Though the number of dengue cases reported is so far low compared to last year, experts are warning of an outbreak as July to September is the period when cases are likely to peak.
"We are still getting high density of Aedes mosquito at different parts of the capital for which we may say there is a possibility of increasing dengue cases in August," said Kabirul Bashar, an entomologist of Jahangirnagar University.
Under a Jahangirnagar University project, his team worked in six areas of Dhaka city in June -- Uttara, Gulshan-Banani, Paribagh, Lalmatia-Shyamoli, Shakharibazar and Khilgaon-Taltola -- and found the Breteau Index (BI) over 20, which is an alarming level of Aedes mosquito density.
The Breteau Index measures the number of positive containers per 100 houses inspected, essentially water-holding containers found infested with Aedes larvae or pupae.
Kabirul suggested the authorities concerned immediately take necessary measures on an immediate basis to control Aedes mosquitoes -- which carry and spread the dengue and chikungunya viruses.
NUMBER OF CASES LOW THIS YEAR
According to the Directorate General of Health Services (DGHS), a total of 326 dengue cases were reported in the country as of yesterday, 69 of which are from outside Dhaka. The number of cases reported last month was 20.
This time last year, the number of dengue cases was 2,208 till June -- but in July there were 16,253 cases, and 52,636 in August alone, said Dr Aysha Akhter, assistant director of the DGHS control room.
In total, 1,01,354 dengue cases were reported across the country last year -- of which 49,554 were outside Dhaka -- and the number of deaths resulting from dengue was 179, she said.
While it is true the number of dengue cases this year is relatively low compared to last year's number, there are a number of factors contributing to this, said Kabirul.
Less cases of dengue are being reported as people are reluctant to go to the hospital with fever as hospitals in many cases do not want to admit patients with this common symptom, fearing them to be Covid-19 infected.
In addition, those admitted for Covid-19 treatment are not in many cases being tested for dengue, he said.
Another reason is that people are going out of their homes less which means the viral transmission rate is lower compared to previous years, added Kabirul.
Monzur Chowdhury, fellow entomologist and former president of the Zoological Society of Bangladesh, also said dengue cases usually peak in August but can also happen in July or September. So, there is still a chance of increasing dengue cases in the coming months.
So, the concerned authorities should be aware about this and take the necessary measures, he said.
Countries like India, Singapore, Malaysia, and Sri Lanka, are getting dengue cases in Covid-19 patients, he said, so there are chances of Covid-19 patients here also being infected with dengue.
Dr Meerjady Sabrina Flora, director of the Institute of Epidemiology Disease Control and Research (IEDCR), said the institute does not predict a large outbreak in Dhaka this year like last year.
Last year, serotype-3 was the main cause of the outbreak, she said, and as long as a new serotype of the virus does not emerge in the city, a large-scale outbreak is not expected.
This is because many people in Dhaka have developed antibodies for serotype-3 and this serotype of the virus is still pre-dominant.
Aside from this, people are leaving their homes less and more alert about keeping their homes clean, due to which the rate of transmission is lower than before. The city corporations are also taking various measures for which the number of dengue cases is very low this year, she added.
However, there are chances of getting more dengue cases from outside Dhaka, for which the concerned authorities will have to take necessary steps to control Aedes mosquitoes there too, said Dr Flora.
Chief Health Officer of DSCC Brig Gen Sharif Ahmed said the DSCC has been undertaking mosquito control activities under a master plan since June 1.
"But we will start mobile courts from August 1 to take actions against owners of places where Aedes mosquito larvae is found," he said.
Brig Gen Mominur Rahman Mamun, chief health officer of Dhaka North City Corporation, said the DNCC has conducted combing operations twice since June to destroy Aedes mosquito larvae.
He said they are also going to conduct another combing operation against Aedes mosquitoes from July 4.
"We are doing follow-up at houses according to the data collected from previous combing operations and if we find Aedes mosquitoes at these houses or places again, we will go for legal action against them," he said.