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1.
Mem Inst Oswaldo Cruz ; 116: e200513, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33566952

RESUMO

BACKGROUND: Different strategies for improvement of malaria control and elimination are based on the blockage of malaria parasite transmission to the mosquito vector. These strategies include the drugs that target the plasmodial sexual stages in humans and the early developmental stages inside mosquitoes. OBJECTIVES: Here we tested Malaria Box compounds in order to evaluate their activity against male and female gametocytes in Plasmodium berghei, mosquito infection in P. vivax and ookinete formation in both species. METHODS/FINDINGS: The membrane feeding assay and the development of ookinetes by a 24 h ex vivo culture and the ookinete yield per 1000 erythrocytes were used to test transmission-blocking potential of the Malaria Box compounds in P. vivax. For P. berghei we used flow cytometry to evaluate male and female gametocyte time course and fluorescence microscopy to check the ookinete development. The two species used in this study showed similar results concerning the compounds' activity against gametocytes and ookinetes, which were different from those in P. falciparum. In addition, from the eight Malaria Box compounds tested in both species, compounds MMV665830, MMV665878 and MMV665941 were selected as a hit compounds due the high inhibition observed. CONCLUSION: Our results showed that P. berghei is suitable as an initial screening system to test compounds against P. vivax.


Assuntos
Malária Vivax/prevenção & controle , Mosquitos Vetores/parasitologia , Plasmodium berghei/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Animais , Malária Vivax/tratamento farmacológico , Malária Vivax/transmissão
2.
PLoS Negl Trop Dis ; 14(12): e0008962, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33315861

RESUMO

Malaria incidence in Panama has plateaued in recent years in spite of elimination efforts, with almost all cases caused by Plasmodium vivax. Notwithstanding, overall malaria prevalence remains low (fewer than 1 case per 1000 persons). We used selective whole genome amplification to sequence 59 P. vivax samples from Panama. The P. vivax samples were collected from two periods (2007-2009 and 2017-2019) to study the population structure and transmission dynamics of the parasite. Imported cases resulting from increased levels of human migration could threaten malaria elimination prospects, and four of the samples evaluated came from individuals with travel history. We explored patterns of recent common ancestry among the samples and observed that a highly genetically related lineage (termed CL1) was dominant among the samples (47 out of 59 samples with good sequencing coverage), spanning the entire period of the collection (2007-2019) and all regions of the country. We also found a second, smaller clonal lineage (termed CL2) of four parasites collected between 2017 and 2019. To explore the regional context of Panamanian P. vivax we conducted principal components analysis and constructed a neighbor-joining tree using these samples and samples collected worldwide from a previous study. Three of the four samples with travel history clustered with samples collected from their suspected country of origin (consistent with importation), while one appears to have been a result of local transmission. The small number of Panamanian P. vivax samples not belonging to either CL1 or CL2 clustered with samples collected from Colombia, suggesting they represent the genetically similar ancestral P. vivax population in Panama or were recently imported from Colombia. The low diversity we observe in Panama indicates that this parasite population has been previously subject to a severe bottleneck and may be eligible for elimination. Additionally, while we confirmed that P. vivax is imported to Panama from diverse geographic locations, the lack of impact from imported cases on the overall parasite population genomic profile suggests that onward transmission from such cases is limited and that imported cases may not presently pose a major barrier to elimination.


Assuntos
Erradicação de Doenças , Genética Populacional , Malária Vivax/parasitologia , Plasmodium vivax/genética , Viagem , Animais , Anopheles , Colômbia/epidemiologia , Feminino , Humanos , Incidência , Malária Vivax/prevenção & controle , Metagenômica , Panamá/epidemiologia , Plasmodium vivax/isolamento & purificação
3.
PLoS One ; 15(12): e0244479, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33370376

RESUMO

Malaria is a vector-borne disease transmitted by Anopheline mosquitoes. In Korea, Plasmodium vivax malaria is an endemic disease and the main vector is Anopheles sinensis. Plasmodium vivax malaria is common in the northwestern part of South Korea, including in the city of Goyang in regions near the demilitarized zone. This study aimed to identify the best time-series model for predicting mosquito average abundance in Goyang, Korea. Mosquito data were obtained from the Mosquito Surveillance Program of the Goyang Ilsanseogu Public Health Center for the period 2008-2012. Black light traps were set up periodically in a park, a senior community center, and a village community center, public health center, drainage pumping station, cactus research center, restaurant near forest, in which many activities occur at night. In total, 9,512 female mosquitoes were collected at 12 permanent trapping sites during the mosquito season in the study period. Weekly An. sinensis average abundance was positively correlated with minimum grass temperature (r = 0.694, p < 0.001), precipitation (r = 0.326, p = 0.001). The results showed that seasonal autoregressive integrated moving average (SARIMA) (1,0,0)(0,0,1)21 with minimum grass temperature variable at time lag0 weeks and the precipitation variable at time lag1 weeks provided that best model of mosquito average abundance. The multivariate model accounted for about 54.1% of the mosquito average abundance variation. Time-series analysis of mosquito average abundance and climate factors provided basic information for predicting the occurrence of malaria mosquitoes.


