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Dengue Prevention: How Does Wolbachia Help to Control Dengue?

Dengue Prevention: How Does Wolbachia Help to Control Dengue?

We have a large history of dealing with deadliest viruses as viral epidemics are not new to humans. Whether it was prehistoric smallpox disaster or the recently ongoing COVID 19 pandemic, such disease outbreaks have changed the course of human history for the worse.

Although at this time we only talk about COVID 19, unfortunately, diseases like dengue viruses are not leaving for our convenience. Particularly, in countries like Pakistan with weak healthcare infrastructure and endemic for dengue, the overall situation calls for action and response against dengue.

You may already know about Dengue, but let us revamp what dengue is and how it’s impacting the world in 2021.

What is Dengue Fever?

Dengue is the mosquito-borne viral illness that can result from mild flu-like illness to the life-threatening hemorrhagic fever. Despite the availability of far-reaching knowledge on dengue prevention, the disease has continued to wreak havoc. Talking in numbers, Pakistan is no different from the rest of the world. Since the first confirmed dengue outbreak in 1994, Pakistan has reported approximately 1.5 lakh dengue cases so far.  

How Dengue Spreads?

Female mosquitoes are the culprit! 

The minuscule, long-legged mosquitoes are responsible for the spread of dengue. Actually, the tiny creature doesn’t cause the disease, instead, it carries dengue virus inside its body. The virus resides inside the mosquito’s body and passes on from an infected to an uninfected person through a mosquito bite. Thus, mosquito basically acts as the vehicle which aids disease spread.

Surprisingly, only female mosquitoes can spread the virus. In Pakistan, Aedes aegypti mosquito is known to cause the disease. While another mosquito species, known as Aedes albopictus also exists here that can cause the disease in future.

Clinical signs and symptoms

For the most part, dengue fever can cause mild to severe clinical manifestations. The most common symptom of dengue can include

  • Fever
  • Nausea
  • Aches and pain
  • Body rash
  • Vomiting

Most of the time, symptoms of dengue can last for 2-7 days, however, a more severe form of dengue also exists known as ‘Dengue Hemorrhagic Fever’ or ‘Dengue Shock Syndrome’. Dengue hemorrhagic fever is the fatal form of the disease characterized by internal bleeding, blood pressure drop leading to shock and organ damage.

What is an Effective Dengue Prevention Strategy? 

Dengue prevention and control is quite important because it can significantly lower the global disease burden on public health. Despite the availability of an approved vaccine, the global strategy for dengue prevention and control relies upon the control of mosquito population. 

Ways to Prevent Deadly Mosquito Bites

Some of the most recommended practices to prevent mosquito bites are;

  1. Using mosquito repellents
  2. Staying in screened places
  3. Wearing protective clothing
  4. Reduction in mosquito breeding sites

Mosquito Population Control- Why and How? 

Apart from preventive measures controlling the mosquito population is an effective way to regulate disease spread. While talking about dengue control measures, these control methods can be classified as

1- Chemical Control

The use of different insecticides to control mosquito population lies under this category. However, the excessive use of these chemicals over the decades has resulted in insecticide resistance in the targeted vector population. Moreover, these chemicals are doing more harm than good because of their toxic nature.

2- Biological Control

The use of biological agents such as fish larvae, bacterial spores is another effective practice to control the mosquito population. Due to effectiveness and less toxicity of biological methods, these methods are definitely considered a better option.

Wolbachia– A Promising Tool for Dengue Fever Prevention

The global scenario of mosquito control totally got changed after the discovery of a tiny bacterium, known as Wolbachia that can effectively control the mosquito. Surprisingly, Wolbachia is naturally found in 60% of the insect’s population.

How Can Wolbachia Bacteria Help in Dengue prevention?

Wolbachia can interfere with the ability of mosquitoes to spread the disease. The presence of bacteria inside the mosquito body stops the growth of viruses. Besides this, Wolbachia bacteria control the mosquito population by two important mechanisms

1- Replacement of local mosquito population

As already discussed, the presence of Wolbachia bacteria can block the spread of dengue virus in the mosquito body. So, if we replace our natural mosquito population (not having Wolbachia) with the Wolbachia infected population, the disease spread will automatically reduce by several folds.

2- Suppression of the mosquito population

Suppression of mosquito population is basically a method to reduce mosquito numbers by limiting their reproduction. In this second method, Wolbachia transferred mosquitoes are released in the field. These special mosquitoes stop the reproduction in mosquitoes, reducing their overall number. Fewer mosquitos will spread less disease resulting in dengue control.

How to Use Wolbachia Bacteria for Dengue Control?

Mosquito eggs are injected with the bacterium! 

This bacterium, Wolbachia, is not present in the mosquito Aedes aegypti that is responsible for the spread of dengue. However, we can use a technique called, “microinjection” to artificially transfer this bacterium into the bodies of mosquitos.

Mosquito Factories! Nurturing “ Disease Friendly Mosquitoes

Wolbachia dengue control strategy requires millions of mosquitoes to be released. Both replacement and suppression strategies require millions of mosquitoes for field releases. To release such a huge number of mosquitoes, we have breeding facilities, or mosquito factories, where scientists are raising “Disease Friendly Mosquitoes” in a huge number. Once released, these dengue blocker mosquitoes can effectively control the disease.

The bottom line!

Dengue virus is a mosquito-borne illness and for now, control of disease solely depends upon mosquito control. Among all the methods to control the mosquito population, Wolbachia based mosquito control is a potential approach. 

In the past few years, many countries have successfully controlled dengue by mass releasing mosquitoes. For instance, the dengue mosquito population has considerably reduced the disease spread in the Australian region under the World Mosquito Program.

Other than Australia and Singapore, our neighbouring country India is also planning to mass release mosquitoes for dengue control. Previously, in Pakistan, there was very limited work done in this regard. However, scientists are now diligently working on dengue control using disease-friendly mosquitoes.

Once successfully established, this Wolbachia based dengue strategy will be an effective tool to control several mosquito-borne diseases in Pakistan. 

If you find any signs and symptoms, immediately get in touch with top infectious disease specialists.

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