Botched dengue response: Where does the fault lie?

2019 was a watershed for dengue, with the highest number of cases ever reported globally. For Bangladesh too, it was a loud wake-up call, with record caseload and deaths. But the government continued with its slumber.

The local government, rural development and co-operatives minister and the two Dhaka mayors, however, maintain they have done enough. And yet, the Aedes aegypti mosquito, the primary vector for dengue, is having its most successful outing, already besting its 2019 record, thanks to insufficient preparedness.

A complete lack of planning, coordination and accountability among the government bodies has emerged as the narrative of Bangladesh's fight against the Aedes mosquito, according to entomologists.

The starting point for any definitive largescale action is a policy that would serve as a guideline. Bangladesh's Vector Management Policy -- which is being drafted by the ministry of local government, rural development and co-operatives -- is yet to see the light of day.

In the absence of a policy, one would think that the city mayors would be proactive in keeping the residents safe from the dangerousmosquito population. But it was all lip service.

Take the case of the Dhaka Mosquito Control Department. For a long time, the two-storied building in Dhakeshwari area was a breeding ground for the mosquito that has so far infected 123,808 and claimed 593 lives -- the highest yet for a single year.

Although vector control is not in its jurisdiction, the ministry of health and family welfare's role has been found wanting to. It hasn't created a database, so the actual gravity of the dengue outbreak remains undetermined.

The daily dengue bulletin from the Directorate General of Health Services is based on data from only 57 public and private hospitals in Dhaka and 81 district- and divisional-level hospitals.

But as many as 16,000 public and private hospitals, clinics, diagnostic centres and blood banks across the country are providing dengue care.

Dengue is a reportable disease in other countries, meaning data on every single dengue patient must be recorded, according to Manjur A Chowdhury, a former president of the Zoological Society of Bangladesh.

In the absence of data on the exact number of victims and their locations and serotype distribution, any vector control programme would be akin to driving blind.

"Without information of all dengue patients, cluster elimination is not possible," Chowdhury said.

Genome sequencing is no less important as identifying any potential changes in the dengue virus gene would inform the dengue management programme.

Dengue virus exists as four distinct serotypes (closely related forms of the virus). Immunity from infection with one serotype may provide lifelong protection from that serotype but is only partially protective against other serotypes. A second infection with a different serotype than the first infection increases the risk of severe dengue, which can lead to fatality.

Similarly, Bangladesh Meteorological Department's role was found lacking too.

One of the reasons for the rising incidence and transmission of dengue over the last decade has been the warming temperatures, falling humidity levels and heavier summer rainfall -- thanks to climate change.

Due to climate change, Bangladesh's temperature remains favourable for the breeding of Aedes mosquitoes all year round, said Kabirul Bashar, professor of medical entomology at Jahangirnagar University.

A temperature between 20 to 30 degrees Celsius is required for Aedes mosquito breeding.

"We get 20 degrees Celsius temperature even during winter -- this is why we are getting dengue cases round the year," he said.

Had the Met department given a warning about the conducive conditions for dengue incidence and transmission this year, the authorities, perhaps, would have been goaded into preparation mode sooner.

What transpired was a complete lack of initiative from anywhere, leaving it to citizens to fend for themselves this year from dengue, whose symptoms of high fever and painful body aches have earned it the nickname of "breakbone fever".

The authorities concerned failed to chalk out an early plan when they saw over 62,000 cases last year, said GM Saifur Rahman, assistant professor of medical and applied entomology at the National University in Gazipur.

Both the city corporations failed to destroy the Aedes mosquito eggs laid towards the end of last year, according to Chowdhury, also the former chief executive officer of Safeway Pest Control.

Those eggs hatched at the beginning of this year, earlier than their usual time, thanks to the shorter winter.

Serious anti-mosquito drive identifying active clusters during the lean period of dengue (November to April) is very important as during this time the number of Aedes mosquitoes remains low, said Chowdhury, currently the chairman of the Centre for Governance Studies.

The authorities will have to carry out an extensive drive including source reduction, larviciding and adulticide to destroy Aedes and its larvae.

"But authorities concerned did not take steps following this method," he said.