Assuntos
Anopheles/parasitologia , Monitorização de Parâmetros Ecológicos/estatística & dados numéricos , Doenças Endêmicas/prevenção & controle , Malária Vivax/prevenção & controle , Mosquitos Vetores/parasitologia , Animais , Estudos Transversais , Feminino , Humanos , Malária Vivax/epidemiologia , Malária Vivax/parasitologia , Malária Vivax/transmissão , Controle de Mosquitos , Análise Multivariada , Plasmodium vivax/isolamento & purificação , República da Coreia/epidemiologia , Medição de Risco/métodos , Estações do Ano
4.
PLoS Med ; 17(8): e1003177, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32817632

RESUMO

BACKGROUND: The World Health Organization has yet to endorse deployment of topical repellents for malaria prevention as part of public health campaigns. We aimed to quantify the effectiveness of repellent distributed by the village health volunteer (VHV) network in the Greater Mekong Subregion (GMS) in reducing malaria in order to advance regional malaria elimination. METHODS AND FINDINGS: Between April 2015 and June 2016, a 15-month stepped-wedge cluster randomised trial was conducted in 116 villages in Myanmar (stepped monthly in blocks) to test the effectiveness of 12% N,N-diethylbenzamide w/w cream distributed by VHVs, on Plasmodium spp. infection. The median age of participants was 18 years, approximately half were female, and the majority were either village residents (46%) or forest dwellers (40%). No adverse events were reported during the study. Generalised linear mixed modelling estimated the effect of repellent on infection detected by rapid diagnostic test (RDT) (primary outcome) and polymerase chain reaction (PCR) (secondary outcome). Overall Plasmodium infection detected by RDT was low (0.16%; 50/32,194), but infection detected by PCR was higher (3%; 419/13,157). There was no significant protection against RDT-detectable infection (adjusted odds ratio [AOR] = 0.25, 95% CI 0.004-15.2, p = 0.512). In Plasmodium-species-specific analyses, repellent protected against PCR-detectable P. falciparum (adjusted relative risk ratio [ARRR] = 0.67, 95% CI 0.47-0.95, p = 0.026), but not P. vivax infection (ARRR = 1.41, 95% CI 0.80-2.47, p = 0.233). Repellent effects were similar when delayed effects were modelled, across risk groups, and regardless of village-level and temporal heterogeneity in malaria prevalence. The incremental cost-effectiveness ratio was US$256 per PCR-detectable infection averted. Study limitations were a lower than expected Plasmodium spp. infection rate and potential geographic dilution of the intervention. CONCLUSIONS: In this study, we observed apparent protection against new infections associated with the large-scale distribution of repellent by VHVs. Incorporation of repellent into national strategies, particularly in areas where bed nets are less effective, may contribute to the interruption of malaria transmission. Further studies are warranted across different transmission settings and populations, from the GMS and beyond, to inform WHO public health policy on the deployment of topical repellents for malaria prevention. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry (ACTRN12616001434482).


Assuntos
Serviços de Saúde Comunitária/métodos , Repelentes de Insetos/administração & dosagem , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Malária Vivax/epidemiologia , Malária Vivax/prevenção & controle , Voluntários , Administração Tópica , Adolescente , Adulto , Criança , Análise por Conglomerados , Serviços de Saúde Comunitária/economia , Análise Custo-Benefício/métodos , Feminino , Humanos , Repelentes de Insetos/economia , Malária Falciparum/economia , Malária Vivax/economia , Masculino , Mianmar/epidemiologia , Gravidez , Resultado do Tratamento , Adulto Jovem
5.
BMC Infect Dis ; 20(1): 573, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32758164

RESUMO

BACKGROUND: Malaria during pregnancy leads to serious adverse effects on mothers and the fetus. Approximately 25 million pregnant women in sub-Saharan Africa live at risk of malaria. This study would help to achieve Sustainable Development Goals (SDGs) by improving programs that deal with the prevention of malaria. Therefore, this study aimed to assess the prevalence and associated factors of malaria among pregnant women. METHODS: A community-based cross-sectional study was conducted from July to August 2018 in Sherkole district, West Ethiopia. A multi-stage sampling technique was used to select 504 pregnant women. The interviewer-administered semi-structured questionnaire was used for data collection. Malaria was also diagnosed using a rapid diagnostic test. The data was entered using EPI info version 7.2.2.2 and transferred to SPSS version 20 for analysis. Descriptive statistics were done using frequency and percentages. Both bivariable and multivariable logistic regression models were employed. Variables having p-value < 0.2 were included in the final multivariable model. Variables having p-values < 0.05 from the multivariable model were considered to be significantly associated with the dependent variable. The adjusted odds ratio with its 95% confidence interval (CI) was used as a measure of association. RESULTS: Of the total 498 pregnant women who participated in this study, 51(10.2, 95% CI: 7.72-13.24) were found to have malaria. Of these, 46 (90.2%) and 5 (9.8%) were caused by Plasmodium falciparum and Plasmodium vivax, respectively. Decreasing Age (Adjusted Odds Ratio (AOR) 0.78; 95% CI 0.67-0.911), not using insecticide-treated bed net (ITN) (AOR 12.5; 95% CI 4.86-32.21), lack of consultation and health education about malaria prevention (AOR 7.18; 95% CI 2.74-18.81), being on second-trimester pregnancy (AOR 7.58; 95% CI 2.84-20.2), gravidae II (AOR 5.99; 95% CI 1.68-21.44) were found to be significantly associated with malaria during pregnancy. CONCLUSION: Malaria is still a public health problem among pregnant women in the Sherkole district. Age, ITN use, gravidity, gestational age, and health education had a significant association with malaria. Screening pregnant women for asymptomatic malaria infection and educating and consulting on the appropriate malaria preventive methods shall be provided.


