Browsing by Author "Tyagi, B K"

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    Dengue fever caused by dengue virus serotype - 3 (subtype-III) in a rural area of Madurai district, Tamil Nadu.
    (2010-09) Paramasivan, R; Dhananjeyan, K J; Leo, S Victor Jerald; Muniaraj, M; Thenmozhi, V; Rajendran, R; Tewari, S C; Arunachalam, N; Varatharaj, M; Victor, T John; Charles, Janshi; Ilango, S; Tyagi, B K
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    Diagnostic methods for detection & isolation of dengue viruses from vector mosquitoes.
    (2006-05-29) Philip Samuel, P; Tyagi, B K
    Dengue is a deadly mosquito-borne infection warranting urgent attention for its containment particularly in the tropical and subtropical countries. In the absence of a vaccine or any specific drug for its treatment, an early diagnosis is considered indispensable to prevent any casualty. Detection of viruses in human sera particularly in endemic areas is cumbersome, difficult and also not desirable. Therefore, as an alternative approach, detection of the dengue virus antigen in mosquitoes has provided a reliable tool to (i) comprehend the types of viruses circulating in nature; and (ii) help in designing vector-specific control strategies. A mélange of diagnostic techniques are currently available with some advantages or disadvantages. Traditionally, cell cultures and suckling mice have been employed for virus isolations. While the virus isolation method in baby mice is time consuming, slow and expensive, the mosquito cell cultures offer a good degree of specificity. Mosquito inoculation techniques have been reported for detection and propagation of flaviviruses. Though this technique is sensitive for routine virological confirmation of dengue fever, it requires large number of infected mosquitoes, besides being time consuming. Insect bioassays (Toxo-IFA) are generally cumbersome requiring special facilities and are not suitable for large-scale epidemiological surveillance. ELISA has been shown to be a rapid and sensitive alternative to insect bioassays for monitoring arboviruses in wild populations. Reverse transcriptase polymerase chain reaction (RT-PCR) is a recent molecular diagnostic technology used for detecting virus infections in mosquitoes, which gives rapid results but is expensive and prone to contamination. This review describes the development of various techniques involved in detection and isolation of dengue viruses in mosquitoes. Definite diagnosis of the impending dengue epidemic can be made using ELISA for virological surveillance system on dengue virus antigen in the mosquito vectors. Therefore, ELISA offers a potential tool and a convenient system for quickly screening large number of samples up to the serotype level which can be employed effectively and efficiently for large scale dengue surveillance programmes on wild caught mosquito vectors. ELISA positive samples can be screened further by Toxo-IFA system for virus isolation. On the other hand, techniques like mosquitoes cell culture, mosquito inoculation (Toxo-IFA) and RT-PCR techniques can be employed for dengue virus amplification.
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    Dual infection in human by Japanese encephalitis virus & chikungunya virus in Alappuzha district, Kerala, India.
    (2013-09) Thenmozhi, V; Paramasivan, R; Samuel, P Philip; Kamaraj, T; Balaji, T; Dhananjeyan, K J; Venkatasubramani, K; Tyagi, B K
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    Effect of permethrin impregnated bednets in reducing population of malaria vector Anopheles culicifacies in a tribal village of Orissa state (India).
    (1989-01-01) Jambulingam, P; Gunasekharan, K; Sahu, S S; Hota, P K; Tyagi, B K; Kalyanasundaram, M
    The role of permethrin impregnated bednets at the application rate of 0.5 g (ai)/m2 in reducing A. culicifacies population in a tribal village of Orissa, highly endemic for Plasmodium falciparum was studied. The per man-hour density was significantly reduced in the Kenduguda village for about three months where impregnated bednets were supplied to the villagers, while in the control village Deulaguda where unimpregnated nets were supplied, vector density remained high during the study period. Bioassay carried out on the treated nets showed that there was 100 per cent mortality in A. culicifacies for over three months with the unwashed nets as well as with bednets washed once or twice.
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    Entomo-virological study of a suspected Japanese encephalitis outbreak in Muzaffarpur district, Bihar, India.
    (2013-05) Samuel, P Philip; Muniaraj, M; Thenmozhi, V; Tyagi, B K
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    Entomological investigations into an epidemic of Japanese encephalitis (JE) in northern districts of West Bengal, India (2011-2012).
