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Smith M.E.,University of Notre Dame | Singh B.K.,University of Notre Dame | Irvine M.A.,University of Warwick | Stolk W.A.,Rotterdam University | And 3 more authors.
Epidemics | Year: 2017

Mathematical models of parasite transmission provide powerful tools for assessing the impacts of interventions. Owing to complexity and uncertainty, no single model may capture all features of transmission and elimination dynamics. Multi-model ensemble modelling offers a framework to help overcome biases of single models. We report on the development of a first multi-model ensemble of three lymphatic filariasis (LF) models (EPIFIL, LYMFASIM, and TRANSFIL), and evaluate its predictive performance in comparison with that of the constituents using calibration and validation data from three case study sites, one each from the three major LF endemic regions: Africa, Southeast Asia and Papua New Guinea (PNG). We assessed the performance of the respective models for predicting the outcomes of annual MDA strategies for various baseline scenarios thought to exemplify the current endemic conditions in the three regions. The results show that the constructed multi-model ensemble outperformed the single models when evaluated across all sites. Single models that best fitted calibration data tended to do less well in simulating the out-of-sample, or validation, intervention data. Scenario modelling results demonstrate that the multi-model ensemble is able to compensate for variance between single models in order to produce more plausible predictions of intervention impacts. Our results highlight the value of an ensemble approach to modelling parasite control dynamics. However, its optimal use will require further methodological improvements as well as consideration of the organizational mechanisms required to ensure that modelling results and data are shared effectively between all stakeholders. © 2017 The Authors


Ramaiah K.D.,Vector Control Research Center Indian Council of Medical Research | Vanamail P.,Vector Control Research Center Indian Council of Medical Research
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2013

Background: While various studies provided insight into the impact of mass drug administration (MDA), information on the dynamics of the post-MDA threshold level lymphatic filariasis (LF) infection facilitates understanding its disappearance pattern and determining the duration of post-MDA monitoring and evaluation. Methods: The changes in microfilaraemia (Mf) prevalence and vector infection rates were monitored for four (2005-2008) and six years (2005-2010) respectively after stopping ten rounds of annual mass diethylcarbamazine (DEC) administration in a group of five villages located in South India. Four years after stopping MDA, circulating filarial antigenaemia (Ag) status among children and adults was also assessed in two villages. Results: Overall Mf prevalence (n 1/4 700) and vector infection rates (n1/4 803-3520) showed a declining trend. Two villages maintained zero Mf status in each of the four years, vector infection rate was zero from the third year onwards and Ag prevalence in adults was 0.4% (n 1/4 226). In two other villages despite persistence of Mf and vector infection there was zero vector infectivity rate during the third to sixth year and Ag prevalence among children (n 1/4 50) was nil. In the fifth village Mf prevailed at, 1.0% and Ag prevalence among 1-7 year old children was 4.6% (n 1/4 44) and vector infectivity rate during the sixth year was 0.1% (n 1/4 852). Conclusion: The incidence of sporadic new infections is evident in highly endemic communities such as the fifth village. However, there is uncertainty on the potential of the Ag positive children to reestablish infection. Six years of post-MDA monitoring and evaluation appears to be adequate to discern the status of transmission interruption and appropriate decision making. © Royal Society of Tropical Medicine and Hygiene 2013. All rights reserved.


Srinivasan R.,Vector Control Research Center Indian Council of Medical Research | Jambulingam P.,Vector Control Research Center Indian Council of Medical Research
Journal of Medical Entomology | Year: 2012

Phlebotomus (Phlebotomus) papatasi (Scopoli) collected in human dwellings from an agricultural villages Chaura, located in Gaya district, Bihar, India, showed morphological and anatomical variations. Male sand flies of this species exhibited variations in the genital structures, while females showed differences in the spermathecae and antenna segment three (A3). When the mitochondrial DNA of both male and female P. (P.) papatasi sensu lato population subjected to DNA barcoding, both the sexes of P. (P.) papatasi variants were found to be associated. The differences in the morphometric characteristics clearly constitutes preliminary evidence for infraspecific variation in P. (P.) papatasi s.l. population in India. © 2012 Entomological Society of America.


