The Origin and Spread of SARS

1
The Origin and Spread of SARS

• Troy D. Gepte, MD, MPH
• National Epidemiology Center Department of Health

2
Background

• Suspected to have originated in Guandong, China
• November 2002 outbreak of SARS in China

• February 2003 reported outside China
• March 12, 2003 WHO issued global alert

• March 17 Philippine DOH started response
• April 11 first Philippine probable case reported

3
International spread from hotel in Hong Kongto
Viet Nam, United States, Singapore, Canada,
Ireland
http//www.cdc.gov/mmwr/preview/mmwrhtml/mm5212a1
.htm
4
Epidemiological features

• - health care workers and close contacts at
  highest risk
• - strict isolation and infection control can
  halt spread
• - ? super-infectors (super-spreaders) vs. high
  social mobility with many contacts

5
Clinical features
exposure to SARS case
incubation period
prodrome
lower respiratory phase
1 to 13 days(2 to 5 days)
2 daysfever (gt38ºC)
begins day 3fever, dry cough, short of
breathCXR changes
infectivity
? very low / low
low
high / super-infectors
6
Clinical features
severe respiratory phase
10
intubationmechanical ventilationdeath lt4
then
In the first 10 patients in HK, only one patient
discharged off supplemental O2 day 12CXR
resolution day 18discharge day 20still with
malaise day 26.
continued illness
90
O2 supportslow recovery
infectivity unclear, possibly high to very
highpatients still isolated on discharge
7
Infectious Agent

• Cause mild to moderate respiratory illnesses such
  as common cold.
• Able to survive in inanimate objects for up to 4
  hours.
• Can be killed by exposure to ultra-violet light,
  so they will not survive under sunlight.
• Mutate easily, and each mutation triggers off an
  epidemic of respiratory disease.

• The name coronavirus refers to the protein
  molecules surrounding the virus, making it look
  like a crown (n.corona lat crown).

8
The virus has a pattern of proteins on its
surface and this pattern must click with its
hosts, just like the pieces of a jigsaw puzzle.
Only when the pieces fit together can the virus
invade the cell.
9
Once inside the body, the virus attaches to the
cell wall and injects itself into the cell.
10
Its genetic material is released into the human
cell, and it replicates.
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The host cell bursts and infection spreads. The
fast-mutating flu virus can quickly become
resistant to drugs, making it difficult to treat.
12
Infectious Agent
a new and previously unrecognized coronavirus
that has been detected in patients with SARS   
13
According to the WHO,as of May 7, 2003,the
total number of casesof SARS worldwide is
6903with 495 deaths.(Death Rate 7.2)At
present, there are have been ten cases of SARS
reported in the Philippines two of these had
died seven cases had been infected from one
index case (AC). Two have already recovered.As
of May 7, 2003,the WHO has included the
Philippines in the list of areas with recent
local transmission of SARS(i.e. with more than
one generation of local probable SARS cases).