Adaptative processes, control measures, genetic background, and resilience of malaria vectors and environmental changes in the Amazon region

Abstract Background: Environmental changes resulting from the urbanization process represent a challenge for malaria control. The majority of malaria cases in South America occur in rural areas, areas of recent occupation, mining and indigenous areas of the Amazon region. Although these areas have a significant impact on malaria cases, few entomological studies have been carried out in areas of recent occupation. This study aimed to describe the density, natural infection rate and hematophagic behavior of anopheline species in two settlements in the state of Rondonia, Brazil in order to understand how malaria transmission occurs in areas that have been settled at different times.Methods: An area of recent occupation, denominated Acampamento Fortaleza (AF), and an old settlement, denominated Projeto de Assentamento Florestal Jequitibá (PAFJ), were studied. Peridomicile collections of anopheles were carried out using the Protected Human Attraction Technique (PHAT). The risk and potential for malaria transmission were assessed using the human biting rate (HBR), sporozoite rate (SR) and the entomological inoculation rate (EIR).Results: The results confirmed that Nyssorhynchus darlingi, the main vector responsible for the transmission of malaria in the state of Rondônia, is the predominant species in the two studied locations. Although settlement of the two study sites has occurred at different times, the species richness found was low, showing that the environmental changes caused by anthropological actions probably favor the adaptation of the Ny. darlingi species. Of the 615 anopheline mosquitoes assessed, 7 (1.1%) were positive for Plasmodium infections. The EIR revealed that Ny. darlingi contributes to the transmission of malaria in both locations, since it was responsible for 0.41 infectious bites in humans at night in PAFJ and 0.16 in AF. In the two study sites, the biting occurred more frequently at dusk.Conclusions: Ny. darlingi is the principal vector found in the studied locations. Its prevalence occurs in areas of recent colonization but, even when present in a low density, this species could maintain transmission of malaria in an older settlement. The entomological information obtained in this study is important and may aid the selection of vector control actions in these locations that are considered as having a high risk of malaria transmission.

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Extensive genetic diversity among populations of the malaria mosquito Anopheles moucheti revealed by population genomics

10.1101/068247 ◽

2016 ◽

Author(s):

Caroline Fouet ◽

Colince Kamdem ◽

Stephanie Gamez ◽

Bradley J. White

Keyword(s):

Genetic Diversity ◽

Genetic Structure ◽

Large Scale ◽

Environmental Changes ◽

Population Genomics ◽

Demographic History ◽

Control Measures ◽

Malaria Vectors ◽

African Countries ◽

Population Size Estimates

AbstractMalaria vectors are exposed to intense selective pressures due to large-scale intervention programs that are underway in most African countries. One of the current priorities is therefore to clearly assess the adaptive potential of Anopheline populations, which is critical to understand and anticipate the response mosquitoes can elicit against such adaptive challenges. The development of genomic resources that will empower robust examinations of evolutionary changes in all vectors including currently understudied species is an inevitable step toward this goal. Here we constructed double-digest Restriction Associated DNA (ddRAD) libraries and generated 6461 Single Nucleotide Polymorphisms (SNPs) that we used to explore the population structure and demographic history of wild-caught Anopheles moucheti from Cameroon. The genome-wide distribution of allelic frequencies among samples best fitted that of an old population at equilibrium, characterized by a weak genetic structure and extensive genetic diversity, presumably due to a large long term effective population size. Estimates of FST and Linkage Disequilibrium (LD) across SNPs reveal a very low genetic differentiation throughout the genome and the absence of segregating LD blocks among populations, suggesting an overall lack of local adaptation. Our study provides the first investigation of the genetic structure and diversity in An. moucheti at the genomic scale. We conclude that, despite a weak genetic structure, this species has the potential to challenge current vector control measures and other rapid anthropogenic and environmental changes thanks to its great genetic diversity.

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Inadequate management of natural ecosystem in the Brazilian Amazon region results in the emergence and reemergence of arboviruses

Cadernos de Saúde Pública ◽

10.1590/s0102-311x2001000700025 ◽

2001 ◽

Vol 17 (suppl) ◽

pp. S155-S164 ◽

Cited By ~ 81

Author(s):

Pedro F. C. Vasconcelos ◽

Amélia P. A. Travassos da Rosa ◽

Sueli G. Rodrigues ◽

Elizabeth S. Travassos da Rosa ◽

Nicolas Dégallier ◽

...

