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1.
Nat Commun ; 12(1): 2635, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976132

RESUMO

The scale-up of malaria control efforts has led to marked reductions in malaria burden over the past twenty years, but progress has slowed. Implementation of indoor residual spraying (IRS) of insecticide, a proven vector control intervention, has been limited and difficult to sustain partly because questions remain on its added impact over widely accepted interventions such as bed nets. Using data from 14 enhanced surveillance health facilities in Uganda, a country with high bed net coverage yet high malaria burden, we estimate the impact of starting and stopping IRS on changes in malaria incidence. We show that stopping IRS was associated with a 5-fold increase in malaria incidence within 10 months, but reinstating IRS was associated with an over 5-fold decrease within 8 months. In areas where IRS was initiated and sustained, malaria incidence dropped by 85% after year 4. IRS could play a critical role in achieving global malaria targets, particularly in areas where progress has stalled.


Assuntos
Anopheles/parasitologia , Inseticidas , Malária/epidemiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/parasitologia , Animais , Monitoramento Epidemiológico , Geografia , Humanos , Incidência , Malária/parasitologia , Malária/prevenção & controle , Malária/transmissão , Uganda/epidemiologia
2.
Nat Commun ; 12(1): 2443, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33903595

RESUMO

Plasmodium falciparum gametocyte kinetics and infectivity may differ between chronic and incident infections. In the current study, we assess parasite kinetics and infectivity to mosquitoes among children (aged 5-10 years) from Burkina Faso with (a) incident infections following parasite clearance (n = 48) and (b) chronic asymptomatic infections (n = 60). In the incident infection cohort, 92% (44/48) of children develop symptoms within 35 days, compared to 23% (14/60) in the chronic cohort. All individuals with chronic infection carried gametocytes or developed them during follow-up, whereas only 35% (17/48) in the incident cohort produce gametocytes before becoming symptomatic and receiving treatment. Parasite multiplication rate (PMR) and the relative abundance of ap2-g and gexp-5 transcripts are positively associated with gametocyte production. Antibody responses are higher and PMR lower in chronic infections. The presence of symptoms and sexual stage immune responses are associated with reductions in gametocyte infectivity to mosquitoes. We observe that most incident infections require treatment before the density of mature gametocytes is sufficient to infect mosquitoes. In contrast, chronic, asymptomatic infections represent a significant source of mosquito infections. Our observations support the notion that malaria transmission reduction may be expedited by enhanced case management, involving both symptom-screening and infection detection.


Assuntos
Anopheles/crescimento & desenvolvimento , Insetos Vetores/crescimento & desenvolvimento , Malária Falciparum/transmissão , Plasmodium falciparum/crescimento & desenvolvimento , Animais , Anopheles/parasitologia , Burkina Faso/epidemiologia , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Incidência , Insetos Vetores/parasitologia , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Masculino , Plasmodium falciparum/fisiologia , Densidade Demográfica , Fatores de Tempo
3.
J Med Entomol ; 58(2): 983-989, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33710313

RESUMO

Madagascar is a hotspot of biodiversity, but poverty and population growth provoke a high risk of conflict between food security and biodiversity conservation in this tropical country. Numerous vector-borne diseases, including viral infections, affect public health in Madagascar and a continuous expansion of anthropogenically used areas intensifies contact on the human-wildlife interface. However, data on human and animal pathogens in potential insect vectors is limited. Therefore, we conducted a parasitological and virological survey of 785 adult female mosquitoes between March and May 2016 at the Ankarafantsika National Park in northwestern Madagascar. Screening included Alpha-, Phlebo-, and Flaviviridae and the recently described filarial nematode species, Lemurfilaria lemuris. The predominant mosquito genus was Culex (91%), followed by Mansonia (4.1%), Anopheles (3.4%), and Aedes (0.9%). Viral screening revealed no arboviruses, but an insect-specific flavivirus in two Culex sitiens pools. No pools screened positive for the lemur-specific filarial nematode L. lemuris.


