Journal of Vector Borne Diseases最新文献

Background objectives: Mosquito vectors are a significant cause of pathogen transmission to both animals and humans. Mosquitoes are responsible for transmitting various diseases, including chikungunya, filariasis, West Nile fever, dengue, malaria, and Zika fever, placing approximately 80% of the world's population at risk of infection at any given time. Controlling mosquitoes has become a multifaceted challenge, influenced by diverse environmental factors such as deforestation, urbanization, and climate change on a global scale. For centuries, medicinal plants have been utilized as bioinsecticides to control insect pests. Ziziphus mauritiana, also known as Chinese apple or Indian jujube is a deciduous thorny tree or shrub. Different parts of the Z. mauritiana plant have been traditionally used to treat various common diseases, a practice still prevalent in India and China.

Methods: In the current investigation, the chemical properties of the Z. mauritiana leaf extract were examined through UV-Vis Spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), and GC-MS Analysis. Second and fourth instar larvae, as well as pupae, of Aedes aegypti and Culex quinquefasciatus were subjected to different concentrations of the methanolic extract of Z. mauritiana for 24 h and 48 h to assess larvicidal and pupicidal activity.

Results: The FT-IR spectrum analysis revealed the presence of various functional groups in the chemical compounds extracted from Z. mauritiana , including amines, aromatics, alkanes, alkyls, carbonyls, and carboxylic acids. Additionally, GC-MS analysis identified Isoborneol (25.37%), 4-Acetylbutyric Acid (26.82%), and 2-Vinyl-9-[Beta-D-Ribofuranosyl] Hypoxanthine (24.24%) as the three major phytoconstitutents in the methanol extracts of Z. mauritiana. Regarding the larvicidal activity, the methanolic extract of Z. mauritiana exhibited LC 50 values of 155.67 mg/L and 208.57 mg/L for second instar larvae, and 177.68 mg/L and 252.13 mg/L for fourth instar larvae of Cx. quinquefasciatus and Ae. aegypti, respectively, after 24 h of exposure. For pupicidal activity, the LC 50 values were 502.02 mg/L and 514.99 mg/L on pupae of Cx. quinquefasciatus and Ae. aegypti, respectively, within 24 h.

Interpretation conclusion: Overall, the GC-MS analysis provides valuable insights into the chemical composition of the Z. mauritiana extract, highlighting its potential as a natural and eco-friendly alternative for combating insect vectors and contributing to integrated mosquito management programs.

Background objectives: Mass Drug Administration of Di-Ethyl Carbamazine and Albendazole is an effective strategy recommended by World Health Organization (WHO) to prevent transmission and eliminate Lymphatic Filariasis. Under the National Vector Borne Disease Control Programme in India, Mass Drug Administration (MDA) is carried out as a yearly activity in endemic areas to accelerate the progress towards elimination of lymphatic Filariasis. The study was carried with the objective to determine the coverage of Mass Drug Administration against Lymphatic Filariasis among the eligible population in Kalaburagi district and delineate the common reasons for non acceptance of MDA.

Methods: Field based cross sectional survey was carried out in Kalaburagi. Cluster sampling of 4 clusters (3 rural and 1 urban) from four different taluks (one cluster from each taluk) of the district reporting high, medium and low coverage of MDA (as reported by District Malaria Office) Members from selected Households in all clusters were interviewed regarding MDA administration, Directly Observed treatment, side effects and any co morbidities which ruled out MDA administration. Responses documented as tally marks in assessment sheets shared by National Vector Borne Disease Control Programme office. Proportions, frequencies, and mean were calculated and inferential statistics were used.

Results: A total of 1263 individuals were assessed for Mass Drug administration from a total of 240 households (60 households in each cluster). The coverage of MDA varied from 90.33% in Heerapur in Kalaburagi Urban to 97.87% in Mogala thanda (Chittapur Taluk).

