|Year : 2018 | Volume
| Issue : 1 | Page : 34-37
Effectiveness of evaporative desert cooler mounted with fabricated metal mesh in preventing Aedes mosquito breeding in a North Indian City
Archana Singh1, Reema Mukherjee2, Atul Kotwal SM, VSM 3, Rajiva (Retd) 4
1 Department of Community Medicine, Army College of Medical Sciences, New Delhi, India
2 Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India
3 Dy DGAFMS(P), Min of Defence, New Delhi, India
4 CMO, THDC India Ltd, Rishikesh, Uttarakhand, India
|Date of Web Publication||9-Jul-2018|
Lt Col Reema Mukherjee
Department of Community Medicine, Armed Forces Medical College, Pune - 411 040, Maharashtra
Source of Support: None, Conflict of Interest: None
Context: We modified conventional metal body evaporative desert coolers by covering the water sump with fabricated metal mesh. Aedes mosquito breeding in these modified desert coolers was then tested during dengue transmission season. Aim: This study was carried out with the aim of providing an effective modification which can be carried out locally in evaporative metal body desert room coolers, to prevent Aedes mosquito breeding. The authors also compared the effectiveness of such desert coolers mounted with fabricated metal mesh against the standard National Centre for Disease Control, mosquito proof coolers (NCDC-MPC). Settings and Design: This study was carried out from October 2015 to 2016 in a large military cantonment area of North India. The data collection for larval breeding was done during late summer and monsoon months, namely May–October 2016. Subjects and Methods: Conventional metal body evaporative desert cooler was modified by covering its sump water tank with a fine mesh. These modified coolers were then monitored for larval breeding and compared with the NCDC-MPC, and conventional nonmodified routinely used desert coolers. Statistical Analysis Used: A database was created in MS Excel and observations were recorded analyzed and tabulated. Results: No breeding was detected in the NCDC coolers and the coolers mounted with fabricated metal mesh. Conclusion: The conventional desert cooler locally modified by mounting a fabricated metal mesh to cover sump water tank of the cooler, was found to be effective in preventing Aedes breeding. It offers the advantage of simplicity, low cost, and improved availability.
Keywords: Aedes aegypti, breeding, chikungunya, cooler mounted with fabricated metal mesh, dengue, mosquito proof desert cooler
|How to cite this article:|
Singh A, Mukherjee R, Kotwal A, Rajiva. Effectiveness of evaporative desert cooler mounted with fabricated metal mesh in preventing Aedes mosquito breeding in a North Indian City. J Mar Med Soc 2018;20:34-7
|How to cite this URL:|
Singh A, Mukherjee R, Kotwal A, Rajiva. Effectiveness of evaporative desert cooler mounted with fabricated metal mesh in preventing Aedes mosquito breeding in a North Indian City. J Mar Med Soc [serial online] 2018 [cited 2019 Jul 22];20:34-7. Available from: http://www.marinemedicalsociety.in/text.asp?2018/20/1/34/236247
| Introduction|| |
The global prevalence of dengue has grown dramatically in recent decades and breeding of Aedes aegypti and Aedes albopictus has seen an unprecedented increase because of unplanned rapid urbanization, population migration, industrialization, water storage practices, and paucity of piped water supply in rural areas.,,,
A. aegypti mainly breeds in desert room coolers, unused tire dumps, and other domestic and peridomestic containers where chemical vector control methods though indicated are difficult to employ. Desert coolers are extensively used in Northern, Western, and Central India during the summer and monsoon months. Studies carried out in Delhi have revealed that around 90% of Aedes breeding is found in coolers, especially during September–November. Various studies have brought out the role played by evaporative desert coolers in the survival of the vector from one transmission season to another, in most north Indian states.,,,,, Control of breeding in desert coolers relies on either weekly emptying of the water in the sumps and cleaning and drying of the coolers which is usually difficult to comply with, or the use of chemical larvicides. Using chemicals for vector control have given rise to the serious problem of insecticide resistance in vectors practically worldwide. The National Centre for Disease Control (NCDC), New Delhi, in the year 2007 came out with the mosquito-proof cooler (MPC). Despite the apparent effectiveness of the MPC in preventing Aedes breeding; it has not been used extensively in India, due to lower awareness and higher cost of the MPC.
The aim of this study was to effectively modify metal body evaporative desert room coolers to prevent Aedes mosquito breeding in the water sump. The objectives of this study were to mosquito-proof a conventional cooler by a simple procedure of covering its sump water tank with a fine mesh and assess its effectiveness in preventing Aedes breeding and to compare its effectiveness with that of the NCDC MPC. A fine metal (mesh size 1.2 mm × 1.2 mm) wire mesh was fixed to a metal frame after measuring the internal dimensions of the desert cooler to ensure no gaps between the body of the cooler and the frame. These removable frames mounted meshes were then fitted inside the conventional desert coolers to make them mosquito proof (hereafter referred to as modified desert cooler).
