How (not) to fight dengue

What can the city corporations do to fight the raging dengue after the High Court has asked steps in 24 hours against the Aedes mosquito, the carrier of the virus that has already claimed 11 lives so far?

With the conventional war plan, very little. It has already been proven ineffective and dengue has returned even after spraying insecticide which has rather harmed the environment.

But worldwide, there are now many innovative, effective and sometimes cheap methods that can control the spread of dengue.

These include simple cleanliness to destroy dengue breeding grounds to more sophisticated use of genetically engineered mosquitoes.

On an average 150 persons are being affected with dengue fever every day in Bangladesh.  

In the first 14 days of July, some 2,164 persons have been infected with dengue. Although the number of dengue patients is rising alarmingly, only spraying of insecticide is coming in view to prevent the menace.

A research, conducted about one and a half years ago, proved that mosquito sprays have become ineffective. 

Worldwide 725,000 people die of mosquito-borne diseases every year. Mosquito has been the world’s deadliest animal year after year.  

According to the World Health Organisation (WHO), some 20,000 people die of dengue throughout the world every year. 

The mosquito-borne disease is also on the rise in Bangladesh. Other countries have been adopting different methods to destroy mosquitoes but no such attempt has been taken yet in Bangladesh.

Killing Aedes with ‘good mosquito’

Monash University in Melbourne took a programme in 2014 which employs “good mosquitoes” to kill other mosquitoes.

“Good mosquitoes” were released in Townsville town in Australia from 2014 to 2016. 

During the programme, only four persons were detected with dengue fever, who have never travelled outside the town. Before the start of the programme, the number was 54.

The good mosquito is Wolbachia, a type of infected bacteria which is risk-free for humans. It is not natural preventive of Aedes mosquitoes. Scientists set it inside the mosquito ovum and it is not any genetic modification. 

When mosquitoes are born of this ovum they infect themselves and also their ovum.

The governments of 12 countries, including Australia, Vietnam, Indonesia, Brazil, Colombia and Sri Lanka, have been conducting the programme at field level on an experimental basis. Australia and Indonesia have already reaped benefits from the programme. 

WHO said Wolbachia-infected Aedes aegypti is a new effective method to reduce the number of mosquitoes.

There is no such method in Bangladesh.

Using Guppy fish to kill mosquitoes 

Guppy fish is an effective method of killing mosquitoes. These small fishes can be released in water inside or near the house where they can eat up the Aedes mosquito larvaes. The Phillipines, Vietnam and Cambodia have taken up programmes to kill mosquitoes with guppy fish. 

Cambodia introduced a programme of releasing guppy fish in two districts from 2009 to 2011. It resulted in reduction of the mosquito larvaes in the water to a great extent. 

Health experts at the ADB said guppy fish is a low-cost and safe method to prevent dengue.

However, Dhaka South City Corporation (DSCC) Mayor Sayeed Khokon told The Business Standard that Aedes mosquitoes are born in clean water, so guppy fish is not effective here. 

Guppy fish is helpful in killing mosquitoes in dirty water. So there is no programme to release guppy fish to prevent dengue.

He said the DSCC has been working to make people aware alongside spraying insecticides to prevent dengue. 

He said insecticides are distributed free of cost and city corporation workers will soon make door-to-door visit to destroy larvae of Aedes mosquito.

Vaccine to prevent dengue

The WHO in 2017 gave approval to applying dengue vaccine on humans with the aim of bringing down the dengue infection rate to at least 25 percent and the death rate to 50 percent. 

The age limit for the vaccine has been set at 9 to 45 years old.

Multinational pharmaceutical company Sanofi Pastaeur manufactured the vaccine named Dengvaxia. It marketed the vaccine in Mexico in 2015 for the first time after getting the WHO approval. 

The Philippines and Brazil also introduced the vaccine the same year.

At present the vaccine is marketed in 20 countries, including Indonesia, Thailand, Singapore, El Salvador, Costa Rica, Guatemala, Peru and Paraguay.

According to the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA) has given permission to introduce the vaccine in the USA in May this year. However, the FDA fixed age limit from 9 to 16 years. 

The Bangladesh government’s Institute of Epidemiology, Disease Control and Research (IEDCR) is an affiliated organisation of the CDC, but there is no progress in this regard.

IEDCR Director Prof Dr Meerajdy Sabrina Flora said many countries have introduced dengue vaccine following the WHO guidelines. However, the issue of the vaccine is somewhat sensational.  

She said a company applied to the Directorate General of Drug Administration for importing the vaccine but it did not get any response. So, the matter has been stalled for now.

Dengue changes type

Swapna Roy, 35, has been undergoing treatment at a private hospital in the capital’s Panthapath after being affected with dengue fever. 

The platelet in her blood has been fluctuating.  Physicians are worried about her falling in blood pressure. 

To keep her blood pressure (BP) normal, doctors are administering her saline drips for 24 hours. 

They said it would be known after two more days whether she was out of danger. 

Swapna Roy has been affected by Stage-3 dengue.  

Till now, some 938 dengue patients are under treatment in different hospitals across the country. 

The intensity of dengue has been increasing alarmingly in the country this year.  

However, the matter of most concern is that dengue is changing type.  

Physicians said this year most of the cases are of Stage-3 which is riskiest.

Some 124 persons were infected with dengue in last 24 hours. In the first 14 days of July, some 2,164 persons have been affected by dengue. Last year in July, some 946 persons were infected with dengue, according to the Health Information and Emergency Control Room of the Directorate of Health statistics.

A total of 4,247 dengue patients have taken treatment since January this year.  Of them 3,336 patients have returned home after being treated.

The statistics with the Directorate of Health said three persons have so far died of dengue till now. 

However, the real figure would be much more, physicians said. 

Doctors said this time the cases of Stage-3 dengue are more.  The risk of death in Stage-3 dengue is the highest. In Stage-3 dengue, both the platelet and BP of the patient quickly fall.

Preventive medicine specialist Dr MH Choudhury Lelin said dengue has changed its pattern from last year.  

In earlier years, shock syndrome started when the temperature was normally 104 to 105 degrees. But this year Shock syndrome is being found when the temperature is 101 to 102 degrees and without any pain in the body.

In this type of dengue, the patient’s BP falls, dehydration increases, water deposits in the abdomen and lungs, and the patient loses consciousness. 

The patient should be given more water. If the fever lingers more than one or two days, doctor should be consulted.