A Treat for Mosquitoes: Class 5 EVS NCERT Chapter 8

Malaria, Dengue, and Chikungunya: The Unwanted Gifts from Mosquitoes

When a mosquito bites, it might leave behind more than just an itchy spot. Some mosquitoes are carriers of tiny germs called parasites or viruses. When they bite a person, these germs can enter the blood and make the person sick. This is how diseases spread. The most common diseases spread by mosquitoes are Malaria, Dengue, and Chikungunya.

• Malaria: This is caused by a tiny parasite. A person with malaria will have a high fever that comes with shivering and feeling very cold (chills and rigors). They may also feel very weak.
• Dengue and Chikungunya: These are caused by viruses. They also cause high fever, but are often accompanied by severe headaches, pain in the muscles and joints, and sometimes rashes on the skin. It's very important to see a doctor if you have these symptoms so they can do a blood test to find out exactly what is making you sick.

The Secret Life of a Mosquito

1. Step 1: The Egg — The mother mosquito finds still or stagnant water—like in a puddle, an old tyre, or a cooler—and lays her eggs on the water's surface. Hundreds of eggs can be laid at once!
2. Step 2: The Larva — In a day or two, tiny worm-like larvae hatch from the eggs. You might have seen these little 'wrigglers' in collected water. They hang from the water surface to breathe and feed on tiny organisms.
3. Step 3: The Pupa — After a few days, the larva changes into a pupa. The pupa does not eat. It just floats in the water while the adult mosquito develops inside its casing. This is a resting stage.
4. Step 4: The Adult Mosquito — Finally, the pupal case splits and the fully formed adult mosquito comes out. It rests on the water for a short while, its wings dry and harden, and then it flies off, ready to find its next meal... and maybe lay more eggs!

Stop the Bite! How to Prevent Mosquito Breeding

• Don't Let Water Stand: This is the most important rule! Mosquitoes lay eggs in stagnant water. So, clean your coolers, flower pots, and bird-baths at least once a week.
• Cover and Clean: Keep water tanks and containers tightly covered. Turn over buckets, pots, and old tyres so they don't collect rainwater.
• Fill the Pits: Fill up any pits or ditches in your surroundings where water might collect.
• Use Kerosene: If you cannot remove stagnant water (like in a drain), you can pour a little kerosene or oil. This creates a thin film that prevents larvae from breathing, so they die.
• Introduce Fish: In larger water bodies like ponds, put in fish like Gambusia. These fish love to eat mosquito larvae!
• Protect Yourself: Use mosquito nets while sleeping, wear long-sleeved clothes, and use mosquito repellents, especially during evenings.

What is Anaemia? A Different Kind of Health Check

In this chapter, we also learn about another health condition called Anaemia. While it's not caused by mosquitoes, it can make you feel weak and tired, just like when you are sick. Anaemia happens when there is not enough haemoglobin in your blood. Haemoglobin is what makes our blood red and its main job is to carry oxygen all over our body. Without enough oxygen, our body can't work properly. A blood test can measure the level of haemoglobin. To prevent or treat anaemia, we need to eat foods rich in iron. Iron helps our body make haemoglobin. Good sources of iron include green leafy vegetables like spinach, jaggery (gur), amla, and beetroot.

Exam Tip: Remember the Mosquito Detective, Ronald Ross

A very important person mentioned in this chapter is Ronald Ross. Remember his name! He was a doctor who spent years trying to find out how malaria spreads. For a long time, people thought it was caused by bad air from swampy areas. But Ronald Ross, through many experiments, discovered the tiny parasite that causes malaria inside the stomach of a female Anopheles mosquito. He proved that it is these mosquitoes that spread malaria from a sick person to a healthy person. For this amazing discovery, he won the highest prize in science, the Nobel Prize. You might be asked in your exam: 'Who discovered that mosquitoes spread malaria?' The answer is Ronald Ross.

Practice Questions with Solutions

• Q: Rajat's blood report says his haemoglobin is 9 g/dL. Is he healthy? What advice would you give him? A: Step 1: Understand the normal range. The normal haemoglobin range for a child Rajat's age is around 11 to 13 g/dL. Step 2: Compare Rajat's value. Rajat's haemoglobin is 9 g/dL, which is below the normal range. This means he has anaemia. Step 3: Give advice. Rajat should eat foods rich in iron to help his body make more haemoglobin. He should eat spinach, jaggery (gur), amla, and beetroot. Final answer: No, Rajat is not healthy as he has anaemia. He should eat iron-rich foods like spinach, jaggery, and amla.
• Q: List four places around your house or school where mosquitoes can breed. What should be done about them? A: Step 1: Identify places with stagnant water. Think about where water can collect and not move. Step 2: List four such places. 1. Water coolers that are not cleaned. 2. Puddles in the playground after rain. 3. Old tyres lying in the open. 4. Flower pot plates that collect extra water. Step 3: Suggest a solution for each. 1. Coolers should be cleaned every week. 2. Puddles should be filled with mud. 3. Old tyres should be removed or kept under a roof. 4. Flower pot plates should be emptied daily. Final answer: Mosquitoes can breed in coolers, puddles, old tyres, and flower pot plates. These should be cleaned, emptied, or removed to prevent mosquitoes.
• Q: What are the main symptoms of malaria? What is the first thing a doctor will do to confirm it? A: Step 1: Recall the symptoms of malaria. The key symptom is fever that comes and goes. Step 2: List the symptoms. The main symptoms of malaria are high fever with shivering and chills (feeling very cold), headache, and body weakness. Step 3: State the doctor's action. To be sure if it is malaria, the doctor needs to look for the malaria parasite in the blood. Final answer: The main symptoms of malaria are fever with chills and shivering. To confirm it, a doctor will ask for a blood test.
• Q: Why is it important to put up posters and make people aware of mosquito-borne diseases? A: Step 1: Think about why sharing information is useful. When people know about a danger, they can protect themselves. Step 2: Explain the purpose of posters. Posters can quickly show pictures of breeding spots (like coolers, tyres) and tell people how to prevent them. They remind everyone of their responsibility. Step 3: Describe the overall benefit. When everyone in a neighbourhood works together to keep the area clean and free of stagnant water, it protects the whole community from diseases like malaria and dengue. Awareness leads to action. Final answer: It is important to make people aware so that everyone takes action to prevent mosquito breeding. When the whole community works together, it helps in controlling the spread of diseases and keeping everyone safe.

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