- Note - Once again we are proud to be first to present
more of Dr. Lee's frontline research and information regarding the SARS
epidemic and its dynamics. He deserves worldwide recognition for his numerous
personal contributions and citations of other key data and information
as below. - ed
- Jeff, More news you've not heard elsewhere...
- Avian Dis 2003 Jan-Mar;47(1):149-53 Mechanical transmission
of turkey coronavirus by domestic houseflies (Musca domestica Linnaeaus).
Calibeo-Hayes D, Denning SS, Stringham SM, Guy JS, Smith LG, Watson DW.
Department of Entomology, College of Agriculture and Life Sciences, North
Carolina State University, Raleigh, NC 27695, USA.
- Domestic houseflies (Musca domestica Linnaeaus) were
examined for their ability to harbor and transmit turkey coronavirus (TCV).
Laboratory-reared flies were experimentally exposed to TCV by allowing
flies to imbibe an inoculum comprised of turkey embryo-propagated virus
(NC95 strain). TCV was detected in dissected crops from exposed flies for
up to 9 hr postexposure; no virus was detected in crops of sham-exposed
flies. TCV was not detected in dissected intestinal tissues collected from
exposed or sham-exposed flies at any time postexposure. The potential of
the housefly to directly transmit TCV to live turkey poults was examined
by placing 7-day-old turkey poults in contact with TCV-exposed houseflies
3 hr after flies consumed TCV inoculum. TCV infection was detected in turkeys
placed in contact with TCV-exposed flies at densities as low as one fly/bird
(TCV antigens detected at 3 days post fly contact in tissues of 3/12 turkeys);
however, increased rates of infection were observed with higher fly densities
(TCV antigens detected in 9/12 turkeys after contact with 10 flies/bird).
This study demonstrates the potential of the housefly to serve as a mechanical
vector of TCV. PMID: 12713170
- Am J Vet Res 1983 Nov;44(11):2078-82 Identification of
porcine transmissible gastroenteritis virus in house flies (Musca domestica
Linneaus). Gough PM, Jorgenson RD.
- Transmissible gastroenteritis (TGE) virus was detected
in house flies (Musca domestica Linneaus) by staining with specific fluorescent
antibody. The flies were collected within a swine confinement facility
in which TGE was enzootic. Laboratory-reared flies were infected experimentally
with TGE virus and the virus was recovered from the insects for 72 hours
after infection. The TGE virus was identified both by the fluorescent antibody
technique and by isolation in cell culture. The nature of plaque formation
in cell monolayers inoculated with the virus passaged through flies changed
from a large plaque (4 mm or greater in diameter) to a small plaque (1
mm in diameter) over the period. Large plaques were observed early after
infection and were attributed to TGE virus mechanically carried by the
flies. Small plaques occurred 8 to 12 hours after infection and were considered
to be produced by virus replicated in the dipterous cell. PMID: 6316821
- So, Jeff, it is my reasonable guess that SARS coronavirus
can be spread by house flies for between 3 and 72 hours after a fly has
come into contact with SARS coronavirus as is likely to happen if a fly
lands on any infected human waste/body fluids. You will note that, for
turkey coronavirus, it is sufficient to have one single infected fly land
on a bird and the bird can become infected. It is a reasonable infection-control
policy, as summer approaches and flies begin flying, for any infected nation
to institute fly abatement programs immediately and for individual citizens
of infected nations to be concerned about and proactive about preventing
contact with flies.
- This is going to be a challenging summer in Asia. As
flies (and perhaps other insects?) are likely to spread the disease in
the summer and the virus appears to spread by close human contact in the
winter and summer it is not likely that SARS coronavirus will display any
seasonality. Once flies begin flying, I anticipate there will be an increase
in SARS cases particularly in areas where flies have access to human waste/body
fluids and subsequent access to humans.
- This is a really troublesome finding and does not bode
well for quarantine effectiveness. How does a nation protect itself from
- Bob Lee