|Year : 2013 | Volume
| Issue : 3 | Page : 159-161
Assessment of environmental factors associated with dengue transmission in Udupi Taluk, Karnataka
Ramachandra Kamath, Roshan Gupta, Varalakshmi Chandrasekaran, Sanjay Pattanshetty
Department of Public Health, Manipal University, Manipal, Karnataka, India
|Date of Web Publication||19-Oct-2013|
Department of Public Health, Manipal University, Manipal, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Dengue fever is a major public health problem in India. Dengue is a re-emerging arboviral disease in the World. Assessment of environmental factors in the rural and urban areas is extremely important to understand vectors, its transmission and vector breeding sites. Aim: The study was conducted to assess the environmental factors associated with dengue transmission and its protective factors. Settings and Design: A Community based cross sectional study was conducted in Udupi Taluk. Materials and Methods: The Study period was conducted during March 2012 to August 2012. Sample size was calculated by the formula of estimation of proportion (n = Z 2pq/ͺ2 ) at 95% significance level. Stratified multistage cluster sampling was used. A total of 500 households of Udupi Taluk were selected randomly for the study. Statistical Analysis Used: Data was analyzed using the SPSS version 15, Chicago, IL. Results are presented in proportions. P < 0.05 was considered to be significant. Results: Results showed that foremost risk factor for vector breading was abundance of coconut shells around houses (73%), containers without covers 50.8% (outdoor) and 20% (indoor). The P < 0.05 was significant for usage of mosquito coil or repellents, having a protective screen for windows, doors in living rooms and use of insecticide spray to reduce mosquito density in urban and rural areas. Conclusions: Health education, specific protection and source reduction need to be emphasized to control dengue fever in rural and urban areas.
Keywords: Dengue fever, environmental factors, transmission
|How to cite this article:|
Kamath R, Gupta R, Chandrasekaran V, Pattanshetty S. Assessment of environmental factors associated with dengue transmission in Udupi Taluk, Karnataka. J Sci Soc 2013;40:159-61
|How to cite this URL:|
Kamath R, Gupta R, Chandrasekaran V, Pattanshetty S. Assessment of environmental factors associated with dengue transmission in Udupi Taluk, Karnataka. J Sci Soc [serial online] 2013 [cited 2019 May 23];40:159-61. Available from: http://www.jscisociety.com/text.asp?2013/40/3/159/120060
| Introduction|| |
Dengue fever is a public health problem of global importance. About 2.5 billion people are at risk of dengue infection, of which 50 million get infected annually.  Dengue is the fastest re-emerging arboviral disease in the world.  Dengue is currently a major epidemiological threat for over 100 countries. Currently, 40% of the world's population lives in areas with high risk of dengue infection. The World Health Organization (WHO) estimates that 50-100 million of dengue infections occurs yearly including 500,000 dengue hemorrhagic fever cases and 22,000 deaths, mostly among children.  In 2006, ten out of eleven countries in South-East Asia Region the region (except Korea) reported dengue cases. In India, Dengue is endemic in Delhi, Gujarat, Punjab, Karnataka, Tamil Nadu, Kerala and Andhra Pradesh. 
Dengue is caused by four serotypes of viruses (DENV 1-4) and transmitted between human hosts almost exclusively by Aedes Aegypti (principal vector) and Aedes Albopictus mosquitoes. The vectors predominantly bread in artificial containers.  Climate change, temperature, rainfall and other weather variables play a major role in spreading the disease.  The objective of this study was to do an environmental assessment of risk factors associated with dengue transmission in Udupi Taluk.
