Saturday, March 5, 2016

A TREAT FOR MOSQUITOES-TEXT

 A TREAT FOR MOSQUITOES
ENVIRONMENTAL STUDIES
CBSE-V

Mosquitoes are small, midge-like flies which comprise the family Culicidae. Females of most species are ectoparasites, whose tube-like mouthparts pierce the hosts' skin to consume blood. The word "mosquito" is Spanish for "little fly".

Mosquitoes have six legs.  They also have a head, thorax and abdomen.   Mosquitoes can't fly very far or very fast. 

The Anophelesis a malaria carrier, and the other two are known to spread various forms of encephalitis. Only female mosquitoes bite and suck the blood.  

Both male and female feed mainly on fruit and plant nectar, but the female also needs the protein in blood to help her eggs develop. Once she's had her fill of blood, she'll rest for a couple of days before laying her eggs.

Male mosquitoes indentify  females mosquitioes  by the sound of their wings.  Females can beat their wings up to 500 times per second.

Mosquitoes can smell human breatha. They have receptors on their antennae that detect the carbon dioxide released when we exhale. There are more than 3,500 species of  mosquitoes. 

 Malaria is caused by a parasite that lives in mosquitoes.  The parasite gets into mosquito saliva and is passed on when the insect bites someone. Mosquitoes are considered the deadliest “animal” in the world.  

The Anopheles mosquito, in particular, is dangerous because it transmits malaria, which kills more than one million people every year, primarily in Africa.

Blood test:
Rajat is back at school today. He had been absent for many days. “How are you now?” asked Aarti. “I’m alright,” Rajat replied softy.

Jaskirat: You must have played a lot while you were at home.
Rajat : Who wants to play when you have fever! On top of it I had to take a bitter medicine! I even had a blood test.

Jaskirat: A blood test? Why? It must have been very painful.

Rajat: Actually, when the needle pricked my finger, it felt like an ant bite. They took 2-3 drops of blood, and sent it for testing. That’s how we came to know that I had malaria.

Nancy: But you get malaria when a mosquito bites you.
Rajat: Yes, but we find out by the blood test.

Jaskirat: There are a lot of mosquitoes in my house these days, but I did not get malaria.

Nancy: Who says that every mosquito bite causes malaria? Malaria spreads only by the disease carrying mosquitoes.

Aarti: All mosquitoes look the same to me.
Rajat: There must be some difference.

Dr Maryam looking at the blood slide under the microscope. This miscroscope makes things look thousand times bigger. The details inside the blood can be seen clearly. There are some miscroscopes which make things look even more bigger  than this one.

Nancy: Did they take the blood from the place where the mosquito
had bitten you?
Rajat: Of course not! How do I know when and where the mosquito bit me?

Nancy: But how could they find out that you had malaria by your blood test? Do you think they could see something in the blood?

Medicine for Malaria
From early times, the dried and powdered bark of the Cinchona tree was used to make a medicine for malaria. Earlier people used to boil the bark powder and strain the water which was given to patients. Now tablets are made from this.

Anaemia–What’s that?
Aarti: You know, I also had to get a blood test done. But they took
a syringe full of blood. The blood test showed that I had anaemia.

Rajat: What is that?
Aarti: The doctor said that there is less ‘haemoglobin’ or iron in the blood. The doctor gave some medicines to give me strength. He also said that I should eat jaggery, amla and more green leafy vegetables, because these have iron.

Nancy: How can there be iron in our blood?
Jaskirat: There was something about this in the newspaper
yesterday.

Rajat (laughing) : So then you ate iron or what?!
Aarti: Silly! This is not the iron used to make these keys. I don’t know exactly what it was. After I ate a lot of vegetables and whatever the doctor had said, my haemoglobin went up.

Anaemia common in Delhi school -17 November, 2007 – Thousands of children studying in the Municipal Corporation schools in Delhi suffer from anaemia. This is affecting both their physical as well as mental health.

Due to anaemia, children do not grow well, and their energy levels are low. This also affects their ability to study properly. Now health check ups are being done in the schools and health cards are being made for all the children. Anaemic children are also being given iron tablets.

Baby mosquitoes
Jaskirat: There is a poster on malaria just outside our class.
Rajat: The poster says something about larvae. What are those?
Nancy: They are baby mosquitoes. But they don’t look like mosquitoes at all.
Aarti: Where did you see them?
Nancy: There was an old pot lying behind our house. It was full of water for some days. When I looked there I saw some tiny thread-like grey things swimming. I was surprised when Mummy told me that these had come out of the eggs which mosquitoes lay in water. They are called larvae. I also heard something about this on the radio.
Rajat: What did you do?
Nancy: Papa immediately threw away the water. He cleaned and dried the pot and kept it upside down, so that no water would collect.

Jaskirat: Shazia aunty told me that even flies spread diseases, especially stomach problems.
Rajat: But flies don’t bite. Then how do they spread diseases?

Survey report Some children did this survey. Here are some of their reports  We found something green around the taps in our school which is called algae. It was also slippery there. The algae spreads a lot during the rainy season. We think that they are some kind of small plants that grow in water.

There is a pond near the school. At first you cannot see the water in the pond as it is completely covered with plants. One aunty told us that t h e s e p l a n t s have grown themselves in water.

Around the pond there are pits full of water. We also saw some larvae in the water. As we moved around, lots of mosquitoes flew from the plants growing around. Jaskirat feels that there are so many mosquitoes in her house because of this dirty pond nearby.

A scientist peeps into a mosquito’s stomach

This interesting incident took place almost a hundred years ago. A
scientist found out that mosquitoes spread malaria. Let's read about
this discovery in his own words.

“My father was a general in the Indian Army. I studied to become a
doctor, but what I really liked was reading stories, writing poetry, music
Ronald Ross and drama. In my free time I enjoyed doing all this.

In those days, thousands of people used to die from a disease that we now call malaria. The disease was found in areas where there was a lot of rain, or in swampy places.

People thought that the illness was caused by some poisonous gas that came from the dirty swampy areas. They gave it the name 'malaria' which means 'bad air'.

One doctor had seen tiny germs in the blood of one of the patients, when he observed it under a microscope. But he could not understand how these had got into the patient’s blood.

My professor had some ideas about this. “I think that these may be carried by some kind of mosquito.” As his student, I spent all my time chasing mosquitoes, to catch and observe. We used to carry empty bottles and chase mosquito after mosquito.
Then we would put the mosquitoes into a mosquito net in which there was a patient of malaria. The mosquitoes would have a feast, biting these patients.

The patients were paid one anna for allowing one mosquitoe to bite them. I will always remember those days at the hospital in Secundrabad – how we used to cut open the mosquito’s stomach and peep into it.

I would spend hours and hours bent over the microscope. By night my neck would be stiff and my eyes could not see clearly! It used to be very hot but we dared not fan ourselves, as all the mosquitoes would fly off in the breeze! Once I also fell ill with malaria.

I spent months like this with the microscope, but could not find anything. One day we caught a few mosquitoes that looked different. They were brownish with spotted wings.

When I looked into the stomach of one of the female mosquitoes, I saw something black there. I looked closer. I saw that these tiny germs looked just like the ones that were found in the blood of malaria patients.

At last we had the proof! Mosquitoes did spread malaria!” In December 1902, Ronald Ross got the highest award for his discovery—the Nobel Prize for medicine. In 1905, even as he lay dying, Ross’s last words were, “I will find something, I will find something new.”

THANKYOU,

NANDITHA AKUNURI

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