Journal of Vector Borne Diseases最新文献

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.

The Chandipura virus (CHPV) is an emerging arbovirus in India, transmitted primarily by sandflies and associated with outbreaks of acute encephalitis in children. First identified in 1965 in Maharashtra, CHPV has since been linked to Acute Encephalitis Syndrome (AES) in several states, including Maharashtra, Gujarat, Telangana, and Madhya Pradesh. The virus predominantly affects children under 15 years, particularly in rural areas with poor housing conditions, and is most prevalent during the monsoon season when sandfly activities are high. Its clinical presentation includes a rapid-onset febrile illness progressing to encephalitis, often with a high case fatality rate. Diagnostic challenges arise due to similarities with other arboviral infections, complicating outbreak management. Current public health interventions emphasize vector control, environmental sanitation, and community awareness, though the lack of specific antiviral treatment and vaccines remains a significant barrier. This review highlights the need for improved surveillance, diagnostic tools, and vaccine development to mitigate the potential public health impact of CHPV in India. A One Health approach, integrating human, animal, and environmental health, is crucial for the effective management and prevention of CHPV outbreaks.

Background objectives: Visceral leishmaniasis (VL, or Kala-azar) is a potentially lethal vector-borne disease caused by intracellular protozoa of the genus Leishmania , serves as the primary reservoir; traditionally endemic to Bihar, Jharkhand, West Bengal, and Eastern Uttar Pradesh Indian states along river belts. VL has recently been observed in the past few years at a tertiary care teaching hospital located in the Himalayan region (non-endemic state, Uttarakhand). This study was done to identify the clinical features, demographics, complications and the risk factors involved in patients of non-endemic region a tertiary care hospital.

Methods: This retrospective study with present-day follow-up of all patients was done on VL patients who were admitted from January 2018 to January 2024. Diagnosis was established by rK 39 antigen test and/or Leishman-Donovan (LD) bodies on bone marrow examination. The clinical and laboratory data, duration of hospital stay and outcomes, and associated risk factors were collected on a proforma and analysed. Factors associated with Himalayan region (Uttarakhand) above Rishikesh (>1120 feet from sea level) were analysed using Chi-square.

Results: Males constituted 92% of the study population from which 67% of the population was from the Himalayan region of this middle Southern Himalaya (Uttarakhand). Risk factors such as residence in the rural area (p=0.47), residence near vegetation (p=0.12), poor household characteristics (p=0.073), low educational status (p=0.073), nearby water body (p=0.073), poor sewage or garbage disposal (p=0.241), insect bites (p=0.040) were associated with Himalayan region emergence. Fever (100%) and malaise (100%) were the most common symptoms presented followed by pain abdomen (29%). Pallor (100%) and splenomegaly (100%) were the most common abnormalities identified on examination followed by hepatomegaly (83%). Anemia (100%) and leukopenia (100%) were the most common biochemical abnormality detected followed by thrombocytopenia (79%), acute liver injury (63%), and hemophagocytic lymphohistiocytosis (HLH) (58%). The disease was diagnosed by the rK39 antigen test (67%), LD bodies in bone marrow examination (67%) and both positive in 29% patients. Mortality was seen in 17 % patients secondary to sepsis (75%) and one case post-discharge due to unknown reasons.

Interpretation conclusion: VL is emerging in Himalayan (Uttarakhand) region and has been found to have higher mortality and organ involvement (hepatomegaly) compared to non-Himalayan region. This calls for initiating a surveillance program before declaring elimination/eradication.

Background objectives: In 2010, artesunate and sulfadoxine-pyrimethamine (AS+SP) were adopted as the first-line artemisinin based combination therapy for treatment of uncomplicated Plasmodium falciparum malaria in India. Continuous therapeutic efficacy monitoring of first line anti-malarial drugs is required to update the treatment policy for malaria control and elimination. This study aimed to assess the therapeutic efficacy of artesunate and sulfadoxine-pyrimethamine (AS+SP) at three sites with different diseases transmission intensity.

Methods: A 28-day, single-arm, prospective study was conducted to evaluate the clinical and parasitological response to AS+SP. Patients received a six-dose regimen of AS+SP over three days and were monitored for 28 days through clinical and laboratory assessments. Participant recruitment and outcome classification was done as per WHO guidelines for surveillance of anti-malarial drug efficacy.

Results: A total of 170 participants were enrolled and 147 of them completed the follow-up. Adequate clinical and parasitological response (ACPR) was observed in 100% of the study participants who completed the follow-up. 100% fever clearance as well as parasite clearance was observed on day 3.

Interpretation conclusion: This study demonstrated high therapeutic efficacy and a good safety profile for artesunate and sulfadoxine-pyrimethamine at different transmission intensities. This suggests the continuation of the current artemisinin-based combination therapy for the treatment of P. falciparum malaria in India.

Background objectives: With an annual prevalence of 2000 cases, India has the highest global burden of Japanese encephalitis (JE). However, the distribution of the disease is not uniform across the country, wherein the states and districts considered endemic are prioritized for vaccination and other control measures. The central Indian state of Madhya Pradesh (MP), which is not yet considered JE-endemic, possesses multiple agents, hosts, and environmental risk factors and is geographically close to several hotspots of transmission. In this study, we explored the potential endemicity of JE in MP by estimating its prevalence in acute encephalitis syndrome (AES) cases, examining its geospatial and temporal distribution, and demonstrating evidence of viremia in known animal reservoirs.

Methods: A total of 761 human samples were analyzed using an ELISA kit to detect anti-JEV IgM antibodies. Nested and hemi-nested RT-PCR targeting the C-prM region were employed for 93 ELISA-positive human samples, as well as 100 swine and 99 equine samples.

Results: We observed a prevalence of 13% (99 out of 761) of JE in AES cases, predominantly affecting the pediatric population (73.74%) without any gender predisposition. We found JE viremia in 7% of swine and 8% of equine samples as potential animal reservoirs.

Interpretation conclusion: The study revealed a geospatial distribution of the virus in reservoirs and/or hosts across 22 districts, with high- and intermediate-burden districts clustering near the state's border with other JE-endemic states. The temporal distribution indicated that the virus circulated throughout the year.

Background objectives: The present study aimed to assess the impact of various blood or food sources on specific biological parameters of Phlebotomus sergenti Parrot, 1917, adult and immature stages, as well as the development of Leishmania tropica Wright 1903.

Methods: Sandflies were collected from a rural district and subsequently reared in an insectary using standard methods. Three larval diets were formulated and administered to the larvae. Adult sandflies were provided with three blood sources: BALB/c mice, humans, and poultry. The infection of sandflies with the parasite was examined to determine the development of Leishmania .

Results: The duration of larval and pupal stage development exhibited significant differences among the three food sources. However, these variations did not significantly affect the overall length of the immature period of Ph. sergenti (P= 0.098) or the mortality rate (P= 0.338) across the groups. The time required for oviposition differed significantly depending on the blood source (P= 0.007). Nevertheless, the fecundity and longevity of sandflies that fed on the three different blood sources did not show statistically significant differences (fecundity (P= 0.106)/longevity (P= 0.209)). Furthermore, no significant disparity was observed among the three types of blood sources concerning their ability to support L. tropica infection within Ph. sergenti's gut.

Interpretation conclusion: Redirecting the vector, Ph. sergenti , towards these specific food or blood sources as a means to reduce vector population or their vectorial capacity would not be a successful approach for interrupting the transmission cycle.