Interpretation conclusion: MDA Coverage against Lymphatic Filariasis has improved when compared to previous reported studies carried out and it has also exceeded the coverage threshold as determined by programme for elimination of Lymphatic Filariasis.

Background objectives: Mosquitoes vectors are the key threat that spread viruses, bacteria, nematodes, protozoans, and other infections responsible for the transmission of serious public health ailments including dengue, yellow fever, malaria, chikungunya, etc.

Methods: To rear and cultivate mosquitoes at multiple stages of development (egg, larva, pupa, and adult) to be employed in various biomedical research, an innovative tool mosquito larva adult 2-in-1 rearing jar was designed and developed. The eggs/larvae or adults collected from the field or laboratory cultures can be released into the lower larvae or upper adult-rearing chamber so that they can find a suitable breeding place to oviposit or metamorphose into wrigglers and tumblers attaining the adult stage. Aedes, Anopheles, and Culex are three significant genera (Diptera: Culicidae) that were reared in experiments using this jar (Method I) in contrast to other conventional instruments available (Method II).

Results: Results of one-way ANOVA showed that the prototype was compatible and competitive for rearing as the data was non-significant when compared in both groups. However, throughout the trials, it was discovered that the prototype had a greater record of mean percentage of adult emergence (98.33), which supports the novelty of the instrument.

Interpretation conclusion: This unique device eliminates the need for multiple tools, causes minimum bodily damage to stages during handling, can be used in both the lab and the field, is inexpensive, lightweight, portable, and requires a single manpower to operate.

Background objectives: Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease caused by several species of the protozoan parasite Leishmania. The need for new anti-leishmanial drugs for the treatment of CL is highlighted by factors such as high cost, toxicity, potential for resistance and limited long-term use of existing anti-leishmanial drugs. The aim of this study was to investigate the therapeutic effect of Tarantula cubensis alcoholic extract (TCE), which has been shown to have wound-healing, anti-inflammatory, regenerative, resolving and epithelialising effects, on L. major promastigotes in vitro and in vivo in an experimental mouse model of CL.

Methods: The effect of TCE on L. major promastigotes in vitro was investigated after determination of non-cytotoxic concentrations of TCE using the XTT method. To establish a CL model, L. major amastigotes were injected into the paws of BALB/c mice. Lesion size and histopathological evaluation were used to assess the effect of treatment.

Results: TCE was found to be effective against L. major promastigotes at 24 h and 48 h at concentrations of 250 μg/mL, 125 μg/mL and 62.5 μg/mL ( P <0.05). TCE was found to be more effective than meglumine antimonate in treating CL in the experimentally induced CL model in BALB/c mice.

Interpretation conclusion: The results suggest that TCE holds promising potential therapeutic agent for the treatment of CL. However, further extensive investigations are required to substantiate and expand understanding in this area.

Background objectives: Mosquito-borne diseases are a major health issue among communities in Asia, and dengue has grown up as a serious public health concern in Sri Lanka with varying magnitude since 1960. With the realization of the failures and limitations of current vector control strategies, the authorities are moving towards simple, low-cost, and eco-friendly vector management methods. Thus, the present study was devised to evaluate the potential densities of mosquito natural enemies in natural water habitats in Galle district, Sri Lanka, and to investigate the feeding efficacy of prominent mosquito natural enemies on main dengue vectors ( Aedes sp.) in a laboratory setting.

Methods: The survey was carried out using eight sentinel sites in Galle district, and samples of mosquito natural enemies and mosquito larvae were collected, and then they were identified using taxonomic keys.

Results: Study records, the aquatic insects of Family Hydrometridae, Belostomatidae, Notonectidae, Nepidae, Ranatridae, and Corixidae as dominant mosquito natural enemies, and Libellulidae and Dytiscidae insects as sub-dominant families. The highest density of the family Hydrometridae was recorded in rural, natural inland, and rocky study sites. The order Hemiptera was recorded as the key order of the mosquitoes natural enemies in Galle district. The family Hydrometridae had the highest density of recorded mosquito natural enemies.

