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1.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 33(3): 274-280, 2021 Jul 05.
Artigo em Chinês | MEDLINE | ID: mdl-34286529

RESUMO

OBJECTIVE: To understand the density, populations and habitats of malaria vector Anopheles in Guizhou Province from 2005 to 2019, so as to provide the evidence for formulating the countermeasures to tackle the risk of local transmission of imported malaria in the province. METHODS: The malaria vector Anopheles density and populations were monitored using human bait trapping and light trapping techniques in Guizhou Province from 2005 to 2019, and all captured Anopheles was morphologically identified and counted. In addition, the distribution of Anopheles habitats was investigated. RESULTS: During the period from 2005 through 2019, the malaria vector Anopheles density increased from early June in Guizhou Province, peaked on early July and then declined, which appeared a single peak. The greatest Anopheles density was seen on early August, 2018 [57.34 mosquitoes/(person-night)], and the lowest density was found on late October, 2009 [1.29 mosquitoes/(person-night)]. The annual mean Anopheles density slowly reduced from 17.91 mosquitoes/(person-night) in 2005 to 12.34 mosquitoes/(person-night) in 2012, with a 38.02% reduction (χ2trend = 115.04, P < 0.01), while the annual mean Anopheles density showed a tendency towards a rise from 2017 to 2019 (χ2trend = 420.00, P < 0.01). The malaria vector Anopheles was captured during the period between 19 : 00 and 7 : 00 of the next day in Guizhou Province from 2017 to 2019, with the overall density appearing a tendency towards a rise followed by a decline, and the Anopheles activity was highly frequent during the period between 19 : 00 and 21 : 00. The malaria vector Anopheles was monitored for 938 times using the light trapping method in Guizhou Province from 2005 to 2019, and a total of 52 781 Anopheles mosquitoes were captured, including 49 705 An. sinensis, 804 An. minimus, 238 An. anthropophagus, and 2 034 other Anopheles mosquitoes, with a significant difference seen in the Anopheles composition (χ2 = 165.68, P < 0.01). From 2017 to 2019, a total of 24 557 Anopheles mosquitoes were captured in human housings, outdoors and livestock housings in Guizhou Province, with 67.65% captured in livestock housings and 12.01% in human housings, and there was a significant difference in the number of Anopheles mosquitoes captured from the three types of habitats (χ2 = 55.04, P < 0.01). An. sinensis, An. minimus and An. anthropophagus were captured form all three types of habitats, in which 98.07% was An. sinensis, and 0.09% was An. anthropophagus. CONCLUSIONS: The population structure of malaria vector Anopheles has changed in historically malaria-endemic areas of Guizhou Province, and An. sinensis has replaced An. minimus and An. anthropophagus to become the predominant malaria vector. The malaria vector Anopheles density has shown a tendency towards a rise in Guizhou Province during the recent years, and there have been a rise in the type and number of Anopheles mosquitoes, leading to a potential risk of local transmission of imported malaria. Long-term, persistent and extensive surveillance of malaria vectors is recommended in Guizhou Province.


Assuntos
Anopheles , Malária , Animais , Humanos , Malária/epidemiologia , Mosquitos Vetores
2.
Artigo em Inglês | MEDLINE | ID: mdl-34200607

RESUMO

Makkah city, Kingdom of Saudi Arabia (KSA), contains many of the world's mosquito vectors of parasitic and arboviral disease and is the site of the Hajj mass gathering. As such there is a risk of exportation and globalization of vector-borne viruses, including the re-emerging Zika virus (ZIKV). There was international concern regarding the introduction of ZIKV to KSA and potential international spread of the virus following the 2016 Hajj which took place few days after the Rio summer Olympics at the height of the ZIKV pandemic. We aimed to detect flaviviruses, including ZIKV, circulating among mosquito hosts in the city of Makkah during and post the 2016 Hajj pilgrimage. Mosquitos (adults and larvae) were sampled from 15 sites in Makkah city during and post the 2016 Hajj and identified to species by morphological keys. Mosquitos were pooled according to date of collection, location, and species. A Pan-Flaviviruses RT-PCR assay that enables identification of 51 flaviviruses species and three tentative species was used to detect flavivirus RNA directly from mosquito homogenates. Between the 10 September and 6 October 2016, 9412 female mosquitos were collected. Of these, 81.3% were Aedes aegypti, 18.6% were Culex species, and 0.1% were Anopheles species. Of the total 493 mosquito pools generated, 242 (49%) were positive by the Pan-Flaviviruses primer set. Sequence analysis revealed that none of the mosquitos carried a pathogenic flavivirus, including ZIKV, but were infected with a novel insect-specific flavivirus. We found no pathogenic flaviviruses circulating in Makkah city during and post the 2016 Hajj and no evidence of introduction of ZIKV through the pilgrimage. Enhanced vector-borne diseases surveillance, prevention, and control are crucial in KSA especially during international mass gatherings such as the annual Hajj to prevent outbreaks and the spread of viruses with epidemic and pandemic potentials.


