|Year : 2019 | Volume
| Issue : 4 | Page : 324-329
Bio-eco-social determinants of Aedes breeding in field practice area of a medical college in Pune, Maharashtra
Gurpreet Singh1, Rina Tilak2, SK Kaushik3
1 Assistant Professor, Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India
2 Scientist G, Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India
3 Associate Professor, Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India
|Date of Web Publication||18-Dec-2019|
Dr. Gurpreet Singh
Department of Community Medicine, Armed Forces Medical College, Pune - 411 040, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Major determinant of dengue incidence is interaction between ecology, vector bionomics, and social factors. Objectives: The objective of the study is to find out bio-eco-social determinants of Aedes breeding. Methods: Background, household, entomological, and knowledge, attitude, and practice (KAP) surveys were undertaken post- and premonsoon showers from May to June 2016 in urban and rural practice area of medical college. Results: A total of 181 and 204 households, 131 and 137 individuals, and 1250 and 1268 water-holding containers were included in household survey, KAP survey, and larval survey in urban slum and rural area, respectively. In both locations, maximum water-holding containers were indoors (41.4% and 61.8%, respectively); however, maximum positivity was peridomestic (63.6% and 83.1%, respectively). Pupae per container were 0.9 and 1.9 in respective locations and pupae per person were 1.2 and 2.3, respectively. Container positivity was seen in containers with rain as water source (8.8%) as well as among those who were never used (10.7%). Irregular water supply was significantly more in rural area (P < 0.05). KAP survey revealed that majority (90.1% and 71.5%, respectively) had heard about dengue, with significantly higher knowledge in urban slum, and television was the main source of information. Majority (89% and 83%, respectively) were unaware that peak biting time of Aedes is daytime. Use of mosquito repellent coils was the predominant preventive practice (46.6% and 61.2%, respectively). Pupae were reared; all were found to be Aedes aegypti. Conclusions: Despite enhanced awareness campaigns, an integrated vector management approach is required for prevention of dengue.
Keywords: Aedes, dengue, determinants, larval indices, prevention
|How to cite this article:|
Singh G, Tilak R, Kaushik S K. Bio-eco-social determinants of Aedes breeding in field practice area of a medical college in Pune, Maharashtra. Indian J Public Health 2019;63:324-9
|How to cite this URL:|
Singh G, Tilak R, Kaushik S K. Bio-eco-social determinants of Aedes breeding in field practice area of a medical college in Pune, Maharashtra. Indian J Public Health [serial online] 2019 [cited 2020 Jul 9];63:324-9. Available from: http://www.ijph.in/text.asp?2019/63/4/324/273355
| Introduction|| |
Dengue, caused by bite of infective female Aedes mosquito is rapidly increasing and poses a huge economic burden across the globe including India. At present, half of the global population is considered at risk of dengue. Recent estimates on burden of dengue indicates annual incidence rate of dengue infections to be 390 million globally. Country-specific data for India on dengue shows that in 2016, more than a lakh cases occurred due to dengue. Further, dengue which was predominantly in urban and semi-urban locations is now spreading to rural areas.
In the absence of specific treatment and effective vaccine for all, prevention through integrated vector control is the only strategy currently available. Integrated vector management has been proved to reduce vector density and disease transmission considerably. However, the rising incidence and inclusion of new geographical regions being affected by dengue imply inherent limitations in vector control programs. Systematic review on functioning of vector control programs has identified enhanced stress on use of insecticides, lack of community participation, absence of surveillance measures, and technical expertise as major reasons for failure of these services among others. Furthermore, critical review of the vector control programs being undertaken indicates ineffectiveness of routine antilarval measures. This suggests that there is a felt need for understanding the bionomics, ecological and spatial distribution, and social factors prevalent specific to the communities in totality by public health professionals before undertaking the vector control programs. Further, 'one-size-fit-all' approach cannot be applied in different settings for effective vector control.
