Lawsonia intracellularis
Test code:
B0035 -
Ultrasensitive qualitative detection of
Lawsonia intracellularis
by real time polymerase chain reaction
Proliferative enteropathy, also known as proliferative ileitis,
is caused by infection with
Lawsonia intracellularis, an obligate intracellular,
curve-shaped, argyrophilic bacterium. The disease has been
detected in domestic and laboratory animals including primates,
pig, horse, dog, rat, ferret, guinea pig, rabbit and hamster.
The disease has been reported sporadically in foals 3-7 months
of age and one outbreak involving 3 different breeding farms has
been described. All reported cases were in the eastern half of
Canada or the United States. The swine industry suffers the most
significant impact from this disease. The disease has two
clinical manifestations in pigs: an acute hemorrhagic form often
called porcine hemorrhagic enteropathy, and a more chronic
proliferative form often referred as porcine intestinal
adenomatosis.
Environmental contamination with feces of infected animals
appears to be the most important route of transmission of
disease, but it is currently unknown how long
Lawsonia intracellularis
can remain infectious outside the animal. Infection occurs most
often during the post-weaning period, when passive maternal
immunity declines. After ingestion, the bacteria infect
intestinal proliferating crypt epithelial cells and multiply
within the apical cytoplasm. There is no evidence of infection
of tissues other than intestine. Most animals have subclinical
infection but shed the bacteria in their feces, leading to
environmental contamination. Clinical manifestation of an
infection can be triggered by stressors, such as overcrowding,
transport, change in diet, and experimental manipulation.
Bacterial
culture and isolation of the bacteria are difficult because
cultured enterocytes are required to support the growth of
Lawsonia intracellularis.
Electron microscopy can be used to detect the curved bacterial
rods in apical cytoplasm of enterocytes but this is a very
time-consuming process and few laboratories have such
capability. Immunohistochemical detection can be performed on
formalin-fixed, paraffin-embedded tissue from affected intestine
to detect the bacteria in following biopsy or necropsy, but this
is also a very time-consuming process. Molecular detection using
PCR is the most sensitive, rapid and specific method to confirm
presence of the Lawsonia
intracellularis genome within tissue samples (Jones
et al., 1993).
Utilities:
-
Help confirm the disease causing agent
-
Shorten the time required to confirm a clinical
diagnosis of Lawsonia
infection.
-
Help ensure that herds are free of
Lawsonia
bacteria
-
Early prevention of spread of the bacteria among a
herd
-
Minimize personnel exposure to the bacteria
-
Safety monitoring of biological products that derive from pigs
References:
Jones, G. F., Ward, G.E., Murtaugh, M.P., Lin, G. and Gebhart,
C.J. (1993) Enhanced detection of intracellular organism of
swine proliferative enteritis, ileal symbiont intracellularis in
feces by polymerase chain reaction. J. Clin. Microbiol.
31:2611-2615.
Specimen requirements: 0.2 ml feces, or rectal swab, or 0.2 ml fresh, frozen or fixed
ileum tissue.
Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.
For all
specimen types, if there will be a delay in shipping, or during
very warm weather, refrigerate specimens until shipped and ship
with a cold pack unless more stringent shipping requirements are
specified. Frozen specimens should be shipped so as to remain
frozen in transit. See shipping
instructions for more information.
Turnaround time:
2 business days
Methodology:
Qualitative real time PCR
Normal range:
Nondetected
Methodology:
Qualitative
real time PCR