Assuntos
Aedes , Flavivirus , Infecção por Zika virus , Zika virus , Animais , Feminino , Flavivirus/genética , Mosquitos Vetores , Arábia Saudita/epidemiologia , Zika virus/genética , Infecção por Zika virus/epidemiologia
3.
Artigo em Inglês | MEDLINE | ID: mdl-34204166

RESUMO

Surveillance and control activities for virus-transmitting mosquitoes have primarily focused on dwellings. There is little information about viral circulation in heavily trafficked places such as schools. We collected and analyzed data to assess the presence and prevalence of dengue, chikungunya, and Zika viruses in mosquitoes, and measured Aedes indices in schools in Medellín (Colombia) between 2016-2018. In 43.27% of 2632 visits we collected Aedes adults, creating 883 pools analyzed by RT-PCR. 14.27% of pools yielded positive for dengue or Zika (infection rates of 1.75-296.29 for Aedes aegypti). Ae. aegypti was more abundant and had a higher infection rate for all studied diseases. Aedes indices varied over time. There was no association between Aedes abundance and mosquito infection rates, but the latter did correlate with cases of arboviral disease and climate. Results suggest schools are important sources of arbovirus and health agencies should include these sites in surveillance programs; it is essential to know the source for arboviral diseases transmission and the identification of the most population groups exposed to these diseases to research and developing new strategies.


Assuntos
Vírus da Dengue , Dengue , Infecção por Zika virus , Zika virus , Animais , Colômbia , Dengue/epidemiologia , Mosquitos Vetores , Instituições Acadêmicas , Infecção por Zika virus/epidemiologia
4.
Molecules ; 26(12)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204264

RESUMO

The present research investigated the chemical characterization and insecticidal activity of n-Hexane extracts of Epaltes divaricata (NH-EDx) along with their chief derivatives n-Hexadecanoic acid (n-HDa) and n-Octadecanoic acid (n-ODa) against the dengue vector Aedes aegypti and lepidopteran pest Spodoptera litura. Chemical screening of NH-EDx through GC-MS analysis delivered nine major derivatives, and the maximum peak area percentage was observed in n-Hexadecanoic acid (14.63%) followed by n-Octadecadienoic acid (6.73%). The larvicidal activity of NH-EDx (1000 ppm), n-HDa (5 ppm), and n-ODa (5 ppm) against the A. aegypti and S. litura larvae showed significant mortality rate in a dose-dependent way across all the instars. The larvicidal activity was profound in the A. aegypti as compared to the S. litura across all the larval instars. The sublethal dosages of NH-EDx (500 ppm), n-HDa (2.5 ppm), and n-ODa (2.5 ppm) also showed alterations in the larval/pupal durations and adult longevity in both the insect pests. The enzyme activity revealed that the α- and ß-carboxylesterase levels were decreased significantly in both the insect pests, whereas the levels of GST and CYP450 uplifted in a dose-dependent manner of NH-EDx, n-HDa, and n-ODa. Correspondingly, midgut tissues such as the epithelial layer (EL), gut lumen (GL), peritrophic matrix (Pm), and brush border membrane (BBM) were significantly altered in their morphology across both A. aegypti and S. litura against the NH-EDx and their bioactive metabolites. NH-EDx and their bioactive metabolites n-HDa and n-ODa showed significant larvicidal, growth retardant, enzyme inhibition, and midgut toxicity effects against two crucial agriculturally and medically challenging insect pest of ecological importance.


