Mosquito-Borne Diseases

Mosquitoes are ubiquitous, more so in India. Annually, mosquitoes infect over 700 million people worldwide and one million of these infections lead to death. That is the devastating effect of mosquitoes! The sad part is that infection from mosquitoes is more in children below the age of 5, and cause very serious illnesses in them.

There are several bacterial, viral and protozoal diseases caused by mosquitoes.

Some of the diseases are:

• Malaria
• Dengue
• Chikungunya
• Filariasis
• West nile fever
• Yellow fever
• Eastern equine encephalitis
• Saint Louis encephalitis
• La Crosse encephalitis
• Western equine encephalitis

How do mosquitoes transmit infection?

Mosquitoes themselves do not get affected by the disease. However, they support the growth of the microorganisms and effectively transmit them to humans and other animals.

When a virus, protozoa or bacteria enters a mosquito, it undergoes a series of changes leading to its maturation and development within the mosquito. Once they reach the infective stage, the mosquitoes rid themselves of the microorganisms through their saliva. When an infected mosquito bites a human, it injects the microorganism into the human host through its saliva. The saliva also contains anticoagulants. Although there is no immediate response of the human body to this bite, several series of bites elicit an immune response where antibodies are formed against them and local signs of inflammation are seen within 24 hours.

What happens to the organisms inside the human host?

The microorganism that is injected by the bite of the infected mosquito again undergoes a sequence of transformations. It develops within the human body and infects various cells, causing continuous immune reaction, and ultimately leads to the symptoms of the disease.

The typical symptoms of mosquito borne diseases are:

• Mild to high-grade fever
• Lethargy
• Joint pain
• Headache
• Increased perspiration
• Dry cough
• Local immune reactions in the form of hives, itchiness, superficial papules

Malaria is one of the deadliest mosquito borne illnesses affecting humans, particularly the young.

Dengue and chikungunya have a debilitating effect on the infected person in terms of walking and carrying out physical activities.

West nile fever and other mosquito-borne encephalitis can cause excruciating headaches, pain in the neck and joints, raised intracranial pressure, and heaviness in the head and eyeballs.

The treatment for mosquito-borne diseases is aimed at killing the infecting parasite, virus or bacteria. Anti-malarial drugs, NSAIDs, fluid and electrolyte balance, and antipyretics are all used in the treatment of such infections.

What are the preventive measures for mosquito-borne illness?

• Mosquito breeding: Prevent the stagnation of water for long periods of time. Constantly remove or replenish containers like disposable cups, shells, buckets, pots and other objects that can collect and hold water in and around the house.
• Mosquito bites: Several anti-mosquito measures have been formulated, such as mosquito repellants (coils, mats, electrical devices and liquidators), the use of topical anti-mosquito creams and lotions, and the usage of mosquito nets.
• To kill the mosquitoes: Anti-malarial and anti-mosquito measures such as the use of DDT, anti-larval measures have all been used in the past to control and kill mosquitoes. However, mosquitoes are increasingly becoming resistant to these anti-mosquito measures.
• The spread of mosquito-borne illnesses: There are many measures that can be taken to reduce the spread of mosquito-borne illnesses: 

1. Create awareness through health education
2. Practice effective sanitary measures and keep your surroundings clean
3. Isolate infected people with the illness
4. Vaccinate the exposed population

Stay free; stay healthy! Keep away from mosquitoes; keep your surroundings clean!