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dog and cat assay data sheet Toxoplasma gondii
Test code:
X0002 -
Ultrasensitive qualitative detection of
Toxoplasma gondii by real time PCR
X0002 is included
on
P0028 - feline diarrhea panel
Toxoplasmosis is the most common parasitic infection worldwide
affecting humans and a number of domestic animals. The organism that
causes toxoplasmosis is Toxoplasma gondii - a single-celled
organism in order Coccidia.
The cat is the only animal in which sexual reproduction of the
organism occurs. Thus, cats are the only domestic animal that has the
potential to shed the organism’s eggs. Although there is generally a
high prevalence of infection in cats, most surveys show a less than 1%
incidence of oocyst shedding. This is to be expected as infected cats
generally do not re-shed oocysts following their first exposure to
Toxoplasma gondii.
Dogs may transmit Toxoplasmosis to humans by rolling in foul-smelling
substances and by ingesting fecal material. The fact that 50% of stray
dogs and cats carry T. gondii antibodies suggests that they
have been infected with the parasite. Reports show that dogs in
shelters, dogs living in close contact with wild birds and rodents in
rural areas, and dogs fed raw meat are at much higher risk for being
infected by T. gondii.
Despite the high prevalence of Toxoplasma gondii infection,
significant clinical disease in cats (and other species) appears to be
very rare. This implies that many infected animals can be carriers of
the parasite with unnoticed symptoms. When disease does occur, it may
develop either following primary infection due to an inadequate immune
response to stop the invasive tachyzoites, or as a result of
reactivated infection due to compromised immunity. Clinical disease
appears to be most common in young cats (less than 2 years of age),
and this may be due, in part, to a poorly developed immune response in
these cats. Reactivation of infection in older cats may be linked to
co-infection with feline leukemia virus or feline immunodeficiency
virus in some cats. The most commonly reported clinical signs
associated with feline toxoplasmosis are anorexia, weight loss,
lethargy, dyspnea (due to pneumonia), ocular signs (iritis,
chorioretinitis) and pyrexia. Other less common features include
gastrointestinal signs (vomiting and diarrhea), neurological signs,
lymphadenopathy, jaundice, myositis and abortion.
Toxoplasmosis presents a serious health risk for people living in
close contact with these animals. Infection is especially dangerous
for people with suppressed immune system, such as AIDS and cancer
patients, and for pregnant women. Swollen glands and fever are the
most common findings in those who have any symptoms. Infected infants
may show various symptoms including jaundice, encephalitis, mental
defects, and eye disease.
The diagnosis of toxoplasmosis is problematic and a definitive
diagnosis rests on demonstration of the active form of the organism in
tissues taken at post mortem examination or in biopsy samples.
Laboratory tests may also be used as diagnostic aids. The “gold
standard” for the detection of T. gondii in clinical specimens
is mouse inoculation and then the detection of T. gondii-specific
antibodies. This method is sensitive and specific but very
time-consuming, taking up to six weeks to obtain a diagnosis. Cell
culture detection of this parasite is also slow and lacks sensitivity.
An ELISA test may be used, but is difficult in animals with severe
immune dysfunction. Furthermore, serological tests cannot detect cats
that are shedding the parasite in their feces. Molecular detection by
PCR overcomes these difficulties and provides a highly
sensitive and specific determination of an animal’s infection status.
Utilities:
References:
Specimen requirement: 0.2 ml whole blood in EDTA
(purple top) tube, or 0.2 ml feces, or 0.2 ml
amniotic fluid or CSF, or 0.2 ml fresh, frozen or fixed 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
polymerase chain reaction
Normal range: Nondetected |
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