Assuntos
Aedes/efeitos dos fármacos , Asteraceae/metabolismo , Extratos Vegetais/farmacologia , Spodoptera/efeitos dos fármacos , Animais , Asteraceae/efeitos dos fármacos , Culex/efeitos dos fármacos , Dengue/prevenção & controle , Hexanos/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mosquitos Vetores/efeitos dos fármacos , Folhas de Planta/química , Solventes/química
5.
Mem Inst Oswaldo Cruz ; 116: e210064, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34259737

RESUMO

Unforeseen Plasmodium infections in the Atlantic Forest of Brazilian Extra-Amazonian region could jeopardise malaria elimination. A human malaria case was registered in Três Forquilhas, in the Atlantic Forest biome of Rio Grande do Sul, after a 45 years' time-lapsed without any malaria autochthonous notification in this southern Brazilian state. This finding represents the expansion of the malaria distribution areas in Brazil and the southernmost human malaria case record in South America in this decade. The coexistence of the bromeliad-breeding vector Anopheles (Kerteszia) cruzii and non-human primates in the Atlantic Forest regularly visited by the patient claimed for the zoonotic origin of this infection. The reemergence of Atlantic Forest human malaria in Rio Grande do Sul was also discussed.


Assuntos
Anopheles , Malária , Animais , Brasil/epidemiologia , Florestas , Humanos , Malária/epidemiologia , Mosquitos Vetores
6.
Gene ; 798: 145810, 2021 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-34224830

RESUMO

Anopheles stephensi and Anopheles culicifacies are dominant malarial vectors in urban and rural India, respectively. Both species carry significant biological differences in their behavioral adaptation and immunity, but the genetic basis of these variations are still poorly understood. Here, we uncovered the genetic differences of immune blood cells, that influence several immune-physiological responses. We generated, analyzed and compared the hemocyte RNA-Seq database of both mosquitoes. A total of 5,837,223,769 assembled bases collapsed into 7,595 and 3,791 transcripts, originating from hemocytes of laboratory-reared 3-4 days old naïve (sugar-fed) mosquitoes, Anopheles stephensi and Anopheles culicifacies respectively. Comparative GO annotation analysis revealed that both mosquito hemocytes encode similar proteins. Furthermore, while An. stephensi hemocytes showed a higher percentage of immune transcripts encoding APHAG (Autophagy), IMD (Immune deficiency pathway), PRDX (Peroxiredoxin), SCR (Scavenger receptor), IAP (Inhibitor of apoptosis), GALE (galactoside binding lectins), BGBPs (1,3 beta D glucan binding proteins), CASPs (caspases) and SRRP (Small RNA regulatory pathway), An. culicifacies hemocytes yielded a relatively higher percentage of transcripts encoding CLIP (Clip domain serine protease), FREP (Fibrinogen related proteins), PPO (Prophenol oxidase), SRPN (Serpines), ML (Myeloid differentiation 2-related lipid recognition protein), Toll path and TEP (Thioester protein), family proteins. However, a detailed comparative Interproscan analysis showed An. stephensi mosquito hemocytes encode proteins with increased repeat numbers as compared to An. culicifacies. Notably, we observed an abundance of transcripts showing significant variability of encoded proteins with repeats such as LRR (Leucine rich repeat), WD40 (W-D dipeptide), Ankyrin, Annexin, Tetratricopeptide and Mitochondrial substrate carrier repeat-containing family proteins, which may have a direct influence on species-specific immune-physiological responses. Summarily, our deep sequencing analysis unraveled that An. stephensi evolved with an expansion of repeat sequences in hemocyte proteins as compared to An. culicifacies, possibly providing an advantage for better adaptation to diverse environments.


Assuntos
Anopheles/genética , Hemócitos/metabolismo , Mosquitos Vetores/genética , Animais , Anopheles/citologia , Feminino , Ontologia Genética , Variação Genética , Leucina , Malária/transmissão , Mosquitos Vetores/citologia , RNA-Seq
7.
Front Public Health ; 9: 649672, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34222167

