Emergence, then Disappearance? SARS and Nipah viruses
Topics
Viruses
Viral diseases
Viral emergence
Investigating virus disease
outbreaks
Rapid and deadly emergence: SARS
The unusual multiple phase epidemic
curve of SARS;
Probable source of SARS
Case Control investigation
Characteristics of Cases
“Field Investigation”
What “viral” ecological
changes lead to emergence?
Viruses have evolved stable
relationships with their natural hosts and can cause
Severe
disease in dead-end alternate hosts
Is control of the virus in
its ecological niche possible?
Interrupting transmission
Geographic
delineation of viruses: SARS and Nipah
Questions
1. Describe the methods
(observations, ways, and means) that are used to understand emergence of these
two viruses.
Are these methods the same?
2. Do you think theses
viruses might re-emerge? Why or why not?
3. Should people in parts of
China
(or elsewhere) be vaccinated?
Case: How do we investigate etiology?
Beijing has been severely affected by SARS,
and SARS-associated coronavirus
has been confirmed as its cause. However, clinical and experimental evidence
implicates the possibility of co-infection. In a recent report, reovirus was isolated from throat swabs of SARS patients, including the first case in Beijing and her mother. Identification with
the electron microscopy revealed the characteristic features of reovirus. Now, 24 of 38 samples from other SARS cases have been found to have the reovirus,
which appears to be a unique reovirus (orthoreovirus). Preliminary animal experiment showed that
inoculation of the reovirus in mice caused death with
atypical pneumonia. Nevertheless the association of reovirus
with SARS outbreak requires to be further
investigated.
