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Malaria Journal Jun 2024Elimination of malaria has become a United Nations member states target: Target 3.3 of the sustainable development goal no. 3 (SDG3). Despite the measures taken, the... (Review)
Review
Elimination of malaria has become a United Nations member states target: Target 3.3 of the sustainable development goal no. 3 (SDG3). Despite the measures taken, the attainment of this goal is jeopardized by an alarming trend of increasing malaria case incidence. Globally, there were an estimated 241 million malaria cases in 2020 in 85 malaria-endemic countries, increasing from 227 million in 2019. Malaria case incidence was 59, which means effectively no changes in the numbers occurred, compared with the baseline 2015. Jennifer Doudna-co-inventor of CRISPR/Cas9 technology-claims that CRISPR holds the potential to lessen or even eradicate problems lying in the centre of SDGs. On the same note, CRISPR/Cas9-mediated mosquito-targeting gene drives (MGD) are perceived as a potential means to turn this trend back and put momentum into the malaria elimination effort. This paper assessed two of the critical elements of the World Health Organization Genetically modified mosquitoes (WHO GMM) Critical Pathway framework: the community and stakeholders' engagement (inability to employ widely used frameworks, segmentation of the public, 'bystander' status, and guidelines operationalization) and the regulatory landscape (lex generali, 'goldilocks dilemma', and mode of regulation) concerning mosquito-oriented gene drives (MGD) advances. Based on the assessment findings, the author believes that CRISPR/Cas-9-mediated MGD will not contribute to the attainment of SDG3 (Target 3.3), despite the undisputable technology's potential. This research pertains to the state of knowledge, legal frameworks, and legislature, as of November 2022.
Topics: CRISPR-Cas Systems; Malaria; Animals; Disease Eradication; Humans; Sustainable Development; Community Participation; Mosquito Vectors; Gene Drive Technology; Mosquito Control; Gene Editing
PubMed: 38898518
DOI: 10.1186/s12936-024-04996-x -
Revista Da Sociedade Brasileira de... 2024Pressatia choti is a common sand fly found in the Atlantic Forest of Brazil, which is suspected to be involved in the transmission of Leishmania braziliensis. Herein, we...
BACKGROUND
Pressatia choti is a common sand fly found in the Atlantic Forest of Brazil, which is suspected to be involved in the transmission of Leishmania braziliensis. Herein, we aimed to establish a Pr. choti laboratory colony.
METHODS
Wild-caught female sand flies were blood fed on hamsters and maintained under controlled conditions (temperature: 26 °C; relative humidity: 70%).
RESULTS
Of the 301 collected female sandflies, 288 were identified as Pr. choti. The life cycle duration ranged from 31 to 56 days.
CONCLUSIONS
We successfully established a Pr. choti colony, whose biological parameters were similar to those of other neotropical sand flies.
Topics: Animals; Psychodidae; Leishmania braziliensis; Female; Insect Vectors; Brazil; Cricetinae
PubMed: 38896655
DOI: 10.1590/0037-8682-0060-2024 -
Parasite (Paris, France) 2024Anopheles coustani has long been recognized as a secondary malaria vector in Africa. It has recently been involved in the transmission of both Plasmodium falciparum and...
Anopheles coustani has long been recognized as a secondary malaria vector in Africa. It has recently been involved in the transmission of both Plasmodium falciparum and P. vivax in Madagascar. As most secondary malaria vectors, An. coustani mainly bites outdoors, which renders the control of this mosquito species difficult using classical malaria control measures, such as the use of bed nets or indoor residual spraying of insecticides. For a better understanding of the biology and vector competence of a vector species, it is useful to rear the species in the laboratory. The absence of a colony hinders the assessment of the bionomics of a species and the development of adapted control strategies. Here, we report the first successful establishment of an An. coustani colony from mosquitoes collected in Madagascar. We used a forced copulation procedure as this mosquito species will not mate in cages. We describe our mosquito colonization procedure with detailed biological features concerning larval to adult development and survival, recorded over the first six critical generations. The procedure should be easily applicable to An. coustani from different African countries, facilitating local investigation of An. coustani vector competence and insecticide resistance using the colony as a reference.
Topics: Animals; Anopheles; Madagascar; Mosquito Vectors; Female; Male; Malaria; Larva
PubMed: 38896103
DOI: 10.1051/parasite/2024032 -
Frontiers in Public Health 2024Insecticide-treated mosquito bed nets and indoor residual spraying are widely used for malaria vector control. However, their effectiveness can be affected by household...
BACKGROUND
Insecticide-treated mosquito bed nets and indoor residual spraying are widely used for malaria vector control. However, their effectiveness can be affected by household members' habits, requiring alternative approaches toward malaria vector control.