Poopathi S.,Vector Control Research Center Indian Council of Medical Research | Abidha S.,Vector Control Research Center Indian Council of Medical Research
International Journal of Dairy Technology | Year: 2012

Dairy industries worldwide discard ghee sediment waste and clarified butter sediment waste (CBSW) in bulk every day. The aim of the present study was to explore the possibility of utilising the CBSW to prepare culture media so as to produce mosquitocidal bacteria. The bacteria achieved complete degradation of CBSW for its toxin synthesis. The bacterial growth, biomass, toxin production and larvicidal activity against mosquito vectors were comparable with those using conventional culture medium (NYSM) as a control. We obtained a cell mass yield of 9.7g/L and larvicidal activity (LC 50 and LC 90) of 0.0036mg/L and 0.01mg/L against Culex quinquefasciatus using bacteria grown in CBSW. Cost-effective analysis indicated that CBSW is highly economical. © 2011 Society of Dairy Technology.


Poopathi S.,Vector Control Research Center Indian Council of Medical Research | De Britto L.J.,Vector Control Research Center Indian Council of Medical Research | Praba V.L.,Vector Control Research Center Indian Council of Medical Research | Mani C.,Vector Control Research Center Indian Council of Medical Research | Praveen M.,Vector Control Research Center Indian Council of Medical Research
Environmental Science and Pollution Research | Year: 2015

Mosquitoes transmit major communicable diseases such as dengue, malaria, filariasis, Japanese encephalitis, chikungunya, and so on. Vector control is important in epidemic disease situations as there is an urgent need to develop new and improved mosquito control methods that are economical and effective yet safe for non-targeted organisms. In the present study, silver nanoparticles (AgNPs) were synthesized from the aqueous leaf extract of neem plant (Azadirachta indica), and their effects on mosquito vectors (Aedes aegypti and Culex quinquefasciatus) were assessed. The synthesised AgNPs were characterized by UV–vis spectroscopy, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). The nanoparticles have maximum absorption at 442 ± 1.5 nm with an average size of 41–60 nm. The XRD data showed six well-defined diffraction peaks, corresponding to a relative intensity of the crystal structure of metallic silver 36.42, 100.00, 53.70, 14.20, 16.05, and 6.79, respectively. The FT-IR data showed strong prominent peaks in different ranges, reflecting its complex nature. The mosquito larvae were exposed to varying concentrations of AgNPs synthesized from the neem leaves under investigation (0.07–25 mg/l) for 24 h; this revealed larvicidal activity of AgNPs with LC50 and LC90 values of 0.006 and 0.04 mg/l for A. aegypti, respectively. Further, the LC50 and LC90 values were also identified as 0.047 and 0.23 mg/l for Cx. quinquefasciatus, respectively. The result obtained from this study presents biosynthesized silver nanoparticle from A. indica as the biolarvicidal agent with the most potential for mosquito control. © 2014, Springer-Verlag Berlin Heidelberg.


Srinivasan R.,Vector Control Research Center Indian Council of Medical Research | Jambulingam P.,Vector Control Research Center Indian Council of Medical Research
Journal of the American Mosquito Control Association | Year: 2011

A new species of phlebotomine sand fly, Sergentomyia (Parrotomyia) vadhanurensis, is described from Puducherry Union Territory, India, with illustrations of adult female and male specimens. This species was collected in tree holes, tree buttresses, termite mounds, cattle sheds, and human dwellings from rural areas. © 2011 by The American Mosquito Control Association, Inc.


Poopathi S.,Vector Control Research Center Indian Council of Medical Research | Archana B.,Vector Control Research Center Indian Council of Medical Research
Tropical Biomedicine | Year: 2012

Bacillus thuringiensis subsp. israelensis (Bti) has been used for mosquito-control programmes the world-wide. Indeed, the large-scale production of Bti for mosquito control is very expensive due to the high cost of its culture. In the present study, we attempted to widen the scope in developing cost-effective culture medium for Bti production, based on the raw materials available on the biosphere, including coconut cake powder, CCP (Cocos nucifera), neem cake powder, NCP (Azadirachta indica) and groundnut cake powder, GCP (Arachis hypogea). Among these raw materials, the biomass production of Bti, sporulation and toxin synthesizing from 'CCP' in combination with mineral salt (MnCl 2) was comfortably satisfactory. Bioassays with mosquito species (Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti) and field trials were also satisfactory. The present investigation suggests that coconut cake-based culture medium can be used as an alternative for industrial production of Bti in mosquito-control programme. Therefore, the study is very important from the point of effective production of Bti from cost-effective culture medium for the control of mosquito vectors.