Assuntos
Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Plasmodium falciparum/imunologia , Plasmodium vivax/imunologia , Complicações Parasitárias na Gravidez/epidemiologia , Adolescente , Adulto , Antígenos de Protozoários/sangue , Infecções Assintomáticas , Estudos Transversais , Testes Diagnósticos de Rotina/métodos , Etiópia/epidemiologia , Feminino , Seguimentos , Humanos , Mosquiteiros Tratados com Inseticida , Modelos Logísticos , Malária Falciparum/prevenção & controle , Malária Vivax/prevenção & controle , Razão de Chances , Gravidez , Complicações Parasitárias na Gravidez/prevenção & controle , Prevalência , Fatores de Risco , Inquéritos e Questionários , Adulto Jovem
6.
PLoS Negl Trop Dis ; 14(7): e0008526, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32735631

RESUMO

Each year, 4.3 million pregnant women are exposed to malaria risk in Latin America and the Caribbean. Plasmodium vivax causes 76% of the regional malaria burden and appears to be less affected than P. falciparum by current elimination efforts. This is in part due to the parasite's ability to stay dormant in the liver and originate relapses within months after a single mosquito inoculation. Primaquine (PQ) is routinely combined with chloroquine (CQ) or other schizontocidal drugs to supress P. vivax relapses and reduce the risk of late blood-stage recrudescences of parasites with low-grade CQ resistance. However, PQ is contraindicated for pregnant women, who remain at increased risk of repeated infections following CQ-only treatment. Here we apply a mathematical model to time-to-recurrence data from Juruá Valley, Brazil's main malaria transmission hotspot, to quantify the extra burden of parasite recurrences attributable to PQ ineligibility in pregnant women. The model accounts for competing risks, since relapses and late recrudescences (that may be at least partially prevented by PQ) and new infections (that are not affected by PQ use) all contribute to recurrences. We compare recurrence rates observed after primary P. vivax infections in 158 pregnant women treated with CQ only and 316 P. vivax infections in non-pregnant control women, matched for age, date of infection, and place of residence, who were administered a standard CQ-PQ combination. We estimate that, once infected with P. vivax, 23% of the pregnant women have one or more vivax malaria recurrences over the next 12 weeks; 86% of these early P. vivax recurrences are attributable to relapses or late recrudescences, rather than new infections that could be prevented by reducing malaria exposure during pregnancy. Model simulations indicate that weekly CQ chemoprophylaxis extending over 4 to 12 weeks, starting after the first vivax malaria episode diagnosed in pregnancy, might reduce the risk of P. vivax recurrences over the next 12 months by 20% to 65%. We conclude that post-treatment CQ prophylaxis could be further explored as a measure to prevent vivax malaria recurrences in pregnancy and avert their adverse effects on maternal and neonatal health.


Assuntos
Antimaláricos/uso terapêutico , Malária Vivax/prevenção & controle , Plasmodium vivax , Complicações Parasitárias na Gravidez/prevenção & controle , Primaquina/administração & dosagem , Adolescente , Adulto , Brasil , Estudos de Casos e Controles , Criança , Cloroquina/administração & dosagem , Cloroquina/uso terapêutico , Feminino , Humanos , Malária Vivax/tratamento farmacológico , Modelos Biológicos , Gravidez , Primaquina/uso terapêutico , Recidiva , Adulto Jovem
7.
PLoS One ; 15(5): e0232786, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32379804

RESUMO

BACKGROUND: A low proportion of P. vivax-exposed individuals acquire protective strain-transcending neutralizing IgG antibodies that are able to block the interaction between the Duffy binding protein II (DBPII) and its erythrocyte-specific invasion receptor. In a recent study, a novel surface-engineered DBPII-based vaccine termed DEKnull-2, whose antibody response target conserved DBPII epitopes, was able to induce broadly binding-inhibitory IgG antibodies (BIAbs) that inhibit P. vivax reticulocyte invasion. Toward the development of DEKnull-2 as an effective P. vivax blood-stage vaccine, we investigate the relationship between naturally acquired DBPII-specific IgM response and the profile of IgG antibodies/BIAbs activity over time. METHODOLOGY/PRINCIPAL FINDINGS: A nine-year follow-up study was carried-out among long-term P. vivax-exposed Amazonian individuals and included six cross-sectional surveys at periods of high and low malaria transmission. DBPII immune responses associated with either strain-specific (Sal1, natural DBPII variant circulating in the study area) or conserved epitopes (DEKnull-2) were monitored by conventional serology (ELISA-detected IgM and IgG antibodies), with IgG BIAbs activity evaluated by functional assays (in vitro inhibition of DBPII-erythrocyte binding). The results showed a tendency of IgM antibodies toward Sal1-specific response; the profile of Sal1 over DEKnull-2 was not associated with acute malaria and sustained throughout the observation period. The low malaria incidence in two consecutive years allowed us to demonstrate that variant-specific IgG (but not IgM) antibodies waned over time, which resulted in IgG skewed to the DEKnull-2 response. A persistent DBPII-specific IgM response was not associated with the presence (or absence) of broadly neutralizing IgG antibody response. CONCLUSIONS/SIGNIFICANCE: The current study demonstrates that long-term exposure to low and unstable levels of P. vivax transmission led to a sustained DBPII-specific IgM response against variant-specific epitopes, while sustained IgG responses are skewed to conserved epitopes. Further studies should investigate on the role of a stable and persistent IgM antibody response in the immune response mediated by DBPII.