OBJECTIVE
To assess the effectiveness of modified houses in preventing mosquito entry; to assess the impact of house modifications on indoor air conditions and evaluate the acceptability of modified houses in the community where the study was conducted.
METHODS
Five traditional and five modified houses were constructed in Nampula district, Mozambique and underwent a 90-day overnight indoor mosquito collection using Centers for Disease Control and nitride ultraviolet light traps during the rainy season. Mosquitoes were identified morphologically. Indoor temperature, relative humidity, carbon dioxide levels and wind speed were also collected. The Student's -test was used to compare the means of the number of mosquitos and environmental factors between both house types. A binomial form of the Generalized Linear Model identified the factors associated with the community volunteer's preference for house type.
RESULTS
Modified houses reduced the number of by an average of 14.97 mosquitos (95% CI, 11.38-18.56, < 0.000) and non- by 16.66 mosquitoes (95% CI, 8.23-25.09, < 0.000). Although fewer mosquitoes were trapped in modified houses compared to traditional ones, the modifications were more effective against (94% reduction) than for non- (71% reduction). The average temperature increased at 0.25°C in modified houses but was not statistically significant (95% CI, -0.62 to 0.12, = 0.181). Community volunteers preferred modified houses due to reduced mosquito buzzing. The efficacy of modified houses including its acceptability by community, highlight its potential to lower malaria risk. Effective integration of modified houses into the vector control strategy will require raising awareness among communities about malaria risks associated with house structure and training them to modify their houses.
Topics: Mozambique; Malaria; Animals; Mosquito Control; Humans; Housing; Anopheles; Mosquito Vectors; Female
PubMed: 38894994
DOI: 10.3389/fpubh.2024.1404493 -
Parasites & Vectors Jun 2024Fleas, considered to be the main transmission vectors of Bartonella, are highly prevalent and show great diversity. To date, no investigations have focused on Bartonella...
BACKGROUND
Fleas, considered to be the main transmission vectors of Bartonella, are highly prevalent and show great diversity. To date, no investigations have focused on Bartonella vectors in Southeast China. The aim of this study was to investigate the epidemiological and molecular characteristics of Bartonella in fleas in Southeast China.
METHODS
From 2016 to 2022, flea samples (n = 1119) were collected from 863 rodent individuals in seven inland and coastal cities in Southeast China. Flea species, region, gender, host species and habitat were recorded. The DNA samples from each individual flea were screened by real-time PCR for the Bartonella ssrA gene. All positive samples were confirmed by PCR based on the presence of the gltA gene and sequenced. The factors associated with Bartonella infection were analyzed by the Chi-square test and Fisher's exact test. ANOVA and the t-test were used to compare Bartonella DNA load.
RESULTS
Bartonella DNA was detected in 26.2% (293/1119) of the flea samples, including in 27.1% (284/1047) of Xenopsylla cheopis samples, 13.2% (5/38) of Monopsyllus anisus samples, 8.3% (2/24) of Leptopsylla segnis samples and 20.0% (2/10) of other fleas (Nosopsyllus nicanus, Ctenocephalides felis, Stivalius klossi bispiniformis and Neopsylla dispar fukienensis). There was a significant difference in the prevalence of Bartonella among flea species, sex, hosts, regions and habitats. Five species of Bartonella fleas were identified based on sequencing and phylogenetic analyses targeting the gltA gene: B. tribocorum, B. queenslandensis, B. elizabethae, B. rochalimae and B. coopersplainsensis.
CONCLUSIONS
There is a high prevalence and diversity of Bartonella infection in the seven species of fleas collected in Southeast China. The detection of zoonotic Bartonella species in this study, including B. tribocorum, B. elizabethae and B. rochalimae, raises public health concerns.
Topics: Animals; Bartonella; China; Siphonaptera; Bartonella Infections; Genetic Variation; Rodentia; Female; Flea Infestations; Insect Vectors; Male; Phylogeny; DNA, Bacterial; Rodent Diseases; Prevalence
PubMed: 38890667
DOI: 10.1186/s13071-024-06305-6 -
BMC Plant Biology Jun 2024Little leaf disease caused by phytoplasma infection is a significant threat to eggplant (also known as brinjal) cultivation in India. This study focused on the molecular...
BACKGROUND
Little leaf disease caused by phytoplasma infection is a significant threat to eggplant (also known as brinjal) cultivation in India. This study focused on the molecular characterisation of the phytoplasma strains and insect vectors responsible for its transmission and screening of brinjal germplasm for resistance to little leaf disease.
