Download June-2012 - Swine Vet Center

JUNE
2012
www.swinevetcenter.com
SVC
NE WSL ET T E R
SWINE VET CENTER, P.A.
1608 SO. MINNESOTA AVE.
P.O. BOX 269
ST. PETER, MN. 56082
PHONE: 507-934-3970
FAX: 507-934-3968
THE SCOOP ON DIAGNOSTIC LABS AND TESTING
As we travel around the globe, a constant finding is how fortunate we are to have the quality of diagnostics available to us on a daily basis. We (and our clients) often take for granted the quality of service and the
dedication of the people running the diagnostic labs in the upper Midwest.
Most of our diagnostic lab submissions from the Swine Vet Center go to the University of Minnesota Veterinary Diagnostic lab. An individual drives to the lab daily to deliver submissions directly from our office in St
Peter. Dr Kurt Rossow works up most of our cases to maintain consistency and focus communication.
Last year over 50,000 cases
were submitted for a disease investigation. Over 1.4 million tests were
requested. A typical case would
look like the diagram to the left.
Many of the current tests we
take for granted were not available
until the last several years. New
tests are being developed monthly.
Many of the tests are quite complicated and technologically challenging.
An example of an extremely valuable but quite complex test that is
used daily is the PCR test. PCR
stands for polymerase chain reaction. The purpose of this test is to
find and amplify minute quantities
of genetic material in a specific
sample. For example, some bacteria are very difficult to grow but the
PCR test can find the genetic material of the organism so we know it is
present even if the lab did not grow
the pathogen.
Another example is the PRRS
PCR test. Whether in serum, saliva
or tissue samples, the PCR test
looks for virus material in the sample and if present, amplifies it to
detectable levels.
Currently the MN. Veterinary
Diagnostic lab runs 2500-3000
PCR tests per week. Here is how
the test works:
 The sample is heated to open
up and separate the double strands
of the DNA material in the sample.
Continued on next page —————->
THE SCOOP ON DIAGNOSTIC LABS AND TESTING
(CONTINUED)
 Primers are put into the sample to be tested. The role of the prim-
ers is to find and attach to the beginning and end of the specific segment of genetic material we are looking to find and amplify. This is
like a lock and key. It is extremely specific.
 Next DNA polymerase is added, as well as base pairs adenine, cytosine, guanine and thymine (A,C,G,T). The bases are the building
blocks of all genetic material and are needed for the amplification
steps. The polymerase then uses the bases to build the exact sequence of the targeted DNA segment.
 The test then goes through multiple cycles to keep amplifying the
genetic material we are looking for. Two goes to four, four to eight and
so on. The test usually goes to 40 cycles. The diagram to the right
depicts 3 cycles of a PCR test.
The PCR test is just one of the many tests that the diagnostic lab
runs for us on a daily basis. Others include:
 Bacteriology- growing and identifying swine pathogens as well as
telling us what antibiotics the bacteria are sensitive too.
 Histology- looking at thin tissue segments under the microscope to
look for lesions and pathogens.
 Electron microscopy- A super powerful microscopy that uses electron beams instead of light waves to be able to see very tiny pathogens like viruses.
 Serology- looking for antibodies produced by the body’s immune
system that indicates exposure to a specific pathogen.
 Virology- growing and identifying specific swine viruses. Some are saved and used in autogenous vaccine production (such as
influenza).
 Clinical chemistry- tests to look for serum enzymes and products that indicate health status.
 Toxicology- test to look for specific toxins in blood or tissue.
 Parasitology- tests to look for parasites. Often this is used on fecal samples.
 Nutrition- tests to look for specific levels of minerals and other agents in feed or tissue.
Finally, as you can imagine, diagnostic testing is an expensive process. The amount billed is usually a fraction of the total
cost of all the testing with tax dollars being used for additional support. The MN. Veterinary Diagnostic Lab applies case subsidies to tissue and fecal cases for disease investigation. For example, 80-90% of the actual costs are waived in a typical nursery diarrhea workup (a case running $1540 if priced by individual test is charged out at under $200.) In some cases of larger
disease investigations running thousands of dollars in tests, all diagnostic fees may be waived. As Dr. Rossow puts it, “The
point isn’t that we are good at undercharging, but rather that it represents a small cost to the people of Minnesota to help
keep pigs happy, healthy and safe to eat.”
Our ability to understand and react to disease situations would be vastly limited without the quality diagnostic labs like we
have available to us.
Make sure you let your elected officials know the importance of our state diagnostic lab whenever you get the opportunity!
ANOTHER
REASON TO STAY AWAY FROM ORGANIC MEAT
An article in a recent issue of “Clinical Infectious Diseases” warns that the trend in the production of
free-range organically raised meat could increase the risk of Toxoplasma gondii contamination of meat
because animals raised this way have greater exposure to contaminated soil and feed.
Domestic and wild cats are the primary host for this parasite. Infected cats shed oocysts in their feces which become infective in the environment and once ingested by an intermediate host (humans,
birds, animals), develop in the intestine and then travel through the bloodstream to encyst in muscle
and nerve tissue. Humans are most commonly infected by eating the undercooked meat of an infected
animal or bird. Cysts can remain for many decades in skeletal muscle, brain, heart muscle and eyes.
Toxoplasmosis is a common parasite that is carried by an estimated 30% of the human population
worldwide. Approximately 60 million Americans are thought to be infected. Only about 22.5% have
symptoms (flu-like that can last several weeks), but it is a serious disease in pregnant women (causing
miscarriage and congenital problems of the fetus) and in those with compromised immune systems (fever, confusion, headache,
seizures, eye problems). T.gondii can be found in raw or undercooked meat, as well as in cured, dried or smoked meat.
The journal article aims to make the public more aware of T.gondii as a potential food-borne illness, joining the ranks of Salmonella and E. coli. Avoiding free-range organic meat is one way to help avoid infection!
(Sources: Clinical Infectious Diseases, Vol.54 Issue 10 5-15-12 & Genetic Choice Services Inc e-commentary 6-14-12 & www.parasitesinhumans.org)
SVC Office Hours: Monday through Friday 7:30 AM to 5:00 PM
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