The focus of research in dengue in the country has been on bionomics of the vector; knowledge, attitude, and practices (KAPs) studies; epidemiology; eco-epidemiology; clinical characteristics; vector prevalence; and seasonal patterns. Systematic reviews and meta-analysis on these 'single-focus' studies are available, however, has a potential limitation of different backgrounds, in which studies are being carried and thus limiting the pooling of results and their interpretation. Although multiple domains related to dengue have been studied and the factors determining vector breeding, vector density and vector transmission potential identified, namely, biological, ecological, and social, there is limited analysis including these factors in combination. Thus, the present work was carried out to find out biological, ecological, and social determinants of Aedes breeding which have important implications for public health professionals for control of dengue.
| Materials and Methods|| |
The present study was a cross-sectional community-based study designed in the Department of Community Medicine. Ethics clearance was obtained from institutional ethics committee and informed consent was obtained from the study participants during the conduct of the study. A training workshop on survey methodology by entomologist faculty was undertaken before commencement of the study. A total of six health teams were constituted and each team comprised of one postgraduate resident in community medicine and four health assistants. The study was carried out post- and premonsoon showers from May to June 2016 in the rural and urban field practice areas of Armed Forces Medical College, Pune, Maharashtra, around 40 km apart from each other.
An initial background survey was carried out to determine the spatial orientation and infrastructural determinants at both locations. Subsequently, household, entomological, and KAP survey was undertaken simultaneously in the study sites. Background survey checklist and survey forms were developed, pilot tested, corrected, and then administered. During the conduct of surveys, health teams evaluated each sublocation in the clockwise direction. Survey of an area was considered complete when the team reached the household which has been previously inspected. All public/private places were included in the survey to ensure that probable breeding hot spots were not missed (streets, pathways, playground, butchery, unused areas of land, places of worship, abandoned buildings, construction sites, hospitals/dispensaries, and shops were considered as public spaces).
Presence of sites near the households capable of holding rainwater, infrastructure development status, status of sanitation around households, presence of shady places, and well water sources were checked. On basis of background surveys, area allocation to health teams for subsequent surveys was planned and executed.
Household survey questionnaire was used to determine the total number of individuals residing in the house, construction type as “kuccha” if the building did not have concrete roof and water supply was considered as regular where households had at least once-daily supply of tap water in the past 1 month. Sanitation practices were evaluated on the basis of the presence of latrines within homes, using community latrines and open defecation practices.
Entomological survey was undertaken in domestic, peridomestic, and public spaces. Larval survey was carried out to assess the vector breeding preferences, whereas pupal survey was considered as a proxy for adult vector population and vector transmission potential. All water collection sites and water-holding containers were examined. The containers were categorized on basis of their dimensions, water source, frequency of use, and presence/absence of lid cover. Larval indices and pupal indices were calculated. Percentage of households wherein breeding was found (positive) and percentage of positive containers was defined as “Household index” (HI) and “container index,” respectively. “Breteau index” (BI) was calculated as number of positive containers per 100 inspected households. At places where large collections of water were present, investigators determined pupal count by filtering water through well nets.
Knowledge, attitude, and practice survey
KAP survey was conducted along with household surveys to determine awareness levels and common practices being followed for prevention and control of dengue.
Data were entered in Excel sheets and analyzed using SPSS version 21.0 (Chicago, IL, U.S.A). Descriptive measures were calculated for variables under the study. Chi-square test was applied for qualitative/categorical data. P ≤ 0.05 was considered as statistically significant.
| Results|| |
Background survey of the study area revealed infrastructural differences between urban slum and rural area. On a dichotomous scale, most of the public spaces were present in both locations; however, they were found to be intermixed with residential houses in urban slum. Furthermore, multistoried buildings were seen in urban slum only. On the other hand, only rural area was found to have houses with garden/open spaces as well as households with trees/bushes.
