Journal of Vector Borne Diseases最新文献

Visceral leishmaniasis (kala-azar) is caused by a protozoan parasite of genus Leishmania. India and neighboring countries comprise the largest focus of VL. Moderate to higher degree of fever accompanied by rigor and hepatosplenomegaly is the most typical clinical picture. We present a case of 50 years old male from Bhadohi (Uttar Pradesh) with high grade fever for 2 months without hepatosplenomegaly. On evaluation, there was bicytopenia with hyper-gammaglobulinemia. Work-up for tropical fever, tuberculosis, chronic viral etiologies and multiple myeloma was negative. Further evaluation on lines of fever of uncertain cause showed amastigote forms of Leishmania donovani (LD bodies) in bone marrow aspiration smears. Serology test rk-39 was positive. Thus final diagnosis of visceral leishmaniasis (kala-azar) with the atypical presentation without splenomegaly was made. Fever totally resolved in a week of starting treatment and blood parameters improved at 1 month follow-up. As definite treatment options are available, duration of illness and case fatality rate can be reduced by timely detection of atypical cases.

Background objectives: Vector-borne diseases have had a profound global impact causing millions of deaths each year. Essential oils (EOs) offer a promising alternative due to their natural properties. The EO collected from Pulicaria wightiana (DC.) C.B. Clarke was tested for its toxicity against the early life stages of three important vectors of diseases.

Methods: Concentrations of 3.125, 6.25, 12.5, 25 and 50 ppm were tested for their mosquitocidal properties.

Results: The EO from P. wightiana displayed 100% ovicidal mortality against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti eggs at 50 ppm concentration within 24 hours; it was similar to that of temephos the positive control. Strong mosquitocidal toxicity was observed, with LC50 values of 8.22, 13.27 and 10.80 ppm for larvae of Culex, Anopheles and Aedes, respectively at 24 hours. Caryophyllene oxide (22.44) and D-Limonene (19.08) were the main components in the EO accountable for the observed mosquitocidal toxicity. Toxicity studies indicated that the EO from P. wightiana did not adversely affect the tested predators. Additionally, the EO-mediated formulation presented strong ovicidal (100%) and larvicidal (89-95%) activities with no toxicity to natural predators such as Gambusia affinis and Poecilia reticulata at 24 hours.

Interpretation conclusion: These findings underscore the significance of plant-derived EO from P. wightiana as environmentally friendly and effective tool in combating mosquito-borne diseases, especially in regions facing resource constraints.

Background objectives: Mosquito-borne diseases such as malaria, dengue, zika, chikungunya, and filaria severely affect the health and economy of the countries which are endemic to these diseases. With the revolution in technology, insecticidal paint has been used in to control mosquitoes and other pests in developed countries.

Methods: In Indian market, several of water and oil-based surface coating paints are available that somehow also affect mosquito longevity.

Results: Among these paints, we have selected a few brands for the present study and observed that the water-based paint brand (WBP1) was found to be more potent in reducing vector density with KD50: 9.89, 13.09, 15.75, and 19.69 min; KD90: 25.59, 36.88, 38.88, 60.55 min with 92.5, 75, 75 and 30% mortality after the time period of 3, 30, 60, and 90 days respectively. In another brand paint (WBP2), knockdown time found to be KD50: 8.28, 9.86, 20.84 and 33.83 min; KD90: 24.53, 29.48, 49.55, 81.95 min with mortality of 90, 67.5, 16.66 and 5% after time duration of 3, 30, 60 and 90 days respectively. Oil based paint (OBP1) also found to be mosquitocidal with KD50: 12.11, 19.03, 27.48 and 37.36 min; KD90: 31.74, 53.19, 67.97, 81.38 min having 75, 70, 20 and 10% mortality in the time duration of 3, 30, 60 and 90 days after treatment.

Interpretation conclusion: This study might help open a window for sustainably controlling mosquito borne diseases.

Background objectives: Dengue virus (DENV), a Flaviviridae member, poses a global health challenge due to the absence of effective antiviral therapies. The viral nonstructural protein 5 (NS5), responsible for RNA synthesis and methylation, is a validated drug target. This study aimed to identify potential chalcone-based inhibitors of the NS5 methyltransferase domain.

Methods: Forty chalcone derivatives from the PubChem database were docked against the NS5 methyltransferase domain (PDB ID: 6KR2). The top six compounds were evaluated for drug-likeness (SwissADME) and toxicity (ProTox-II). Electronic properties were assessed using Density Functional Theory (DFT).

Results: Six chalcones showed better binding affinities (≥-7.0 kcal/mol) than the reference ligand S-adenosylhomocysteine (SAH, -6.2 kcal/mol), interacting effectively with the SAM-binding pocket. BL-1 had the strongest docking score (-7.8 kcal/mol) but showed toxicity concerns. BL-3 emerged as the most promising, with strong binding (-7.4 kcal/mol), excellent drug-likeness, low toxicity, and good synthetic accessibility. DFT analysis revealed that BL-4 had the lowest energy gap (ΔE = 3.59 eV), indicating high reactivity, while BL-3 had a stable HOMO (-6.45 eV) and a moderate energy gap (ΔE = 4.22 eV), suggesting a favorable balance of reactivity and stability.

