Fate and Transport of Zoonotic Bacterial, Viral, and - The Pork Store ...

virus B5. In an outbreak of waterborne disease due to
contaminated sewage in Switezerland, Norovirus and
enteroviruses were detected by reverse transcriptionpolymerase
chain reaction (RT-PCR) in one of two
drinking water samples. The enteroviral amplicon
showed high sequence similarity with SVDV, indicating
the potential of SVDV to cause gastroenteritis (Hafliger,
Hubner, and Luthy 2000).
Environmental Survival
Contact with contaminated environment has
been shown to cause rapid spread of disease among
a susceptible population of pigs (Dekker et al. 1995).
Drying the virus at high relative humidity kills it faster
than drying at low relative humidity (Batty et al. 1979).
The presence of salts and organic material also may
influence virus survival. For example, drying of virus
suspended in distilled water resulted in a rapid kill as
compared with virus suspended in tissue culture fluid.
Because of the cytotoxic nature of slurry, it may not be
possible to detect the presence of SVDV in pig slurry
unless cytotoxic substances are removed by treatment
with chemicals such as Freon (Turner, Williams, and
Wilkinson 1999). Turner and colleagues (1999) studied
the inactivation of SVDV in a pilot-scale treatment
plant that treated pig slurry continually at a rate of up
to 100 l/hr. The plant functioned by heating the slurry,
maintaining at least 99.99% of the slurry at the required
temperature for at least 5 min, and then recovering the
heat to raise the temperature of the incoming slurry.
The SVDV was inactivated in pig slurry (pH 7.5–8.0) to
below detectable levels at 50–55°C. In acidified slurry
(pH 6.4), on the other hand, heating to 55–60ºC was
needed for inactivation.
In another study, Turner and Williams (1999)
compared chemical treatment and heat treatment for
the inactivation of SVDV in pig slurry. The addition
of NaOH or Ca(OH)2 at different concentration/time
combinations at 4 and 22ºC was examined, as was virus
stability at different temperature/time combinations.
In slurry, SVDV inactivation required at least 2 min at
65°C. The addition of 1.0% (w/v) NaOH or Ca(OH)2 was
not effective against SVDV at 22ºC after 30 min, but
the addition of 1.5% (w/v) NaOH or Ca(OH)2 caused
inactivation of SVDV at both 4 and 22ºC (Turner and
Williams 1999).
Inactivation
The SVDV is resistant to physical and chemical
agents and may survive for up to six months in the
barn environment. It can survive at 3.9-9.1 pH for 38
days under refrigeration conditions. The virus can also
survive processing of pork products.
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