RESUMO

Background: Malaria is endemic in Sierra Leone, with stable and perennial transmission in all parts of the country. At present, the main prevention and control measures for mosquito vectors here involve insecticide treated nets (ITN) and indoor residual spraying (IRS). The most recent entomological surveillance was conducted prior to the civil war, between 1990 and 1994. Therefore, a new entomological surveillance required to support targeted malaria control strategies. Methods: Anopheles mosquitoes were collected between June and December 2019 using the light trap method. On these, we conducted species identification, analyzed seasonal fluctuation and Plasmodium infection rate, and monitored insecticide resistance. Results: Surveillance of seasonal fluctuation showed that there were two peak of Anopheles density in July (mean 13.67 mosquitoes/trap/night) and October (mean 13.00 mosquitoes/trap/night). Meanwhile, the lowest Anopheles density was seen in early September. Ninety-one representatives of Anopheles gambiae s.l. were selected and identified as An. coluzzii (n = 35) and An. gambiae s.s. (n = 56) using PCR. An. coluzzii and An. gambiae s.s. were found to be heterozygous resistant to the knockdown resistance (kdr) L1014F mutation (100%). Meanwhile, the East African mutation (kdr L1014S) was absent in the tested mosquitoes. Three mosquitoes that tested positive for the parasite, had an individual Plasmodium falciparum infection rate of 12.50, 16.67, and 14.29%. The sampling dates of positive mosquitoes were distributed in the two periods of peak Anopheles mosquito density. Conclusion: This study identified the dominant Anopheles species in Freetown as An. gambiae while the predominant species within the An. gambiae complex was An. gambiae sensu stricto. Surveillance of seasonal fluctuations and high P. falciparum infection rates in Anopheles indicate that the alternation of drought and rainy seasons from June to July, and from October to November, are the key periods for malaria control and prevention in Freetown, Sierra Leone. The high frequency of kdr allele mutations in An. gambiae calls for close monitoring of vector susceptibility to insecticides and tracing of resistance mechanisms in order to develop more effective vector control measures and strategies.


Assuntos
Anopheles , Malária , Animais , Anopheles/genética , Resistência a Inseticidas/genética , Mosquitos Vetores/genética , Serra Leoa/epidemiologia
8.
Front Cell Infect Microbiol ; 11: 690087, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34249780

RESUMO

Aedes aegypti is inherently susceptible to arboviruses. The geographical expansion of this vector host species has led to the persistence of Dengue, Zika, and Chikungunya human infections. These viruses take advantage of the mosquito's cell to create an environment conducive for their growth. Arboviral infection triggers transcriptomic and protein dysregulation in Ae. aegypti and in effect, host antiviral mechanisms are compromised. Currently, there are no existing vaccines able to protect human hosts from these infections and thus, vector control strategies such as Wolbachia mass release program is regarded as a viable option. Considerable evidence demonstrates how the presence of Wolbachia interferes with arboviruses by decreasing host cytoskeletal proteins and lipids essential for arboviral infection. Also, Wolbachia strengthens host immunity, cellular regeneration and causes the expression of microRNAs which could potentially be involved in virus inhibition. However, variation in the magnitude of Wolbachia's pathogen blocking effect that is not due to the endosymbiont's density has been recently reported. Furthermore, the cellular mechanisms involved in this phenotype differs depending on Wolbachia strain and host species. This prompts the need to explore the cellular interactions between Ae. aegypti-arboviruses-Wolbachia and how different Wolbachia strains overall affect the mosquito's cell. Understanding what happens at the cellular and molecular level will provide evidence on the sustainability of Wolbachia vector control.


Assuntos
Aedes , Arbovírus , Wolbachia , Infecção por Zika virus , Zika virus , Animais , Humanos , Mosquitos Vetores
9.
Front Cell Infect Microbiol ; 11: 654216, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34262880

RESUMO

Malaria transmission relies on parasite-mosquito midgut interaction. The interactive proteins are hypothesized to be ideal targets to block malaria transmission to mosquitoes. We chose 76 genes that contain signal peptide-coding regions and are upregulated and highly abundant at sexual stages. Forty-six of these candidate genes (60%) were cloned and expressed using the baculovirus expression system in insect cells. Six of them, e.g., PF3D7_0303900, PF3D7_0406200 (Pfs16), PF3D7_1204400 (Pfs37), PF3D7_1214800, PF3D7_1239400, and PF3D7_1472800 were discovered to interact with blood-fed mosquito midgut lysate. Previous works showed that among these interactive proteins, knockout the orthologs of Pfs37 or Pfs16 in P. berghei reduced oocysts in mosquitoes. Here we further found that anti-Pfs16 polyclonal antibody significantly inhibited P. falciparum transmission to Anopheles gambiae. Investigating these candidate proteins will improve our understanding of malaria transmission and discover new targets to break malaria transmission.


