Biology Reference
In-Depth Information
CDC-based processing entities for handling surges of human specimens.
CDC's creation of this processing unit reflects its more general efforts to
develop additional rapid diagnostic tests for use by the constituents of the
LRN.
The SARS outbreak that began in China in late 2002 served as an unpar-
alleled example of collaboration between the laboratory and epidemiologic
sciences. Multidisciplinary CDC and WHO teams descended on sites where
cases of SARS first emerged in Hong Kong and Southeast Asia, with (1) early
epidemiologic confirmation that the mystery disease was being transmitted
from person to person and (2) the suggestion that a single infectious person
may be a point source for the outbreak.
Armed with these key parameters, CDC and other labs tested specimens
from multiple persons diagnosed with SARS for a variety of plausible patho-
gens. Their inquiry was bounded by a search for those infectious agents that
may be plausibly transmitted person-to-person and may cause upper and
lower respiratory illness—the clinical and epidemiologic characteristics of
the outbreak at that point. The laboratory assessment proceeded systemati-
cally, with initial culture of the putative virus (after select bacterial patho-
gens had been ruled out), followed by morphologic characterization, and
then molecular confirmation that SARS represented a novel infection with a
heretofore unrecognized coronavirus. Within weeks of this discovery, mem-
ber labs of the LRN, as well as other diagnostic labs worldwide, were pro-
vided with the molecular primers and other reagents to permit widespread
testing for this novel and emergent virus (Ksiazek 2003).
The emergence of novel influenza A (H1N1) in the spring of 2009 heralded
another opportunity for CDC and the LRN to demonstrate its diagnostic
prowess. In April 2009, CDC diagnosed two patients from California (who
were not epidemiologically linked) with infection from a novel influenza
A (H1N1) of swine origin. In a matter of months, this novel influenza A
virus became pandemic, causing thousands of cases in countries world-
wide (Dawood 2009). In June 2007, human infection from novel influenza
A virus became a nationally notifiable disease. State health laboratories
typically forward influenza isolates that cannot be subtyped using the
commonly available subtyping reagents. In 2005, CDC first identified a
human case of infection with a triple-reassortant swine influenza A (H1)
virus. Triple reassortant viruses contain genetic material from human,
swine, and avian influenza strains. In subsequent years, an additional 11
cases of human infection from triple reassortant swine influenza A were
detected, and epidemiologic investigations found that a majority of these
ill persons had had close or proximate contact with pigs by participat-
ing or visiting agricultural fairs (Shinde 2009). CDC developed an FDA-
approved real-time RT-PCR test to subtype these swine-origin viruses.
When the novel influenza A (H1N1) strains emerged in the two patients
from California in April 2009, CDC was able to modify the PCR test to
detect this emergent strain and distribute to all the members of the LRN
