Last data update: May 28, 2024. (Total: 46864 publications since 2009)
Records 1-8 (of 8 Records) |
Query Trace: De Oliveira AM [original query] |
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Physical durability and insecticidal activity of long-lasting insecticidal nets in Cruzeiro do Sul, Brazil
Feio-Dos-Santos AC , Reis CC , Sucupira IMC , Lenhart A , Santos MMM , Reis ER , do Carmo EL , Daniel S , Mesones Lapouble OM , de Oliveira AM , Povoa MM . Sci Rep 2024 14 (1) 9044 Vector control is one of the principal strategies used for reducing malaria transmission. Long-lasting insecticidal bed nets (LLINs) are a key tool used to protect populations at risk of malaria, since they provide both physical and chemical barriers to prevent human-vector contact. This study aimed to assess the physical durability and insecticidal efficacy of LLINs distributed in Cruzeiro do Sul (CZS), Brazil, after 4 years of use. A total of 3000 LLINs (PermaNet 2.0) were distributed in high malaria risk areas of CZS in 2007. After 4 years of use, 27 'rectangular' LLINs and 28 'conical' LLINs were randomly selected for analysis. The evaluation of physical integrity was based on counting the number of holes and measuring their size and location on the nets. Insecticidal efficacy was evaluated by cone bioassays, and the amount of residual insecticide remaining on the surface of the LLINs was estimated using a colorimetric method. After 4 years of use, physical damage was highly prevalent on the rectangular LLINs, with a total of 473 holes detected across the 27 nets. The upper portion of the side panels sustained the greatest damage in rectangular LLINs. The overall mosquito mortality by cone bioassay was < 80% in 25/27 rectangular LLINs, with panel A (at the end of the rectangular bednet) presenting the highest mortality (54%). The overall mean insecticide concentration was 0.5 µg/sample, with the bednet roof containing the highest average concentration (0.61 µg/sample). On the conical LLINs, 547 holes were detected, with the bottom areas sustaining the greatest damage. The cone bioassay mortality was < 80% in 26/28 of the conical LLINs. The mean insecticide concentration was 0.3 µg/sample. After 4 years of use, the insecticidal efficacy of the LLINs was diminished to below acceptable thresholds. |
Multiple genetic origins of histidine-rich protein 2 gene deletion in Plasmodium falciparum parasites from Peru.
Akinyi S , Hayden T , Gamboa D , Torres K , Bendezu J , Abdallah JF , Griffing SM , Quezada WM , Arrospide N , De Oliveira AM , Lucas C , Magill AJ , Bacon DJ , Barnwell JW , Udhayakumar V . Sci Rep 2013 3 2797 The majority of malaria rapid diagnostic tests (RDTs) detect Plasmodium falciparum histidine-rich protein 2 (PfHRP2), encoded by the pfhrp2 gene. Recently, P. falciparum isolates from Peru were found to lack pfhrp2 leading to false-negative RDT results. We hypothesized that pfhrp2-deleted parasites in Peru derived from a single genetic event. We evaluated the parasite population structure and pfhrp2 haplotype of samples collected between 1998 and 2005 using seven neutral and seven chromosome 8 microsatellite markers, respectively. Five distinct pfhrp2 haplotypes, corresponding to five neutral microsatellite-based clonal lineages, were detected in 1998-2001; pfhrp2 deletions occurred within four haplotypes. In 2003-2005, outcrossing among the parasite lineages resulted in eight population clusters that inherited the five pfhrp2 haplotypes seen previously and a new haplotype; pfhrp2 deletions occurred within four of these haplotypes. These findings indicate that the genetic origin of pfhrp2 deletion in Peru was not a single event, but likely occurred multiple times. |
Field evaluation of a real time loop-mediated isothermal amplification assay (RealAmp) for malaria diagnosis in Cruzeiro do Sul, Acre, Brazil.