Assuntos
Malária , Parasitos , Plasmodium , Animais , Mosquitos Vetores , Plasmodium falciparum/genética
11.
Front Cell Infect Microbiol ; 11: 702081, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34268140

RESUMO

Aedes albopictus is the only vector that can transmit the dengue virus in Zhejiang Province, central China, and it can develop insecticide resistance due to long-term exposure to pyrethroids. The presence of knockdown resistance (kdr) mutations is one of the mechanisms responsible for pyrethroid resistance, and has been reported in some Ae. albopictus populations in southern China. However, little is known about the DNA diversity of the voltage-gated sodium channel (VGSC) gene in Ae. albopictus populations in central China. Four Ae. albopictus field populations were collected, in Yiwu (YW), Quzhou (QZ), Wenzhou (WZ), and Jiaxing (JX) from Zhejiang Province, central China. The susceptibility of Ae. albopictus adults to three pyrethroids (beta-cypermethrin, deltamethrin, and permethrin) was tested using the WHO tube assay, and Kdr mutations were identified via PCR and sequencing. The relationship between kdr mutations and pyrethroid phenotypes was also analyzed. Of the four populations, none was sensitive to any pyrethroid tested, and the YW population showed the strongest pyrethroid resistance. Non-synonymous kdr mutations were detected in codons 1532 and 1534, domain III. At codon 1534, one mutant allele, TCC(S), was detected in the four populations with a frequency of 42.08%, while at codon 1532, one mutant allele, ACC(T), was detected in the JX and QZ populations, with frequencies of 4.22 and 3.03%, respectively. The F1534S mutant allele was positively correlated with both beta-cypermethrin and deltamethrin resistance phenotypes (OR > 1, P < 0.05), whereas the I1532T mutant allele was possibly negatively correlated with beta-cypermethrin, deltamethrin, and permethrin resistance phenotypes (OR < 1, P > 0.05). In conclusion, resistance and resistance mutations regarding to three pyrethroids are already present in the Ae. Albopictus populations from Zhejiang, central China, which prompts the need to use non-insecticide-based methods of insect control.


Assuntos
Aedes , Inseticidas , Aedes/genética , Animais , China , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Mutação
12.
Front Cell Infect Microbiol ; 11: 633905, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34307185

RESUMO

Malaria, one of the most serious parasitic diseases, kills thousands of people every year, especially in Africa. São Tomé and Príncipe are known to have stable transmission of malaria. Indoor residual spraying (IRS) of insecticides and long-lasting insecticidal nets (LLIN) are considered as an effective malaria control interventions in these places. The resistance status of Anopheles gambiae s.s. from Agua Grande, Caue, and Lemba of São Tomé and Príncipe to insecticides, such as dichlorodiphenyltrichloroethane (DDT) (4.0%), deltamethrin (0.05%), permethrin (0.75%), fenitrothion (1.0%), and malathion (5.0%), were tested according to the WHO standard protocol. DNA extraction, species identification, as well as kdr and ace-1R genotyping were done with the surviving and dead mosquitoes post testing. They showed resistance to cypermethrin with mortality rates ranging from 89.06% to 89.66%. Mosquitoes collected from Agua Grande, Caue, and Lemba displayed resistance to DDT and fenitrothion with mortality rates higher than 90%. No other species were detected in these study localities other than Anopheles gambiae s.s. The frequency of L1014F was high in the three investigated sites, which was detected for the first time in São Tomé and Príncipe. No ace-1R mutation was detected in all investigated sites. The high frequency of L1014F showed that kdr L1014F mutation might be related to insecticide resistance to Anopheles gambiae s.s. populations from São Tomé and Príncipe. Insecticide resistance status is alarming and, therefore, future malaria vector management should be seriously considered by the government of São Tomé and Príncipe.


Assuntos
Anopheles , Malária , África , Animais , Anopheles/genética , Humanos , Malária/prevenção & controle , Mosquitos Vetores/genética , Mutação , São Tomé e Príncipe
13.
Front Cell Infect Microbiol ; 11: 705129, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34307199

RESUMO

Currently, Aedes aegypti, the principal vector of dengue virus in Indonesia, has spread throughout the archipelago. Aedes albopictus is also present. Invasion and high adaptability of the Aedes mosquitoes to all of these areas are closely related to their ecology and biology. Between June 2016 and July 2017, larval and adult mosquito collections were conducted in 43 locations in 25 provinces of Indonesia using standardized sampling methods for dengue vector surveillance. The samples collected were analyzed for polymorphism and phylogenetic relationship using the mitochondrial cox1 gene and the nuclear ribosomal internal transcribed spacer 2 (ITS2). Almost all Ae. aegypti samples collected in this study (89%) belonged to the same haplotype. A similar situation is observed with the nuclear ITS2 marker. Populations of Ae. aegypti characterized few years ago were genetically different. A closely related observation was made with Aedes albopictus for which the current populations are different from those described earlier. Ae. aegypti populations were found to be highly homogenous all over Indonesia with all samples belonging to the same maternal lineage. Although difficult to demonstrate formally, there is a possibility of population replacement. Although to a lower extent, a similar conclusion was reached with Ae. albopictus.