Interpretation conclusion: Aedes aegypti and Ae. albopictus were recorded as abundant vector mosquitoes. Family Nepidae is the most effective natural mosquito predator on Ae. aegypti and Ae. albopictus, and this knowledge will be vital for implementing future biological control strategies for Aedes vectors in Sri Lanka.

Background objectives: Scrub typhus is clinically undifferentiated from other aetiologies for acute febrile illness such as enteric fever, dengue, malaria, and leptospirosis. Rapid ELISA tests are being used as an alternative to immunofluorescence assay in tropical countries.

Methods: In this study, we compared and evaluated commercially available InBios Scrub Typhus Detect IgM Rapid Test (USA) for diagnosing human scrub typhus infection using archived and prospectively collected samples against the reference standard, InBios Scrub Typhus Detect IgM ELISA (USA).

Results: The data analysis of archived samples on rapid test revealed a moderate sensitivity of 53.92% and a specificity of 100%. Meanwhile, prospective serum samples demonstrated higher sensitivity and specificity of 96.4% and 94.6%, respectively.

Interpretation conclusion: The InBios Scrub Typhus Detect IgM rapid test can be a good point-of-care assay during surveillance, outbreak investigations, and case identification.

Background objectives: Aedes aegypti and Aedes albopictus are two sympatric mosquito species that compete with each other for resources when their breeding habitats overlap. This study examines what happens when sympatric Aedes aegypti and Aedes albopictus mosquitoes' mate with each other and other species by looking at insemination rates, fecundity, and hatchability rate.

Methods: We performed controlled mating experiments in laboratory setting, assessing both conspecific and interspecific crosses. We measured insemination rates, egg numbers, and hatching success to examine the reproductive interference dynamics between these two distinct mosquito species.

Results: In the context of conspecific mating, it was observed that both female Ae. aegypti and Ae. albopictus exhibited high insemination rates, with percentages of 98% and 94%, respectively. However, interspecific mating exhibited interesting asymmetries: Ae. albopictus males achieved a notable insemination success rate of 28% when mating with Ae. aegypti females, while Ae. aegypti males achieved only 8% insemination success with Ae. albopictus females. Additionally, females that mated with interspecific males had reduced production of viable eggs compared to conspecific mating. Most notably, interspecific mating resulted in the production of infertile eggs, while conspecific mating led to successful hatching.

Interpretation conclusion: The study reveals that, Ae. aegypti and Ae. albopictus can asymmetrically interfere with each other's reproduction, causing a 'satyr' effect. This understanding of interspecific competition and reproductive interference in these mosquito species could impact their coexistence in shared breeding habitats.

Background and objectives: RNA viruses are complex pathogens in terms of their genetic makeup, mutation frequency, and transmission modes. They contain the RNA helicase enzyme, which plays a crucial role in the viral genome replication process. This work aims to develop and screen a potential molecule that could function as a dengue virus (DENV) RNA helicase inhibitor.

Methods: The present study was performed by taking 26 potential derivatives of gedunin phytochemicals from the PubChem database as ligands. The binding study of the compounds were analyzed by in silico docking method considering DENV RNA helicase enzyme as the receptor.

Results: After a thorough analysis of the docking scores, toxicity, and physicochemical properties, compound tetrahydrogedunin was obtained as the best. Based on tetrahydrogedunin molecular structure, 100 drug-like molecules were designed using the Data Warrior tool. After the screening process for drug-likeness and ADMET properties, the derivative number 42 was considered as the promising. Further comparative docking of derivative 42 and a standard inhibitor molecule ST-610 with DENV RNA helicase enzyme showed binding affinity as -10.0 kcal/mol and -9.6 kcal/mol, respectively. The favorable interaction between DENV RNA helicase and derivative 42 was further validated by 50 nanoseconds molecular dynamics simulation and MM-GBSA analysis.