A total of 181 households in urban slum and 204 in rural area were included in household survey [Table 1]. Kuccha houses were present in both locations (P = 0.979), whereas irregular water supply was found in 21.6% of rural households as compared to only 8.3% households in urban slum (P < 0.05).
Findings of the larval and pupal survey are presented in [Table 2]. Among a total of 1250 and 1268 water-holding containers examined in the urban slum and rural area, 11 and 83 containers and 8 and 46 households were found to have Aedes larvae breeding, respectively. In both urban slum and rural area, maximum water-holding containers were found indoors (41.4% and 61.8%, respectively); however, maximum positive containers were found in peridomestic area (63.6% and 83.1%, respectively). HI of >5 and BI of >20 was found in rural area. Pupal indices were also found to be higher in rural area as compared to urban slum. Pupae per container were 1.89 and 0.85 and pupae per person were 2.3 and 1.2 in rural area and urban slum, respectively. Pupae were reared and identified up to species level; all were found to be Aedes aegypti.
|Table 2: Larval and pupal distribution pattern and indices (entomological survey)|
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Further, Aedes breeding preferences were found to be significant for containers which were less frequently used and were filled with rainwater. Container positivity was seen in 8.8% of containers with rain as source of water as compared to 1.9% among containers filled with tap water (P < 0.05). Further, container positivity was found to be 10.7% among never used water-holding containers as compared to 0.5% among containers which were used daily (P < 0.05) [Table 3]. Five most common types of containers found positive (containing larvae/pupal stages) at both locations were drums, tires, cement tanks, metal containers, and earthen pots.
|Table 3: Source of water and frequency of use as determinants of breeding preference for Aedes|
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Knowledge, attitude and practice survey
A total of 131 and 137 individuals participated in the KAP survey in urban slum and rural area, respectively [Table 4]. The mean age of the study participants was 37 years and female respondents were 58% and 48.9%, respectively, at both locations. Majority (90.1% in urban slum and 71.5% in rural area) had heard about dengue; however, the awareness levels were found to be significantly lower in rural area (P < 0.05). Among those who had heard about dengue, majority knew that dengue is caused by mosquito bite (89.0% and 88.8% in urban slum and rural areas, respectively, P = 0.961) and significantly higher percentage (89.8%) in urban slum opined that incidence increases after rains as compared to 80.6% in rural areas, P = 0.054). Individuals in urban slum (84.7%) were more aware of symptoms and mentioned fever as first symptom, P < 0.05. About 86% of urban population were aware of complications of dengue as compared to 44.9% of rural population, and they also knew that dengue can cause death, P < 0.05. Only a few knew that dengue mosquitoes bite peak time is during the day in both locations (11.0% and 16.3% in urban and rural areas, respectively, P = 0.255). Further, measures to prevent breeding as well as mosquito bites were similar in both locations except practice of keeping the water-holding containers covered which was significantly more practiced in urban slum (P < 0.05). Multiple sources of information were enumerated by the study participants with television being the most common source of information (93 [70.9%] in urban slum and 55 [40.14%] in rural area, respectively).
|Table 4: Level of knowledge regarding dengue and practices followed to control mosquito breeding and against mosquito bites (knowledge, attitude, and practice survey)|
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| Discussion|| |
The present study brings forward important bio-eco-social determinants which need to be incorporated in evidence-based decision-making among public health specialists in the field as well as academicians to combat against dengue. The determinants of Aedes breeding have a complex association; however, the findings of this study provide specific messages for dengue control programs and are discussed in subsequent paragraphs.
In the present study, infrastructural differences were contrasting between the rural area and urban slum. Furthermore, the vector indices were found to be higher in rural area as compared to urban slum. The shift of ecology of Aedes mosquito has resulted in enhanced disease transmission potential for the vector. Previous studies carried in the country  as well as other developing nations  have established the effect of spatial patterns resulting from urbanization in an unplanned manner as an important cause of rapidly increasing incidence of dengue.