Assuntos
Aedes , Dengue , Animais , Indonésia , Mosquitos Vetores , Filogenia
14.
Front Public Health ; 9: 649190, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34178915

RESUMO

After spreading in the Americas, West Nile virus was detected in Guadeloupe (French West Indies) for the first time in 2002. Ever since, several organizations have conducted research, serological surveys, and surveillance activities to detect the virus in horses, birds, mosquitoes, and humans. Organizations often carried them out independently, leading to knowledge gaps within the current virus' situation. Nearly 20 years after the first evidence of West Nile virus in the archipelago, it has not yet been isolated, its impact on human and animal populations is unknown, and its local epidemiological cycle is still poorly understood. Within the framework of a pilot project started in Guadeloupe in 2019, West Nile virus was chosen as a federative model to apply the "One Health" approach for zoonotic epidemiological surveillance and shift from a sectorial to an integrated surveillance system. Human, animal, and environmental health actors involved in both research and surveillance were considered. Semi-directed interviews and a Social Network Analysis were carried out to learn about the surveillance network structure and actors, analyze information flows, and identify communication challenges. An information system was developed to fill major gaps: users' needs and main functionalities were defined through a participatory process where actors also tested and validated the tool. Additionally, all actors shared their data, which were digitized, cataloged, and centralized, to be analyzed later. An R Shiny server was integrated into the information system, allowing an accessible and dynamic display of data showcasing all of the partners' information. Finally, a series of virtual workshops were organized among actors to discuss preliminary results and plan the next steps to improve West Nile Virus and vector-borne or emerging zoonosis surveillance. The actors are willing to build a more resilient and cooperative network in Guadeloupe with improved relevance, efficiency, and effectiveness of their work.


Assuntos
Febre do Nilo Ocidental , Vírus do Nilo Ocidental , Animais , Região do Caribe/epidemiologia , Guadalupe/epidemiologia , Cavalos , Mosquitos Vetores , Projetos Piloto , Índias Ocidentais , Febre do Nilo Ocidental/epidemiologia
15.
Pan Afr Med J ; 38: 248, 2021.
Artigo em Francês | MEDLINE | ID: mdl-34104296

RESUMO

Yellow fever (YF) is a viral haemorrhagic fever caused by yellow fever virus transmitted by Aedes mosquitoes. Since 2013, in Chad, four cases of yellow fever have been detected and confirmed as part of the national fever surveillance program. We here report the last clinical case confirmed in the health district of Lai. The patient was a 57-year-old man with no significant medical and surgical history and unknown immunisation status. He consulted on April 21st, 2020 for fever, moderate to low abundance jaundice and epistaxis (nosebleed) and painful hepatomegaly. Paraclinical examinations, such as RT-PCR, objectified yellow fever virus in post-mortem tissue sample. Thus, confirmed yellow fever cases in this district, the low level of vaccination coverage, the circulation of the virus and the presence of vector in the country should warn of a real threat of reemergence of yellow fever in Chad.


Assuntos
Febre Amarela/diagnóstico , Vírus da Febre Amarela/isolamento & purificação , Aedes/virologia , Animais , Chade , Humanos , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Recidiva , Febre Amarela/transmissão , Febre Amarela/virologia , Vacina contra Febre Amarela/administração & dosagem
16.
Pestic Biochem Physiol ; 176: 104882, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34119224