    (2014-05) Mariappan, T; Samuel, P Philip; Thenmozhi, V; Paramasivan, R; Sharma, Puran Kumar; Biswas, Asit Kumar; Tyagi, B K
    Background & objectives: Japanese encephalitis (JE) is one of the most important arboviral diseases of human beings with outbreaks in many parts of Southeast Asia including India. We present the entomological findings of an outbreak occurred in northern part of West Bengal during 2011-2012 with special emphasis on the role of JE vectors in different seasons. Methods: Adult mosquito collections were made with the help of mouth aspirators, aided by flash lights during day time resting inside human and animal habitations as indoor, and resting outside field grasses, bushes, underneath of culverts and bridges as outdoor, and in and around the pig enclosures and cattle sheds during dusk period in JE affected villages from Cooch Behar, Dakshin Dinajpur, Darjeeling and Jalpaiguri districts in North West Bengal. In all study villages, a long handled with enamel bowl dipper was used to obtain immature stages of mosquitoes from various breeding habitats. Results: A total of 19 different types of mosquito breeding habitats were examined for vectors of JE. From these habitats, 23.7 per cent were positive for breeding during the study period. Overall, nine different species were recorded through emergence, but none was positive for JE virus when subjected for detection of virus. Adult mosquitoes of more than 50 per cent of the potential JE vector species obtained through dusk and the rest through indoor and outdoor collections in all seasons. Altogether, 27 different species were recorded. Most of these were JE vectors. Interpretation & conclusions: Our results showed that in addition to Cx. vishnui subgroup, detection of JE virus antigen in Cx. quinquefasciatus indicated the possible maintenance of JE virus in nature through poor vector mosquitoes throughout the year. Since, all potential vector species reported elsewhere in India were also found in this region and fluctuated in density in different seasons, a proper integrated vector control programme needs to be implemented to control JE transmission.
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    Evaluation of a new compound (VCRC/INS/A-23) with juvenile hormone activity against mosquito vectors.
    (1985-07-01) Tyagi, B K; Kalyanasundaram, M; Das, P K; Somachary, N
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    Evaluation of a synthetic pyrethroid (cyfluthrin) for insecticidal activity against different mosquito species.
    (1987-02-01) Rajavel, A R; Vasuki, V; Paily, K P; Ramiah, K D; Mariappan, T; Kalyanasundaram, M; Tyagi, B K; Das, P K
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    Evaluation of alphamethrin, a synthetic pyrethroid for insecticidal activity against mosquitoes.
    (1987-11-01) Amalraj, D; Ramaiah, K D; Rajavel, A R; Mariappan, T; Vasuki, V; Paily, K P; Tyagi, B K; Kalyanasundaram, M; Das, P K
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    Evaluation of fenfluthrin (OMS 2013), a synthetic pyrethroid for insecticidal efficacy against mosquito vectors.
    (1985-07-01) Mariappan, T; Kalyanasundaram, M; Panicker, K N; Balakrishnan, N; Tyagi, B K; Das, P K
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    Evaluation of two new juvenile hormone compounds against mosquito vectors.
    (1988-01-01) Amalraj, D; Vasuki, V; Sadanandane, C; Kalyanasundaram, M; Tyagi, B K; Das, P K
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    Field evaluation of FICAM W (bendiocarb), a carbamate adulticide in two villages of Pondicherry.
    (1986-11-01) Amalraj, D; Kalyanasundaram, M; Mariappan, T; Ramaiah, K D; Arunachalam, N; Rajavel, A R; Paily, K P; Tyagi, B K; Bheema Rao, U S; Narayan, K
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    A focal outbreak of dengue fever in a rural area of Tamil Nadu.
    (2007-02-14) Samuel, P Philip; Thenmozhi, V; Tyagi, B K
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    Impact on prevalence of intestinal helminth infection in school children administered with seven annual rounds of diethyl carbamazine (DEC) with albendazole.