Further, larval survey findings in both the locations showed that breeding preferences were for peridomestic containers. This qualifies as an important consideration for public health professionals in dengue control programs. Evidence from multiple studies including systematic reviews recommend that integrated vector control measures should be undertaken. However, targeting peridomestic spaces will be instrumental in decreasing Aedes breeding significantly in scenarios where households are reluctant to undertake vector control activities in their premises. Furthermore, unused discarded containers filled with natural sources of water should be targeted on priority as an effective strategy in vector control programs.
Larval indices were indicative of rural area as dengue sensitive, requiring adequate preventive measures. The spatial distribution of dengue, which was considered as a disease of urban areas is now rapidly spreading to newer ecological zones including rural parts of the country. Evidence-based public health is the key to successful vector control and as managers of vector control program, public health specialists need to ensure that larval surveys are undertaken at the inception as well as an interim measure and priority areas for vector control be decided on larval indices. Any cluster with reporting of dengue cases must be allocated as Priority 1, followed by those with HI >5 and/or BI >20 as per the WHO area prioritization protocol for dengue surveillance. Pupal indices were also found to be higher in rural areas suggesting increased vector density and transmission potential. Pupal indices are considered as better indicators of the vector density due to the sturdy nature of pupal stage and thereby significantly lower mortality in pupal stage as compared to larvae which are better indicator of breeding preferences. This fact needs to be incorporated in determining vector potential and critical density for control of dengue. Further, cutoff values of pupal indices vary according to the IgG seroprevalence rates in the community. Due to the absence of seroprevalence rates in both the locations, this study is unable to comment on interpretation of pupal indices. However, the present study brings forward an unmet need for undertaking seroprevalence studies to comment more accurately on disease transmission potential in various parts of the country.
The level of knowledge in urban slum was found to be better than in rural area. Furthermore, urban slum had significantly higher proportion of water-holding containers which were properly covered. Close proximity of the urban slum to medical college as well as information, education, and communication campaigns by Municipal Corporation may be a possible explanation for the same. Similar findings were also present in a study carried out previously in the city. However, in both the study locations, only a few (11% and 16.3% in urban slum and rural area, respectively) were aware that dengue mosquito peak biting time is during the day. Enhanced awareness levels are crucial not only to minimize vector breeding in the locality but also for early detection and prompt treatment. Analysis of sources of information brings forward that television outnumbered common health education modes used locally by vector control programs, such as banners and newspapers at both study locations. This implies the need for strengthening existing local health awareness campaigns. Furthermore, the distribution of source of information was found to be different in both locations, suggesting that information platforms for a community should be established before planning an awareness program.
| Conclusions|| |
The bio-eco-social determinants of Aedes breeding in the community need to be understood by public health professionals before undertaking the vector control program. Selected determinants identified in this study which needs to be considered along with integrated vector control measures are elucidated as under.
First, identification of productive container types with special attention to those which are outdoors, unused, and filled with natural sources of water is required. Second, in communities where dwellers are reluctant to implement indoor vector control measures; targeting peridomestic unused and discarded containers outdoors can still make a big difference. Third, strengthening of local awareness campaigns for maximum outreach is required. Measures to assess implementation of ongoing government efforts with awareness survey and by medical colleges in rural and urban field practice areas also needs to be deliberated upon.
Finally, multicentric ecological studies focusing on the immunoglobulin G seroprevalence rates for dengue viruses in the community are required to estimate vector transmission potential in the country. Integrated vector management encompassing multiple determinants is required to be incorporated to curb the rapidly increasing incidence of dengue.
Dr. Mona Dubey, Dr. Rekha Sharma, Dr. Manoj Kumar Gupta, Dr. Naveen Phuyal, Dr. Lee Budhathoki, Dr. Amol Nath, Dr. Rohit, Dr. Sunil Diwate, and Mrs. Urmila Wankhade for their help in data acquisition.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]