Chandhiran K.,Vector Control Research Center Indian Council of Medical Research | Paily K.P.,Vector Control Research Center Indian Council of Medical Research
Biological Control | Year: 2015

Natural habitat of Romanomermis iyengari, an entomophilic mermithid nematode, is rice field. Parasitism of this nematode on mosquito larvae breeding in rice fields in Pondicherry, India, has been studied in 1979. The present study was to find out its persistence in the same habitat, after many years of agricultural practices. Evaluation of parasitism on mosquito larvae was carried out during two rice cultivation seasons at a schedule of 1. week prior, and 1 and 2. weeks after transplantation of paddy. Larval stages of mosquito species such as Culex tritaeniorhynchus, Culex vishnui, Anopheles vagus, and Anopheles subpictus showed parasitism of R. iyengari. Parasitism was the highest on C. tritaeniorhynchus with a maximum of 15.38% during season I and 17.85% during season II. Followed by this, it was on A. vagus (10.82% and 9.43%), C. vishnui (7.37% and 8.69%), and A. subpictus (3.70% and 6.36%). The overall density of mosquito larvae and level of parasitism of R. iyengari on them during season II was significantly higher than that of season I. The parasitism was maximum at 1. week before transplantation and showed a decreasing trend towards 2. weeks after transplantation, during both the seasons. The level of natural parasitism of R. iyengari during the present investigation was higher than that observed in the same ecosystem almost 35. years ago. This is clearly an indication towards the capability of the nematode to withstand several years of agricultural practices, including pesticide and agrichemical application. Hence, if applied at sufficient level and frequency, this nematode could act as a successful biocontrol agent against mosquitoes breeding in rice fields. © 2015 Elsevier Inc.


Srinivasan R.,Vector Control Research Center Indian Council of Medical Research | Jambulingam P.,Vector Control Research Center Indian Council of Medical Research | Vanamail P.,Vector Control Research Center Indian Council of Medical Research
Journal of Medical Entomology | Year: 2013

Abundance pattern of sand flies in relation to several environmental factors, such as type of areas, dwellings, landforms, land usage pattern, and surface soil pH, was assessed in 81 areas or villages of Puducherry district, Puducherry Union Territory, located on the coastal plain of southern India, for three seasons, between November 2006 and October 2008, adopting hand-catch method. In total, 1,319 sand fly specimens comprising 12 species under two genera, viz., Phlebotomus and Sergentomyia, were collected. Among them, Phlebotomus (Euphlebotomus) argentipes Annandale & Brunetti, the vector of visceral leishmaniasis in India, was the predominant species in all habitats surveyed. The hierarchical cluster analysis showed that the density of sand flies was 10-fold higher in high-density group and fivefold higher in medium-density group, compared with the no or low-density group. Sand fly density was found to be influenced significantly with the type of areas, dwellings, landforms, land usage pattern, and surface soil pH in different groups. Rural areas located on fluvial landform with alkaline surface soil pH, supporting rice cultivation and luxuriant vegetation, are the most influencing factors that favor sand fly abundance and diversity in this district. © 2013 Entomological Society of America.


Srinivasan L.,Vector Control Research Center Indian Council of Medical Research | Mathew N.,Vector Control Research Center Indian Council of Medical Research | Karunan T.,Vector Control Research Center Indian Council of Medical Research | Muthuswamy K.,Vector Control Research Center Indian Council of Medical Research
Parasitology Research | Year: 2011

Setaria digitata is a filarial worm of the cattle used as a model system for antifilarial drug screening, due to its similarity to the human filarial parasites Wuchereria bancrofti and Brugia malayi. Since filarial glutathione S-transferase (GST) is a good biochemical target for antifilarial drug development, a study has been undertaken for the biochemical characterization of GST from S. digitata. Cytosolic fraction was separated from the crude S.digitata worm homogenate by ultracentrifugation at 100,000 g and subjected to ammonium sulfate precipitation followed by affinity chromatography using GSH-agarose column. The kinetic parameters K m and V max values with respect to GSH were 0.45 mM and 0.105 μmol min -1 mL -1 respectively. With respect to 1-chloro-2,4-dinitrobenzene, the K m and V max values were 1.21 and 0.117 μmol min -1 mL -1 respectively. The effect of temperature and pH on GST enzyme activity was studied. The protein retained its enzyme activity between 0°C and 40°C, beyond which it showed a decreasing tendency, and at 80°C, the activity was lost completely. The enzyme activity was varying with change in pH, and the maximum GST activity was observed at pH 7.5. Gel filtration chromatographic studies indicated that the protein has a native molecular mass of about 54 kDa. The single band of GST subunit appeared in sodium dodecyl sulfate polyacrylamide gel electrophoresis was found to have molecular mass of ≈ 27 kDa. This shows that cytosolic S. digitata GST protein is homodimeric in nature. © 2010 Springer-Verlag.

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