RESULTS
Surveys conducted across districts in the Tamil Nadu state of India during 2021-2022 showed a higher incidence of phytoplasma during the Zaid (March to June), followed by Kharif (June to November) and Rabi (November to March) seasons with mean incidence ranging from 22 to 27%. As the name indicates, phytoplasma infection results in little leaf (reduction in leaf size), excessive growth of axillary shoots, virescence, phyllody, stunted growth, leaf chlorosis and witches' broom symptoms. PCR amplification with phytoplasma-specific primers confirmed the presence of this pathogen in all symptomatic brinjal plants and in Hishimonus phycitis (leafhopper), providing valuable insights into the role of leafhoppers in disease transmission. BLAST search and phylogenetic analysis revealed the phytoplasma strain as "Candidatus Phytoplasma trifolii". Insect population and disease dynamics are highly influenced by environmental factors such as temperature, relative humidity and rainfall. Further, the evaluation of 22 eggplant accessions revealed immune to highly susceptible responses where over 50% of the entries were highly susceptible. Finally, additive main effect and multiplicative interaction (AMMI) and won-where biplot analyses identified G18 as a best-performing accession for little leaf resistance due to its consistent responses across multiple environments.
CONCLUSIONS
This research contributes essential information on little leaf incidence, symptoms, transmission and resistance profiles of different brinjal genotypes, which together ensure effective and sustainable management of this important disease of eggplants.
Topics: Solanum melongena; Plant Diseases; Phytoplasma; Disease Resistance; Plant Leaves; India; Phylogeny; Animals; Hemiptera; Incidence; Insect Vectors
PubMed: 38890568
DOI: 10.1186/s12870-024-05257-4 -
Nature Communications Jun 2024Resistance to clinical malaria takes years to develop even in hyperendemic regions and sterilizing immunity has rarely been observed. To evaluate the maturation of the...
Resistance to clinical malaria takes years to develop even in hyperendemic regions and sterilizing immunity has rarely been observed. To evaluate the maturation of the host response against controlled repeat exposures to P. falciparum (Pf) NF54 strain-infected mosquitoes, we systematically monitored malaria-naïve participants through an initial exposure to uninfected mosquitoes and 4 subsequent homologous exposures to Pf-infected mosquitoes over 21 months (n = 8 males) (ClinicalTrials.gov# NCT03014258). The primary outcome was to determine whether protective immunity against parasite infection develops following repeat CHMI and the secondary outcomes were to track the clinical signs and symptoms of malaria and anti-Pf antibody development following repeat CHMI. After two exposures, time to blood stage patency increases significantly and the number of reported symptoms decreases indicating the development of clinical tolerance. The time to patency correlates positively with both anti-Pf circumsporozoite protein (CSP) IgG and CD8 + CD69+ effector memory T cell levels consistent with partial pre-erythrocytic immunity. IFNγ levels decrease significantly during the participants' second exposure to high blood stage parasitemia and could contribute to the decrease in symptoms. In contrast, CD4-CD8 + T cells expressing CXCR5 and the inhibitory receptor, PD-1, increase significantly after subsequent Pf exposures, possibly dampening the memory response and interfering with the generation of robust sterilizing immunity.
Topics: Humans; Malaria, Falciparum; Plasmodium falciparum; Male; Protozoan Proteins; Animals; Adult; Antibodies, Protozoan; Interferon-gamma; Female; Immunoglobulin G; Young Adult; CD8-Positive T-Lymphocytes; Mosquito Vectors; Anopheles
PubMed: 38890271
DOI: 10.1038/s41467-024-49041-2 -
Bulletin of Mathematical Biology Jun 2024Malaria remains a global health problem despite the many attempts to control and eradicate it. There is an urgent need to understand the current transmission dynamics of...
Malaria remains a global health problem despite the many attempts to control and eradicate it. There is an urgent need to understand the current transmission dynamics of malaria and to determine the interventions necessary to control malaria. In this paper, we seek to develop a fit-for-purpose mathematical model to assess the interventions needed to control malaria in an endemic setting. To achieve this, we formulate a malaria transmission model to analyse the spread of malaria in the presence of interventions. A sensitivity analysis of the model is performed to determine the relative impact of the model parameters on disease transmission. We explore how existing variations in the recruitment and management of intervention strategies affect malaria transmission. Results obtained from the study imply that the discontinuation of existing interventions has a significant effect on malaria prevalence. Thus, the maintenance of interventions is imperative for malaria elimination and eradication. In a scenario study aimed at assessing the impact of long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), and localized individual measures, our findings indicate that increased LLINs utilization and extended IRS coverage (with longer-lasting insecticides) cause a more pronounced reduction in symptomatic malaria prevalence compared to a reduced LLINs utilization and shorter IRS coverage. Additionally, our study demonstrates the impact of localized preventive measures in mitigating the spread of malaria when compared to the absence of interventions.
