For a large population like ours, earlier mosquito control intervention is still the best

Ever since the year 2000, Bangladesh has experienced episodes of dengue fever every year.

Twenty two years is a pretty long time for any authority to set a standardized protocol to contain any outbreak. So, why do we still fall short in controlling this health hazard?

The unfortunate reality is that there are just way too many variables working against us.

The last two decades saw an eight-fold increase in dengue cases all around the world and the World Health Organization considers dengue to be the most critical mosquito borne-virus now.

The infection currently exists in 129 countries and almost all of these are in Latin America and Asia.

Brazil, Vietnam, Philippines, Indonesia, and Peru are the hardest hit, closely followed by Colombia, Nicaragua, Malaysia, Bangladesh, Sri Lanka, Singapore, India, and Thailand.

Despite being so widespread, 70% of the disease burden is in Asia.

Let us be clear about one thing — dengue will not be eliminated any time soon. Disease elimination requires either a preventative vaccine or a curative drug therapy that can kill the pathogen. Unfortunately, dengue has neither.

There are four closely related serotypes of dengue virus — DEN-1, DEN-2, DEN-3, and DEN-4. Infection from one kind gives lifelong immunity against that particular strain but no cross immunity from the other three kinds.

So, persons living in dengue-prone regions can potentially get infected four times in their lifetimes.

The other complexity is that there are two hosts of this virus — human and Aedes aegypti mosquitoes. Elimination of pathogens having one host is hard enough and from two hosts will certainly require herculean effort, commitment, and resource utilization.

Does that mean, there is no hope ever? Of course not!

Science is magical; we can now safely say that we defeated Covid, right?

One dengue vaccine is already available, but the jury is still out on how safe that vaccine is because it can only be inoculated to a person who has already had dengue once.

So, we have to wait till a vaccine is invented that protects against all four types of the virus.

Is there no cure? There is no dengue specific antiviral but if the infection is detected early on and people take precautions right away, then the treatment protocol is simple — the guidelines of which are widely circulated.

What is the scare, then? 

Bangladesh is a densely populated country with far from the best healthcare system. Any infectious disease can escalate very fast and swamp the healthcare facilities.

People also tend to seek treatment at a much later stage which increases the risk of fatality.

This year, till date, we have had over 161 deaths as of November 3; there were 179 in 2019. The number of dengue infections was 101,345 in 2019 — which was much higher than the recorded 40,100 till date this year.

Clearly, from the ratio of hospitalizations to deaths, there is a deadlier strain going around — and an alarming number of hospitalized patients are children.

Also, this surge of cases happened in October which is unusual since the previous years’ trends show that by this time in the year, dengue would be in a declining state.

I did mention earlier that the variables are too many and none are in our favour. High population density, rapid unplanned urbanization, poor waste management system, small wastewater reservoirs, disregard for dengue prevention behaviours, low community engagement, and not correlating the changing climate aspect — all precipitate in causing an outbreak.

The mosquito control agencies and advocacy groups in Bangladesh are always talking about integrated vector control management. There is no strategic plan that is specifically designed to take short-term or long-term actions against vector population.

What can be done?

An early warning system that analyzes the seasonal shift of rainfall, temperature, humidity, and data on mosquito population to predict an outbreak will give a clear indication of expected seasonal/nonseasonal disease surge, which in turn can hasten the response system of vector control.

A data intelligence system was introduced in 2019 or 2020 but very few know about its existence.

Scientific projects of releasing Wolbachia bacteria infected Aedes aegypti mosquitoes introduced in small parts of Brazil and Indonesia have successfully declined dengue infection by over 70% in those areas. This is a method where the mosquitoes infected with the bacteria lose the ability to multiply the virus and in turn fails to infect people.

Despite this small success, Brazil continues to log the highest number of cases. Australia also executed the Wolbachia project in North Queensland and dengue was successfully eradicated from there.

But the program there was carried out for eight years with a population size of barely 150,000, and economists suggest that it may cost anywhere between $12 to $21 per person.

Bangladesh was planning to do a similar project. Given our population size, how feasible will it be?

Fortunately for us, there is a reporting cell at DGHS that counts the daily number of dengue cases. This data helps to identify the dengue outbreak hotspots which gives some direction to city corporations to drive the mosquito fogging.

Changing people’s behaviour is difficult — digital platforms can be used for more increased awareness during dengue season to clean up their homes and community.

Ultimately for a large population like ours, earlier mosquito control intervention is still the best, but coordination and guidelines are missing among the stakeholders. It is an urban disease, measures taken in city epicentres will lower the infection rate everywhere else.

Dr Maliha Mannan Ahmed is the Founder and Executive Director of Organikare. She has an MBBS, MBA, and a Master’s in Health Care Leadership.

Source of Dhaka Tribune