Assuntos
Antígenos de Protozoários/imunologia , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Vacinas Antimaláricas/uso terapêutico , Malária Vivax/prevenção & controle , Plasmodium vivax/imunologia , Proteínas de Protozoários/imunologia , Receptores de Superfície Celular/imunologia , Adulto , Anticorpos Neutralizantes/imunologia , Formação de Anticorpos , Feminino , Humanos , Vacinas Antimaláricas/imunologia , Malária Vivax/imunologia , Masculino , Pessoa de Meia-Idade
8.
Am J Trop Med Hyg ; 103(1): 415-420, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32394882

RESUMO

Failures of primaquine for the treatment of relapsed Plasmodium vivax malaria is a serious challenge to malaria elimination in Ethiopia, where P. vivax accounts for up to 40% of malaria infections. We report here occurrence of a total of 15 episodes of primaquine treatment failure for radical cure in three historical P. vivax malaria patients from Gambella, Ethiopia, during 8-16 months of follow-up in 1985-1987. The total primaquine doses received were 17.5 mg/kg, 25.8 mg/kg, and 35.8 mg/kg, respectively. These total doses are much higher than in previous reports of patients with treatment failure in Ethiopia and East Africa. The possibility of new infection was excluded for these cases as the treatment and follow-up were carried out in Addis Ababa, a malaria-free city. Recrudescences were unlikely, considering the short duration pattern of the recurrences. The cytochrome P450 2D6 (CYP2D6) status for these patients is unknown, but polymorphisms have been described in Ethiopia and may have contributed to primaquine treatment failures. It is suggested that further studies be carried out in Ethiopia to determine the prevalence and distribution of primaquine treatment failures in different ethnic groups, considering the impact of CYP2D6 polymorphisms and the potential value of increasing the primaquine dose to avoid relapse.


Assuntos
Antimaláricos/uso terapêutico , Cloroquina/uso terapêutico , Malária Vivax/tratamento farmacológico , Primaquina/uso terapêutico , Adulto , Quimioprevenção , Etiópia , Humanos , Malária Vivax/prevenção & controle , Masculino , Pessoa de Meia-Idade , Carga Parasitária , Plasmodium vivax , Retratamento , Falha de Tratamento
9.
Trends Parasitol ; 36(6): 560-570, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32407682

RESUMO

Plasmodium vivax is an important cause of malaria, associated with a significant public health burden. Whilst enhanced malaria-control activities have successfully reduced the incidence of Plasmodium falciparum malaria in many areas, there has been a consistent increase in the proportion of malaria due to P. vivax in regions where both parasites coexist. This article reviews the epidemiology and biology of P. vivax, how the parasite differs from P. falciparum, and the key features that render it more difficult to control and eliminate. Since transmission of the parasite is driven largely by relapses from dormant liver stages, its timely elimination will require widespread access to safe and effective radical cure.


Assuntos
Malária Vivax/epidemiologia , Animais , Antimaláricos/uso terapêutico , Erradicação de Doenças , Humanos , Incidência , Malária Falciparum/tratamento farmacológico , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Malária Vivax/tratamento farmacológico , Malária Vivax/parasitologia , Malária Vivax/prevenção & controle , Plasmodium falciparum/fisiologia , Plasmodium vivax/fisiologia
10.
Malar J ; 19(1): 145, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32268906

RESUMO

BACKGROUND: Countries within the Greater Mekong Sub-region (GMS) of Southeast Asia have committed to eliminating malaria by 2030. Although the malaria situation has greatly improved, malaria transmission remains at international border regions. In some areas, Plasmodium vivax has become the predominant parasite. To gain a better understanding of transmission dynamics, knowledge on the changes of P. vivax populations after the scale-up of control interventions will guide more effective targeted control efforts. METHODS: This study investigated genetic diversity and population structures in 206 P. vivax clinical samples collected at two time points in two international border areas: the China-Myanmar border (CMB) (n = 50 in 2004 and n = 52 in 2016) and Thailand-Myanmar border (TMB) (n = 50 in 2012 and n = 54 in 2015). Parasites were genotyped using 10 microsatellite markers. RESULTS: Despite intensified control efforts, genetic diversity remained high (HE = 0.66-0.86) and was not significantly different among the four populations (P > 0.05). Specifically, HE slightly decreased from 0.76 in 2004 to 0.66 in 2016 at the CMB and increased from 0.80 in 2012 to 0.86 in 2015 at the TMB. The proportions of polyclonal infections varied significantly among the four populations (P < 0.05), and showed substantial decreases from 48.0% in 2004 to 23.7 at the CMB and from 40.0% in 2012 to 30.7% in 2015 at the TMB, with corresponding decreases in the multiplicity of infection. Consistent with the continuous decline of malaria incidence in the GMS over time, there were also increases in multilocus linkage disequilibrium, suggesting more fragmented and increasingly inbred parasite populations. There were considerable genetic differentiation and sub-division among the four tested populations. Temporal genetic differentiation was observed at each site (FST = 0.081 at the CMB and FST = 0.133 at the TMB). Various degrees of clustering were evident between the older parasite samples collected in 2004 at the CMB and the 2016 CMB and 2012 TMB populations, suggesting some of these parasites had shared ancestry. In contrast, the 2015 TMB population was genetically distinctive, which may reflect a process of population replacement. Whereas the effective population size (Ne) at the CMB showed a decrease from 4979 in 2004 to 3052 in 2016 with the infinite allele model, the Ne at the TMB experienced an increase from 6289 to 10,259. CONCLUSIONS: With enhanced control efforts on malaria, P. vivax at the TMB and CMB showed considerable spatial and temporal differentiation, but the presence of large P. vivax reservoirs still sustained genetic diversity and transmission. These findings provide new insights into P. vivax transmission dynamics and population structure in these border areas of the GMS. Coordinated and integrated control efforts on both sides of international borders are essential to reach the goal of regional malaria elimination.


