Ocular and encephalic toxoplasmosis in canaries

In this report we describe the lesions produced by the protozoal organism, Toxoplasma gondii, in the eyes and brain of the common yellow canary (Serinus canaria). Nine of 15 birds in a flock were affected with blindness, which developed over a 3-mo span, and two birds developed torticollis. Microscopic alterations within the eye consisted of a nonsuppurative chorioretinitis with large numbers of macrophages that contained the tachyzoite form of T. gondii in the subretinal space, and aggregates of tachyzoites were found in the nerve fiber layer of the retina with and without necrosis. Tissue cysts with bradyzoites were scattered throughout the meninges and neuropil of the cerebrum and cerebellum. Both forms were confirmed by transmission electron microscopy in the eye and brain. Frozen brain samples reacted with T. gondii-specific cat sera in indirect fluorescent antibody tests. The source of infection was hypothesized to be from a stray cat the owner kept that had access to some of the bird feed. Treatment (trimethoprim 0.08 g/ml H2O and sulfadiazine 0.04 g/ml in water for 2 wk) was instituted by the referring veterinarian on the remaining birds. A second treatment regime was given for 3 wk. The owner of the canaries did not return for further treatment.     

Assessing the agreement of Western blot test results for paired serum and cerebrospinal fluid samples from horses tested for antibodies to Sarcocystis neuronaf

Equine protozoal myeloencephalitis (EPM) is a neurological disease of equids that is caused by infection of the central nervous system with Sarcocystis neurona. Veterinarians diagnose EPM by performing a neurological examination and by ordering Western blot tests for antibodies to S. neurona in the blood and/or cerebrospinal fluid (CSF). The negative predictive value of the Western blot test is generally accepted to be high for both serum and CSF. If the agreement between serum and CSF test results is strong, serum tests could be used to substitute for CSF tests in some cases. The purpose of this study was to assess the agreement of the results of 181 paired serum and CSF Western blot antibody tests on equine samples submitted to the Michigan State University Animal Health Diagnostic Laboratory. The agreement of the paired serum and CSF results was assessed for three possible test outcomes--negative, positive or suspect. An additional analysis was performed in which samples reported as suspect were reclassified as negative. The kappa statistic for negative, positive and suspect samples was 0.469. The kappa statistic for the analysis in which the suspect results were reclassified as negative was 0.474. In addition, 29% (33/112) CSF samples from seropositive horses were negative. Our results demonstrate that the level of agreement is only moderate in diagnostic samples. This supports the practice of testing CSF of seropositive horses suspected of having EPM.     

Safety of temperature sensitive mutant Mycoplasma gallisepticum vaccine

A temperature sensitive (ts) vaccine strain designated ts-11 was selected after exposure of a low passage culture of the immunogenic Australian field isolate (strain 80083) of Mycoplasma gallisepticum to 100 mg/ml of N-methyl-N-nitro-N-nitrosoguanidine. Viable counts (assayed as colour changing units (CCU)/25 microliters) of a thawed stock culture of ts-11 were typically log10 3 to log10 5 higher when incubated at 33 degrees C (the permissive temperature) than duplicate viable counts incubated at 39.5 degrees C (the restrictive temperature). Doses of approximately 2 x 10(7) CCU of ts-11 caused no gross lesions or loss of egg production when inoculated into the air sacs of susceptible chickens and no clinical or pathological signs of sinusitis when inoculated into the infraorbital sinuses of susceptible turkey poults, whereas the parent strain 80083 was demonstrably pathogenic. However, 1 of 10 poults inoculated intra-abdominally with approximately 2 x 10(7) CCU of ts-11 did show signs of mild airsacculitis. Eight-week-old pullets were vaccinated by eye drop with up to 1.4 x 10(7) CCU of ts-11 and simultaneously subjected to several stressful management practices, without apparent ill effects. Administration by coarse aerosol of 5 ml of ts-11 vaccine/25 day-old broilers, with or without 25 doses of infectious bronchitis virus vaccine caused no obvious signs of respiratory disease. The non virulent ts phenotype was maintained after 3 passages of strain ts-11 in chickens. Chickens vaccinated 3 weeks previously with ts-11 or with strain 80083 were placed in contact with susceptible chickens for a period of 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)