Journal of Vector Borne Diseases最新文献

Loiasis colloquially known as tropical eye worm is a neglected tropical helminthic disease that affects the rural poor population of Gabon. A systematic review of 51 documents (45 peer reviewed papers and six dissertations) over four decades has documented many knowledge gaps on loiasis and its vectors. Higher prevalence and high microfilaremia is typical wherever Chrysops vectors occur. The two main vectors were C. silacea and C. dimidiata along with the savanna species C. longicornis. The two main vectors were only caught around forested national parks at low density (<1 Chrysops per trap per day). Chrysops longicornis was trapped in the savanna zone at higher numbers at a cattle ranch in Nyanga province. Leukoconcentration and Field's stain for L. loa diagnosis performed well as diagnostic tools. However, studies on diagnostic efficacy remain scant, and no study has focused on the evolution of L. loa at the wildlife-human interface of Gabon.

Background objectives: More than 1 million people die every year from vector-borne diseases, which constitute more than 17% of all infectious diseases. This study's primary focus is on the detailed evolutionary history and expression analysis of immune genes, one of the key gene families in the immune system of vectors that play a role in the regulation and interaction of parasites in vector bodies, particularly the mosquitoes that transmit malaria and dengue, significant vector borne disease.

Methods: The vector potentiality and participation of TLR genes in vector parasite interaction in the Indian context will be explained by the differential expression study of this potential gene family in Indian populations of vector species.

Results: This knowledge is supportive undoubtedly for creating new pharmacological targets and inhibitors that can create insect-based transmission stopping techniques for many vector-borne diseases.

Interpretation conclusion: However, the genetic diversity was found to be comparatively lower in the Toll1A gene than in the NOS immune gene in the malaria vector An. minimus population samples which supports the hypothesis of positive selection in recent evolutionary time scale in malaria vectors. This is one of the novel strategies to identify transmission regulating genetic traits that are controlling the vector-parasite interaction and co-evolution in vector borne disease.

Background objectives: Aedes albopictu and Culex pipiens pallens are important vectors of many viruses and have had resistance to chemical pesticide. Spinosad is a selective biological insecticide to control urban mosquito. The aim of this study was to reveal the sublethal effects of spinosad on mosquito and provide reference basis for integrated mosquito management.

Methods: The toxicity of spinosad against Ae. albopictus and Cx. pipiens pallens were determined under laboratory conditions by exposing early third-instar larvae to different concentrations.

Results: The LC50 values of spinosad to Ae. albopictus and Cx. Pipiens pallens larvaes were 4.44×10-3 mg∙L-1 and 1.93×10-3 mg∙L-1 respectively after 72 h exposure. Spinosad at sublethal concentrations has many negative effects on Ae. albopictus and Cx. Pipiens pallens larval, pupae, adult and offspring eggs, including significantly reduced their larvae pupation rate by 51.37% and 58.47%, significantly prolonged pupae length by 21.43% and 16.18%, reduced female wing-spans by 20.19% and 14.89%, reduced male wing-spans by 3.84% and 7.54%, reduced female weight by 29.04% and 31.52%, reduced male weight by 7.47% and 9.07%, reduced female and male ratio by 51.98% and 45.21%, reduced individual egg-laying amount by 15.73% and 35.51%, in addition, offspring egg hatchability were dramatically decreased by 25.71% and 34.04%, egg periods were significantly prolonged by 14.42% and 62.82% respectively. No significant effect on larval period, pupae emergence rate, female bite rates were observed.

Interpretation conclusion: These results suggest that spinosad might affect pest population dynamics significantly and is fairly expected to be a candidate biological pesticide for mosquito control.

Background objectives: Biting midges are hematophagous arthropods responsible for zoonotic infectious diseases and have a wide distribution in temperate and tropical latitudes of the world.

Methods: The genomic DNA of midge samples was extracted using the Chelex method and the ITS1gene was amplified by PCR to identify the midge species via BLAST. The sequence characteristics and the genetic diversity were analyzed using ClustalOmega, DnaSP, Arlequin, PopART, and TCS software tool. The validity of the ITS1 gene as a DNA barcode marker was evaluated using DAMBE. The phylogenetic relationship was established in the MEGA software. The ABGD web determined the species boundary and the SDT software visualized the pairwise sequence comparisons.

Results: A total of 39 midge samples possessed the range from 364 to 429 bp of the ITS1 sequences. The midge samples were identified as Culicoides imicola, Culicoides oxystoma, Culicoides peregrinus, Culicoides jacobsoni, Forcipomyia peregrinator, and Culicoides fulvus, respectively. The ITS1 sequences had 288 conserved sites (60.25%), 167 variable sites (34.94%), 141 parsimony-informative sites (29.50%), and 26 singleton sites (5.44%), with a considerable sequence variation with a high haplotype diversity. Populations in Lingao, Haikou, Tunchang were relatively independent, with a low level of gene flow. A separate population of Forcipomyia genus in Danzhou was observed.