Assuntos
Flavivirus/isolamento & purificação , Mosquitos Vetores , Nematoides/isolamento & purificação , Aedes/parasitologia , Aedes/virologia , Animais , Anopheles/parasitologia , Anopheles/virologia , Biodiversidade , Culex/parasitologia , Culex/virologia , Reservatórios de Doenças , Filariose/transmissão , Lemur , Madagáscar , Mosquitos Vetores/parasitologia , Mosquitos Vetores/virologia , Viroses/transmissão
4.
Nat Commun ; 12(1): 909, 2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568678

RESUMO

Malaria control may be enhanced by targeting reservoirs of Plasmodium falciparum transmission. One putative reservoir is asymptomatic malaria infections and the scale of their contribution to transmission in natural settings is not known. We assess the contribution of asymptomatic malaria to onward transmission using a 14-month longitudinal cohort of 239 participants in a high transmission site in Western Kenya. We identify P. falciparum in asymptomatically- and symptomatically-infected participants and naturally-fed mosquitoes from their households, genotype all parasites using deep sequencing of the parasite genes pfama1 and pfcsp, and use haplotypes to infer participant-to-mosquito transmission through a probabilistic model. In 1,242 infections (1,039 in people and 203 in mosquitoes), we observe 229 (pfcsp) and 348 (pfama1) unique parasite haplotypes. Using these to link human and mosquito infections, compared with symptomatic infections, asymptomatic infections more than double the odds of transmission to a mosquito among people with both infection types (Odds Ratio: 2.56; 95% Confidence Interval (CI): 1.36-4.81) and among all participants (OR 2.66; 95% CI: 2.05-3.47). Overall, 94.6% (95% CI: 93.1-95.8%) of mosquito infections likely resulted from asymptomatic infections. In high transmission areas, asymptomatic infections are the major contributor to mosquito infections and may be targeted as a component of transmission reduction.


Assuntos
Anopheles/parasitologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Mosquitos Vetores/parasitologia , Plasmodium falciparum/genética , Adulto , Animais , Anopheles/fisiologia , Infecções Assintomáticas/epidemiologia , Estudos de Coortes , Feminino , Genótipo , Humanos , Quênia/epidemiologia , Estudos Longitudinais , Malária Falciparum/epidemiologia , Masculino , Mosquitos Vetores/fisiologia , Plasmodium falciparum/classificação , Plasmodium falciparum/isolamento & purificação
5.
Exp Parasitol ; 222: 108064, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33421382

RESUMO

Experimental studies for understanding the relationship between Plasmodium vivax and its vector hosts are difficult, because of to the lack of a long-term, in vitro continuous culture system unavailability of infected blood samples, seasonality of the disease, and the concentration of most cases in remote areas. This study evaluates the duration of the infectivity of P. vivax to Anopheles aquasalis after collecting blood from malaria-infected patients. Blood was collected from patients and stored at 4 °C and 37 °C. Every day, for 4 days, the blood was fed to An. aquasalis adult females, and a Giemsa-stained thick blood smear was mounted to account for sexual (gametocytes) and asexual (trophozoites and schizonts) stages and calculate parasitemia. Oocysts in the midgut of the mosquitoes were counted on the seventh day after feeding. Kruskal-Wallis test was used to compare the mean number of oocysts (MO) and the parasite density (PD) in each storage condition and post-infection time-points. The Mann-Whitney test was used to compare the number of oocysts for each day between temperatures. The results show that P. vivax stored at 4 °C and at 37 °C has its infectivity to An. aquasalis preserved for 2 days and 3 days, respectively. Infection rate (IR), PD and MO were higher on the day of blood collection and decreased gradually over time. The parasite density (number of parasites/µL) diminished faster at 4 °C than at 37 °C. In this study, a preservation protocol is shown for long-lasting infectivity of P. vivax in a blood sample taken from malaria-infected patients. These results show that infectivity of P. vivax stored at 4 °C and at 37 °C to An. aquasalis persist until 3 days after blood collection, but parasite density, infection rate, and mean of oocysts decreased 24h after blood collection. Since the malaria cases are increasingly far from the urban areas these results indicate that is possible, losing some infectivity, to realize experimental infections several dozen hours after the blood collection. However, it is necessary to improve the procedures for preserving P. vivax gametocytes for mosquito infection in the laboratory.


