UPD8

Deadly Dengue

Learning objectives

Students will learn how the spread of a major viral disease can be limited by biological and environmental control and reinforce their understanding of food chains.

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Curriculum link

Microbes and disease [QCA 8c] – viruses are microorganisms and can cause diseases; antibiotics are not effective against viruses; scientific advances may depend on creative thought.

Environment and feeding relationships [QCA 7c] – describe food chains within an environment; relate habitats to the organisms found in them.

Running the activity

Suggested time: 20 minutes – a whole lesson, depending on how much time students are given to prepare their posters.

Possible starter:
To set the scene, show students page 1. Elicit some suggestions as to how the virus could be controlled before letting them see page 2.

Main activity:
Students use the information on page 2 to complete a poster. There is a template for the poster on page 3. This has lots of gaps for drawing diagrams and pictures, so they can make it very visual. It's worth stressing that they need to make sure that poor readers can understand the message too. You may want to photocopy this page onto A3 so that pupils have more space for their diagrams.

Possible plenary:
Each student looks at another's poster. They say one thing they like about it and suggest one improvement. Students could also be encouraged to say why this form of control is preferable to chemical controls, and to suggest why the project has been so successful in the Vietnamese villages.

Background Notes:
Spraying the mosquitoes that carry dengue fever with insecticide is expensive and ineffective. The insecticide particles have to come in contact with the mosquito to kill it. Unfortunately, the Aedes aegypti mosquito tends to spend a lot of time inside houses. They hide away in cupboards that are not easily penetrated by the sprays. The low-tech strategy the children are involved in has eradicated the disease in most of the villages where it has been implemented. They pour tiny crustaceans called Mesocyclops into the large water tanks and wells used in poor areas, where piped water supplies are unreliable. This is where the mosquitoes prefer to lay their eggs. The crustaceans ensure that few mosquito larvae survive to adulthood. The children also put lids on the tanks to keep mosquitoes out and clear away any rubbish, like old buckets and cartons, that could collect rainwater. Whilst the project has been very successful in the villages, different strategies will be needed in towns where the mosquitoes breed mainly in places like roof gutters.

Web links

News links

BBC

A good introduction to the story.

New Scientist

More information on both dengue and the eradication project in Vietnam.

Division of Vector-Borne Infectious Diseases.

Detailed background information about the transmission and distribution of the disease. Good slide shows, with useful pictures, and a PDF Dengue Fact Sheet.

GM mosquitoes

Videos about how GM mosquitoes can be used to control the spread of the disease.

Media links

Dengue virus replication

This visualization represents the process by which a dengue virus releases its genetic contents inside a host cell, allowing viral replication.

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