Aedes Larval Survey Report November 2000

1.	Both Ae. aegypti and Ae. albopictus, the proven vectors of dengue, were present in all but 5 wards of the Dhaka City Corporation area. The density of Ae. aegypti was much higher than that of Ae. albopictus. The density of these vectors varied considerably among the 90 wards of DCC

2.	Three indices commonly used for Aedes population estimation were calculated as follows: Breteaau Index (BI) 22.6, Container Index (CI) 6.0, House Index (HI) 13.9

3.	The BI calculated for each individual wards ranged from 0 to 94. 45 wards out of the total 90 had BI values more than the WHO designated significant level of 20.

4.	The density of Aedes larvae was high in some particular types of containers such as cemented tanks, gallon jar, clay pot, pitcher, jar, bucket and drum. These types of containers accounted for at least 90% of all the larvae found inside and outside of houses

5.	Motor tyres had the highest positive rate (28.3%). However, because of their relatively low frequency (4.4%) and low density of Aedes, their absolute contribution to total larvae productivity is quite low (1.68%).

6.	The densities of Ae. aegypti and Ae. albopictus were higher in the outside of house than inside.

7.	Independent houses had the highest percentage of Aedes positive containers.

8.	Generally large-sized containers had high larval density.

9.	Among the containers found outside houses, cement tanks were the most productive for Ae. aegypti mosquitoes followed by gallon jar, bucket, etc.

10.	Among the containers inside houses, clay pot/jar, etc. had the highest density of Aedes mosquitoes, followed by bucket, gallon jar, etc.

11.	Nearly everybody in the city already have heard about DF/DHF and most of them know that dengue is transmitted by mosquito bites.

12.	Most of the people know that mosquitoes transmitting DF/DHF bite during daytime; on the other hand, a lot of people are confused about the methods for prevention of DF/DHF.

13.	Nearly 50% people do not know that Aedes aegypti breed in containers.

14.	In slums and semi-pucca houses water is stored in earthen jars, drums, etc. which may be the main sources of Aedes breeding in those types of houses.

15.	Nearly 60% of slum dwellers cannot spend any money for mosquito control in their houses; on the other hand, more than 60% people of independent houses spend more than US$ 2 per month for this purpose.

16.	Most of the city dwellers have the opinion that both Government and people are responsible for mosquito control in the city.

Dr. Manjur A. Chowdhury	Pr. M. Ismail Hossain	Mr. Touhid Uddin Ahmed
Safeway Pest Control	Department of Zoology	Ex-Principal Scientific Officer
Banani, Dhaka	University of Dhaka	IEDCR, Mohakhali, Dhaka