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3 Most dangerous community outbreak InfectedDeath Hong Kong Amoy Gardens % of the cases are from block E

4 蘋果 日報 SARS cases in Amoy Gardens rise drastically in just one week Why?

5 Amoy Gardens Source: SARS Expert Committee A majority of victims found In Wings 7 and 8: This is the infection pattern of the virus!

6 Mar 31 -The Hong Kong Department of Health imposed quarantine on Block E. The residents were later moved to an isolation camp, while the investigation team entered the buildings to find out the cause of the outbreak.

7 Video watching: Still remember the “Isolation camp” ?

8 As shown in the video, all the Amoy Gardens Block E residents were moved to an isolation camp … You are the investigators trying to find out how the SARS virus is transmitted in Block E. Action now!

9 Let’s recall the knowledge about transmission of diseases first … The way that viruses spread depends on the type of virus. They can spread through: Carrier organisms – e.g. mosquitoes, fleas, rats, cockroaches Air and water – by droplets or dust Direct transfer of body fluids – e.g. sweat, blood saliva and semen Surfaces on which body fluids have dried – door handles, lift buttons etc.

10 Let’s start the investigation! In the video, the investigators said “Search every inch of the building for clues…” Do you have any ideas in mind of what to search for? What samples could you collect?

11 air 蘋果日報 Tips 1: List all the possibilities and collect samples. What’s next? Sewage system

12 Sewage system 蘋果日報 Water tank Cockroach Rat air Tips 2: Now we have known which samples contain virus, then?

13 Rat Cockroach Match the infection pattern? Sewage system 蘋果日報 Tips 3: more than one sample contains virus, We have to figure out which samples match the infection pattern. But how? Match the infection pattern? Additional Information: Some Residents suffer from diarrhoea ( 腹瀉 )

14 Step by step Analysis Rats, Cockroaches, Sewage system Which one?

15 Rat Cockroach Residents suffer diarrhoea Infection patterns match! Do not match the infection pattern Sewage system 蘋果日報 Analysis result: Sewage system is the most possible cause for SARS to spread through the building!

16 Let’s read the summary of WHO’s report about their investigation in Amoy Gardens The sewage system of Amoy Gardens is presented in the picture

17 “Super spreader” suffered from diarrhoea and passed the virus into the sewage system WHO’s report on Amoy Gardens

18 Virus survives longer periods in sewage U-trap of floor drains dried up providing a pathway for the droplets containing Virus into the bathroom Exhaust fan on, door closed creates low air pressure in bathroom “Super spreader” suffered from diarrhoea and passed the virus into the sewage system WHO’s report on Amoy Gardens

19 The exhaust fan sucks contaminated droplets to the light well ( 天井 ) The viruses are carried to higher levels by the warm humid air “Super spreader” suffered from diarrhoea and passed the virus into the sewage system Virus survives longer periods in sewage U-trap of floor drains dried up providing a pathway for the droplets containing Virus into the bathroom Exhaust fan on, door closed causes low pressure in bathroom WHO’s report on Amoy Gardens

20 So….. What can you do to reduce the risk of spreading or contacting virus?

21 Cover your mouth or nose when you sneeze or cough. Wash your hands with soap frequently, especially after going to the bathroom or preparing food. Dry with hot air or paper towel Avoid contact with the body fluids of others. Examples

22 After the investigation, you should be aware that careful analysis and logical arguments are very important for scientific investigation.