Multi-storied buildings in the capital are the most common breeding ground for Aedes mosquitoes — carriers of both dengue and chikungunya viruses — followed by the buildings under construction.
A survey conducted by the Directorate General of Health Services (DGHS) during the monsoon has revealed that 51.34 percent of the spots, where Aedes larvae have been detected, were in multistoried buildings while 20.32 percent spots were in under-construction buildings.
Among others, 12.83 percent were in slum areas, 12.57 percent in individual buildings and 2.94 percent in abandoned lands.
The survey was conducted at 2,999 houses in 100 areas — 41 in Dhaka North City Corporation (DNCC) and 59 in Dhaka South City Corporation (DSCC) — from July 19 to July 28. It detected Aedes larvae in 374 houses.
Experts urged the two city corporations and its residents to take necessary steps against Aedes as it spreads most rapidly during August and September.
According to the survey, the highest Breteau Index (BI) of 43.3 was measured in Kallyanpur, Paikpara and Mid Paikpara under ward-11 of DNCC.
A BI of 40 was found in Khilkhet, Kuril and Nikunja areas under ward-17 of DNCC and Mirhajirbagh, Dholaipar and Gandaria under ward-51 of DSCC.
Breteau Index (BI) is defined as the number of mosquito positive containers found in every 100 houses inspected in a given area. BI of an area over 20 means the area very risky for dengue virus.
Among the positive containers, 15.6 percent were flooded floor, 12.17 percent plastic drum, 9 percent plastic buckets, discarded tiers 8.52 percent, tray and flower tab 8.27 percent, water tank 6.08 percent, clay pot 5.11 percent, plastic bottle 3.65 percent, buckets of tin 3.16 percent and plastic mug 2.92 percent.
On the other hand, House Index (HI) is used as an indicator to measure the risk of contracting vector-borne diseases in a particular area. The situation is considered ‘hazardous’ if Aedes larvae or pupa are present in five or more houses out of every 100 in an area.
Though BI is comparatively low this year compared to the monsoon survey in 2018 and 2019, HI has remained almost the same, which indicates that the number of positive houses has not reduced, said Entomologist of Jahangirnagar University Kabirul Bashar.
He said as people have become aware, they destroyed many breeding sources, but their efforts were not up to the mark.
LGRD minister Md Tazul Islam told the Daily Star that they have taken various steps through two Dhaka city corporations to control the Aedes mosquitoes and this is why the number of cases was still very low.
He said the anti-mosquito drives have been going on by dividing different areas into zones and sub-zon es.
The minister said mobile courts are also to be formed to conduct drives against Aedes mosquitoes.
INITIATIVES OF TWO CITY CORPORATIONS
DNCC has conducted a combing operation from August 8 to August 20. This is the fourth combing operation it has carried out this year.
In the last three operations, DNCC found Aedes mosquito larvae at 2,686 houses after visiting 2,74,576 houses, said an official of DNCC.
The mobile courts have realised Tk 48,12,510 from the owners of the houses where the larvae were found.
DSCC has launched a year-long master plan in June this year to prevent the mosquito menace, said a DSCC official.
It started a mobile court drive from August 16 to control Aedes mosquitoes.
According to DGHS data, a total of 389 dengue cases were reported with one death till August 16, of which 73 were outside Dhaka.