− | Demonstration of ''Toxoplasma gondii'' in the tissues with associated inflammation is required for the definitive diagnosis of clinical toxoplasmosis. For example, tachyzoites may be seen in blood, cerebrospinal fluid, peritoneal and pleural effusions, aqueous humour or transtracheal washes from clinically ill animals. ''Toxoplasma gondii'' may also be detected in these samples using PCR, tissue culture or animal inoculation techniques<sup>1</sup>. These methods may be employed on tissue biopsies too, as well as examination under haematoxylin and eosin or immunohistochemical staining. Immunohistochemistry is preferred to H&E because it is specific for ''T. gondii''. Demonstration of the organism is often most easily achieved post-mortem, as the size of the sample is not restrictive to the likelyhood of seeing ''T.gondii''. In the absence of demonstration of ''Toxoplasma gondii'' in the tissues or fluids ante-mortem, there is no one specific test to diagnose toxoplamosis. However, a combination of various diagnostic procedures can be used to build a presumptive diagnosis. | + | Demonstration of ''Toxoplasma gondii'' in the tissues with associated inflammation is required for the definitive diagnosis of clinical toxoplasmosis. For example, tachyzoites may be seen in blood, cerebrospinal fluid, peritoneal and pleural effusions, aqueous humour or transtracheal washes from clinically ill animals. ''Toxoplasma gondii'' may also be detected in these samples using PCR, tissue culture or animal inoculation techniques<sup>1</sup>. These methods may be employed on tissue biopsies too, as well as examination under haematoxylin and eosin or immunohistochemical staining. Immunohistochemistry is preferred to H&E because it is specific for ''T. gondii''. Demonstration of the organism is often most easily achieved post-mortem, as the size of the sample is not restrictive to the likelihood of seeing ''T.gondii''. In the absence of demonstration of ''Toxoplasma gondii'' in the tissues or fluids ante-mortem, there is no one specific test to diagnose toxoplamosis. However, a combination of various diagnostic procedures can be used to build a presumptive diagnosis. |
| Firstly, clinical signs should be suggestive of toxoplasmosis, despite variation in the presentation of disease between individuals. Although no pathognomic changes for toxoplasmosis are seen on routine haematology, biochemistry and urinalysis, certain results results are often seen in ''T. gondii'' infection. For example, most cats show a mild non-regenerative anaemia, and 50% of pateients are initially leukopenic due to lymphopenia. Neutropenia may occur in conjunction with lymphopenia, and leukocytosis may occur during recovery<sup>4</sup>. Most patients also show and increase in creatine kinase, ALT, SAP, and hypoalbuminaemia is also common<sup>1, 4</sup>. 25% of cats show hyperbilirubinemia and icterus, and pancreatitis may cause low to low normal serum calcium. A mild proteinuria and bilirubinuria are often revealed by urinalysis. | | Firstly, clinical signs should be suggestive of toxoplasmosis, despite variation in the presentation of disease between individuals. Although no pathognomic changes for toxoplasmosis are seen on routine haematology, biochemistry and urinalysis, certain results results are often seen in ''T. gondii'' infection. For example, most cats show a mild non-regenerative anaemia, and 50% of pateients are initially leukopenic due to lymphopenia. Neutropenia may occur in conjunction with lymphopenia, and leukocytosis may occur during recovery<sup>4</sup>. Most patients also show and increase in creatine kinase, ALT, SAP, and hypoalbuminaemia is also common<sup>1, 4</sup>. 25% of cats show hyperbilirubinemia and icterus, and pancreatitis may cause low to low normal serum calcium. A mild proteinuria and bilirubinuria are often revealed by urinalysis. |
| ''T. gondii'' oocysts may be demonstrated in cat faeces. This diagnostic procedure is not of value in dogs, since as intermediated hosts they do not prodice oocysts. Oocysts are roughly 10 x 12 microns in size and can be seen microscopically following a flotation technique. It is not possibly to visibly differentiate between ''Toxoplasma'' oocysts and those from other, non-pathogenic coccidia such as ''Hammondia hammondi' and ''Besnoitia darlingi'': laboratory animal innoculation is necessary for this. Unfortunately, most cats with clinical toxoplasmosis have already finished shedding oocysts, and so faecal examination is of little use ase a stand-alone diagnostic test. However, it will evaluate the zoonotic risk posed by cats showing signs of toxoplasmosis. | | ''T. gondii'' oocysts may be demonstrated in cat faeces. This diagnostic procedure is not of value in dogs, since as intermediated hosts they do not prodice oocysts. Oocysts are roughly 10 x 12 microns in size and can be seen microscopically following a flotation technique. It is not possibly to visibly differentiate between ''Toxoplasma'' oocysts and those from other, non-pathogenic coccidia such as ''Hammondia hammondi' and ''Besnoitia darlingi'': laboratory animal innoculation is necessary for this. Unfortunately, most cats with clinical toxoplasmosis have already finished shedding oocysts, and so faecal examination is of little use ase a stand-alone diagnostic test. However, it will evaluate the zoonotic risk posed by cats showing signs of toxoplasmosis. |