| Materials and Methods|| |
A community based cross-sectional study was conducted during March 2012 to August 2012. A multi country study in Asian cities by Arunachalam et al.  found the prevalence of most productive indoor container was cement tank (39.9%) and outdoor container was tyres (43.6%). The sample size for the study was calculated using the formula of estimation of proportion (n = Z 2pq/є2 ) at 95% confidence level. Considering 10% non-response rate and design effect of two, the total sample size was 490. A Stratified cluster sampling was used to select the households. Udupi Taluk is stratified into urban (40 wards) and rural area (99 villages). Based on probability proportional to population, seven urban wards and 18 villages were selected randomly. From each ward/village, 20 households were selected randomly. Total household covered was 500. A pre-designed structured questionnaire was used to obtain the socio-demographic information and to assess factors associated with dengue transmission. Data on rainfall (last 5 years 2007-2011) was gathered form Meteorology Department. Data was analyzed using the SPSS version 15.0, Chicago IL.
| Results|| |
Out of 500 participants, 72% were from rural and 28% from the urban area. Majority of the respondents were females 70.6%. Median age of the respondents was 42 years (ranges from 15 to 89 years). Majority of the study participants were married (84.2%). Out of 500, 15% respondents had no education. Majority of the study participants lived in mixed (64.6%) kind of houses and 32% were living in pakka house. Only 3.4% participants lived in kutcha houses. Open well (50%) was the major source of water for drinking and other day-to-day activities. In the urban area, people were disposing home waste through municipal waste collection (88%). Conversely, in a rural area burning (75.8%) was the most common method for solid waste management. About 43.4% of total respondents were draining waste water in to their kitchen garden. However, 26% of total respondents had open drainage system.
[Table 1] shows the association between presences of risk factors for A. aegypti mosquito breeding and place of residence. The P value was significant for artificial collection sources such as coconut shells in rural areas, flower pots filled with water and water storage without proper cover in urban areas.
[Table 2] shows the practice of protective factors in urban and rural areas. The P value was significant for usage of mosquito coil or repellents, having a protective screen for windows, doors in living rooms and use of insecticide spray to reduce mosquito density in urban and rural areas. Proper maintenance of the yard and elimination of standing water source to reduce mosquito around the house were significantly different in urban and rural areas. However, practice of using bed nets was more (35.8%) in a rural area. It is well-known that the roles of bed nets are not very effective for prevention of dengue transmission because Aedes mosquitos are day biters; however, awareness regarding the use of bed nets was more in rural areas of Udupi.
|Table 2: Relationship between protective factors and place of residence (urban/rural)|
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| Discussion|| |
In the present study, we found that most artificial containers were coconut shells. A study by Fulmali et al. in three districts of Maharashtra found that water in plastic containers was one of the risk factors.  Similar results were reported by Swaddiwudhipong et al. in Thailand.  Unused and unprotected outdoor containers were the most highest contributors to mosquito breeding. ,,, Entomological survey was conducted in selected village of Udupi Taluk. House index was 4.4, container index was 3.78 and Breteau index was 3.32 in our study. A survey performed by Sharma et al. in Thiruvananthapuram also found similar results.  Average rainfall in last 5 year (from 2007 to 2011) in Udupi was 4741.52 mm (standard deviation = 535.13). The ecological and climatic factors influence the seasonal prevalence of the vectors and intensity of breeding. According to WHO if annual rainfall is >1500 mm it comes under tropical monsoon zone. Data shows that annual rainfall in Udupi Taluk is much higher and it fell under the tropical monsoon zone.  Several studies have shown that higher rainfall was associated with vector abundance and high dengue incidence. ,, In Udupi Taluk, the foremost factor for mosquito breeding is an abundance of coconut shells around houses (73%), which are not properly disposed and forming constructive environment for mosquito breeding. In 50% of the houses, we found water containers without covers around the house and 20% inside the home, which were not used in the past 5-6 days. Trash was also found to be discarded indiscriminately around most homes (67%).
Interruption of dengue virus transmission depends upon control of the vectors, prevention of stagnation of water, control of breeding of mosquitos through proper environmental management and prevention of human - vector contact. Health education and specific protection are the key messages to interrupt the transmission. This can be achieved through advocacy, social mobilization and legislation. Involvement of grass root level workers in advocating behavior change at the level of individual, family and the community will help to implement good environmental management practices and prevent dengue in the society.
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[Table 1], [Table 2]