Vector Control Research Centre

The larvicidal efficacy of methanol, petroleum ether, and chloroform extracts derived from P. rubra and T. erecta flowers and T. peruviana leaves was evaluated against larvae of Culex quinquefasciatus and Ae. aegypti following WHO guidelines. Soxhlet extraction was used to prepare the plant extracts, and gas chromatography-mass spectrometry (GC-MS) was performed on the most active petroleum ether fractions. The major constituents were further assessed using Molinspiration Cheminformatics software to predict physicochemical properties and bioactivity scores. For T. peruviana, petroleum ether and chloroform extracts showed strong larvicidal activity, with LC₅₀ values of 43.87 and 54.76mg/L and LC₉₀ values of 96.06 and 132.20mg/L, respectively, against Cx. quinquefasciatus, and LC₅₀ values of 70.30 and 87.30mg/L and LC₉₀ values of 156.78 and 186.84mg/L, respectively, against Ae. aegypti. Petroleum ether extracts of P. rubra and T. erecta showed LC₅₀ values of 39.61 and 49.31mg/L, respectively, against Cx. quinquefasciatus, and 158.71 and 166.59mg/L against Ae. aegypti. Molinspiration analysis indicated moderate to high predicted biological activity for several triterpenoids and phytosterols, consistent with the observed larvicidal effects. Overall, the results indicate that extracts from P. rubra, T. peruviana, and T. erecta are promising sources of mosquitocidal compounds that could be further explored for the development of environmentally compatible larvicidal products.

The launch of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) in 2000 catalysed a surge in research and programmatic initiatives worldwide. However, a systematic evaluation of global LF research output over the past two decades remains limited. This scientometric analysis maps LF research from 2000 to 2024, with a special focus on India's contribution. Original research articles on LF published between 2000 and 2024 were retrieved from the Web of Science Core Collection using title-specific MeSH keywords. Bibliographic data were analysed using the bibliometrix package in R. A total of 1,746 documents were identified, with an average annual growth rate of 1.13%. Global output peaked in 2014, while India's highest was in 2012. India showed a declining trend, reaching a low of 12 articles in 2018. The USA led in overall publication output (21.1%), followed by India (18.3%) and the UK (10.3%). Despite high volume, India exhibits fewer international collaborations and a moderate citation impact. Major contributors included the Indian Council of Medical Research (219 publications) and the Liverpool School of Tropical Medicine (152). Although parasitology remained a dominant theme, there was a gradual shift toward microbiology, pharmacology, and science and technology. PLOS Neglected Tropical Diseases was the most productive journal. Globally, the Gates Foundation and the National Institutes of Health were leading funders, while the Council for Scientific and Industrial Research and the ICMR were India's leading domestic funders. LF research in India has shown a noticeable decline since 2017, despite its high disease burden. High-income countries dominate in citation impact and collaborations, whereas low- and middle-income countries, including India, lag behind even with a high publication volume. Strategic efforts to strengthen international partnerships, research funding, equitable co-authorship between endemic and non-endemic countries, facilitating early-career exchange programmes, adopting open-access agreements and building institutional capacity are essential to enhance the impact of LF research in India and other endemic countries. Equally important is ensuring that research priorities and implementation strategies are tailored to local programmatic and epidemiological contexts.

Disease surveillance activities are usually resource-constrained and should be optimised to generate the most informative scientific findings, and to make the best use of time, finances, and personnel. India has a high population density, diverse geography and climatic conditions, and difficult terrain. With respect to malaria, Plasmodium falciparum and Plasmodium vivax are endemic, with substantial variability of transmission across the country. While for P. vivax, drug efficacy appears to be homogeneous within the country, for P. falciparum malaria, the drug resistance pattern varies from the northeastern region to the central region. Accounting for these complexities, we develop a decision-making framework guided by geospatial modelling outputs to identify prospective study sites for surveillance of molecular markers of antimalarial drug resistance in P. falciparum malaria in India. We first retrieve existing data on the prevalence of validated markers of resistance to artesunate and sulfadoxine-pyrimethamine from the World Wide Antimalarial Resistance Network (WWARN) Surveyor database. We then incorporate these data into a geostatistical model to estimate the prevalence of these markers across India and identify areas with high median estimated marker prevalence and high uncertainty. Finally, we create an interactive dashboard using the RShiny software package to simplify the process of selecting sites for future molecular surveillance. Our framework helps to ensure that operational decision-making is supported by data and modelling outputs. We demonstrate the utility of our framework by selecting sites for molecular surveillance of P. falciparum malaria in India.