RESUMO

In order to increase the virulence of two commonly used entomopathogens namely Beauveria bassiana and Metarhizium anisopliae for effective mosquito control programs, we developed new combined formulation by the use of immunosuppressive concentration of imidacloprid. Exposure of sublethal concentration (LC10 1.34 ppb) of imidacloprid to second instar larvae for 92 h that differently modulated the larval biochemical markers by decreasing the total protein (20.65% reduction), acetylcholinesterase (35.74% reduction) and increases the ß-carboxylesterase (26.59% increase) and acid phosphatase (30.69% increase) levels while no significant difference was noticed in alkaline phosphatase of C. quinquefasciatus. Further we demonstrated that the imidacloprid exposure brings about reduction in phenoloxidase level (39.48% decrease) and nitric oxide production (37.64% decrease) in larval homogenate over control. The reduction in viability of hemocytes (15.37% decrease) and phagocytic activity of hemocytes (32.18% decrease) was noticed in imidacloprid treatment. Moreover in laboratory condition, exposure of 1 × 107 spores/ml of B. bassiana (984) and M. anisopliae (6060) alone for 92 h cumulative toxicity assay exhibited larval mortality of 36.47% and 47.64% respectively against C. quinquefasciatus. However in the synergistic experimental studies with LC10 of imidacloprid and 1 × 107 spores/ml of B. bassiana or M. anisopliae to the larvae for 92 h cumulative assay brought 60% and 50.59% more insecticidal activity than the respective entomopathogens alone. The substantial increase of larvicidal activity noticed in the synergistic test conditions against larvae of C. quinquefasciatus revealed that the inclusion of sublethal concentration was proved to be useful for effective larval control.


Assuntos
Beauveria , Culex , Metarhizium , Animais , Larva , Mosquitos Vetores , Neonicotinoides , Nitrocompostos , Controle Biológico de Vetores , Virulência
17.
N Engl J Med ; 384(23): 2177-2186, 2021 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-34107180

RESUMO

BACKGROUND: Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia pipientis are less susceptible than wild-type A. aegypti to dengue virus infection. METHODS: We conducted a cluster-randomized trial involving releases of wMel-infected A. aegypti mosquitoes for the control of dengue in Yogyakarta, Indonesia. We randomly assigned 12 geographic clusters to receive deployments of wMel-infected A. aegypti (intervention clusters) and 12 clusters to receive no deployments (control clusters). All clusters practiced local mosquito-control measures as usual. A test-negative design was used to assess the efficacy of the intervention. Patients with acute undifferentiated fever who presented to local primary care clinics and were 3 to 45 years of age were recruited. Laboratory testing was used to identify participants who had virologically confirmed dengue (VCD) and those who were test-negative controls. The primary end point was symptomatic VCD of any severity caused by any dengue virus serotype. RESULTS: After successful introgression of wMel into the intervention clusters, 8144 participants were enrolled; 3721 lived in intervention clusters, and 4423 lived in control clusters. In the intention-to-treat analysis, VCD occurred in 67 of 2905 participants (2.3%) in the intervention clusters and in 318 of 3401 (9.4%) in the control clusters (aggregate odds ratio for VCD, 0.23; 95% confidence interval [CI], 0.15 to 0.35; P = 0.004). The protective efficacy of the intervention was 77.1% (95% CI, 65.3 to 84.9) and was similar against the four dengue virus serotypes. The incidence of hospitalization for VCD was lower among participants who lived in intervention clusters (13 of 2905 participants [0.4%]) than among those who lived in control clusters (102 of 3401 [3.0%]) (protective efficacy, 86.2%; 95% CI, 66.2 to 94.3). CONCLUSIONS: Introgression of wMel into A. aegypti populations was effective in reducing the incidence of symptomatic dengue and resulted in fewer hospitalizations for dengue among the participants. (Funded by the Tahija Foundation and others; AWED ClinicalTrials.gov number, NCT03055585; Indonesia Registry number, INA-A7OB6TW.).


Assuntos
Aedes/microbiologia , Controle de Doenças Transmissíveis/métodos , Dengue/transmissão , Mosquitos Vetores , Wolbachia , Adolescente , Adulto , Aedes/virologia , Animais , Criança , Pré-Escolar , Dengue/diagnóstico , Dengue/epidemiologia , Dengue/prevenção & controle , Vírus da Dengue/isolamento & purificação , Feminino , Humanos , Incidência , Indonésia/epidemiologia , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/microbiologia , Mosquitos Vetores/virologia , Adulto Jovem
18.
Parasitol Res ; 120(7): 2343-2350, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34110501

