A high tech method to control dengue mosquitoes | Sunday Observer

A high tech method to control dengue mosquitoes

In mid 2017, seeing a rise in dengue cases, exceeding 10,000 patients and nearing an epidemic situation, it is imperative to ensure that steps are taken continuously to ensure that the virus doesn’t blow out of proportion.

Two approaches to ensure this is, prevention and adopting new ways and methods to eradicate mosquito breeding.

During this year, according to the information set out in the Epidemiology Unit 180,939 suspected Dengue cases have been reported islandwide.

“Approximately, 41.58% of Dengue cases were reported from the Western Province. The highest number of cases were reported during the first 29 weeks of 2017,” the Epidemiology website states, while encouraging that such a drastic situation warrants regular removal of possible mosquito breeding sites from the environment.

Dr. Hasitha Tissera, head of National Dengue Program, Ministry of Health, emphasized the importance of maintaining a clean environment throughout despite the Dengue spread in the country.

“We are currently facing the North East monsoon rains, which means by the end of this season we can expect a rise in Dengue mosquitoes, owing to stagnated water, which is the breeding ground for the Dengue mosquito,” he told the Sunday Observer.

The National Dengue Program intends to initiate and carry out several programs to clean public places and places that have been identified as possible breeding grounds.

“The public too has a responsibility to ensure that the areas are kept clean and no room is left for breeding mosquitoes,” he said.

The holiday season, Dr. Tissera says, is the best time to clean schools before the schools start the 1st term of the academic year, 2018.

During the past months, there were several incidents, especially, when the spread of Dengue was at its peak, where students got infected during school hours due to the schools failing to maintain a clean environment.

Preventive and proactive measures must continue, in order to eradicate Dengue completely from society. With this in mind, the Management and Science University and National Dengue Control Unit have jointly announced the importance of community involvement in Dengue control, future knowledge providing and epidemic eradicating activities. Accordingly, an awareness activity is scheduled to take place on January 20, 2018, from 8.30am to 12.30pm in the Piliyandala area.

As much as preventive measures are important, more research and new technology too should be looked at. Speaking to the Sunday Observer Prof Ranil Dassanayake, Genetic Scientist at the University of Colombo said, he and his team are on the verge of releasing something that could be the answer to this national issue. “This is an important technology that we have developed in Sri Lanka for the first time. And no one has developed this technology so far,” he initiated the explanation on their findings which is currently at trial stage.

Accordingly, the team’s attempt is to modify the genome of the Dengue mosquito famously known as Aedesaegypti, to be able to kill the virus when it enters the mosquito within itself ensuring that the disease is not transmitted.

“There is a massive technology behind this, called transgenic technology which is being used for the first time in Sri Lanka.” The team has been carrying out this research for the past three years.

There are four different ‘Dengue zero’ types in Sri Lanka circulating according to historical research. Under this project, a DNA molecule is developed utilizing tools and programs. Every organism including human has a genetic material.

Therefore, even mosquitoes have genetic material.

Experiments included studying the genetic materials of the Dengue viruses that are circulating in the country.

Based on this research the team was able to develop a molecule that has been developed for all the four types of mosquitoes and be able to kill the virus that is within the mosquito.

The tedious process of injecting the eggs with the molecule is known as micro-injections.

What is done here is using a very fine needle that cannot be seen by the naked eye, (has to be done under the microscope in 1,000 magnification) then the eggs are injected a very little amount of molecule.

“The size of the mosquito egg is just one millimetre. And then we integrate it into the mosquito genome. The research requires us to inject at least 1,000 eggs, and trace about sixty to eighty thousand larvae,” Dr. Dissanayake said.

The research is carried out with limited resources, while technology and machinery had to be acquired from the beginning. Experiments were carried out for the past three years and now we have finally developed the mosquito and are currently carrying out the Dengue challenging studies. “We have to feed the mosquito with the virus and see how effective the molecule would be inside the mosquito.

“We are currently in the trial stage and a student of mine who is in the research team will be going to Brazil to carry out lab test. We have to have a containment facility as we still cannot release these mosquitoes into the environment,” he said.

This work is carried out jointly with the Department of Chemistry, Faculty of Medicine, Ragama, funded by the National Research Council of Sri Lanka and International Atomic Energy Agency.

There are two different approaches. One is suppression where we kill the mosquito at the larvae stage. The other is where we release the male mosquito so that they go to the atmosphere and mate and transfer it to the female mosquito.

Accordingly, the transgenic mosquito that has been developed has been released in Brazil, the Panama, and Florida among other countries.

According to the Brazil scientific literature, 95 percent of the vile mosquitoes have been suppressed. We have to have an integrated strategy to prevent Dengue. But of course, this is a high tech method to control mosquitoes and even other insects.

“We have to educate the people and the hierarchy and authorities of the new developments and trends in the field.

This is the only way to control the Dengue disease. It is going to be an epidemic situation every year. We have had conventional strategies with limited success. We must, therefore, have the latest cutting-edge approach to control and eliminate the Dengue virus,” Dr. Dassanayake said. 

WHO advises Dengvaxia be used only in people previously infected with dengue

Following a consultation of the Global Advisory Committee on Vaccine Safety, the World Health Organization (WHO) finds that the dengue vaccine CYD-TDV, sold under the brand name Dengvaxia, prevents disease in the majority of vaccine recipients but it should not be administered to people who have not previously been infected with dengue virus.

This recommendation is based on new evidence communicated by the vaccine’s manufacturer (Sanofi Pasteur), indicating an increase in incidence of hospitalization and severe illness in vaccinated children never infected with dengue.

The WHO Global Advisory Committee on Vaccine Safety considered the company’s new results from clinical trial data analyses. Those studies indicate that increased risk of severe dengue disease in people who have never been infected affects about 15% of the vaccinated individuals. The magnitude of risk is in the order of about 4 out of every 1000 seronegative patients vaccinated who developed severe dengue disease during five years of observation. The risk of developing severe dengue disease in non-vaccinated individuals has been calculated as 1.7 per 1000 over the same period of observation. By contrast, for the 85% who have had dengue disease before immunization, there is a reduction of 4 cases of severe dengue per 1 000 who are vaccinated.

The possibility of risk for seronegative people was raised by WHO and published in a position paper in July 2016: “…vaccination may be ineffective or may theoretically even increase the future risk of hospitalized or severe dengue illness in those who are seronegative at the time of first vaccination regardless of age.”[i] As this risk had at that time not been seen in the age groups for which the vaccine was licensed, WHO issued a conditional recommendation, emphasizing the use of the vaccine in populations having been previously infected with dengue virus.