From January 1 to August 7 this year, the Ministry of Health and Family Welfare of Bangladesh reported a total of 69 483 laboratory-confirmed dengue cases and 327 related deaths

The World Health Organization blames the climate crisis and El Nino weather pattern for fueling the spike as Bangladesh battles its largest dengue outbreak, with authorities reporting 909 dengue-related deaths this year, compared to 281 in all of 2022.

The current dengue outbreak in Bangladesh has emerged much earlier than usual, in late April. It is thought that the reason behind this early appearance of dengue is El Niño which has caused an unusual episodic amount of rainfall, combined with high temperatures and high humidity, which have resulted in an increased mosquito population throughout the country.

In early September, Health Minister Zahid Maleque said that some 700,000 bags of saline will be imported to address the shortage caused by the rising dengue cases in the country.

“We are working diligently to ensure that patients can easily access beds, medications, and saline in hospitals,” Maleque said.

“We have said it repeatedly that as long as there are mosquitoes, there will be dengue patients because mosquitoes transmit the disease. So, we need to eliminate mosquitoes first. Killing mosquitoes will decrease the number of patients and save lives. We are not only treating patients but also spreading awareness through TV and newspaper ads, as well as using microphones. We are also collaborating with city corporations to tackle this issue.”

Data

From January 1 to August 7 this year, the Ministry of Health and Family Welfare of Bangladesh reported a total of 69 483 laboratory-confirmed dengue cases and 327 related deaths, with a case fatality rate (CFR) of 0.47%. Of these, 63% of cases and 62% of the deaths were reported in July. Although dengue is endemic in Bangladesh, the current surge is unusual in terms of seasonality and the early sharp increase in comparison to previous years, when the surge started around late June.

Epidemiology of dengue

Dengue is a viral infection transmitted to humans through the bite of infected mosquitoes and is found in tropical and sub-tropical climates worldwide, mostly in urban and semi-urban areas. The primary vectors that transmit the disease are Aedes aegypti mosquitoes and, to a lesser extent, Aedes albopictus.

There is no specific treatment for dengue; however, the timely detection of cases, identifying any warning signs of severe dengue infection, and appropriate case management are key elements of care to lower case fatality rates to less than 1%.

Dengue was first recorded in the 1960s in Bangladesh (then known as East Pakistan) and was known as “Dacca fever”. Since 2010, cases of dengue appear to coincide with the rainy season from May to September and higher temperatures. Bangladesh’s climate conditions are becoming more favorable for the transmission of dengue and other vector-borne diseases including malaria and chikungunya virus due to excessive rainfall, waterlogging, flooding, rise in temperature and the unusual shifts in the country’s traditional seasons.

WHO’s risk assessment

The WHO says dengue is endemic in Bangladesh with recurrent outbreaks and is one of the major public health concerns in Bangladesh. Dengue virus has the potential to cause epidemics resulting in high morbidity and mortality. 

All four serotypes of the dengue virus have been reported in Bangladesh with the predominance of DENV 1 and DENV2 until 2016. Since 2019, when the largest dengue outbreak was reported, DENV3 has been the predominant serotype, while this year DENV2 has become the predominant serotype.

There is no specific treatment for cases and clinical management is based on supportive therapy. However, the early detection of infection and appropriate clinical management of patients can reduce the severity of disease and mortality.

Dengue vaccine for Bangladesh

A dengue vaccine has not been approved in Bangladesh. The dengue risk at the national level is assessed as ‘High’ due to the ongoing rapidly increasing number of cases and deaths with the peak not yet reached. There is some pressure on the healthcare capacity due to the very high number of admissions for dengue; high vector density; and an anticipated prolonged monsoon.

“Bangladesh shares 94% of its land border with India with frequent population movement across the land crossing. However, dengue is already endemic in India including the eastern Indian states which share land borders with Bangladesh and where Aedes mosquitoes breed and circulate,” WHO said.

Climate Change

In its latest issue, the Lancet has written an editorial on dengue in Bangladesh, saying, “climate change is affecting temperatures and amount of rainfall in many countries, thus favouring the spread of vector-borne diseases.”

“Development of effective vaccines for dengue is pivotal, but there are inherent challenges to achieve this goal,” the editorial said, adding the spread of the disease is intertwined with the dramatic alterations brought by climate change.

“Any effort to control dengue will need to go in parallel with developing measures to counteract climate change: the time to act is now, we cannot delay,” Lancet warned.

Already read: Not just prevention needed to fight dengue in India