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GIDSAS
PART V: Discussion
Chotani, 2003
GIDSAS
Factors leading to the emergence of
infectious diseases
Changes in society, technology, environment and microorganisms are
leading to increases in host susceptibility and/or disease transmission
and the evolution of new or drug-resistant microorganisms
Chotani, 2003
GIDSAS
Candidate Factors Affecting
Emergence of SARS
 Human demographics and behavior
 Human susceptibility to infection
 Economic development and land use
 Changing ecosystems
 International travel and commerce
 Microbial adaptation and change
 Breakdown of public health measures
 To be determined . . .
Chotani, 2003
IOM: Microbial Threats to Health: Emergence, Detection, and Response. March
2003.
GIDSAS
Infectivity
Infectivity is the ability of a virus to jump
from one person to another
The recipient must receive a dose large
enough to cause the disease
From epidemic reports, it appears that
SARS virus has low infectivity (ie it
requires a large dose to pass on to the
recipient)
Other members of the coronavirus family
have very high infectivity.
Chotani, 2003
GIDSAS
Virulence
Virulence is the property of the virus to
cause damage to the patient’s organs
The SARS virus is very virulent
Other members of the coronavirus
family have low virulence.
Chotani, 2003
GIDSAS
Attenuation
Attenuation is a phenomenon seen in some
members of the coronavirus family, where the
virulence decreases when it jumps from
person to person.
Initial decrease in cases suggested
attenuation
Enough information is still not available to
suggest this phenomenon in the current
SARS outbreak
Recent clusters suggest that the virus might
be getting more virulent
Chotani, 2003
GIDSAS
Seasonal incidence of
coronavirus infections
Disease is now in the Spring season?
Chotani, 2003
GIDSAS
Research in China
Organ samples of 7 fatal cases of SARS
293 cell line inoculated from materials derived
from lung to isolated the agent(s)
Agents in organs and cell cultures revealed by
immunoassay
Result
• Chlamydia-like & Coronavirus-like particles found
on EM
• Chlamydia-like agent visualized in both organs and
cells
– Were non-reactive with
– genus-specific antibodies against Chlamydia
– monoclonal antibodies against chlamydia
pneumoniae and c. psittaci
• Results consistent with a novel chlamydia-like agent
Source: Hong T. et al. Chlamydia-like and coronavirus-like agents found in dead cases of
atypical pneumonia by electron microscopy. National Medical Journal China 2003;83:632-6
Chotani, 2003
GIDSAS
Addressing the Threat of SARS
 Enhancing global response capacity
 Improving global infectious disease
surveillance
 Rebuilding domestic public health capacity
 Developing diagnostics
 Educating and training multidisciplinary
workforce
 Vaccine development and production
 Need for new antimicrobial drugs
Chotani, 2003
IOM: Microbial Threats to Health: Emergence, Detection, and Response. March
2003.
GIDSAS
Unanswered Questions?
Future course of
outbreak
Source of virus
Mode of transmission
in community
Risk of household
transmission
Risk of transmission
on airplanes and
ships
Environmental
persistence/deconta
mination
Chotani, 2003
Period of
infectiousness
Explanation for age
distribution
Importance of
“hypertransmitters”
Role of co-infection
Optimal diagnostic
test(s)
Effective therapy
Vaccine approaches
GIDSAS
Thank you!!!!!!
Chotani, 2003