Dengue peaked in Sept in 2023 but why not this year

Last year, September marked the peak for dengue, but this year has seen a shift in the peak period. This change has been observed in recent years, prompting experts to raise concerns and urge policymakers to take action.

Dengue cases and fatalities are on the rise this year, with entomologists and experts predicting the peak of the outbreak to occur between late October and early November.

The delayed monsoon has brought more rainfall, and government efforts to control the spread of dengue have been largely unsuccessful. As a result, this year is feared to become the second deadliest for dengue in Bangladesh.

In just the first 12 days of this month, 47 dengue-related deaths have been recorded, including nine deaths and 915 hospitalisations on Saturday alone.

We have observed an increase in dengue infections during the rainy period, with cases even being reported at the village level. If the weather remains suitable, the number of dengue patients will likely continue to rise for another month.

Entomologist Dr Manjur Ahmed Chowdhury

Data from the Directorate General of Health Services (DGHS) reveals that the death toll from dengue this year has reached 210, making it the third highest since the outbreak began in 2000. Experts warn that the death toll may surpass the second-highest figure of 281 recorded in 2022.

Entomologist Dr Manjur Ahmed Chowdhury told The Business Standard, "Compared to previous years, this year's dengue death rate is significantly higher. Our local authorities have completely failed to control the spread of dengue. As the monsoon is expected to end soon, the post-rainfall period will be critical for mosquito breeding. We anticipate a rise in mosquito bites and dengue cases during this time."

He further explained, "Due to mismanagement in controlling dengue and changing weather patterns, the peak period for dengue has shifted. We may see a sharp increase in deaths by late October or early November."

Dr Chowdhury also pointed to poor governance and corruption as major barriers to effective dengue control efforts.

According to the DGHS, 1,705 dengue deaths have been recorded in 2023, marking the highest annual toll to date. The third-highest figure, 179 deaths, was recorded in 2019.

As of 12 October, 41,810 hospitalisations have been reported this year, and the current death toll places 2023 as the deadliest year on record for dengue in Bangladesh.

Why shift in dengue peak?

According to WHO, dengue was first recorded in Bangladesh (then known as East Pakistan) in the 1960s, where it was referred to as "Dacca fever." Since 2010, dengue cases have tended to coincide with the rainy season from May to September and with higher temperatures.

Bangladesh's climate conditions are increasingly favourable for the transmission of dengue and other vector-borne diseases, including malaria and chikungunya, due to excessive rainfall, waterlogging, flooding, rising temperatures, and unusual shifts in the country's traditional seasons, it added.

Experts have noted that weather patterns in Bangladesh have changed since 2010. The monsoon period shifts each year, and the dengue peak season has changed accordingly.

Last year, dengue cases and deaths peaked in September. In September 2023, there were 79,598 dengue cases and 396 deaths. In 2022, dengue cases peaked in October, while the highest number of deaths occurred in November.

Before 2022, the peak season for dengue cases and deaths was typically between August and September. However, this pattern has now changed.

Manjur Ahmed Chowdhury stated that this year, there has been significant rainfall toward the end of the season, followed by persistently high temperatures. This environment is highly conducive to mosquito proliferation.

He explained, "We have observed an increase in dengue infections during the rainy period, with cases even being reported at the village level. If the weather remains suitable, the number of dengue patients will likely continue to rise for another month."

He added, "Dengue will naturally fluctuate, and the actions of local government bodies and city corporations cannot have much of an impact."

According to DGHS records, 14 people died in January this year, three in February, five in March, two in April, 12 in May, eight in June, 12 in July, 27 in August, and 80 in September.

Hospitalisation data shows that 36.7% of patients are female and 63.3% are male. However, death data reveals that 50.5% of the deceased are female and 49.5% are male.

The highest number of deaths occurred among individuals aged 21 to 30, accounting for around 22% of fatalities in this age group. Additionally, 10 children aged 0-5 and 12 children aged 6-10 have died from dengue.

As of 12 October this year, the highest number of deaths has been recorded in Dhaka South City Corporation with 112 deaths, followed by Dhaka North City with 29 deaths, and the Barishal division with 25 deaths.