- Study on the Behavior of Dengue Viruses during Outbreaks with Reference to Entomological and Laboratory Surveillance in the Cuddalore, Nagapattinam, and Tirunelveli Districts of Tamil Nadu, India
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Parasuraman Basker, Karumana Gounder Kolandaswamy
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Osong Public Health Res Perspect. 2015;6(3):143-158. Published online June 30, 2015
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DOI: https://doi.org/10.1016/j.phrp.2015.05.001
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 Abstract
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- Objectives
This study was carried out in order to understand the behavior of dengue viruses through the entomological and laboratory surveillance of outbreaks. The aim of the study was to provide additional research to support current knowledge of epidemiological, clinical, and laboratory diagnosis of dengue virus and ultimately to use this information to forecast dengue as well as to justify intervention measures.
Methods
Data on the presence of Aedes larvae in human dwellings during the entomological surveillance in Cuddalore, Nagapattinam, and Tirunelveli dengue outbreaks were taken to compute indices, namely the House Index (HI), Container index (CI), and the Breteau Index (BI). Standard procedures were followed for nonstructural Protein 1 (NS1) and immunoglobulin M enzyme linked immunosorbent assay for the confirmation of dengue. Serovar confirmation was made in the Kottayam field station of the Vector Control Research Center, Puducherry.
Results
Larval indices HI < 2–3% and BI < 20 contributed to halting the outbreak. Incubation of the dengue viruses in humans was detected at 15 days, NS1 was identified as a tool for the early diagnosis of dengue cases and its presence indicated the need to implement all available interventions. It was also discovered that it is helpful to search for hidden habitats of Aedes when dengue cases have not been reduced even after the sustainable management of the larval indices, HI < 5% and BI < 20. Based on the observed incidences of stopping dengue outbreaks, it was learnt that neighborhood areas of the outbreak villages, around 400 m, should have permissible larval indices < 5% HI and BI < 20. Heterogeneous serovars that led to dengue hemorrhagic fever and Dengue Shock Syndrome (DSS) were identified using reverse transcription polymerase chain reaction and reconfirmed in the field as DEN-1 and DEN-3 viruses and were circulating in Tirunelveli during the outbreak.
Conclusion
The behaviors of dengue viruses experienced in experimental, clinical, epidemiological, entomological, and laboratory surveillance did not deviate from observations in the field during dengue outbreaks in the Cuddalore, Nagapattinam, and Tirunelveli districts of Tamil Nadu, India.
- Study on the Prevalence of Leptospirosis among Fever Cases Reported from Private Clinics in the Urban areas of Villupuram District, Tamil Nadu, India
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Parasuraman Basker, Pichai Kannan, Karumana Gounder Kolandaswamy
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Osong Public Health Res Perspect. 2014;5(1):54-67. Published online February 28, 2014
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DOI: https://doi.org/10.1016/j.phrp.2014.01.003
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1,315
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Abstract
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- Objectives
To know the prevalence of leptospirosis cases reported in private clinics among fever cases in Villupuram District, Tamil Nadu, India to know its real magnitude of the problem and to diagnose Leptospirosis among fever cases from differential diagnosis.
Methods
1502 Blood serum samples collected from three urban towns namely Kallakurichi (Latitude: 11° 73′ N; Longitude: 78° 97′ E), Villupuram (Latitude: 11° 75′ N; Longitude: 79° 92′ E) and Thindivanam (Latitude: 12° 25′ N; Longitude: 79° 65′ E) in fifteen clinics based on case definition of leptospirosis delineated by the National Vector Borne Disease Control Programme (NVBDCP), Government of India. Samples were tested in the laboratory of the Zonal Entomological Team (ZET), Cuddalore with Macroscopic Slide Agglutination Test (MSAT) and Ig-M ELISA.
Result
There were 65 positive cases detected from 1502 blood serum samples in both MSAT and Ig-M ELISA. It could be known that there was 4% cases contributed from private clinics among fever cases. From this study, further it was known that all age groups of people affected irrespective of sexes based on their living condition associated with the environment prevailed of the disease.
Conclusion
From this study, it was quantified that 4% of cases reported in private clinics among fever cases and its findings ascertained both the importance of differential diagnosis as well as reports that should be included to the Government for knowing its real magnitude for planning.
- Study on Entomological Surveillance and its Significance during a Dengue Outbreak in the District of Tirunelveli in Tamil Nadu, India
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Parasuraman Basker, Pichai Kannan, Rajagopal Thirugnanasambandam Porkaipandian, Sivsankaran Saravanan, Subramaniam Sridharan, Mahaligam Kadhiresan
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Osong Public Health Res Perspect. 2013;4(3):152-158. Published online June 30, 2013
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DOI: https://doi.org/10.1016/j.phrp.2013.04.005
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1,505
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Abstract
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- Objectives
To study the significance of entomological surveillance, the house index (HI), container index (CI), and Breteau index (BI) were determined to estimate the degree of a major dengue outbreak in Tirunelveli, Tamil Nadu, India (Latitude: 8°42′N; Longitude: 77°42′E) in May 2012.
Methods
The HI, CI, and BI were determined in a primary health center (PHC) in the village of Maruthamputhur (Pappakudi taluk, Tirunelveli) by carrying out an antilarval (AL) work that involved door-to-door search for immature stages of Aedes spp. mosquitoes by trained field workers and volunteers. The work of field workers was evaluated by a junior and senior entomologist the following day.
Results
Before the AL work, the reported numbers of fever cases from Week 1 to 5 in Maruthamputhur were 211, 394, 244, 222, and 144 with two deaths. By contrast, after the AL work, these numbers were considerably reduced and there was no fever-related death (the HI was reduced from 48.2% to 1.6%, the CI from 28.6% to 0.4%, and the BI from 48.2 to 1.6).
Conclusion
Because no specific medicine and vaccines are available to treat dengue fever and dengue hemorrhagic fever, entomological surveillance and its significance can be used to halt the outbreak of dengue as shown in this study.
- Study on the Correlation of Premises Condition Index and the Presence of Larvae of Aedes Species Mosquitoes in Human Dwellings of the Cuddalore District of Tamil Nadu, India
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Parasuraman Basker, Radhakrishnan Ezhil
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Osong Public Health Res Perspect. 2012;3(1):3-7. Published online December 31, 2011
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DOI: https://doi.org/10.1016/j.phrp.2011.11.046
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1,328
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5
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- Conclusions
It is concluded that this study helps in conducting rapid survey to identify the presence of Aedes larvae with a minimum number of staff for both inspection and treatment of Aedes larvae during the epidemic situation.
Objectives
To predict dwellings for the presence of Aedes larvae rapidly based on Premises Condition Index (PCI) factors, we studied the possible presence of Aedes species mosquitoes larvae among houses in the Chidambaram urban of Cuddalore District in Tamil Nadu, India based on the scores of variables in PCI, namely House, Yard and degree of shadow. Data of these variables were collected in September and October 2006 from 1813 houses in the Chidambaram urban area during the intensive vector control activities employed for the prevention and control of Chikungunya.
Methods
The association between presence of larvae and the variables of PCI was tested by Chi-square and Correlation. The predictability of the presence of Aedes larvae based on PCI factors was computed by logistic regression.
Results
The study shows 301 containers in 132 houses were found positive with Aedes species out of 1813 houses surveyed. It was further observed that the probability of presence of positive premises was four times higher in the premises with 75% shadow compared with premises with a 25% shadow. These findings showed a significant association (p < 0.001) with positive premises.
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