🦟 How do mosquitoes transmit diseases?

How can a mosquito make you sick? The workings of a tiny vector.

It weighs barely a few milligrams, flies relatively quietly, and yet is responsible for millions of illnesses each year: the mosquito. Dengue, malaria, chikungunya, or the Zika virus are not transmitted through the air or food... but through the bite of an infected mosquito. How can this tiny insect become so dangerous?

It all starts with a bite... but not just any bite

Among mosquitoes, only the females bite. Why? Because they need blood to mature their eggs. When a female mosquito (such as Aedes aegypti, the one that transmits dengue) bites an already infected person, it sucks up blood... and the viruses within it.

These viruses don't stay in its stomach. They cross the barriers of its digestive system, then travel through its body until they reach its salivary glands. From there, every new bite can transmit the virus to another person.

A simple vector... but a formidable one

The mosquito doesn't "produce" the virus. It simply acts as a vector, meaning a transporter between two human hosts. What makes the mosquito so dangerous is that it can bite multiple times in its lifetime and infect several people.

Dengue, for example, causes high fevers, joint pain, and sometimes severe, even deadly complications in its worst forms. And there isn't always a specific treatment available.

Why are some regions more affected?

Mosquitoes that transmit diseases thrive in warm, humid areas, where they reproduce quickly. With climate change, they are gradually expanding their territory. They are now found in regions where they were absent 20 years ago, including Southern Europe.

To protect yourself:
- Eliminate stagnant water (pots, buckets, gutters) where mosquitoes lay eggs
- Wear long clothing, especially at dawn and dusk
- Use repellents and mosquito nets
- When traveling, research high-risk areas

Thus, a mosquito can become a real "flying syringe" if infected. It doesn't transmit the disease every time, but just one bite is enough to change everything.