Rapid urbanisation is also to blame for the ongoing dengue outbreak.

"The numbers of multi-storey buildings and cars have increased significantly since 2014, both of which play a significant role in the spread of dengue during the dry season -- many people wash their vehicles in parking lots, where stagnant water accumulates," said Bashar, the entomologist from Jahangirnagar University.

The Aedes mosquito requires pools of stagnant water to breed. These pools may be as small as a teaspoon and are found in nature (in puddles or tree holes) or in human environments (in trash, flower pots, buckets, used tyres and so on).

Going forward, dengue is likely to increase for Dhaka as the climatic conditions have become more suitable, said a 2021 World Bank report titled 'Climate Afflictions'.

Humidity in the range of 60 to 80 percent, maximum temperature between 25°C and 35°C, and rainfall between 200-800mm create ideal conditions for mosquitoes. 

Weather data between 1976 and 2019 indicate Dhaka is experiencing falling humidity levels, rising temperatures, and heavier summer rainfall. These together with factors like urbanisation are increasing the risk of the spread of dengue in Dhaka city, the WB study said.

Subsequently, a coordinated action plan has become the need of the hour. In China, 13 to 18 ministries work together to control mosquitoes, according to Rahman, the entomologist from National University.

"The Vector Management Policy has been prepared -- the approval of the cabinet committee is needed to put it to practice," Md Tazul Islam, LGRD minister, told The Daily Star last month.

The policy, which has been in the works since 2020, has accommodated the research findings of different countries.

"Having a policy is not enough -- we have to work in line with the policy," he said, adding that the LGRD ministry is already functioning as per the policy.

Asked about the lean season management, he said: "During the lean period, eggs are found and it is not possible to destroy them. It is possible to kill the mosquitoes when they turn to larvae."

The city corporation of Chennai has deployed a drone-based mosquito control system under which drones survey and dispense larvicide to effectively eradicate mosquito breeding habitats. The Delhi municipality is also planning to use the system.

"Without public participation, controlling dengue is not possible -- public participation will have to be improved. We are trying our best," Islam said.

Mosquito is mainly found in urban areas and for that, the city corporations have the capacity to control the menace, he added.

"We started working on controlling dengue from the beginning of the year and we are still doing it," Atiqul Islam, mayor of Dhaka North City Corporation since March 2019, told The Daily Star.

He asserts that dengue is under control in his jurisdiction.

"We were not sitting at home. We have worked in coordination with various agencies to prevent dengue.  We have come up with new methods to prevent dengue," Islam added.

One of the new methods the DNCC intended to adopt was the use of the BTI, a naturally occurring bacterium that kills mosquito larvae. When BTI, short for bacillus thuringiensis israelensis, is present in water, mosquito larvae feed on it and die -- long before they can grow up to become flying, biting, disease-spreading adults.

DNCC's BTI supplier, Marshall Aggravate, said the pesticide was imported from a Singaporean company Best Chemicals. The company denied it, prompting DNCC to halt the project and file a case against Marshall Aggravate for their alleged forgery.

"We have taken a comprehensive three-tier plan to combat the spread of dengue fever within the city corporation," said Selim Reza, CEO of DNCC.

The plan involves a coordinated effort to identify and eliminate the breeding grounds of the Aedes mosquito and has been in action since January.

He denied any lack of coordination between different government agencies in controlling dengue.

"We have been successful in controlling dengue, and the health ministry has said so too," Sheikh Fazle Noor Taposh, the mayor of DSCC since 2020, told The Daily Star.

The caseload is stable now and has dropped from July.

"The picture will be clear if you compare the numbers from August last year."

DSCC is announcing red zones to neighbourhoods with more than 10 dengue patients. Larviciding and adulticide are conducted within 300 metres of the dengue patient's home, he said.

But their words ring hollow as at least 342 people died of dengue this August, making it the deadliest month since the health authorities started recording dengue cases in 2000. Of the deaths in August, 17 were reported yesterday, the last day of the month -- and 16 of them were in the capital Dhaka. Besides, of the 593 deaths this year, 438 were reported from Dhaka.