Active monsoon may help spread dengue further

At a time when the country is already grappling with a record outbreak of dengue fever, the current active monsoon conditions may contribute to the further spread of the mosquito-borne disease this month, say experts.

Entomologists are now urgingthe authorities concerned to step up their anti-mosquito drives, which they say will help improve the current dengue situation and reduce the risk of the virus spreading next year.

Bazlur Rashid, meteorologist at the Bangladesh Meteorological Department (BMD), said intermittent rains accompanied by hot and humid weather will continue throughout the month of September, with the dry season likely coming in as late as October 15.

According to BMD's weather forecast for the next three days, light to moderate rain or thundershowers accompanied by temporary gusty wind are likely to occur at many places over Rangpur, Mymensingh, Chattogram, and Sylhet divisions and at a few places over Rajshahi, Dhaka, Khulna, and Barishal divisions.

Meanwhile, data from the Directorate General of Health Services (DGHS) shows that at least 15 dengue patients died, and 1,876 were hospitalised in 24 hours preceding yesterday morning.

With this, the total number of deaths from dengue rose to 706 while the caseload went up to 142,587.

Entomologist Manjur A Chowdhury, former president of Zoological Society of Bangladesh, said intermittent rains and high humidity create the perfect conditions for Aedes aegypti mosquitoes to thrive.

"Intermittent rain can fill discarded containers with water, which is where the Aedes mosquito lays its eggs. Besides, there is a strong link between high humidity and the increased biting behaviour of the Aedes mosquitoes."

So, the likelihood of dengue cases increasing this month is significant, Manjur added.

GM Saifur Rahman, an entomologist at National University, Bangladesh, said, "Dhaka city may develop herd immunity against dengue due to the large number of people infected with the virus since 2000. However, the chances of cases increasing outside the capital remain high.

"If we do not control the Aedes mosquito population, there is a risk that a large number of eggs will be laid by Aedes mosquito this season. These eggs may hatch next season and lead to another outbreak."

During the lean period of dengue (November to April), the authorities need to identify active clusters and carry out an extensive drive, including source reduction, larviciding, and adulticiding, until the reproductive chain of the Aedes mosquitoes is broken, Saifur added.