TOEFL iBT Integrated Writing Task

Reading passage
Malaria is one of the most common infectious diseases on Earth and is a huge public health problem in tropical and subtropical regions. It infects between 300 and 500 million people every year and causes between one and three million deaths annually, mostly among young children in Sub-Saharan Africa. The disease is caused by protozoan parasites usually referred to as malaria parasites.

Malaria parasites are transmitted by female Anopheles mosquitoes. The parasites multiply within red blood cells, causing symptoms that include fever, anemia, chills, flu-like illness, and in severe cases, coma and death. Malaria transmission can be reduced by preventing mosquito bites with mosquito nets and insect repellents, or by mosquito control by spraying insecticides inside houses and draining standing water where mosquitoes lay their eggs.

Unfortunately, no vaccine is currently available for malaria. Instead preventative drugs (that is drugs that stop you catching a disease) must be taken continuously to reduce the risk of infection. These drug treatments are simply too expensive for most people living in areas where malaria is common. Malaria infections are treated through the use of anti-malarial drugs.

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Listening passage
Today, I want to look at one reason why malaria is so easily spread. The disease is spread by female Anopheles mosquitoes, and they have a very developed system for finding people and animals to bite. The female mosquito which carries the malaria parasite has a variety of sensors designed to track its prey. These include chemical sensors, visual sensors, and heat sensors.

Using the first of these mosquitoes can sense, almost smell, carbon dioxide and lactic acid up to 36 metres away. Mammals and birds give off these gases as part of their normal breathing, and the mosquitoes home in on these gases. It seems that certain chemicals in human sweat also attract mosquitoes. People who do not sweat very much tend to get bitten much less than people who do.

Mosquitoes do not only smell their human prey, they also see them. If a person is wearing clothing that contrasts with their background, and especially if that person moves while wearing that clothing, mosquitoes can notice the colour-contrast and the movement and are drawn to it. Anything that moves is probably alive and therefore full of blood, so this is a good technique for the mosquito. Mosquitoes can also feel their prey by using a type of heat sensor. Mosquitoes are able to detect heat so they can to find warm-blooded mammals and birds very easily, once their sight and smell have brought them close enough.

As you can see, the mosquito is, unfortunately, a highly evolved hunter.

Malaria Reading notes
Main Idea: malaria a terrible disease
MP1 --- one of most common diseases on earth
              -- infects 300 to 500million a year
              -- causes 1 to 3 million deaths
MP2 --- how malaria is spread
              -- caused by parasites carried by Anopheles mosquito
                     - parasites multiply in bloodstream after bite, cause fever, sometimes death
              -- spread can be reduced by preventing bites
                    - nets, repellents, spraying insecticide
MP3 --- no vaccine, only drugs taken constantly can stop catching mal.
                    -- too expensive for people in mal.areas
                 
Malaria Listening notes
Main Idea: mosquito sensors (reason why malaria spreads easily)
MP1 --- chemical sensors
                  -- can smell CO2 over 30m away
                        - birds and mammals give off when breathe
                  -- can smell human sweat
MP2 --- visual sensors
                 -- can see colour-contrast (clothes/background)
                 -- can see movement
MP3 --- heat sensors
                  -- can feel heat
                        - find warm-blooded creatures easily


(Do NOT try to include all of the notes above in your essay. These notes are very complete. You will not have time to reproduce them in your essay. Write only what you think is most important.)

Malaria Sample Essay
In this set of materials the reading passage describes a terrible disease, and the listening passage explains how that disease is spread in such an efficient way.

The reading passage presents an outline of malaria, one of the most common diseases on earth. It affects about 300 to 500 million people annually and up to 3 million of these people die. It is caused by a parasite which gets into humans when they are bitten by Anopheles mosquitoes. Using nets which prevent mosquito bites and chemically-spraying mosquito areas can minimize transmission of malaria, but, nfortunately, there is no vaccine, and drugs to prevent it are very expensive.

The listening passage explains why mosquitoes can spread malaria so easily. Malarial mosquitoes have three types of sensors which they depend on to find victims. They have chemical sensors which they use to “smell’ human and animal prey. These sensors can detect CO2 and human sweat from a long way off. In addition, malarial mosquitoes have visually-based sensors. They can see the color-contrast and movement which indicate a living creature is nearby. Finally they have heat sensors which tell them exactly where a warm blooded animal is, once their other sensors have brought them close. (196)