Topics: Humans; Malaria; Mosquito Control; Mathematical Concepts; Insecticide-Treated Bednets; Models, Biological; Insecticides; Animals; Mosquito Vectors; Prevalence; Computer Simulation; Anopheles; Endemic Diseases
PubMed: 38888640
DOI: 10.1007/s11538-024-01321-0 -
Expert Review of Vaccines 2024Malaria continues to remain a major global health problem with nearly a quarter of a billion clinical cases and more than 600,000 deaths in 2022. There has been... (Review)
Review
INTRODUCTION
Malaria continues to remain a major global health problem with nearly a quarter of a billion clinical cases and more than 600,000 deaths in 2022. There has been significant progress toward vaccine development, however, poor efficacy of approved vaccines requiring multiple immunizing doses emphasizes the need for continued efforts toward improved vaccines. Progress to date, nonetheless, has provided impetus for malaria elimination.
AREAS COVERED
In this review we will focus on diverse immune mechanisms targeting gametocytes in the human host and gametocyte-mediated malaria transmission via the mosquito vector.
EXPERT OPINION
To march toward the goal of malaria elimination it will be critical to target the process of malaria transmission by mosquitoes, mediated exclusively by the sexual stages, i.e. male, and female gametocytes, ingested from infected vertebrate host. Studies over several decades have established antigens in the parasite sexual stages developing in the mosquito midgut as attractive targets for the development of transmission blocking vaccines (TBVs). Immune clearance of gametocytes in the vertebrate host can synergize with TBVs and directly aid in maintaining effective transmission reducing immune potential.
Topics: Humans; Malaria Vaccines; Animals; Malaria; Vaccine Development; Mosquito Vectors; Plasmodium
PubMed: 38888098
DOI: 10.1080/14760584.2024.2369583 -
Parasites & Vectors Jun 2024Malaria transmission in Tanzania is driven by mosquitoes of the Anopheles gambiae complex and Anopheles funestus group. The latter includes An. funestus s.s., an...
BACKGROUND
Malaria transmission in Tanzania is driven by mosquitoes of the Anopheles gambiae complex and Anopheles funestus group. The latter includes An. funestus s.s., an anthropophilic vector, which is now strongly resistant to public health insecticides, and several sibling species, which remain largely understudied despite their potential as secondary vectors. This paper provides the initial results of a cross-country study of the species composition, distribution and malaria transmission potential of members of the Anopheles funestus group in Tanzania.
METHODS
Mosquitoes were collected inside homes in 12 regions across Tanzania between 2018 and 2022 using Centres for Disease Control and Prevention (CDC) light traps and Prokopack aspirators. Polymerase chain reaction (PCR) assays targeting the noncoding internal transcribed spacer 2 (ITS2) and 18S ribosomal DNA (18S rDNA) were used to identify sibling species in the An. funestus group and presence of Plasmodium infections, respectively. Where DNA fragments failed to amplify during PCR, we sequenced the ITS2 region to identify any polymorphisms.
RESULTS
The following sibling species of the An. funestus group were found across Tanzania: An. funestus s.s. (50.3%), An. parensis (11.4%), An. rivulorum (1.1%), An. leesoni (0.3%). Sequencing of the ITS2 region in the nonamplified samples showed that polymorphisms at the priming sites of standard species-specific primers obstructed PCR amplification, although the ITS2 sequences closely matched those of An. funestus s.s., barring these polymorphisms. Of the 914 samples tested for Plasmodium infections, 11 An. funestus s.s. (1.2%), and 2 An. parensis (0.2%) individuals were confirmed positive for P. falciparum. The highest malaria transmission intensities [entomological inoculation rate (EIR)] contributed by the Funestus group were in the north-western region [108.3 infectious bites/person/year (ib/p/y)] and the south-eastern region (72.2 ib/p/y).
CONCLUSIONS
Whereas An. funestus s.s. is the dominant malaria vector in the Funestus group in Tanzania, this survey confirms the occurrence of Plasmodium-infected An. parensis, an observation previously made in at least two other occasions in the country. The findings indicate the need to better understand the ecology and vectorial capacity of this and other secondary malaria vectors in the region to improve malaria control.
Topics: Anopheles; Animals; Tanzania; Mosquito Vectors; Malaria; Humans; RNA, Ribosomal, 18S; Polymerase Chain Reaction; Female; Plasmodium; DNA, Ribosomal Spacer
PubMed: 38886827
DOI: 10.1186/s13071-024-06348-9