Interpretation conclusion: BL-3 shows strong potential as an NS5 methyltransferase inhibitor due to its optimal binding, safety profile, and electronic properties. It is recommended for further lead optimization and experimental validation as a candidate anti-DENV agent.

Background objectives: Conventionally, the humoral immune response to scrub typhus (ST) is the early appearance of IgM during the first week of infection, followed by IgG after 2-3 weeks. Recent publications reveal different trends in Immunological response to ST.

Methods: Acute and convalescent blood from 55 (Group-I) and single samples from 152 (Group-II), both clinically suspected as ST, were subjected to ST IgM ELISA, ST IgG ELISA, and ST IgG IFA. Acute samples from Group I and single samples from Group II were subjected to Real-Time PCR (q PCR) to target three genes, 56 kDa, 47 kDa, and groEl.

Results: All 262 blood samples were positive for ST IgM ELISA. Positivity for IgG ELISA, IgG IFA and the presence of any one or more gene targets (56kDa/47kDa/groEL) in qPCR among the 55 acute samples was 70.9%, 36.4%, and 89.1%, respectively and 87.3%, 45.5% and 78.3% respectively in convalescent samples. In 152 unpaired samples, IgG ELISA was positive in 52.6% and 19.1% in ST IgG IFA. Among 207 samples (Group-I Acute and Group II) subjected to q PCR, groEl, 56 kDa and 47 kDa were present in 59.4%, 44.0%, and 35.7% respectively.

Interpretation conclusion: In view of the persistence of IgM in ST over months and, in some cases, years, there is a diagnostic dilemma in confirming ST based on single ST IgM, especially in ST-endemic regions. This is compounded by the additional presence of ST IgG in the early days of acute infection. q PCR is recommended to confirm doubtful cases of ST.

Background objectives: Arinta and Erin-Ijesha are popular waterfalls in Southwest Nigeria where preliminary assessments identified blackfly activity, yet data on vector dynamics and Onchocerca infectivity remain unavailable. This study investigated these parameters to assess the risk of onchocerciasis transmission at both sites.

Methods: Adult blackflies were collected for three consecutive days in a month by two dark complexioned adult male human landing catchers from September 2023 to August 2024. For each hour of sampling, 20% of the catches were randomly selected and dissected in real-time to assess parity and infectivity using standard procedure. The remaining flies were morphologically identified as savannah and forest flies and were preserved for O-150 pool screening.

Results: A total of 1090 Simulium flies were caught, Arinta (n=1012) and Erin-Ijesha (n=78). The peak monthly biting rate (MBR) were 3160.0 (Arinta, September) and 289.3 (Erin-Ijesha, October) bites/person/month while the lowest MBRs were 72.3 (Arinta, July) and 0.0 (Erin-Ijesha, January to March, May, July and August) bites/person/month. The MBR at Arinta was significantly higher than at Erin-Ijesha (p=0.02). The Annual biting rate (ABR) at Arinta (10,231.8 bites/person/year) exceeded the WHO threshold of 1000 bites/person/year, while below at Erin-Ijesha (790 bites/person/year). All morphologically examined flies were identified as forest species. No Onchocerca infectivity was detected in dissected or pool-screened (n = 857) flies.

Interpretation conclusion: Findings suggest low risk of onchocerciasis transmission at both waterfalls, with blackflies merely constituting biting nuisance. Continued public health education of tourist is recommended to allay their fears on the public health risk posed by blackfly bites, along with the use of protective clothing and repellents.

Background objectives: Chikungunya virus (CHIKV) is an alphavirus characterized by a positive-sense, single-stranded RNA genome, and it is transmitted primarily by Aedes mosquitoes. Prompt and precise diagnosis is essential for efficient clinical treatment, monitoring, and public health initiatives aimed at controlling CHIKV spread. Diagnostic methods include reverse transcription-polymerase chain reaction (RT-PCR) and serological assays, with lateral flow chromatographic immunoassays frequently used to detect IgM antibodies. The aim of this study is to compare the RT-PCR and chikungunya IgM antibody detection methods.

Methods: A diagnostic comparative study was conducted within the Pathology department at Aarogyam Hospital in Roorkee, Uttarakhand, India. In this study, two types of diagnostic methods were employed. Blood samples were obtained for the lateral flow chromatographic immunoassay IgM Combo Rapid test and Chikungunya RT-PCR. Statistical data analysis was conducted by using GraphPad and Microsoft Excel 2010.

Results: The study included 50 suspected chikungunya patients. The mean age of participants was 35.6±6.627 (mean±SD) within 7-75 years age groups. There were 26 men and 24 women among the participants. Out of the 50 patients, 27 were identified as chikungunya positive.

Interpretation conclusion: The study reveals the complimentary nature of RT-PCR and IgM chromatographic methods in the diagnosis of chikungunya. While RT-PCR is excellent for confirming current infections, IgM chromatographic methods provide important information on the immune response.