Assuntos
Anopheles/parasitologia , Malária Vivax/parasitologia , Mosquitos Vetores/parasitologia , Plasmodium vivax/fisiologia , Adulto , Idoso , Animais , Brasil , Feminino , Humanos , Malária Vivax/sangue , Malária Vivax/transmissão , Masculino , Pessoa de Meia-Idade , Plasmodium vivax/patogenicidade , População Rural , Temperatura , Fatores de Tempo , Adulto Jovem
6.
PLoS Genet ; 17(1): e1009253, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33476334

RESUMO

Vector population control using insecticides is a key element of current strategies to prevent malaria transmission in Africa. The introduction of effective insecticides, such as the organophosphate pirimiphos-methyl, is essential to overcome the recurrent emergence of resistance driven by the highly diverse Anopheles genomes. Here, we use a population genomic approach to investigate the basis of pirimiphos-methyl resistance in the major malaria vectors Anopheles gambiae and A. coluzzii. A combination of copy number variation and a single non-synonymous substitution in the acetylcholinesterase gene, Ace1, provides the key resistance diagnostic in an A. coluzzii population from Côte d'Ivoire that we used for sequence-based association mapping, with replication in other West African populations. The Ace1 substitution and duplications occur on a unique resistance haplotype that evolved in A. gambiae and introgressed into A. coluzzii, and is now common in West Africa primarily due to selection imposed by other organophosphate or carbamate insecticides. Our findings highlight the predictive value of this complex resistance haplotype for phenotypic resistance and clarify its evolutionary history, providing tools to for molecular surveillance of the current and future effectiveness of pirimiphos-methyl based interventions.


Assuntos
Acetilcolinesterase/genética , Resistência a Inseticidas/genética , Malária/genética , Malária/transmissão , África Ocidental , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Anopheles/parasitologia , Variações do Número de Cópias de DNA/genética , Genes Duplicados/genética , Introgressão Genética/genética , Humanos , Inseticidas/efeitos adversos , Malária/parasitologia , Malária/prevenção & controle , Mosquitos Vetores/genética , Compostos Organotiofosforados/efeitos adversos , Compostos Organotiofosforados/farmacologia
7.
Acta Trop ; 216: 105820, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33400915

RESUMO

Malaria vector control in Mali relies heavily on the use of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) in selected districts. As part of strengthening vector control strategies in Koulikoro district, the National Malaria Control Programme (NMCP) through the support from the US President's Malaria Initiative (PMI) has strategically driven the implementation of IRS, with the LLINs coverage also rising from 93.3% and 98.2%. Due to the increased reports of vector resistance to both pyrethroid and carbamates, there was a campaign for the use of pirimiphos-methyl, an organophosphate at Koulikoro between 2015 and 2016. In this study, the effect of IRS on malaria transmission was assessed, by comparing some key entomological indices between Koulikoro, where IRS was implemented and its neighboring district, Banamba that has never received IRS as vector control intervention. The study was conducted in two villages of each district (Koulikoro and Banamba). Pyrethrum spray catches and entry window trapping were used to collect mosquitoes on a monthly basis. WHO tube tests were carried out to assess mosquito susceptibility to insecticides. Mosquitoes were identified to species level by PCR and their infection to P. falciparum was detected by Enzyme Linked-Immuno-Sorbent Assay (ELISA). Of the 527 specimens identified, An. coluzzii was the most frequent species (95%) followed by An. gambiae (4%) and An. arabiensis (1%). Its density was rainfall dependent in the no-IRS area, and almost independent in the IRS area. The infection rate (IR) in the no-IRS area was 0.96%, while it was null in the IRS area. In the no-IRS area, the entomological inoculation rate (EIR) was 0.21 infective bites /person month with a peak in September. High resistance to pyrethroids and carbamates and susceptibility to organophosphates was observed at all sites. The introduction of pirimiphos-methyl based IRS for vector control resulted in a significant decrease in malaria transmission. An. gambiae s.l., the main malaria vector in the area, was resistant to pyrethroids and carbamates but remained susceptible to the organophosphate pirimiphos-methyl.