Interpretation conclusion: Since the antiviral activity of derivative 42 has not been reported till date, the compound was predicted as a novel therapeutic molecule that can act against the dengue virus (DENV) RNA helicase enzyme.

Background objectives: Biological approaches for vector mosquito control such as sterile insect technique (SIT) requires sterilization of male mosquitoes through specific radiation doses for sterility induction in males. Under the SIT program, the males used must be compatible with the wild males in vigor, flight and selection of mate. Much of this potential is determined by the diet provided in the larval stages and optimizing the irradiation doses that cause complete sterility but have very minimal effect on the lives of irradiated males. The current study is designed to evaluate gamma radiation doses for inducing sterility in male Aedes aegypti mosquitoes with a genomic background from Pakistan (Swat district) and to assess the effects of radiation exposure on the competency of irradiated males and other life traits of irradiated mosquitoes.

Methods: Sterilization of 17-hour-old male pupae (groups of 50 pupa/cup in three replicates) of the Ae. aegypti Swat strain was conducted using radiation doses of 30, 60, 70, 90, and 105 gray (Gy) from (Co60) at the Nuclear Institute for Food and Agriculture (NIFA) in Peshawar, Pakistan. Post-irradiated pupae were released in adult cages. Virgin females of the same cohort were released (1:1) to mate with the irradiated males. Mortality, longevity, mating competitiveness of males, and female fecundity were recorded.

Results: An average of 71 eggs per female was recorded in control with 86% hatch rate. Individual females mated with a 60 Gy treated males produced 60 ± 0.6 eggs per female with 17% hatch rate, and those mated with 70 Gy males produced 42 ± 0.01 eggs with a nil hatch rate, whereas females mated with males treated with ≥70 Gy doses did not reproduce to next generation. Females in groups of 50 mated with 60, 70 Gy treated males (equal pairs), produced 369±1.3 and 98±0.01 eggs with 15% and zero hatch rate. Significant dose dependent reduction in longevity was observed for >30 Gy doses. The matting competence of irradiated males was about half that of un-irradiated males.

Interpretation conclusion: Aedes aegypti with a Pakistani genomic background treated with a ≥70 Gy dose of gamma radiation induced complete sterility in males and provided the first- step foundation for SIT application in Pakistan. Further extensive studies are required to optimize the SIT techniques so that fully sterile males with very minor quality changes can be produced on large scales for field trials.

Background objectives: Leishmaniasis is caused by various species of parasite Leishmania. Approximately twenty of them are pathogenic to mammals. In Sri Lanka, cutaneous leishmaniasis (CL) is an established vector-borne disease. CL originates and spreads mainly through sandfly bite in many endemic countries. The aim of the present study was to compare the geographical distribution and demographic features of CL cases in Hambantota district, Sri Lanka in 2014 and 2016.

Methods: The patients who were presented to the Tangalle Base Hospital from June to December in 2014 and 2016 were examined and a descriptive study was carried out using a structured-questionnaire. Slit-skin smears were collected from each patient, Giemsa-stained and examined under the light microscope to identify Leishmania amastigotes.

Results: Out of 256 and 314 suspected CL patients, 156 and 155 were identified positive for the year 2014 and 2016, respectively. Out of 12 District Secretary Divisions (DSD) in Hambantota district, the highest number of CL cases, 85 and 86 was reported from Tangalle DSD in 2014 and 2016 respectively. Number of identified CL patients in Beliatta DSD had increased from 50 to 67 during the study period. In both years, majority of CL patients were ≥50 years old with males more infected than females. Although CL association with occupations were insignificant, housewives were the highly (23%) infected occupants in this area.

Interpretation conclusion: Based on the present findings, geographical distribution within DSDs in Hambantota district had changed. This emphasizes the importance of CL as a health problem in Hambantota district.