Keyword(s):

Environmental Changes ◽

Epidemiological Data ◽

Brazilian Amazon ◽

Host Population ◽

Amazon Region ◽

Laboratory Animals ◽

Natural Ecosystem ◽

Brazilian Amazon Region ◽

Mining Dam ◽

The Impact

A total of 187 different species of arboviruses and other viruses in vertebrates were identified at the Evandro Chagas Institute (IEC) from 1954 to 1998, among more than 10,000 arbovirus strains isolated from humans, hematophagous insects, and wild and sentinel vertebrates. Despite intensive studies in the Brazilian Amazon region, especially in Pará State, very little is known about most of these viruses, except for information on date, time, source, and method of isolation, as well as their capacity to infect laboratory animals. This paper reviews ecological and epidemiological data and analyzes the impact of vector and host population changes on various viruses as a result of profound changes in the natural environment. Deforestation, mining, dam and highway construction, human colonization, and urbanization were the main manmade environmental changes associated with the emergence and/or reemergence of relevant arboviruses, including some known pathogens for humans.

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Malaria vectors in the municipality of Serra do Navio, State of Amapá, Amazon Region, Brazil

Memórias do Instituto Oswaldo Cruz ◽

10.1590/s0074-02762001000200008 ◽

2001 ◽

Vol 96 (2) ◽

pp. 179-184 ◽

Cited By ~ 61

Author(s):

MM Póvoa ◽

RA Wirtz ◽

RNL Lacerda ◽

MA Miles ◽

D Warhurst

Keyword(s):

Amazon Region ◽

Malaria Vectors

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A Comprehensive Analysis on Abundance, Distribution, and Bionomics of Potential Malaria Vectors in Mannar District of Sri Lanka

Malaria Research and Treatment ◽

10.1155/2019/1650180 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Nayana Gunathilaka ◽

Menaka Hapugoda ◽

Rajitha Wickremasinghe ◽

Wimaladharma Abeyewickreme

Keyword(s):

Waste Water ◽

Sri Lanka ◽

Current Knowledge ◽

Breeding Habitat ◽

Control Measures ◽

Malaria Vectors ◽

Detailed Knowledge ◽

Lagoon Water ◽

Breeding Habitats ◽

The Mean

Background. A detailed knowledge of the distribution of the malaria vectors in Mannar district of Sri Lanka has not been studied after 1927. Past records indicated the presence of only seven species of anophelines, namely, An. culicifacies, An. subpictus, An. barbirostris, An. peditaeniatus, An. nigerrimus, An. Jamesii, and An. maculatus. There have been many changes in terms of distribution of Anopheles in the district over time. Methods. Entomological surveillance was conducted on a monthly basis, comprising indoor hand collection, window trap collection, cattle-baited net collection, cattle-baited hut collection, and larval survey from June 2010 to June 2012 in 12 study areas under three entomological sentinel sites. The relationship between seven abiotic variables of the breeding habitats was measured. Pearson’s correlation coefficients were used to determine the associations between climatic variables and anopheline densities. Results. A total of 74,181 mosquitoes belonging to 14 Anopheles species were recorded. An. subpictus was the most predominant species from all techniques representing 92% (n=68,268) of the total anopheline collection. However, Anopheles culicifacies was not recorded from any site during the study period. Larval surveys identified 12 breeding habitat categories including waste water collections, lagoon water collections, and drains which were not recorded as breeding habitats by previous studies. The mean dissolved oxygen level of waste water collections was 3.45±0.15 mg/l. The mean salinity and conductivity of lagoon water collections were 21105±1344 mg/l and 34734±1974 μs/cm, respectively. Conclusion. The present study provides the updated knowledge on anopheline distribution and vector bionomics. Therefore, documentation of the current knowledge would be useful for learners and health authorities to design appropriate vector control measures in the prevention of reintroduction of malaria.

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Resting behaviour of malaria vectors in highland and lowland sites of western Kenya: Implication on malaria vector control measures

PLoS ONE ◽

10.1371/journal.pone.0224718 ◽

2020 ◽

Vol 15 (2) ◽

pp. e0224718 ◽

Cited By ~ 6

Author(s):

Maxwell G. Machani ◽

Eric Ochomo ◽

Fred Amimo ◽

Jackline Kosgei ◽

Stephen Munga ◽

...

Keyword(s):

Vector Control ◽

Malaria Vector ◽

Control Measures ◽

Malaria Vectors ◽

Malaria Vector Control ◽

Western Kenya ◽

Resting Behaviour

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Current status of Plasmodium knowlesi vectors: a public health concern?