Assuntos
Anopheles/efeitos dos fármacos , Anopheles/parasitologia , Carbamatos/farmacologia , Malária/prevenção & controle , Malária/transmissão , Compostos Organotiofosforados/farmacologia , Piretrinas/farmacologia , Animais , Anopheles/genética , Vetores de Doenças , Feminino , Humanos , Mordeduras e Picadas de Insetos/parasitologia , Resistência a Inseticidas , Inseticidas/farmacologia , Mali , Tipagem Molecular , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Reação em Cadeia da Polimerase
8.
Biochimie ; 181: 176-190, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33346039

RESUMO

The malaria parasite has an extraordinary ability to evade the immune system due to which the development of a malaria vaccine is a challenging task. Extensive research on malarial infection in the human host particularly during the liver stage has resulted in the discovery of potential candidate vaccines including RTS,S/AS01 and R21. However, complete elimination of malaria would require a holistic multi-component approach. In line with this, under the World Health Organization's PATH Malaria Vaccine Initiative (MVI), the research focus has shifted towards the sexual stages of malaria in the mosquito host. Last two decades of scientific research obtained seminal information regarding the sexual/mosquito stages of the malaria. This updated and comprehensive review would provide the basis for consolidated understanding of cellular, biochemical, molecular and immunological aspects of parasite transmission right from the sexual stage commitment in the human host to the sporozoite delivery back into subsequent vertebrate host by the female Anopheles mosquito.


Assuntos
Anopheles/parasitologia , Vacinas Antimaláricas/uso terapêutico , Malária Falciparum , Plasmodium falciparum/metabolismo , Animais , Feminino , Humanos , Malária Falciparum/metabolismo , Malária Falciparum/prevenção & controle , Masculino
9.
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
10.
PLoS One ; 15(12): e0242510, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33382730

RESUMO

The specific immune response to the Anopheles salivary peptide could be a pertinent and complementary tool to assess the risk of malaria transmission and the effectiveness of vector control strategies. This study aimed to obtain first reliable data on the current state of the Anopheles gSG6-P1 biomarker for assess the level of exposure to Anopheles bites in high malaria endemic areas in Cameroon. Blood smears were collected from people living in the neighborhoods of Youpwe (suburban area, continental) and Manoka (rural area, Island), both areas in the coastal region of Cameroon. Malaria infection was determined using thick blood smear microscopy, whereas the level of specific IgG response to gSG-P1 peptide was assessed by enzyme-linked immunosorbent assay from the dried blood spots. Of 266 (153 from Youpwe, 113 from Manoka) malaria endemic residents (mean age: 22.8±19.8 years, age range: 6 months-94 years, male/female sex ratio: 1/1.2, with Manoka mean age: 23.71±20.53, male/female sex ratio:1/1.13 and Youpwe mean age: 22.12±19.22, male/female sex ratio 1/0.67) randomly included in the study, Plasmodium infection prevalence was significantly higher in Manoka than in Youpwe (64.6% vs 12,4%, p = 0.0001). The anti-gSG6-P1 IgG response showed a high inter-individual heterogeneity and was significantly higher among individuals from Manoka than those from Youpwe (p = 0.023). Malaria infected individuals presented a higher anti-gSG6-P1 IgG antibody response than non-infected (p = 0.0004). No significant difference in the level of specific IgG response to gSG-P1 was observed according to long lasting insecticidal nets use. Taken together, the data revealed that human IgG antibody response to Anopheles gSG-P1 salivary peptide could be also used to assess human exposure to malaria vectors in Central African region. This finding strengthens the relevance of this candidate biomarker to be used for measuring human exposure to malaria vectors worldwide.


