Based on a community based block randomized safety and efficacy trial (a part of multi-centric trials) carried out by the ICMR-VCRC in Yadgiri District, Karnataka and LYMFASIM model predictions, the WHO and the MoH & FW, GOI recommended the 3-drug regimen (Ivermectin, DEC, Albendazole - IDA), for mass drug administration (MDA) to accelerate LF elimination.
The stochastic micro-simulation model, LYMFASIM, for filariasis transmission and control was used to predict the duration of MDA with IDA required over the currently used DA (DEC+ Albendazole) for LF elimination. The model predicted that mass drug administration of 3-drug regimen with a coverage of >65% could reduce the number of rounds of MDA by one or two rounds for interruption of transmission.
A two-stage cluster-design based vector surveillance strategy (sampling design, gravid-trap, molecular xenomonitoring-MX) developed and validated at an evaluation unit - considered as a surveillance tool in global LF elimination programs (WHO/HTM/NTD/PCT/ 2013.10; NVBDCP National Programme Guidelines, 2016-Draft) for stopping MDA or post-MDA surveillance.
Developed a process for the Electrochemical Detection of Lymphatic Filarial Infection in Vector Mosquitoes and filed an Indian Patent (application No. 201911039806, filed on December, 2019)
Effectiveness and operational feasibility of mass DEC fortified salt as a supplementary intervention to mass drug administration towards elimination of the lone foci of diurnally sub-periodic Wuchereria bancrofti demonstrated in Andaman & Nicobar Islands.
Prevalence of filariasis transmission hotspots following several rounds of MDA are found to be associated with presence of Culex breeding habitats.
Morbidity Management and Disease Prevention (MMDP) continues to be a challenge in LF elimination programme in India in terms of assessing the clinical impact of limb hygiene and sustaining the MMDP in the community. Interim observations on a cohort of lymphoedema patients showed that there are perceptible improvement in colour (17.2%) and texture (20.8%) of the lymphoedema legs in patients practicing limb hygiene regularly. In addition, more than 10% reduction in intertrigo prevalence was observed on follow-up.
Community based study carried out in 3 sets of population (75, 74 & 63) in Villupuram District of Tamil Nadu has shown that regular practice of leg hygiene along with supportive treatment reduces ADLA episodes significantly and also reduction in LE volume.
In three different epidemiological settings, determinants of community compliance to MDA for LF elimination were identified using Intervention mapping model and site-specific solutions were formulated jointly with the district programmes to enhance community compliance.
Malaria / Leishmaniasis / Scrub Typhus
With the level of coverage recorded, a significant reduction was observed in vector abundance and malaria incidence in all the three arms (IRS alone, LLIN alone and combination of LLIN+IRS) irrespective of the combination.
The performance of MAGNet after 20/ 25 washes was comparable to unwashed MAGNet as well as to the reference net, DuraNet. Compared to the untreated net, the performance of unwashed or washed MAGNet was significantly higher than the untreated net (negative control) and comparable to/marginally better than the positive control (Duranet) in terms of mortality, deterrence effect, blood-feeding inhibition and induced exophily of the malaria vector, Anopheles fluviatilis in experimental huts.
Assessment of the development of insecticide resistance in malaria vectors based on the exposure of different insecticides - mortality was 74.8% with 1x dose, and 95.1% with 10x dose, confirming moderate resistance intensity of Anopheles culicifacies to deltamethrin
Residual efficacy of DDT- results of bio assays (before and after spraying DDT indoors), conducted at 1, 9, 16, 22, 31 and 37 days post-spraying showed corrected mortality of 4.4% to 35.0% indicating that DDT spray has no impact on the mortality of An. Culicifacies.
Prevalence of G6PD deficiency among different tribes was studied in Odisha State. Out of 1,423 people from six tribes screened so far, 67 (4.7%) were found to have G6PD deficiency. Since, Plasmodium vivax is prevalent in tribal areas, the study results provide evidence that has implications on the treatment regimens to be used for the treatment of P. vivax patients in the area.
The performance of unwashed Veeralin LN was significantly higher than the untreated net (negative control) and better than MAGNet (positive control) LN in terms of mortality and bio-efficacy against malaria vector, An. culicifacies in experimental huts.
Detection of JEV in Cx. vishnui during the 2016 severe JE outbreak in Malkangiri district confirmed the transmission of JE virus.
The results of the study on determining the resistance status of three important vectors of JE, i.e., Culex vishnui, Culex tritaeniorhynchus and Culex bitaeniorhynchus (Diptera: Culicidae), against DDT, malathion and deltamethrin in three JE affected districts of Odisha state revealed that Culex vishnui and Cx. tritaeniorhynchus showed resistance to DDT, malathion and deltamethrin, whereas Cx. bitaeniorhynchus was susceptible to all the insecticides.
The current entomological survey in Singhbhum hills region reported the disappearance of An. minimus which had appeared nearly 12 years before.
The study on durability of LLINs reported on the performance of LLINs under operational conditions in Odisha state by checking the physical integrity and the insecticidal potency of nets post deployment. The study revealed that universal coverage of LLINs was not achieved at the time of distribution. Attrition rate measured at 30 months of distribution was 25.0% and among the available nets, 35% were too damaged. This has collectively, however, become an area of major concern resulting in low net usage rate (51%). Therefore, the findings of the study are significant for NVBDCP to replenish the quality LLINs to sustain the gain achieved so far in reducing malaria morbidity and mortality.