Viana GMR , Silva-Flannery L , Lima Barbosa DR , Lucchi N , do Valle SCN , Farias S , Barbalho N , Marchesini P , Rossi JCN , Udhayakumar V , Povoa MM , de Oliveira AM . PLoS One 2018 13 (7) e0200492 Conventional molecular methods, such as nested polymerase chain reaction (PCR), are very sensitive for detection of malaria parasites, but require advanced laboratory equipment and trained personnel. Real-time loop-mediated isothermal amplification (RealAmp), a loop-mediated isothermal amplification-based molecular tool (LAMP), facilitates rapid target amplification at a single temperature setting, reducing the need for sophisticated equipment. We evaluated the performance of a field-adapted RealAmp assay for malaria diagnosis in Cruzeiro do Sul, Acre State, Brazil, a remote area in Brazil with limited laboratory capabilities. We enrolled 1,000 patients with fever (axillary temperature >/= 37.5 C) or history of fever in last 24 h presenting for malaria diagnosis from February through June 2015. DNA was extracted from dried blood spots using a boil and spin method (heat treatment) at the sample processing site, and also using commercial kits at a Brazilian national reference laboratory. RealAmp was performed for Plasmodium genus, P. falciparum, and P. vivax identification. In addition, Giemsa-stained blood smears were prepared and examined by two independent well-trained study microscopists. A combination of Real-time PCR and nested PCR was used as reference test. The sensitivity and specificity of RealAmp in the field site laboratory were 94.1% (95% confidence interval [CI]: 90.1-96.8) and 83.9% (95% CI: 81.1-86.4), respectively. The sensitivity and specificity of local microscopy were 87.7% (95% CI: 82.6-91.7) and 98.9% (95% CI: 97.8-99.4), respectively, while study microscopy showed sensitivity of 96.4% (95% CI: 93.0-98.4) and specificity of 98.2% (95% CI: 97.0-99.0). None of the three tests detected 20 P. falciparum and P. vivax mixed infections identified by the reference test. Our findings highlight that it is possible to implement simple molecular tests in facilities with limited resources such as Cruzeiro do Sul in Brazil. RealAmp sensitivity was similar to that of microscopy performed by skilled professionals; both RealAmp and study microscopy performed poorly in detection of mixed infection. Attempts to develop and evaluate simpler molecular tools should continue, especially for the detection of malaria infection in remote areas. |
Molecular profile of malaria drug resistance markers of Plasmodium falciparum in Suriname.
Chenet SM , Akinyi Okoth S , Kelley J , Lucchi N , Huber CS , Vreden S , de Oliveira AM , Barnwell JW , Udhayakumar V , Adhin MR . Antimicrob Agents Chemother 2017 61 (7) In Suriname, an artesunate monotherapy therapeutic efficacy trial was recently conducted to evaluate partial artemisinin resistance emerging in Plasmodium falciparum. We genotyped the PfK13 propeller domain of P. falciparum in forty samples as well as other mutations proposed to be associated with artemisinin resistant mutants. We did not find any mutations previously associated with artemisinin resistance in Southeast Asia but we found fixed resistance mutations for chloroquine and sulfadoxine-pyrimethamine. Additionally, the Pfcrt C350R mutation, associated with reversal of CQ resistance and piperaquine selective pressure was present in 62% of the samples. Our results from neutral microsatellite data also confirmed a high parasite gene flow in the Guiana Shield. Although recruiting participants for therapeutic efficacy studies in very low malaria endemic areas is challenging due to the low number of malaria cases reported, conducting these studies along with molecular surveillance remains essential to monitor artemisinin resistant alleles and to characterize the population structure P. falciparum in areas targeting malaria elimination. |
Efficacy of chloroquine and primaquine for the treatment of uncomplicated Plasmodium vivax malaria in Cruzeiro do Sul, Brazil
Negreiros S , Farias S , Viana GM , Okoth SA , Chenet SM , de Souza TM , Marchesini P , Udhayakumar V , Povoa MM , Santelli AC , de Oliveira AM . Am J Trop Med Hyg 2016 95 (5) 1061-1068 We evaluated the efficacy of chloroquine and primaquine on uncomplicated Plasmodium vivax malaria in Cruzeiro do Sul, Brazil, in 2014. Patients ≥ 5 years of age with either fever or history of fever, and laboratory-confirmed P. vivax monoinfection received chloroquine (total dose = 25 mg/kg) and primaquine (total dose = 3.5 mg/kg), and were followed up for 168 days (24 weeks). We used microsatellite genotyping to differentiate recurrent infections caused by heterologous parasites from those caused by homologous ones. No new P. vivax episode occurred by Day 28 among 119 enrolled patients, leading to Day 28, with adequate clinical and parasitological response (ACPR) of 100% (95% confidence interval [CI] = 96.7-100%). Twenty-eight P. vivax episodes occurred by Day 168, with uncorrected ACPR of 69.9% (95% CI = 59.5-79.0%). Fifteen of these episodes were caused by either homologous haplotypes or haplotypes that could not be determined. Excluding the 13 recurrent episodes caused by heterologous parasites, Day 168 microsatellite-corrected ACPR was estimated at 81.2% (95% CI = 71.0-89.1%). Chloroquine and primaquine remain efficacious to treat acute uncomplicated P. vivax infection, but moderate recurrence rates were observed within 24 weeks of follow-up. |
Prevalence of pfhrp2 and pfhrp3 gene deletions in Puerto Lempira, Honduras.