Assuntos
Anopheles/parasitologia , Imunoglobulina G/sangue , Proteínas de Insetos/imunologia , Malária Falciparum/epidemiologia , Mosquitos Vetores/parasitologia , Plasmodium falciparum/imunologia , Proteínas e Peptídeos Salivares/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Camarões/epidemiologia , Criança , Pré-Escolar , Teste em Amostras de Sangue Seco , Doenças Endêmicas , Feminino , Humanos , Imunoglobulina G/biossíntese , Lactente , Proteínas de Insetos/sangue , Malária Falciparum/diagnóstico , Malária Falciparum/imunologia , Malária Falciparum/parasitologia , Masculino , Pessoa de Meia-Idade , Prevalência , População Rural , Proteínas e Peptídeos Salivares/sangue , População Urbana
11.
PLoS Pathog ; 16(12): e1008908, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33347501

RESUMO

Anopheles mosquitoes have transmitted Plasmodium parasites for millions of years, yet it remains unclear whether they suffer fitness costs to infection. Here we report that the fecundity of virgin and mated females of two important vectors-Anopheles gambiae and Anopheles stephensi-is not affected by infection with Plasmodium falciparum, demonstrating that these human malaria parasites do not inflict this reproductive cost on their natural mosquito hosts. Additionally, parasite development is not impacted by mating status. However, in field studies using different P. falciparum isolates in Anopheles coluzzii, we find that Mating-Induced Stimulator of Oogenesis (MISO), a female reproductive gene strongly induced after mating by the sexual transfer of the steroid hormone 20-hydroxyecdysone (20E), protects females from incurring fecundity costs to infection. MISO-silenced females produce fewer eggs as they become increasingly infected with P. falciparum, while parasite development is not impacted by this gene silencing. Interestingly, previous work had shown that sexual transfer of 20E has specifically evolved in Cellia species of the Anopheles genus, driving the co-adaptation of MISO. Our data therefore suggest that evolution of male-female sexual interactions may have promoted Anopheles tolerance to P. falciparum infection in the Cellia subgenus, which comprises the most important malaria vectors.


Assuntos
Anopheles/genética , Interações Hospedeiro-Parasita/genética , Plasmodium falciparum/genética , Animais , Anopheles/parasitologia , Ecdisterona/genética , Ecdisterona/metabolismo , Feminino , Fertilidade/genética , Expressão Gênica , Hormônios/fisiologia , Malária/parasitologia , Malária Falciparum/parasitologia , Masculino , Mosquitos Vetores/genética , Oogênese , Plasmodium falciparum/patogenicidade , Reprodução/fisiologia
12.
PLoS Pathog ; 16(12): e1009131, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33382824

RESUMO

Many mosquito species, including the major malaria vector Anopheles gambiae, naturally undergo multiple reproductive cycles of blood feeding, egg development and egg laying in their lifespan. Such complex mosquito behavior is regularly overlooked when mosquitoes are experimentally infected with malaria parasites, limiting our ability to accurately describe potential effects on transmission. Here, we examine how Plasmodium falciparum development and transmission potential is impacted when infected mosquitoes feed an additional time. We measured P. falciparum oocyst size and performed sporozoite time course analyses to determine the parasite's extrinsic incubation period (EIP), i.e. the time required by parasites to reach infectious sporozoite stages, in An. gambiae females blood fed either once or twice. An additional blood feed at 3 days post infection drastically accelerates oocyst growth rates, causing earlier sporozoite accumulation in the salivary glands, thereby shortening the EIP (reduction of 2.3 ± 0.4 days). Moreover, parasite growth is further accelerated in transgenic mosquitoes with reduced reproductive capacity, which mimic genetic modifications currently proposed in population suppression gene drives. We incorporate our shortened EIP values into a measure of transmission potential, the basic reproduction number R0, and find the average R0 is higher (range: 10.1%-12.1% increase) across sub-Saharan Africa than when using traditional EIP measurements. These data suggest that malaria elimination may be substantially more challenging and that younger mosquitoes or those with reduced reproductive ability may provide a larger contribution to infection than currently believed. Our findings have profound implications for current and future mosquito control interventions.