| Subjects and Methods|| |
This study was a field trial to test the effectiveness of a locally modified conventional desert cooler in preventing Aedes breeding and to compare the same against the standard patented NCDC-MPC. The study was carried out from October 2015 to 2016 in a large military cantonment area of North India. The data collection for larval breeding was done during late summer and monsoon months, namely May–October 2016 which is the most active period for Aedes breeding. For routine vector control activity, the area of the military cantonment is divided into five sectors (Sectors A-E). Units and residential accommodations were roughly equally distributed within these five sectors and there were no major differences with respect to terrain or topography. One observation station was set up in each of these five sectors. Each observation station had: one NCDC-MPC cooler; one desert cooler mounted with fabricated metal (modified cooler) [Figure 1]; five conventional coolers; and one electronic meteorological data display machine. All observation stations were visited daily to observe larval breeding. The collection of larvae was done by dipping method as per World Health Organization guidelines and larval density per dip was calculated. Thereafter, the desert cooler/coolers showing breeding were emptied, scrubbed, and allowed to dry for a day. After 24 h, the emptied coolers were refilled with water and observation restarted. To reduce observer bias, a health worker was trained in measuring larval density and larval species identification over a period of 3 weeks by the principal author. The same health worker collected data from all 05 observation stations. In addition, the principal author supervised the procedure on the ground by visiting the 5 study stations regularly to check the correctness of data collection. The temperature of water in all test and control coolers was almost similar and all the coolers were exposed to the similar meteorological conditions. A database was created in MS Excel and observations were recorded, analyzed, and tabulated.
|Figure 1: Average larval breeding in modified cooler*, NCDC MPC$ and conventional coolers in all five sectors between May and October 2016. *Modified cooler = Evaporative metal body desert cooler mounted with fabricated metal mesh. $ NCDC MPC = National Centre for Disease Control mosquito-proof cooler|
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| Results|| |
[Table 1] depicts sector-wise average larval density in the desert coolers between May and October 2016. No breeding was detected in the NCDC-MPC or the modified coolers. The average larval breeding per month in the conventional desert coolers at five locations as shown in the table ranged from 6.0 to 8.7 larvae per dip.
|Table 1: Sector-wise average larval density in desert coolers between May and October 2016|
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[Figure 2] compares the average larval breeding in the modified coolers, NCDC-MPC, and the conventional coolers at all five sectors from May to October 2016. It is apparent that no larval breeding was detected in the NCDC-MPC or the desert cooler mounted with fabricated metal mesh (modified) coolers while varying levels of larval breeding was seen in the conventional coolers in all the sectors.
|Figure 2: Evaporative metal body desert cooler mounted with fabricated metal mesh|
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| Discussion|| |
We studied the effectiveness of desert coolers mounted with fabricated metal mesh, in preventing Aedes breeding, during the dengue transmission season. We compared it with the NCDC-MPC which was developed and patented by the NCDC, New Delhi. No larval breeding was detected in the modified coolers. Varying levels of larval breeding were detected in the other conventional coolers. As expected, nil breeding was detected in the NCDC-MPC too. The authors are not aware of any similar study carried out/published hence no comparison was possible.
The two main advantages of the modified coolers are – low cost of modification (₹ 670/cooler) and ease of modification. A conventional evaporative desert cooler costs upward of ₹ 3000 and can be easily modified at an additional minimal cost. We would like to also bring out that the modification can be done locally in any conventional cooler, irrespective of the size and this is an advantage over the NCDC MPC which is of a fixed large size (fan size 450 mm). When procured through the Government E-marketing site (online), presently, it costs between Rs 11,000 and 14,000 and is delivered only to few states by the authorized vendors. To be used in cities/military stations where an authorized dealer for the NCDC cooler is not available these will need to be transported which will add to the cost. Newspaper reports have revealed poor uptake of the NCDC cooler due to higher costs compared to the conventional cooler.
The modified cooler thus, has an advantage of universal availability, besides lower cost over the NCDC cooler. The only place where the NCDC cooler may have an advantage over the modified cooler is that the metal cover in the NCDC MPC is likely to have a longer life as compared to the mesh used in this study. However, at the same time, the sump water tank of NCDC-MPC cannot be opened for cleaning and drying at the end of the summer whereas the sump tank of the modified cooler can be easily accessed and cleaned simply by removing the mesh frame. These aspects may need to be studied further. In our study, the modified coolers have shown to retain all the advantages of the NCDC-MPC, namely weekly cleaning of the water tank is not required, application of chemicals for larval control is not required, can be conveniently installed in high-rise buildings, even stagnant water in the cooler (when not in use), has no risk of mosquito breeding. Besides the cost of modification is minimal and can be easily carried out locally as a high degree of expertise is not required. Thus, the present study reveals that evaporative desert cooler mounted with fabricated metal mesh showed 100% control on breeding of A. aegypti in a very cost-effective manner.
This study was conducted with the aim to provide a locally available effective alternative to the NCDC-MPC.
| Conclusion|| |
The conventional desert cooler locally modified by mounting a fabricated metal mesh to cover sump water tank of the cooler was found to be effective in preventing Aedes breeding. It offers the advantage of simplicity, low cost, and improved availability.
Financial support and sponsorship
This study was supported by Organizational funds.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]