Assuntos
Erradicação de Doenças , Variação Genética , Desequilíbrio de Ligação , Malária Vivax/prevenção & controle , Plasmodium vivax/fisiologia , China/epidemiologia , Genótipo , Humanos , Incidência , Malária Vivax/epidemiologia , Repetições de Microssatélites , Plasmodium vivax/genética , Dinâmica Populacional , Tailândia/epidemiologia
11.
Malar J ; 19(1): 108, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32131841

RESUMO

BACKGROUND: Ethiopia has set a goal for malaria elimination by 2030. Low parasite density infections may go undetected by conventional diagnostic methods (microscopy and rapid diagnostic tests) and their contribution to malaria transmission varies by transmission settings. This study quantified the burden of subpatent infections from samples collected from three regions of northwest Ethiopia. METHODS: Sub-samples of dried blood spots from the Ethiopian Malaria Indicator Survey 2015 (EMIS-2015) were tested and compared using microscopy, rapid diagnostic tests (RDTs), and nested polymerase chain reaction (nPCR) to determine the prevalence of subpatent infection. Paired seroprevalence results previously reported along with gender, age, and elevation of residence were explored as risk factors for Plasmodium infection. RESULTS: Of the 2608 samples collected, the highest positive rate for Plasmodium infection was found with nPCR 3.3% (95% CI 2.7-4.1) compared with RDT 2.8% (95% CI 2.2-3.5) and microscopy 1.2% (95% CI 0.8-1.7). Of the nPCR positive cases, Plasmodium falciparum accounted for 3.1% (95% CI 2.5-3.8), Plasmodium vivax 0.4% (95% CI 0.2-0.7), mixed P. falciparum and P. vivax 0.1% (95% CI 0.0-0.4), and mixed P. falciparum and Plasmodium malariae 0.1% (95% CI 0.0-0.3). nPCR detected an additional 30 samples that had not been detected by conventional methods. The majority of the nPCR positive cases (61% (53/87)) were from the Benishangul-Gumuz Region. Malaria seropositivity had significant association with nPCR positivity [adjusted OR 10.0 (95% CI 3.2-29.4), P < 0.001]. CONCLUSION: Using nPCR the detection rate of malaria parasites increased by nearly threefold over rates based on microscopy in samples collected during a national cross-sectional survey in 2015 in Ethiopia. Such subpatent infections might contribute to malaria transmission. In addition to strengthening routine surveillance systems, malaria programmes may need to consider low-density, subpatent infections in order to accelerate malaria elimination efforts.


Assuntos
Erradicação de Doenças/métodos , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Estudos Transversais , Teste em Amostras de Sangue Seco , Etiópia/epidemiologia , Feminino , Humanos , Malária Falciparum/diagnóstico , Malária Falciparum/prevenção & controle , Malária Vivax/diagnóstico , Malária Vivax/prevenção & controle , Masculino , Pessoa de Meia-Idade , Plasmodium falciparum , Plasmodium vivax , Prevalência , Estudos Soroepidemiológicos , Adulto Jovem
12.
PLoS Pathog ; 16(2): e1008258, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32078643

RESUMO

The absence of the Duffy protein at the surface of erythrocytes was considered for decades to confer full protection against Plasmodium vivax as this blood group is the receptor for the key parasite ligand P. vivax Duffy binding protein (PvDBP). However, it is now clear that the parasite is able to break through this protection and induce clinical malaria in Duffy-negative people, although the underlying mechanisms are still not understood. Here, we briefly review the evidence of Duffy-negative infections by P. vivax and summarize the current hypothesis at the basis of this invasion process. We discuss those in the perspective of malaria-elimination challenges, notably in African countries.


Assuntos
Antígenos de Protozoários/metabolismo , Sistema do Grupo Sanguíneo Duffy/metabolismo , Malária Vivax/metabolismo , Plasmodium vivax , Proteínas de Protozoários/metabolismo , Receptores de Superfície Celular/metabolismo , África , Humanos , Malária Vivax/prevenção & controle , Plasmodium vivax/metabolismo , Plasmodium vivax/patogenicidade
13.
Infect Dis Health ; 25(1): 60-62, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31481333

RESUMO

Malaria is an acute febrile disease due to Plasmodium species widely distributed in tropical areas of the world and it is a leading cause of death in developing countries. In 2018, 62.141 confirmed cases of malaria were reported in Colombia with P. vivax and Plasmodium falciparum being the causal species. Vectorial transmission is the most common way of acquiring the infection, however it can also occur by blood transfusion, transplacental route and percutaneous exposure. We describe a case of P. vivax infection by needle stick injury in a laboratory technician in Bogotá, Colombia.