Assuntos
Malária Falciparum/transmissão , Mosquitos Vetores/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Animais , Anopheles/parasitologia , Comportamento Alimentar , Feminino
13.
PLoS Negl Trop Dis ; 14(9): e0008617, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32886679

RESUMO

The zoonotic malaria parasite, Plasmodium knowlesi, is now a substantial public health problem in Malaysian Borneo. Current understanding of P. knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in one district, Kudat. These have incriminated Anopheles balabacensis as the primary vector, and suggest that human exposure to vector biting is peri-domestic as well as in forest environments. To address the limited understanding of vector ecology and human exposure risk outside of Kudat, we performed wider scale surveillance across four districts in Sabah with confirmed transmission to investigate spatial heterogeneity in vector abundance, diversity and infection rate. Entomological surveillance was carried out six months after a cross-sectional survey of P. knowlesi prevalence in humans throughout the study area; providing an opportunity to investigate associations between entomological indicators and infection. Human-landing catches were performed in peri-domestic, farm and forest sites in 11 villages (3-4 per district) and paired with estimates of human P. knowlesi exposure based on sero-prevalence. Anopheles balabacensis was present in all districts but only 6/11 villages. The mean density of An. balabacensis was relatively low, but significantly higher in farm (0.094/night) and forest (0.082/night) than peri-domestic areas (0.007/night). Only one An. balabacensis (n = 32) was infected with P. knowlesi. Plasmodium knowlesi sero-positivity in people was not associated with An. balabacensis density at the village-level however post hoc analyses indicated the study had limited power to detect a statistical association due low vector density. Wider scale sampling revealed substantial heterogeneity in vector density and distribution between villages and districts. Vector-habitat associations predicted from this larger-scale surveillance differed from those inferred from smaller-scale studies in Kudat; highlighting the importance of local ecological context. Findings highlight potential trade-offs between maximizing temporal versus spatial breadth when designing entomological surveillance; and provide baseline entomological and epidemiological data to inform future studies of entomological risk factors for human P. knowlesi infection.


Assuntos
Anopheles/parasitologia , Malária/epidemiologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Plasmodium knowlesi/isolamento & purificação , Animais , Bornéu/epidemiologia , Estudos Transversais , Fazendas , Florestas , Humanos , Malásia/epidemiologia , População Rural/estatística & dados numéricos , Soroconversão
14.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 32(4): 389-392, 2020 Aug 11.
Artigo em Chinês | MEDLINE | ID: mdl-32935514

RESUMO

OBJECTIVE: To understand the population distribution, density, seasonal fluctuation and nocturnal activity of malaria vectors in Anhui Province from 2016 to 2018, so as to provide a data support for formulating the control strategy for imported malaria during the malaria post-elimination stage. METHODS: The malaria vectors were monitored in 105 counties (cities or districts) of Anhui Province from 2016 to 2018, and the population density, seasonal fluctuation and nocturnal activity of the mosquitoes were observed using the lamp trapping and human bait trapping methods. The density of Anopheles mosquitoes was compared among different years, regions and mosquito-capturing sites. RESULTS: Anopheles mosquitoes were captured in 103 counties (cities or districts) of Anhui Province during the period from 2016 to 2018, and a total of 32 494 mosquitoes were captured using the lamp trapping method and 36 228 captured using the human bait trapping method. All captured mosquitoes were morphologically identified as Anopheles sinensis, and no An. anthropophagus was found. The density of An. sinensis peaked from June to August, and the peak nocturnal activity was found during the period between 19∶00 and 23∶00. Among all mosquito-capturing sites, the highest mosquito density was seen in the livestock and poultry sheds (H = 18.835, P < 0.05). The density of An. sinensis varied significantly in regions in 2016 and 2017 (H = 16.655 and 11.566, P < 0.01), and a low density was found in north of the Huai River. CONCLUSIONS: An. sinensis is widely distributed in Anhui Province, which is the currently predominant malaria vector in the province. During the malaria post-elimination stage, the malaria vector monitoring should be intensified and vector control interventions should be timely adopted in epidemic foci of Anhui Province to prevent the local re-transmission of overseas imported malaria.