Localized adverse events following mass drug administration for lymphatic filariasis elimination are often selflimiting. However, they are of significant concern to the participants and may affect community drug compliance if not managed appropriately. Here, we report a rather uncommon adverse event, the 'string sign' in a south Indian woman with bancroftian filarial infection treated with the triple drug regimen (IDA: ivermectin, diethylcarbamazine and albendazole). String sign is the manifestation of acute lymphangitis as a cordlike subcutaneous swelling due to the swollen and inflamed lymphatic vessel, which is believed to occur due to the death of the adult filarial worms subsequent to chemotherapy. Health care workers need to be aware of such unusual localized adverse events that may occur following MDA for LF elimination. Prompt medical management of adverse events and health education are important to ensure adherence to drug consumption during mass drug administration program.

Mosquitoes of the Anopheles, Aedes, and Culex genera are responsible for transmitting major vector-borne diseases. Malaria remains a significant public health concern in Odisha, primarily due to the state’s conducive environment for Anopheles mosquito breeding. This study, conducted between March 2021 and February 2023 across 11 traditionally hyper-endemic districts in southern Odisha, aimed to assess seasonal variations in Anopheles diversity, composition, and abundance. A total of 10,807 Anopheles mosquito’s species were collected manually indoors (house dwellings and cattle sheds) and outdoors (burrows, vegetation, tree holes, and culverts). Morphological identification revealed 18 Anopheles species. An. subpictus was the predominant species during the summer of 2021, with (328; 42.99%), and during the rainy season, with (1151; 46.60%), although its prevalence declined in subsequent years. An. culicifacies, a primary malaria vector, exhibited a consistent presence with (780; 31.58%) in the rainy season of 2021 and (798; 38.35%) in the rainy season of 2022. An. varuna remained scarce during summer and rainy seasons but peaked sharply in winter, with the highest prevalence in winter 2021–2022 (730; 35.56%) and winter 2022–2023 (485; 25.18%). Diversity indices (Shannon’s, Simpson’s, Pielou’s) and Correspondence Analysis identified Ganjam as the district with the highest species diversity (1.26–2.2). Seasonal variation had a statistically significant impact on species diversity (p < 0.001), surpassing the influence of district level factors. These findings show that seasonality strongly influences Anopheles populations and highlight the need for localized, evidence-based vector control. Monitoring of mosquito diversity is vital for shaping malaria interventions suited to Odisha’s transmission ecology.

Abstract The electrical impulses, known as electrogastrograms (EGGs), originate from the muscles of the stomach and are due to the physiological activity of the digestive system. The characteristics of these signals can be used to diagnose various human gastrointestinal disorders. Although the recording of EGG signals is a well-recognized diagnostic procedure, acquiring these signals from human subjects is difficult due to movement artifacts, and difficulties in electrode placement, and is also a time-consuming technique. Infrared thermography (IRT) is a non-contact and non-invasive technique used to detect various pathologies in humans. In this work, an attempt was made to establish the correlation between the information content (IC) of electrogastrograms and the information content of abdominal thermal images, in both normal and bradygastric subjects using Rényi entropy. The results show a strong correlation between the entropy of EGG signals and abdominal IRT images, in both normal and bradygastric subjects, with a correlation coefficient of 0.95 and 0.92, respectively. Since the information in the EGG signals and IRT images are strongly correlated, IRT can therefore be proposed as a diagnostic technique to replace EGG in the assessment of digestive diseases.

Background: There was an outbreak of gastroenteritis in the campus of a Private Medical College, Wayanad, Kerala in January, 2021. This study was planned to find-out the epidemiological factors responsible for the gastroenteritis outbreak among the students of the College and recommend prevention and control measures. Methods: This study was conducted in a Private Medical College of Wayanad district Kerala in January 2021. Data was collected using a self-administered questionnaire from 11 cases and 42 controls. Water samples were collected from different sources in ladies’ hostel new block and canteen. Results: All the cases were from the ladies’ hostel new block and from phase I MBBS. The first case was on 10/01/2021, last on 15/01/2021, with peak in the incidence of cases on 12/1/21 (7 cases). Majority of the cases presented with nausea, vomiting and abdominal pain (72.7% each). There was a very strong association between consumption of canteen chutney and sambar and gastroenteritis (OR=11 for both) and both these associations were found to be statistically significant (P=0.02 for both). No statistically significant association was detected between consumption of water from any particular water source and development of gastroenteritis (P&gt;0.15 for all). Water samples from canteen showed the presence of Klebsiella, E coli and Pseudomonas and from Ladies hostel, Pseudomonas. However, Ejikman’s test was negative. Conclusion: All the cases were from ladies’ hostel new block and were from phase I MBBS. The outbreak was a point source single exposure epidemic.Majority of the cases presented with nausea, vomiting and abdominal pain. Consumption of canteen chutney and sambar were found to have a very strong and significant association with gastroenteritis. The organisms were of non-fecal origin.