View full text Add to dashboard Cite

Evolução da resistencia in vitro do Plasmodium falciparum a antimaláricos em área de prospecção de ouro no Estado do Amapá, entre 1983 e 1990

Cited by 10 publications

References 11 publications

Characterization of Plasmodium falciparum isolated from the Amazon region of Brazil: evidence for quinine resistance.

Characterization of Plasmodium falciparum isolated from the Amazon region of Brazil: evidence for quinine resistance.

Chemotherapy of malaria and resistance to antimalarial drugs in Guayana area, Venezuela.

Mefloquine resistance in Plasmodium falciparum

Contact Info

Product

Resources

About