Assuntos
Anopheles , Malária , Mosquitos Vetores , Distribuição Animal , Animais , Anopheles/parasitologia , China , Malária/parasitologia , Malária/transmissão , Mosquitos Vetores/parasitologia , Densidade Demográfica , Estações do Ano
15.
PLoS One ; 15(9): e0238134, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32936796

RESUMO

Malaria is a life-threatening disease, caused by Apicomplexan parasites of the Plasmodium genus. The Anopheles mosquito is necessary for the sexual replication of these parasites and for their transmission to vertebrate hosts, including humans. Imaging of the parasite within the insect vector has been attempted using multiple microscopy methods, most of which are hampered by the presence of the light scattering opaque cuticle of the mosquito. So far, most imaging of the Plasmodium mosquito stages depended on either sectioning or surgical dissection of important anatomical sites, such as the midgut and the salivary glands. Optical projection tomography (OPT) and light sheet fluorescence microscopy (LSFM) enable imaging fields of view in the centimeter scale whilst providing micrometer resolution. In this paper, we compare different optical clearing protocols and present reconstructions of the whole body of Plasmodium-infected, optically cleared Anopheles stephensi mosquitoes and their midguts. The 3D-reconstructions from OPT imaging show detailed features of the mosquito anatomy and enable overall localization of parasites in midguts. Additionally, LSFM imaging of mosquito midguts shows detailed distribution of oocysts in extracted midguts. This work was submitted as a pre-print to bioRxiv, available at https://www.biorxiv.org/content/10.1101/682054v2.


Assuntos
Anopheles/fisiologia , Imageamento Tridimensional , Insetos Vetores/fisiologia , Microscopia de Fluorescência , Plasmodium/fisiologia , Tomografia Óptica , Animais , Anopheles/parasitologia
17.
PLoS One ; 15(9): e0230984, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946446

RESUMO

Insecticide resistance genes are often associated with pleiotropic effects on various mosquito life-history traits. However, very little information is available on the impact of insecticide resistance on blood feeding process in mosquitoes. Here, using two recently detected DNA-based metabolic markers in the major malaria vector, An. funestus, we investigated how metabolic resistance genes could affect the blood meal intake. After allowing both the field F1 and lab F8 Anopheles funestus strains to feed on the human arm for 30 minutes, we assessed the association between key parameters of blood meal process including, probing time, feeding duration, blood feeding success, blood meal size, and markers of glutathione S-transferase (L119F-GSTe2) and cytochrome P450 (CYP6P9a_R)-mediated metabolic resistance. None of the parameters of blood meal process was associated with L119F-GSTe2 genotypes. By contrast, for CYP6P9a_R, homozygous resistant mosquitoes were significantly more able to blood-feed than homozygous susceptible (OR = 3.3; CI 95%: 1.4-7.7; P = 0.01) mosquitoes. Moreover, the volume of blood meal ingested by CYP6P9a-SS mosquitoes was lower than that of CYP6P9a-RS (P<0.004) and of CYP6P9a-RR (P<0.006). This suggests that CYP6P9a gene is inked with the feeding success and blood meal size of An. funestus. However, no correlation was found in the expression of CYP6P9a and that of genes encoding for salivary proteins involved in blood meal process. This study suggests that P450-based metabolic resistance may influence the blood feeding process of Anopheles funestus mosquito and consequently its ability to transmit malaria parasites.