Background objectives: Container-breeding mosquitoes, including vector species such as Aedes aegypti and Aedes albopictus , are medically significant. This study assessed community structure, mutual interactions, and containersharing patterns of mosquito species to understand their community ecology in mid-western Nepal.

Methods: Mosquito larvae were collected from artificial containers of different ecological regions of mid-western Nepal during the post-monsoon season of 2024 using dropper and dipper methods. Mosquito larvae were reared, dead larvae and adults were identified, and their community composition was assessed using Margalef's index, the beta diversity index, Kendall's coefficient of rank correlation (T), Yule's coefficient of association (Q), and assessing co-occurrence patterns.

Results: The larvae of a total 15 mosquito species, including vectors of dengue, lymphatic filariasis, and Japanese encephalitis, were collected from five types of containers. The mosquito community structure varied in different altitudinal gradients and container types. Altitude and container types had an effect on the larval abundance of Ae. aegypti and Ae. albopictus . Mosquito species, including Ae. aegypti and Ae. albopictus showed different patterns of association with each other through container sharing.

Interpretation conclusion: Artificial water-holding containers commonly found around household premises can serve as potential breeding habitats for mosquitoes, including vector species such as Ae. aegypti and Ae. albopictus . The adaptation of dengue vector mosquitoes to other mosquito species in different container types indicates their capacity to establish in different environmental conditions. The presence and adaptability of different vector mosquitoes from the Terai to the high mountain region increased the risk of mosquito-borne diseases in mid-western Nepal and indicate the urgency of mosquito control programs.

Background objectives: Prior studies showed that repeated exposure of insecticides during the larval stage led to increase in vector resistance. However, gap of knowledge persisted in analysing the trend of insecticide resistance and cross resistance in mosquitoes upon sublethal treatment during its larval stage over generations with different insecticides. Therefore, the goal of the current study was to comprehend the pattern of insecticide resistance and cross resistance in Cx. quinquefasciatus larvae following four generations of sublethal deltamethrin, DDT and malathion treatment. The current study's research questions were (1) would there be an increasing trend of larval resistance observed upon repeated sublethal treatment on Cx. quinquefasciatus larvae with several insecticides in each generation, and (2) will the trend of resistance be different for each insecticide?

Methods: The larvae of Cx. quinquefasciatus in their early 3 rd instar were subjected to sublethal doses of deltamethrin (0.01 μg/ml), DDT (1 μg/ml), and malathion (1 μg/ml). The resilience of the larvae was noted after 24 hours of exposure. Statistical analyses were performed using Generalised Mixed Modelling (glmm) and Log likelihood ratio tests (LRT).

Results: The results revealed a trend displaying increase in the larval resistance across generations. Moreover, it was found that the larvae were showing more resistance against DDT followed by deltamethrin and malathion. The cross-resistance analysis demonstrated that larvae resistant to one class of insecticide exhibited an increased level of resistance to other insecticides across successive generations.

Interpretation conclusion: The study successfully evaluated a trend of increase larval resistance in Cx. quinque-fasciatus upon continuous exposure with DDT followed by malathion and deltamethrin over multigeneration. This study can act as a reference for future research especially in vector control management to develop novel vector strategies and stimulating resistance trend for different mosquito species.

Background objectives: Malaria remains a major cause of illness and death among under-five children in Tanzania, particularly in Butiama, a rural area in the Mara region, where high prevalence persists despite prevention efforts. This study examined predictors of insecticide-treated bednets (ITNs) use among caregivers of under-five children in Butiama, aiming to strengthen malaria prevention and improve child health outcomes.

Methods: The study employed a quantitative cross-sectional design with multistage sampling to select 384 caregivers of children under-five from the Butiama District. Data were collected from April to May 2024 using a structured Swahili questionnaire on the Kobo Toolbox. Analysis was performed using SPSS version 26.0, starting with data cleaning and completeness checks. Univariate analysis included descriptive statistics, while bivariate analysis assessed relationships between categorical variables. Multivariate analysis identified predictors at p<0.05.

Results: Among the participants, 82.3% owned a mosquito net, and 50.8% used it the night before the study. Femaleheaded households were 3.6 times more likely to use ITNs than male-headed ones (AOR=3.572, 95% CI [1.675- 7.618], P=0.001). Awareness of immediate ITN use post-delivery increased likelihood by 2.9 times (AOR=2.918, 95% CI [1.868-7.159], P=0.044). Primary-educated individuals were 2.3 times more likely to use ITNs than those with none or primary incomplete (AOR=2.281, 95% CI [1.001-5.618], P=0.017). Self-employed individuals were 36.6% less likely to use ITNs than peasants or homemakers (AOR=0.366, 95% CI [0.161-0.835], P=0.037).

Interpretation conclusion: This study reported a 50.8% ITN usage rate, below the national average. Key predictors of ITN use included being female, having primary education, and being aware of the correct timing for use. Targeted interventions, such as education campaigns and gender-sensitive strategies, are needed to improve ITN adoption and malaria prevention.