Assuntos
Exposição Ambiental , Malária Vivax/epidemiologia , Malária Vivax/transmissão , Plasmodium vivax , Pele/parasitologia , Adulto , Surtos de Doenças , Feminino , Humanos , Malária Vivax/parasitologia , Malária Vivax/prevenção & controle , Carga Parasitária , Profilaxia Pós-Exposição
14.
Immunol Rev ; 293(1): 190-215, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31840844

RESUMO

The efficient spread of malaria from infected humans to mosquitoes is a major challenge for malaria elimination initiatives. Gametocytes are the only Plasmodium life stage infectious to mosquitoes. Here, we summarize evidence for naturally acquired anti-gametocyte immunity and the current state of transmission blocking vaccines (TBV). Although gametocytes are intra-erythrocytic when present in infected humans, developing Plasmodium falciparum gametocytes may express proteins on the surface of red blood cells that elicit immune responses in naturally exposed individuals. This immune response may reduce the burden of circulating gametocytes. For both P. falciparum and Plasmodium vivax, there is a solid evidence that antibodies against antigens present on the gametocyte surface, when co-ingested with gametocytes, can influence transmission to mosquitoes. Transmission reducing immunity, reducing the burden of infection in mosquitoes, is a well-acknowledged but poorly quantified phenomenon that forms the basis for the development of TBV. Transmission enhancing immunity, increasing the likelihood or intensity of transmission to mosquitoes, is more speculative in nature but is convincingly demonstrated for P. vivax. With the increased interest in malaria elimination, TBV and monoclonal antibodies have moved to the center stage of malaria vaccine development. Methodologies to prioritize and evaluate products are urgently needed.


Assuntos
Interações Hospedeiro-Parasita/imunologia , Malária Falciparum/imunologia , Malária Falciparum/parasitologia , Malária Vivax/imunologia , Malária Vivax/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/imunologia , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/imunologia , Anticorpos Bloqueadores/imunologia , Anticorpos Antiprotozoários/imunologia , Humanos , Imunidade , Imunomodulação , Estágios do Ciclo de Vida , Vacinas Antimaláricas/imunologia , Malária Falciparum/prevenção & controle , Malária Falciparum/transmissão , Malária Vivax/prevenção & controle , Malária Vivax/transmissão
15.
Ter Arkh ; 92(11): 77-81, 2020 Dec 26.
Artigo em Russo | MEDLINE | ID: mdl-33720609

RESUMO

Actually one of the main tasks of health workers in the field of the tropical diseases prevention (malaria) is early detection of malaria imported cases and efficacious treatment. In order to prevent the re-establishment of local malaria transmission by Anopheles mosquitoes from imported malaria cases, and fatal cases of disease there is develop and implement the Case Management Protocol of malaria diagnosis and treatment (2014, 2019) based on long-term experience of epidemiologists and clinicians, taking into account recommendations of WHO (2013, 2015). In this article the main principles of diagnosis and treatment of different malaria species Plasmodium falciparumand Plasmodium vivax-malaria, prophylaxis measures of autochthonous cases from imported cases of the word endemic region are discussed.


Assuntos
Anopheles , Malária Vivax , Malária , Animais , Pessoal de Saúde , Humanos , Malária/diagnóstico , Malária/tratamento farmacológico , Malária/epidemiologia , Malária Vivax/diagnóstico , Malária Vivax/epidemiologia , Malária Vivax/prevenção & controle , Federação Russa/epidemiologia , Viagem
16.
Turkiye Parazitol Derg ; 43(4): 170-174, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31865651

RESUMO

Objective: Malaria is an infection disease caused by plamodium parasite. Sporadic cases have not been observed since 2011, but imported cases still present owing to travel. In this study, we aimed to evaluate labotauary and clinical findings patients with malaria who were hospitalized and treated in our hospital. Methods: Between January 2012-November 2018, a total of 31 adult patients was evaluated retrospectively, in terms of their epidemiological, physical examination and laboratory findings, complaints, countries they traveled to, prophylaxis and treatment that they received. Data of the patients were taken from the hospital's database. Results: A total of 31 cases were diagnosed as having malaria. The causative microorganism was P. falciparum in 54.83% (17/31) of the patients, P. vivax in 32.25% (10/31), and P. falciparum-P. vivax co-infection in 12.9% (4/31) of the patients. Co-infections were excluded from the study. None of the cases had used prophylactic drugs for prevention of malaria. All of the cases suffered from chills with fever. The most frequently encountered pathologic laboratory findings were thrombocytopenia and leucopenia. Antibiotics had been initiated in 51.85% (14/27) of the patients with non-specific diagnoses. Rapid antigen test was used in 8148% (22/27) of cases. None of cases needed intensive care. Conclusion: It is important to inform persons who plan to visit malaria endemic areas about malaria and to make them take appropriate prophylaxis against malaria. Although P. falciparum which has a high mortality rate may be considered in the first plan, P. vivax, treatment of which is different due to risk of relapse, should not be overlooked.