Interpretation conclusion: The biting midges in Hainan, a tropical island, had abundant genetic diversity. Timely surveillance is a crucial control measure for the spread of midge-borne diseases.

Background objectives: Dengue is an emerging vector-borne viral disease in tropical and subtropical areas such as Burkina Faso that experienced dengue outbreak in, 2013, 2016, 2017 and more recently in 2023. This study aimed to determine the seroprevalence and dengue serotype in suspected patients in Ouagadougou, Burkina Faso.

Methods: The study was conducted during October and November 2023 and included suspected febrile patients seen at HOSCO and CERBA. Plasma or serum samples were used for the detection of non-structural proteins (NS1) and IgM and IgG antibodies against the dengue virus using SD Bioline Dengue Duo rapid detection kit. Viral RNA was extracted using the QIAamp Viral RNA Mini Kit and dengue serotypes were determined by real-time RT-PCR using the Dengue Real-TM Genotype kit.

Results: The study population consisted of 896 patients, including 397 (44.3%) men and 499 (55.7%) women. Dengue seroprevalence was 16.5% (148/896) with 14.1% (126/896) of patients positive for the NS1 antigen, 1.3% (12/896) positive for IgM, and 2.7% (24/896) positive for IgG. Serotyping among 40 out of 45 positive patients revealed 77.5% (31/40) DENV-3, 17.5% (7/40) DENV-1, and 5.0% (2/40) DENV-2.

Interpretation conclusion: The present study report a high seroprevalence of dengue virus infection among patients during the months considered as the peak of infection in Burkina Faso. The results revealed a predominance of DENV-3. Continuous surveillance of dengue virus serotypes circulating in Burkina Faso is crucial.

Background objectives: Dengue is arthropod-borne, acute potentially fatal viral infection, endemic in many tropical and sub-tropical countries having public health threat globally in recent era. Effective and prompt diagnosis is very essential to reduce morbidity and mortality associated with severe form. Diagnosis by dengue-specific markers like Non-Structural protein 1 antigen or IgM/IgG antibody by serological method is the choice of investigation and the most widely used non-specific biomarker is platelet count. To evaluate and correlate results of two serological diagnostic methods (Dengue NS1 Antigen and Dengue IgM antibodies by Enzyme-Linked Immunosorbent Assay) and with platelet count for diagnosis of Dengue infection.

Methods: Retrospective cross-sectional study for duration of 6 months from April 2022 to September 2022. Total 4063 serum samples of dengue suspected patients were tested according to duration of illness by ELISA for presence of NS1 Ag (≤5 days of illness) or IgM antibody (>5 days of illness).

Results: 393/4063 were detected positive by either method (NS1/IgM) and majority of patients were diagnosed between 3-8 days of illness. 248/2250 were tested positive for dengue NS1-Ag only, while 145/1813 were seropositive by dengue IgM only. Thrombocytopenia (platelet counts <100000/mm3) found in 301/393 seropositive cases which was also observed in NS1 (207/248 cases) and IgM (94/145 cases) seropositive patients.

Interpretation conclusion: Dengue specific parameters (NS1/IgM detection) in combination with platelet count helps in accurate, timely diagnosis and better monitoring in clinical management of patients.

Mosquitoes (Diptera: Culicidae) transmit many pathogens and parasites such as viruses, bacteria, protozoans and nematodes, which cause serious diseases such as malaria, dengue, yellow and Chikungunya fever, encephalitis or filariasis etc. Traditionally, control of these mosquitoes has relied on the use of several chemical insecticides. These insecticides have been used to control the various life stages of mosquitoes, but some of these insecticides are causing harm to the environment, human, plants and animals which in turn cause environmental pollution. Presently, NPs are thought to be used as an effective insecticide. Most of the NPs having insecticidal properties are prepared through green synthesis method, where extracts from plants, fungi, bacteria, and even dead insects have been efficaciously employed to decrease or to kill mosquito population. Biological and green synthesis method has resulted in the production of less toxic or nontoxic and sustainable NPs for further application in mosquito control. The evaluation of green chemistry or biological techniques for synthesizing metal NPs from plant extracts and other biological organisms has drawn the attention of many researchers. This review explores the usefulness of green synthesized various metal NPs on larvae, pupae and adults of mosquitoes.

Background objectives: Dengue fever is one of the most common causes of undifferentiated tropical fevers in hospitalized children across India with the highest recorded morbidity and mortality in children less than 15 years. Although common, there is still a knowledge gap regarding epidemiological factors. The aim was to study the clinical profile and demographic trend over the past 5 years in children with confirmed dengue infection.