Parasitology ◽

10.1017/s0031182016000901 ◽

2016 ◽

Vol 145 (1) ◽

pp. 32-40 ◽

Cited By ~ 11

Author(s):

I. VYTHILINGAM ◽

M. L. WONG ◽

W. S. WAN-YUSSOF

Keyword(s):

Public Health ◽

Plasmodium Knowlesi ◽

Point Of View ◽

Control Measures ◽

Health Concern ◽

Current Status ◽

Malaria Vectors ◽

Future Studies ◽

Simian Malaria ◽

And Control

SUMMARYPlasmodium knowlesi a simian malaria parasite is currently affecting humans in Southeast Asia. Malaysia has reported the most number of cases and P. knowlesi is the predominant species occurring in humans. The vectors of P. knowlesi belong to the Leucosphyrus group of Anopheles mosquitoes. These are generally described as forest-dwelling mosquitoes. With deforestation and changes in land-use, some species have become predominant in farms and villages. However, knowledge on the distribution of these vectors in the country is sparse. From a public health point of view it is important to know the vectors, so that risk factors towards knowlesi malaria can be identified and control measures instituted where possible. Here, we review what is known about the knowlesi malaria vectors and ascertain the gaps in knowledge, so that future studies could concentrate on this paucity of data in-order to address this zoonotic problem.

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Advances in molecular and genomic research to safeguard food and feed supply from aflatoxin contamination

World Mycotoxin Journal ◽

10.3920/wmj2017.2283 ◽

2018 ◽

Vol 11 (1) ◽

pp. 47-72 ◽

Cited By ~ 9

Author(s):

D. Bhatnagar ◽

K. Rajasekaran ◽

M. Gilbert ◽

J.W. Cary ◽

N. Magan

Keyword(s):

Environmental Changes ◽

Safety Issue ◽

Integrated Approach ◽

Aflatoxin Contamination ◽

Control Measures ◽

Genomic Research ◽

Food And Feed ◽

Contamination Levels ◽

Feed Safety ◽

Food And Feed Safety

Worldwide recognition that aflatoxin contamination of agricultural commodities by the fungus Aspergillus flavus is a global problem has significantly benefitted from global collaboration for understanding the contaminating fungus, as well as for developing and implementing solutions against the contamination. The effort to address this serious food and feed safety issue has led to a detailed understanding of the taxonomy, ecology, physiology, genomics and evolution of A. flavus, as well as strategies to reduce or control pre-harvest aflatoxin contamination, including (1) biological control, using atoxigenic aspergilli, (2) proteomic and genomic analyses for identifying resistance factors in maize as potential breeding markers to enable development of resistant maize lines, and (3) enhancing host-resistance by bioengineering of susceptible crops, such as cotton, maize, peanut and tree nuts. A post-harvest measure to prevent the occurrence of aflatoxin contamination in storage is also an important component for reducing exposure of populations worldwide to aflatoxins in food and feed supplies. The effect of environmental changes on aflatoxin contamination levels has recently become an important aspect for study to anticipate future contamination levels. The ability of A. flavus to produce dozens of secondary metabolites, in addition to aflatoxins, has created a new avenue of research for understanding the role these metabolites play in the survival and biodiversity of this fungus. The understanding of A. flavus, the aflatoxin contamination problem, and control measures to prevent the contamination has become a unique example for an integrated approach to safeguard global food and feed safety.

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The Genetic and Environmental Adaptation of the Associated Liana Species Derris trifoliata Lour. (Leguminosae) in Mangroves

Forests ◽

10.3390/f12101375 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1375

Author(s):

Yun Zhang ◽

Kun Xin ◽

Baowen Liao ◽

Xihang Ai ◽

Nong Sheng

Keyword(s):