Assuntos
Malária Falciparum , Malária Vivax , Viagem , Adolescente , Adulto , Antimaláricos/uso terapêutico , Calafrios , Doenças Endêmicas/prevenção & controle , Feminino , Febre , Humanos , Leucopenia/diagnóstico , Malária Falciparum/tratamento farmacológico , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Malária Vivax/tratamento farmacológico , Malária Vivax/epidemiologia , Malária Vivax/prevenção & controle , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Trombocitopenia/diagnóstico , Adulto Jovem
17.
Malar J ; 18(1): 428, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852499

RESUMO

BACKGROUND: Sample size calculations for cluster randomized trials are a recognized methodological challenge for malaria research in pre-elimination settings. Positively correlated responses from the participants in the same cluster are a key feature in the estimated sample size required for a cluster randomized trial. The degree of correlation is measured by the intracluster correlation coefficient (ICC) where a higher coefficient suggests a closer correlation hence less heterogeneity within clusters but more heterogeneity between clusters. METHODS: Data on uPCR-detected Plasmodium falciparum and Plasmodium vivax infections from a recent cluster randomized trial which aimed at interrupting malaria transmission through mass drug administrations were used to calculate the ICCs for prevalence and incidence of Plasmodium infections. The trial was conducted in four countries in the Greater Mekong Subregion, Laos, Myanmar, Vietnam and Cambodia. Exact and simulation approaches were used to estimate ICC values for both the prevalence and the incidence of parasitaemia. In addition, the latent variable approach to estimate ICCs for the prevalence was utilized. RESULTS: The ICCs for prevalence ranged between 0.001 and 0.082 for all countries. The ICC from the combined 16 villages in the Greater Mekong Subregion were 0.26 and 0.21 for P. falciparum and P. vivax respectively. The ICCs for incidence of parasitaemia ranged between 0.002 and 0.075 for Myanmar, Cambodia and Vietnam. There were very high ICCs for incidence in the range of 0.701 to 0.806 in Laos during follow-up. CONCLUSION: ICC estimates can help researchers when designing malaria cluster randomized trials. A high variability in ICCs and hence sample size requirements between study sites was observed. Realistic sample size estimates for cluster randomized malaria trials in the Greater Mekong Subregion have to assume high between cluster heterogeneity and ICCs. This work focused on uPCR-detected infections; there remains a need to develop more ICC references for trials designed around prevalence and incidence of clinical outcomes. Adequately powered trials are critical to estimate the benefit of interventions to malaria in a reliable and reproducible fashion. TRIAL REGISTRATION: ClinicalTrials.govNCT01872702. Registered 7 June 2013. Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT01872702.


Assuntos
Antimaláricos/administração & dosagem , Malária Falciparum/prevenção & controle , Malária Vivax/prevenção & controle , Administração Massiva de Medicamentos/estatística & dados numéricos , Camboja/epidemiologia , Humanos , Incidência , Laos/epidemiologia , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Mianmar/epidemiologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Prevalência , Ensaios Clínicos Controlados Aleatórios como Assunto , Vietnã/epidemiologia
18.
Malar J ; 18(1): 425, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842894

RESUMO

BACKGROUND: Identifying highly immunogenic blood stage antigens which can work as target for naturally acquired antibodies in different eco-epidemiological settings is an important step for designing malaria vaccine. Blood stage proteins of Plasmodium vivax, apical membrane antigen-1 (PvAMA-1) and 19 kDa fragment of merozoite surface protein (PvMSP-119) are such promising vaccine candidate antigens. This study determined the naturally-acquired antibody response to PvAMA-1 and PvMSP-119 antigens in individuals living in three geographically diverse malaria endemic regions of India. METHODS: A total of 234 blood samples were collected from individuals living in three different eco-epidemiological settings, Chennai, Nadiad, and Rourkela of India. Indirect ELISA was performed to measure human IgG antibodies against recombinant PvAMA-1 and PvMSP-119 antigens. The difference in seroprevalence and factors associated with antibody responses at each site was statistically analysed. RESULTS: The overall seroprevalence was 40.6% for PvAMA-1 and 62.4% for PvMSP-119. Seroprevalence to PvAMA-1 was higher in Chennai (47%) followed by Nadiad (46.7%) and Rourkela (27.6%). For PvMSP-119, seroprevalence was higher in Chennai (80.3%) as compared to Nadiad (53.3%) and Rourkela (57.9%). Seroprevalence for both the antigens were found to be higher in Chennai where P. vivax is the dominant malaria species. In addition, heterogeneous antibody response was observed for PvAMA-1 and PvMSP-119 antigens at each of the study sites. Two factors, age and malaria positivity were significantly associated with seropositivity for both the antigens PvAMA-1 and PvMSP-119. CONCLUSION: These data suggest that natural acquired antibody response is higher for PvMSP-119 antigen as compared to PvAMA-1 antigen in individuals living in three geographically diverse malaria endemic regions in India. PvMSP-119 appears to be highly immunogenic in Indian population and has great potential as a malaria vaccine candidate. The differences in immune response against vaccine candidate antigens in different endemic settings should be taken into account for development of asexual stage based P. vivax malaria vaccine, which in turn can enhance malaria control efforts.