Methods: Observational study of children admitted as inpatients over the past 5 years and diagnosed with dengue infection by serology. Categorical data were presented as percentages. Data regarding rainfall was collected from rainfall statistics from the Indian Meteorological website and correlated based on the T-test. The incidence of dengue infection in COVID-19 predominant years was analyzed using the correlation plot and trend of severe dengue infection over the years was noted by Line plot.

Results: The study showed a positive correlation between rainfall and an increase in the incidence of cases. There were relatively reduced number of cases during COVID-19 which was interpreted from the correlation plot. The Line plot determined the trend of severity of presentation and more severe cases presented in the years 2019, 2021 and 2022.

Interpretation conclusion: Other than the pathophysiology, studies to understand the change in the severity of clinical presentation each year could help in augmenting the vector control measures accordingly.

Background and objectives: Occurrence and distribution of vector population are crucial for entomological study in context of prevention, control and elimination of vector-borne diseases. To update some entomological aspects in three districts of Tamil Nadu state namely Kumbakonam, Nagapattinam and Thriuvarur districts, the study was undertaken. The objective of the study was to understand the prevalence of mosquitoes; to assess insecticide resistance and phylogenetic analysis of dengue vectors [Aedes (Ae.) aegypti and Ae.albopictus].

Methods: The immature stages of mosquitoes were collected from different localities by standard WHO methods marking with GPS and mapping was done using ArcGIS 10.4 software for all three districts. Insecticide resistance test was conducted using WHO susceptibility test kits. The F1 generation of female adult mosquitoes of Ae. aegypti and Ae. albopictus were exposed to DDT 4% and Malathion 5% with the control paper of Risella oil and olive oil respectively. Further, genomic DNA of individual mosquito was isolated, and the sequencingwas done through Eurofins, Bangalore, India. The FASTA sequence was analyzed and the phylogenic tree was constructed using the Maximum likelihood method in Molecular Evolutionary Genetics Analysis (MEGA) software (version 10.0).

Results: A totally 5307 specimens were collected through expanded survey in all three study areas. The collection yielded 16 species from six genera of mosquitoes. In total collection, the Ae. albopictus was the dominant species in Kumbakonam and Thiruvarur districts and Ae. aegypti was dominant in Nagapattinam district. The predominant breeding sources were discarded tyre with rainwater, plastic cups, coconut shells, aluminum vessels, sliver containers, bottles, grinding stones and earthen pots etc. The study revealed high pupal indices in all three study areas. Insecticide resistance monitoring revealed possible resistance in Ae. aegypti against DDT in all three districts whereas against Malathion, possible resistance was recorded in Kumbakonam and Nagapattinam and in Thiruvarur district, the species was found to be susceptible. Ae. albopictus showed resistance against DDT in all three districts but susceptible to Malathion. The sequences obtained for Dengue vectors showed 99% similar with Genbank. The phylogenetic tree was constructed using COI region sequences. Certainly, observed the different genetic relationship among Ae. aegypti and Ae. albopictus between the study areas.

Interpretation conclusion: The study confirmed the presence of Ae. aegypti and Ae. albopictus in all three districts. The study further revealed that these vectors are susceptible to Malathion but resistance to DDT. The continue surveillance of dengue vector and monitoring of insecticide resistance will strengthen the control programme for appropriate vector control measurements.

Background objectives: Crimean-Congo Hemorrhagic Fever disease (CCHF) is a potentially deadly viral disease and Turkey is the country in which the disease is seen the most. The purpose of this study is to estimate the frequency and case fatality ratio (CFR) of CCHF disease in Erzurum/Turkey between years 2015-2021.

Methods: The CCHF positivity in patients was detected on serum samples via RT-PCR method with RNA detection. Demographic data belonging to positive patients, such as, age, sex, region of residence, tick contact was analyzed retrospectively.

Results: It was detected that the RT-PCR test of 521 patients out of a total of 1378 sent to the laboratory were positive. Each sample belonged to a single patient and repeating samples were left out of the research. The year with least positive patient ratio in relation to potential CCHF positive samples was 2017 (21.12%) whereas the year with the most positivity ratio was 2020 (55.48%) The case fatality ratio in the six-year period was calculated to be 1.34%.

Interpretation conclusion: This study has demonstrated that there is a significant rise in CCHF patient numbers, especially in 2020 when the Covid-19 pandemic started. In order to prevent this rise, it is crucial that the effect of Covid-19 pandemic on the increase in interactions of humans with ticks is researched thoroughly, a biological intervention is made and the public awareness on CCHF disease is increased.