A total of 32,082 dengue cases and 166 deaths have been reported in the first nine months of 2024, according to the Directorate General of Health Services.

Dengue is usually in the news at this time of year when cases are at their highest, but how bad are 2024’s numbers compared to previous years?

In terms of case numbers, 32,082 is more than was recorded in the same nine-month period during 2021 and 2022; though not more than was recorded in the same period of 2019 or 2023 – which ended as the two largest dengue waves on record in Bangladesh.

In terms of mortality, this year’s 166 deaths give 2024 the third-highest dengue death toll on record – more deaths than in all of 2019, when cases totalled over 100,000.

It all has to do with dengue’s case fatality rate (CFR), or the number of deaths per 100 dengue cases.

This year’s CFR is currently 0.53 (or around one death per 190 cases), which is the same as last year’s 20-year high CFR. It means that 2023 and 2024 are currently tied for killing the highest proportion of dengue patients since 2003.

Dengue’s CFR has risen sharply in recent years (see figure 2), meaning that each year the disease is killing a higher proportion of those it infects. In other words, dengue is becoming increasingly lethal each year.

Dengue has been on the rise since 2018, according to studies, and this year is no exception. This year’s case count and death toll are already over 10 times larger than the average annual case count (2,641 cases) and death tolls (15 deaths) between the years 2000 and 2018.

How the rest of this year’s outbreak will unfold is not yet possible to say. Dengue cases could decrease this month, as they did in 2019, 2021 and 2023. But if they increase in October – as they did in 2022, with late rains and high temperatures – this year could easily overtake 2022 for the second-highest death toll on record.

This year’s end-of-September death count is already larger than that of 2022, and cases rose consistently throughout this September, from 2,366 cases in the month’s first week to 5,457 cases in the fourth week.

October and November will be critical months.