Dengue menace looms large in Chattogram as survey flags alarming trend

Preliminary findings from an ongoing survey in the port city of Chattogram showed a significant rise in the number of households inadvertently harbouring larvae of Aedes aegypti mosquitoes, the known carrier of the dengue virus.

Entezar Ferdous, an entomologist in the district, said the survey team spotted a worrying trend while covering areas such as Bahaddarhat, Muradpur, Akbar Shah, and Khulshi.

“In last year’s survey, we found larvae incubating in every five households. However, the number is far higher this year,” he said, without disclosing the actual number.

The exponential increase in Aedes mosquito larvae may potentially correlate with the high number of hospitalisations for dengue this year.

Dr Mohammed Elias Chowdhury, the district's civil surgeon, said medical experts noticed a shifting pattern in the occurrence of dengue in the city since last year.

According to him, dengue has transformed from being a seasonal disease to a year-round health concern.

"Analysis of hospitalisations with dengue symptoms throughout last year revealed that the cases peaked during October and November, marking the beginning of the dry season. The death toll was also higher during this period."

The pattern suggested that dengue tends to dissipate to some extent during the dry season, as shown by lower hospitalisation rates in December last year and January, he added.

But in light of the significant hospitalisation rate and surging death toll for dengue by mid-July, Chowdhury fears that the number of cases could be extraordinarily high by the time December arrives.

“I believe the Aedes aegypti mosquitoes have somewhat adapted to the changing climate and seasons in Bangladesh, which is why the disease remains prevalent throughout the year,” he said.

Dr Md Mamunur Rashid, an associate professor at the Bangladesh Institute of Tropical and Infectious Diseases (BITID) echoed Elias's view.

"At BITID, we have been treating dengue patients since the beginning of this year, but the number of patients skyrocketed in June, particularly during the Eid-ul-Azha holidays. This has become a continuing trend," he said.

According to a World Health Organization (WHO) study, eggs laid by Aedes aegypti mosquitoes can remain dormant for up to three years. The eggs start to hatch as soon as they come into contact with water, and within 24 hours, larvae emerge. And in the next 72 hours, these larvae metamorphosise into fully grown mosquitoes.

Mamunur believes the WHO research may offer an explanation for the increasing number of hospitalised patients.

Entomologist Entezar has a different theory.

"I believe that Aedes aegypti mosquitoes have adapted to the changing climate and seasons in Bangladesh, which is why the disease is prevalent throughout the year," he explained.

Dr Mahfuzur Rahman, a renowned public health expert in Chattogram, agreed with Entezar.

He believes the authorities should conduct mosquito prevention campaigns throughout the year rather than focusing on a particular season as he emphasised the need for public awareness to combat the disease.

“Unless the authorities prioritise it, the dengue situation will continue to deteriorate," he warned.

“The city authorities cannot run such a comprehensive campaign alone. Residents also need to be involved [in the dengue prevention efforts] by keeping their households clean and free of stagnant water -- the perfect incubation spot for larvae to hatch.”