Assuntos
Anopheles/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Glutationa Transferase/metabolismo , Proteínas de Insetos/metabolismo , Mosquitos Vetores/metabolismo , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Anopheles/parasitologia , Sangue/metabolismo , Camarões , Sistema Enzimático do Citocromo P-450/genética , Comportamento Alimentar , Feminino , Glutationa Transferase/genética , Humanos , Proteínas de Insetos/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Malária/parasitologia , Malária/prevenção & controle , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mosquitos Vetores/parasitologia , Plasmodium/patogenicidade , Piretrinas/farmacologia , Proteínas e Peptídeos Salivares/metabolismo
18.
PLoS Pathog ; 16(9): e1008739, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32946522

RESUMO

Malaria-causing Plasmodium parasites traverse the mosquito midgut cells to establish infection at the basal side of the midgut. This dynamic process is a determinant of mosquito vector competence, yet the kinetics of the parasite migration is not well understood. Here we used transgenic mosquitoes of two Anopheles species and a Plasmodium berghei fluorescence reporter line to track parasite passage through the mosquito tissues at high spatial resolution. We provide new quantitative insight into malaria parasite invasion in African and Indian Anopheles species and propose that the mosquito complement-like system contributes to the species-specific dynamics of Plasmodium invasion.


Assuntos
Anopheles/parasitologia , Sistema Digestório/parasitologia , Interações Hospedeiro-Parasita , Malária/transmissão , Mosquitos Vetores/patogenicidade , Plasmodium berghei/fisiologia , Animais , Anopheles/crescimento & desenvolvimento , Feminino , Malária/parasitologia , Camundongos , Especificidade da Espécie
19.
Am J Trop Med Hyg ; 103(5): 1893-1901, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32815499

RESUMO

Investigations of malaria infection are often conducted by studying rodent Plasmodium species in inbred laboratory mice, but the efficacy of vaccines or adjunctive therapies observed in these models often does not translate to protection in humans. This raises concerns that mouse malaria models do not recapitulate important features of human malaria infections. African woodland thicket rats (Grammomys surdaster) are the natural host for the rodent malaria parasite Plasmodium berghei and the suspected natural host for Plasmodium vinckei vinckei. Previously, we reported that thicket rats are highly susceptible to diverse rodent parasite species, including P. berghei, Plasmodium yoelii, and Plasmodium chabaudi chabaudi, and are a more stringent model to assess the efficacy of whole-sporozoite vaccines than laboratory mice. Here, we compare the course of infection and virulence with additional rodent Plasmodium species, including various strains of P. berghei, P. yoelii, P. chabaudi, and P. vinckei, in thicket rats versus laboratory mice. We present evidence that rodent malaria parasite growth typically differs between the natural versus nonnatural host; G. surdaster limit infection by multiple rodent malaria strains, delaying and reducing peak parasitemia compared with laboratory mice. The course of malaria infection in thicket rats varied depending on parasite species and strain, resulting in self-cure, chronic parasitemia, or rapidly lethal infection, thus offering a variety of rodent malaria models to study different clinical outcomes in the natural host.


Assuntos
Anopheles/parasitologia , Malária/parasitologia , Parasitemia/parasitologia , Plasmodium/imunologia , Vacinas/imunologia , Animais , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Murinae , Plasmodium berghei/imunologia , Plasmodium chabaudi/imunologia , Plasmodium yoelii/imunologia , Esporozoítos
20.
PLoS One ; 15(8): e0236920, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745085

RESUMO

BACKGROUND: Twenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial. METHODS: We carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations. RESULTS: Eight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively. CONCLUSION: The entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.


Assuntos
Anopheles , Resistência a Inseticidas/genética , Malária Falciparum/transmissão , Mosquitos Vetores/genética , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/parasitologia , Burkina Faso/epidemiologia , Culex/classificação , Culex/genética , Culex/parasitologia , Culicidae/classificação , Culicidae/genética , Culicidae/parasitologia , Ecologia , Genótipo , Humanos , Malária Falciparum/prevenção & controle , Controle de Mosquitos/métodos , Controle de Mosquitos/organização & administração , Mosquitos Vetores/classificação , Mosquitos Vetores/parasitologia , Plasmodium falciparum/isolamento & purificação , Estações do Ano
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