    (2015-03) Sunish, I P; Rajendran, R; Munirathinam, A; Kalimuthu, M; Kumar, V Ashok; Nagaraj, J; Tyagi, B K
    Background & objectives: One third of the world’s population is infected with one or more of the most common soil-transmitted helminths (STH). Albendazole (ALB) is being administered with diethyl carbamazine (DEC) in filariasis endemic areas to eliminate lymphatic filariasis (LF) and helminth infections. In this study, the cumulative impact of seven annual rounds of mass drug administrations (MDA) of DEC and ALB on STH infection in school children in selected villages in southern India was determined. Methods: During 2001-2010, seven MDAs were implemented by the Tamil Nadu state health department, India. LF and STH infections were monitored in school children from 18 villages of the two treatment arms (viz, DEC alone and DEC+ALB). Kato-Katz cellophane quantitative thick smear technique was employed to estimate STH infections at three weeks, six months and one year post MDA. Results: Prior to treatment, an overall STH prevalence was 60 per cent. After each MDA, infection markedly reduced at three weeks post-treatment in both the arms. The prevalence increased at six months period, which was maintained up to one year. After seven rounds of MDA, the infection reduced from 60.44 to 12.48 per cent in DEC+ALB arm; while the reduction was negligible in DEC alone arm (58.77 to 52.70%). Interpretation & conclusions: Seven rounds of MDA with DEC+ALB reduced the infection load significantly, and further sustained low level of infection for 10 years. However, complete parasite elimination could not be achieved. To curtail STH infection in the community, MDA should be regularized and environmental sanitation measures need to be improved by effective community-based campaigns.
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    Japanese encephalitis in Gorakhpur Division, Uttar Pradesh.
    (2008-12-28) Arunachalam, N; Samuel, P Philip; Paramasivan, R; Balasubramanian, A; Tyagi, B K
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    Knowledge, attitude and practice towards malaria in rural communities of the epidemic-prone Thar Desert, northwestern India.
    (1999-06-16) Yadav, S P; Tyagi, B K; Ramnath, T
    In order to assess the knowledge, attitude and practice of the rural Thar Desert population about malaria and its vectors, a total of 345 heads of households, including housewives, suffering with malaria were surveyed randomly, along with the same number of healthy control subjects, in four villages of Jodhpur and Jaisalmer districts of Rajasthan, north-western India. Results showed that in the traditionally hypoendemic Thar Desert, with low levels of immunity against malaria particularly Plasmodium falciparum, a large segment of rural people were equally less aware about the dangers of the disease. About three-fourths of the studied population did not quite comprehend the purpose of the five decade-old National Anti Malaria Programme, while nearly 50% respondents were reluctant to accept the programme lacking the component of community participation but directly targetting on the control of the disease. Consequently, about 50% malaria patients and 60% healthy subjects lacked in taking initiative to resort to any anti-mosquito or anti-malaria measure to protect themselves, although 27% malaria patients and 2.9% healthy subjects acknowledge correct causes of malaria. This study, being the first of its kind in a desert community currently facing emergence of P. falciparum-dominated malaria outbreaks, is a testimony to the hitherto prevalent deep gaps in knowledge about the disease, and its results warrant sincere efforts to link up the malaria control programme with the community participation for protection against this scourage in future.
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    Laboratory & field evaluation of three insect growth regulators against mosquito vectors.
    (1988-01-01) Amalraj, D; Vasuki, V; Kalyanasundaram, M; Tyagi, B K; Das, P K
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    Malaria outbreak in the Indira Gandhi Nahar Pariyojna command area in Jaisalmer district, Thar Desert, India.
    (2001-06-13) Tyagi, B K; Yadav, S P; Sachdev, R; Dam, P K
    A focal outbreak of malaria occurred in the villages situated close to the main Indira Gandhi canal near Ramgarh in Jaisalmer district, western Rajasthan. Stagnation of water over a month's period in the main canal as well as long standing rain water in the form of expansive lakes near these villages formed vast breeding grounds for the vectors like Anopheles culicifacies, along with A. stephensi already breeding in the 'tanka' and 'beri' in the epidemichit villages. Rapid mass blood surveys along with other entomological and parasitological investigations were conducted in four of the ten affected villages, viz., Seuva, Raghwa, Raimala and Sadhna. A total of 992 specimens belonging to four vector species were sampled, namely, A. stephensi (47.4%), A. culicifacies (41.0%), A. subpictus (11.2%) and A. annularis (0.4%). Epidemiologically, about one-fourth of the examined persons were positive (SPR 25.5%), although Plasmodium falciparum dominated the parasitaemia (49.5%). Available data are indicative of changed malariological scenario in the Indira Gandhi Nahar Pariyojna command area, where epidemics are regular features every year.