Clonal Growth ◽

Environmental Changes ◽

Principal Component ◽

Clonal Diversity ◽

Control Measures ◽

Nucleotide Polymorphisms ◽

Single Nucleotide ◽

Sexual Propagation ◽

Specific Locus ◽

And Control

Derris trifoliata Lour. is an indigenous and associated liana species of mangroves in China; however, its rapid dispersal is threatening mangrove survival. To explore and evaluate their persistence in past disturbances and their potential resistance to future climate and environmental changes, 120 D. trifoliata samples were collected from three sites in Guangdong Province, China, and they were used to develop single nucleotide polymorphic markers using specific-locus amplified fragment sequencing technology. A total of 351.59 Mb reads and 97,998 polymorphic specific-locus amplified fragment sequencing tags were identified, including 360,672 single nucleotide polymorphisms. The principal component analysis, phylogenetic tree, and genetic structure all clustered the samples according to their geographic positions. The three populations showed medium genetic diversity levels and high clonal diversity, indicating that sexual propagation played vital roles in the populations’ succession, although clonal growth was intense within the populations. An association analysis revealed that 9 out of 16 markers were correlated with nitrogen, which indicated the positive roles of nitrogen in population formation and maintenance. This study provides an ecological and molecular basis for understanding the outbreaks of D. trifoliata in mangroves. To control the further expansion of D. trifoliata in mangroves, preventive and control measures should be taken against clonal growth and sexual propagation, respectively; obstructing the clonal growth, especially that of the stolon, should be mainly considered at the junctions of D. trifoliata and mangroves.

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Resting behaviour of malaria vectors in a highland and a lowland site of western Kenya: Implication on malaria vector control measures

10.1101/815175 ◽

2019 ◽

Author(s):

Maxwell G. Machani ◽

Eric Ochomo ◽

Fred Amimo ◽

Jackline Kosgei ◽

Stephen Munga ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

Malaria Vector ◽

Control Measures ◽

Malaria Vectors ◽

Western Kenya ◽

Sporozoite Rate ◽

Resting Behaviour ◽

Outdoor Resting ◽

Indoor And Outdoor

AbstractBackgroundUnderstanding the interactions between increased insecticide resistance in field malaria vector populations and the subsequent resting behaviour patterns is important for planning adequate vector control measures in a specific context and sustaining the current vector interventions. The aim of this study was to investigate the resting behavior, host preference and infection with Plasmodium falciparum sporozoites by malaria vectors in different ecological settings of western Kenya with different levels of insecticide resistance.MethodsIndoor and outdoor resting Anopheline mosquitoes were sampled during the dry and rainy seasons in Kisian (lowland site) and Bungoma (highland site), both in western Kenya. WHO tube bioassay was used to determine levels of phenotypic resistance of first generation offspring (F1 progeny) of malaria vectors resting indoors and outdoors to deltamethrin. PCR-based molecular diagnostics were used for mosquito speciation, genotype for resistance mutations and to determine specific host blood meal origins. Enzyme-linked Immunosorbent Assay (ELISA) was used to determine mosquito sporozoite infections.ResultsOverall, 3,566 female Anopheles mosquitoes were collected with Anopheles gambiae s.l [In Bungoma, An. gambiae s.s (90.9%), An arabiensis (7.6%) and in Kisian, An. gambiae s.s (38.9%), An. arabiensis (60.2%)] being the most abundant species (74.7%) followed by An. funestus s.l (25.3%). The majority of An. gambiae s.l (85.4 and 58%) and An. funestus (96.6 and 91.1%) were caught resting indoors in Bungoma and Kisian respectively.Vgsc-1014S was observed at a slightly higher frequency in An. gambiae s.s hereafter(An. gambiae) resting indoor than outdoor (89.7 vs 84.6% and 71.5 vs 61.1%) in Bungoma and Kisian respectively. For An. arabiensis, Vgsc-1014S was 18.2% indoor and outdoor (17.9%) in Kisian. In Bungoma, the Vgsc-1014S was only detected in An. arabiensis resting indoors with a frequency of 10%. The Vgsc-1014F mutation was only present in An. gambiae resting indoors from both sites, but at very low frequencies in Kisian compared to Bungoma (0.8 and 9.2% respectively. In Bungoma, the sporozoite rates for An. funestus, An. gambiae, and An. arabiensis resting indoors were 10.9, 7.6 and 3.4 % respectively. For outdoor resting, An. gambiae and An. arabiensis in Bungoma, the sporozoite rates were 4.7 and 2.9 % respectively.Overall, in Bungoma, the sporozoite rate for indoor resting mosquitoes was 8.6% and 4.2% for outdoors. In Kisian the sporozoite rate was 0.9% for indoor resting An. gambiae. None of the outdoor collected mosquitoes in Kisian tested positive for sporozoite infections.ConclusionThe study reports high densities of insecticide-resistant An. gambiae and An. funestus resting indoors and the persistence of malaria transmission indoors with high entomological inoculation rates (EIR) regardless of the use of Long-lasting insecticidal nets (LLINs). These findings underline the difficulties of controlling malaria vectors resting and biting indoors using the current interventions. Supplemental vector control tools and implementation of sustainable insecticide resistance management strategies are needed in western Kenya.

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