Assuntos
Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Malária Vivax/imunologia , Proteínas de Membrana/imunologia , Proteína 1 de Superfície de Merozoito/imunologia , Proteínas de Protozoários/imunologia , Adolescente , Adulto , Formação de Anticorpos , Antígenos de Protozoários/sangue , Criança , Doenças Endêmicas , Ensaio de Imunoadsorção Enzimática , Feminino , Geografia , Humanos , Imunoglobulina G/sangue , Índia , Malária Vivax/prevenção & controle , Masculino , Proteínas de Membrana/sangue , Proteína 1 de Superfície de Merozoito/sangue , Pessoa de Meia-Idade , Plasmodium vivax , Proteínas de Protozoários/sangue , Estudos Soroepidemiológicos , Adulto Jovem
19.
Malar J ; 18(1): 439, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31864358

RESUMO

BACKGROUND: A total dose of chloroquine of 25 mg/kg is recommended by the World Health Organization (WHO) to treat malaria by Plasmodium vivax. In several endemic areas, including the Brazilian Amazon basin, anti-malarial drugs are dispensed in small plastic bags at a dosing regimen based on age. This practice can lead to suboptimal dosing of the drug, which can impact treatment outcomes. The aim of the present study was to estimate the extent of sub-dosing of chloroquine in children and adolescents with vivax malaria using an age-based dose regimen, in addition to investigating the influence of age on the plasma concentrations of chloroquine and desethylchloroquine. METHODS: A study of cases was conducted with male patients with a confirmed infection by P. vivax, ages 2 to 14 years, using a combined regimen of chloroquine and primaquine. Height, weight and body surface area were determined at admission on the study. The total dose of chloroquine administered was estimated based on the weight and on the body surface area of the study patients. Chloroquine and desethylchloroquine were measured on Day 7 in each patient included in the study by a high-performance liquid chromatographic method with fluorescence detection. RESULTS: A total of 81 patients were enrolled and completed the study. The median age was 9 years (2-14 years). All patients presented negative blood smears at 42 days follow-up. The total dose of chloroquine ranged from 13.1 to 38.1 mg/kg. The percentage of patients with a total dose of the drug below 25 mg/kg ranged from 29.4 to 63.6%. The total dose of chloroquine administered based on BSA ranged from 387 to 1079 mg/m2, increasing with age. Plasma chloroquine concentrations ranged from 107 to 420 ng/ml, increasing with age. For desethylchloroquine, the plasma concentrations ranged from 167 to 390 ng/ml, with similar values among age-groups. CONCLUSION: The data demonstrated the widespread exposure of children and adolescents to suboptimal doses of chloroquine in the endemic area investigated.


Assuntos
Antimaláricos/administração & dosagem , Cloroquina/administração & dosagem , Malária Vivax/prevenção & controle , Adolescente , Brasil , Criança , Pré-Escolar , Cloroquina/análogos & derivados , Cloroquina/sangue , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Humanos , Masculino , Plasmodium vivax/efeitos dos fármacos
20.
PLoS One ; 14(9): e0222986, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31568489

RESUMO

INTRODUCTION: Understanding the spatiotemporal clustering of malaria transmission would help target interventions in settings of low malaria transmission. The aim of this study was to assess whether malaria infections were clustered in areas with long-lasting insecticidal nets (LLINs) alone, indoor residual spraying (IRS) alone, or a combination of LLINs and IRS interventions, and to determine the risk factors for the observed malaria clustering in southern-central Ethiopia. METHODS: A cohort of 34,548 individuals residing in 6,071 households was followed for 121 weeks, from October 2014 to January 2017. Both active and passive case detection mechanisms were used to identify clinical malaria episodes, and there were no geographic heterogeneity in data collection methods. Using SaTScan software v 9.4.4, a discrete Poisson model was used to identify high rates of spatial, temporal, and spatiotemporal malaria clustering. A multilevel logistic regression model was fitted to identify predictors of spatial malaria clustering. RESULTS: The overall incidence of malaria was 16.5 per 1,000 person-year observations. Spatial, temporal, and spatiotemporal clustering of malaria was detected in all types of malaria infection (P. falciparum, P. vivax, or mixed). Spatial clustering was identified in all study arms: for LLIN + IRS arm, a most likely cluster size of 169 cases in 305 households [relative risk (RR) = 4.54, P<0.001]; for LLIN alone arm a cluster size of 88 cases in 103 households (RR = 5.58, P<0.001); for IRS alone arm a cluster size of 58 cases in 50 households (RR = 7.15, P<0.001), and for control arm a cluster size of 147 cases in 377 households (RR = 2.78, P<0.001). Living 1 km closer to potential vector breeding sites increased the odds of being in spatial clusters by 41.32 fold (adjusted OR = 41.32, 95% CI = 3.79-138.89). CONCLUSIONS: The risk of malaria infection varied significantly between kebeles, within kebeles, and even among households in areas targeted for different types of malaria control interventions in low malaria transmission setting. The results of this study can be used in planning and implementation of malaria control strategies at micro-geographic scale. TRIAL REGISTRATION: PACT R2014 11000 882128 (8 September 2014).


Assuntos
Mosquiteiros Tratados com Inseticida/estatística & dados numéricos , Malária Falciparum/epidemiologia , Malária Vivax/epidemiologia , Controle de Mosquitos/estatística & dados numéricos , Análise Espaço-Temporal , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Análise por Conglomerados , Estudos de Coortes , Culicidae/parasitologia , Etiópia/epidemiologia , Características da Família , Feminino , Humanos , Incidência , Lactente , Inseticidas , Modelos Logísticos , Malária Falciparum/parasitologia , Malária Falciparum/prevenção & controle , Malária Falciparum/transmissão , Malária Vivax/parasitologia , Malária Vivax/prevenção & controle , Malária Vivax/transmissão , Masculino , Controle de Mosquitos/métodos , Plasmodium falciparum/fisiologia , Plasmodium vivax/fisiologia , Fatores de Risco
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