A new endemic focus of cutaneous leishmaniasis caused by MON-37 strain of Leishmania donovani reported from the tribal populations of Western Ghats, Kerala. The vector species involved was incriminated to be Phlebotomus argentipes. Domestic dogs were found to be naturally infected reservoir of the parasite.
Also MON-37 strain of Leishmania donovani was recorded to cause sporadic indigenous cases of visceral leishmaniasis, in the forest fringe areas of Western Ghats, Kerala.
Natural infection of Orientia tsutsugamushi in animal hosts and vector mites was demonstrated in the AES reporting villages of Gorakhpur district and confirmed transmission of scrub typhus. The finding was useful in sensitization of Medical Officers for early diagnosis, treatment and case management to prevent severe complications
ICMR- VCRC has initiated laboratory studies on Wolbachia pipientis based vector control for prevention of dengue and chikungunya. Wolbachia carrying Aedes aegypti strains have been transferred from Monash University, Australia and cyclic colonies have been raised up to 24th generation. ICMR-VCRC has generated two new Indian Ae. Aegypti colonies by backcrossing Ae. Aegypti females infected with wMel and wAlbB Wolbachia (Aus.) strains with wild type Ae. Aegypti (Pud.) males and the newly generated wMel and wAlbB infected Ae. Aegypti (Pud.) release lines are being maintained over 12 generations, successfully.
Dengue immunology - monocytes mediated MMPs expression was found to significantly participate in the development of dengue pathogenesis in the severe cases of disease and antipyretic has a protective effect in dengue viral disease.
Demonstration of mosquito vector control and prevention of dengue/chikungunya through partnership and community empowerment in selected rural areas of Puducherry. A training workshop was conducted jointly with state NVBDCP for students and teachers of selected schools on consolidation of data collected on mosquito vector breeding and for online transmission to NVBDCP for appropriate action.
Genotype shift of dengue virus (DENV1) recorded during the 2017 outbreak of dengue fever in Thiruvananthapuram, Kerala, India.
Molecular modelling analysis of T219A mutation in the envelope protein revealed novel virulence enhancing factors in Dengue virus-3 isolated from Kerala state, India.
Aedes aegypti as well as Aedes albopictus were incriminated as the vectors of dengue virus in different regions of the country.
Monitoring of JE vector abundance in an area with mixed vegetation and varied water bodies was demonstrated using Remote Sensing data from RISAT 1 and MODIS
Indoor residual spraying in two Blocks significantly reduced the risk of transmission of JE in Gorakhpur district and the impact of the LLIN distributed in another block was monitored. The vector density in the LLIN block reduced, with no JE cases compared to control block during post-LLIN distribution
Studies on Kyasanur Forest Disease virus (KFDV) in ticks and rodents in potential risk areas of adjoining states to Karnataka showed high abundance of Haemaphysalis vectors in the villages of the forest fringes of the six districts surveyed in Western Ghats of Tamil Nadu, Karanataka and Kerala with KFDV infection in the tick vector in two of the six districts. KFD risk maps created at the district level were provided to the Programme personnel for strengthening the ongoing preventive measures such as vaccination, supply of insect repellents to the high risk groups in particular to the Cholanaickan tribe living deep in the forest, Kattunaickan tribe engaged in the fire line works and other forest staff/workers and intensive health education.
Among 65141 Aedes mosquito specimens (5557 pools) screened for ZIKA virus infection status in 49 high risk Districts of 14 states across the country, only 3 pools were found positive for ZIKV infection from Jaipur, Rajasthan. This vector surveillance program indicated only focal sporadic occurrence of ZIKV in India. Transmission of the virus was not recorded from any other regions of the Country.
Microbial / Chemical agents/ Adulticides for vector / parasite control
Development of chemical agents for vector control - alginate granular formulations of DPE-28 is effective in controlling the immature population of the filarial vector Culex quinquefasciatus by causing the pupal mortality up to 3-4 weeks when it was applied at 0.001% (w/v) level in the simulated field.
Development of monoterpenes extracted from the seeds of Trachyspermum ammi as macrofilaricidal composition
Development of naphthoquinone analogues as macrofilaricidal agent.
Development of thiosemicarbazones as macrofilaricidal agents.
Development of new mosquito control agents based on anthranilic diamides targeting the insect ryanodine receptor.
Development of a mosquito diet for Aedes aegypti adults
Development of essential oil based mosquito repellent and mosquito larvicide.
Developed a real time PCR assay for detecting crystal toxin of Bacillus thuringiensis israelensis in treated habitats to monitor spray activities of vector control programme. This assay is further standardized to detect the lowest concentration of Bti DNA. An ELISA has also been developed to estimate the crystal toxin in the product for quality assurance and registration of product for public health use.
The technology developed by the VCRC for preparation of mosquito larvicidal formulation of Bti has been transferred to 20 commercial firms.
DNA finger printing of Bacillus thuringiensis israelensis (VCRC B-17) strain, showed that rpoB gene can be used as molecular/ phylogenetic marker for the identification of Bti
The metabolites of an indigenously isolated Bacillus amyloliquefaciens were also found to exhibit antifungal activity against phytopathogens, Fusarium sp. (VCRC F25) and Curvularia sp. (VCRC F26).
Development of a Vector Informatics Database – ‘VectorInfo’ – a repository of data on medically Important Indian Arthropods is made online.
A new species of Dytiscid beetle Platynectus sahyadraensis, predatory to the immatures of Aedes albopictus was recorded from the foot hills of Western Ghats of Kerala.