RESUMO

Arthropod vectors are frequently exposed to a diverse assemblage of parasites, but the consequence of these infections on their biology and behavior are poorly understood. We experimentally evaluated whether the ingestion of a common protozoan parasite of avian hosts (Haemoproteus spp.; Haemosporida: Haemoproteidae) impacted the survivorship of Culex quinquefasciatus (Say) (Diptera: Culicidae). Blood was collected from wild northern cardinals (Cardinalis cardinalis) in College Station, Texas, and screened for the presence of Haemoproteus spp. parasites using microscopic and molecular methods. Experimental groups of Cx. quinquefasciatus mosquitoes were offered Haemoproteus-positive cardinal blood through an artificial feeding apparatus, while control groups received Haemoproteus-negative cardinal blood or domestic canary (Serinus canaria domestica) blood. Culex quinquefasciatus mosquitoes exposed to Haemoproteus infected cardinal blood survived significantly fewer days than mosquitoes that ingested Haemoproteus-negative cardinal blood. The survival of mosquitoes fed on positive cardinal blood had a median survival time of 18 days post-exposure and the survival of mosquitoes fed on negative cardinal blood exceeded 50% across the 30 day observation period. Additionally, mosquitoes that fed on canary controls survived significantly fewer days than cardinal negative controls, with canary control mosquitoes having a median survival time of 17 days. This study further supports prior observations that Haemoproteus parasites can be pathogenic to bird-biting mosquitoes, and suggests that Haemoproteus parasites may indirectly suppress the transmission of co-circulating vector-borne pathogens by modulating vector survivorship. Our results also suggest that even in the absence of parasite infection, bloodmeals from different bird species can influence mosquito survivorship.


Assuntos
Culex/fisiologia , Culex/parasitologia , Haemosporida/fisiologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/parasitologia , Passeriformes/parasitologia , Animais , Doenças das Aves/parasitologia , Doenças das Aves/transmissão , Canários/sangue , Canários/parasitologia , DNA de Protozoário/sangue , Passeriformes/sangue , Reação em Cadeia da Polimerase/veterinária , Probabilidade , Modelos de Riscos Proporcionais , Infecções Protozoárias em Animais/parasitologia , Infecções Protozoárias em Animais/transmissão , Texas
19.
Nat Commun ; 12(1): 3971, 2021 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-34172729

RESUMO

Studies about the impact of future climate change on diseases have mostly focused on standard Representative Concentration Pathway climate change scenarios. These scenarios do not account for the non-linear dynamics of the climate system. A rapid ice-sheet melting could occur, impacting climate and consequently societies. Here, we investigate the additional impact of a rapid ice-sheet melting of Greenland on climate and malaria transmission in Africa using several malaria models driven by Institute Pierre Simon Laplace climate simulations. Results reveal that our melting scenario could moderate the simulated increase in malaria risk over East Africa, due to cooling and drying effects, cause a largest decrease in malaria transmission risk over West Africa and drive malaria emergence in southern Africa associated with a significant southward shift of the African rain-belt. We argue that the effect of such ice-sheet melting should be investigated further in future public health and agriculture climate change risk assessments.


Assuntos
Camada de Gelo , Malária/transmissão , Animais , Anopheles , Aquecimento Global , Groenlândia , Humanos , Malária/epidemiologia , Modelos Teóricos , Mosquitos Vetores , Prevalência , Chuva
20.
BMC Genomics ; 22(1): 422, 2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34103015

RESUMO

BACKGROUND: Whole genome re-sequencing provides powerful data for population genomic studies, allowing robust inferences of population structure, gene flow and evolutionary history. For the major malaria vector in Africa, Anopheles gambiae, other genetic aspects such as selection and adaptation are also important. In the present study, we explore population genetic variation from genome-wide sequencing of 765 An. gambiae and An. coluzzii specimens collected from across Africa. We used t-SNE, a recently popularized dimensionality reduction method, to create a 2D-map of An. gambiae and An. coluzzii genes that reflect their population structure similarities. RESULTS: The map allows intuitive navigation among genes distributed throughout the so-called "mainland" and numerous surrounding "island-like" gene clusters. These gene clusters of various sizes correspond predominantly to low recombination genomic regions such as inversions and centromeres, and also to recent selective sweeps. Because this mosquito species complex has been studied extensively, we were able to support our interpretations with previously published findings. Several novel observations and hypotheses are also made, including selective sweeps and a multi-locus selection event in Guinea-Bissau, a known intense hybridization zone between An. gambiae and An. coluzzii. CONCLUSIONS: Our results present a rich dataset that could be utilized in functional investigations aiming to shed light onto An. gambiae s.l genome evolution and eventual speciation. In addition, the methodology presented here can be used to further characterize other species not so well studied as An. gambiae, shortening the time required to progress from field sampling to the identification of genes and genomic regions under unique evolutionary processes.


Assuntos
Anopheles , Malária , África , Animais , Anopheles/genética , Guiné-Bissau , Ilhas , Malária/genética , Mosquitos Vetores/genética
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