Abdallah JF , Okoth SA , Fontecha GA , Torres RE , Banegas EI , Matute ML , Bucheli ST , Goldman IF , de Oliveira AM , Barnwell JW , Udhayakumar V . Malar J 2015 14 (1) 19 BACKGROUND: Recent studies have demonstrated the deletion of the histidine-rich protein 2 (PfHRP2) gene (pfhrp2) in field isolates of Plasmodium falciparum, which could result in false negative test results when PfHRP2-based rapid diagnostic tests (RDTs) are used for malaria diagnosis. Although primary diagnosis of malaria in Honduras is determined based on microscopy, RDTs may be useful in remote areas. In this study, it was investigated whether there are deletions of the pfhrp2, pfhrp3 and their respective flanking genes in 68 P. falciparum parasite isolates collected from the city of Puerto Lempira, Honduras. In addition, further investigation considered the possible correlation between parasite population structure and the distribution of these gene deletions by genotyping seven neutral microsatellites. METHODS: Sixty-eight samples used in this study, which were obtained from a previous chloroquine efficacy study, were utilized in the analysis. All samples were genotyped for pfhrp2, pfhrp3 and flanking genes by PCR. The samples were then genotyped for seven neutral microsatellites in order to determine the parasite population structure in Puerto Lempira at the time of sample collection. RESULTS: It was found that all samples were positive for pfhrp2 and its flanking genes on chromosome 8. However, only 50% of the samples were positive for pfhrp3 and its neighboring genes while the rest were either pfhrp3-negative only or had deleted a combination of pfhrp3 and its neighbouring genes on chromosome 13. Population structure analysis predicted that there are at least two distinct parasite population clusters in this sample population. It was also determined that a greater proportion of parasites with pfhrp3-(and flanking gene) deletions belonged to one cluster compared to the other. CONCLUSION: The findings indicate that the P. falciparum parasite population in the municipality of Puerto Lempira maintains the pfhrp2 gene and that PfHRP2-based RDTs could be considered for use in this region; however continued monitoring of parasite population will be useful to detect any parasites with deletions of pfhrp2. |
Historical shifts in Brazilian P. falciparum population structure and drug resistance alleles.
Griffing SM , Viana GM , Mixson-Hayden T , Sridaran S , Alam MT , de Oliveira AM , Barnwell JW , Escalante AA , Povoa MM , Udhayakumar V . PLoS One 2013 8 (3) e58984 Previous work suggests that Brazilian Plasmodium falciparum has limited genetic diversity and a history of bottlenecks, multiple reintroductions due to human migration, and clonal expansions. We hypothesized that Brazilian P. falciparum would exhibit clonal structure. We examined isolates collected across two decades from Amapa, Rondonia, and Para state (n = 190). By examining more microsatellites markers on more chromosomes than previous studies, we hoped to define the extent of low diversity, linkage disequilibrium, bottlenecks, population structure, and parasite migration within Brazil. We used retrospective genotyping of samples from the 1980s and 1990s to explore the population genetics of SP resistant dhfr and dhps alleles. We tested an existing hypothesis that the triple mutant dhfr mutations 50R/51I/108N and 51I/108N/164L developed in southern Amazon from a single origin of common or similar parasites. We found that Brazilian P. falciparum had limited genetic diversity and isolation by distance was rejected, which suggests it underwent bottlenecks followed by migration between sites. Unlike Peru, there appeared to be gene flow across the Brazilian Amazon basin. We were unable to divide parasite populations by clonal lineages and pairwise FST were common. Most parasite diversity was found within sites in the Brazilian Amazon, according to AMOVA. Our results challenge the hypothesis that triple mutant alleles arose from a single lineage in the Southern Amazon. SP resistance, at both the double and triple mutant stages, developed twice and potentially in different regions of the Brazilian Amazon. We would have required samples from before the 1980s to describe how SP resistance spread across the basin or describe the complex internal migration of Brazilian parasites after the colonization efforts of past decades. The Brazilian Amazon basin may have sufficient internal migration for drug resistance reported in any particular region to rapidly spread to other parts of basin under similar drug pressure. |
Efficacy and effectiveness of mefloquine and artesunate combination therapy for uncomplicated Plasmodium falciparum malaria in the Peruvian Amazon
de Oliveira AM , Chavez J , de Leon GP , Durand S , Arrospide N , Roberts J , Cabezas C , Marquino W . Am J Trop Med Hyg 2011 85 (3) 573-8 We evaluated the efficacy and effectiveness of mefloquine (MQ) plus artesunate (AS) to treat patients with uncomplicated malaria in the Peruvian Amazon Basin in April 2005-March 2006. Patients ≥ 1 year of age with fever (axillary temperature ≥ 37.5 degrees C) or history of fever and Plasmodium falciparum monoinfection were included. Patients received antimalarial treatment with MQ (12.5 mg/kg/day for two days) and AS (4.0 mg/kg/day for three days) either by directly observed therapy or without directly observed therapy. After a 28-day follow-up, treatment efficacy and effectiveness were assessed on the basis of clinical and parasitologic outcomes. Ninety-six patients were enrolled in each study group; nine patients were lost to follow-up. All patients, except for one in the observed group, demonstrated adequate clinical and parasitologic response; none had detectable parasitemia on day 3. The efficacy of MQ + AS efficacy was 98.9% (95% confidence interval = 94.1-100.0%) and the effectiveness was 100.0% (95% confidence interval = 95.9-100.0%). Our study shows that MQ + AS is highly efficacious in the Peruvian Amazon. |
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