Enzyme-linked immunosorbent assays for the detection of Toxoplasma gondii-specific antibodies and antigens in the aqueous humor of cats.

Serum and aqueous humor samples, collected from 14 clinically normal cats and 96 cats with clinical evidence of intraocular inflammation, were assayed with ELISA for Toxoplasma gondii-specific immunoglobulin M (IgM), T gondii-specific IgG, T gondii-specific antigens, total IgG, and total IgM. Additionally, serum was assayed with ELISA for feline leukemia virus p27 antigen and antibodies against the feline immunodeficiency virus as well as with an immunofluorescent antibody assay for antibodies against feline coronaviruses. Calculation of the Goldmann-Witmer coefficient (C-value) for the T gondii-specific antibodies detected in aqueous humor established the likelihood of local antibody production. Serologic evidence of present or prior infection by an infectious agent was found in 81.9% of the clinically affected cats from which serologic results were available (77/94 cats). Seropositive results for toxoplasmosis were found in 74.0% of the clinically affected cats. Anterior segment inflammation was found in 93.1% (81/87 cats from which information was available) of the clinically affected cats, most of which were older males. Toxoplasma gondii-specific antibodies were not detected in the aqueous humor of 6 seropositive, clinically normal cats. The C-values for aqueous T gondii antibodies were greater than 1 in 44.8% of the cats and greater than 8 in 24.0% of the cats. Response to treatment with clindamycin HCl was positive in 15/20 (75%) of the T gondii-seropositive, clinically affected cats treated with this drug. In 13/15 (86.7%) T gondii-seropositive, clinically affected cats having a C-value greater than 1, response to treatment with clindamycin HCl was positive.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serologic prevalence of selected infectious diseases in cats with uveitis.

Serologic evidence of infection by Toxoplasma gondii, feline leukemia virus, feline coronaviruses, or feline immunodeficiency virus (FIV) is commonly found in cats with uveitis. Serum samples from 124 cats with uveitis were assayed by use of ELISA for the detection of T gondii-specific immunoglobulin M (IgM), IgG, and circulating antigens (Ag), as well as an ELISA for feline leukemia virus Ag, an ELISA for antibodies to FIV, and an indirect fluorescent antibody assay for antibodies to feline coronaviruses. Serologic evidence of infection by 1 or more of the infectious agents was detected in 83.1% of the samples. Serologic evidence of T gondii infection, defined as the detection of T gondii-specific IgM, IgG, or Ag in serum, was found in 74.2% of the samples. The seroprevalence of T gondii infection was significantly greater in cats with uveitis than in healthy cats from a similar geographic area. Serum samples from cats with serologic evidence of both T gondii and FIV infections were more likely to contain T gondii-specific IgM without IgG than samples from cats with serologic evidence of T gondii infection alone. Cats with serologic evidence of FIV and T gondii coinfection had a higher T gondii-specific IgM titer geometric mean and a lower T gondii-specific IgG titer geometric mean than did cats with serologic evidence of T gondii infection alone. Serologic evaluation for T gondii infection should include assays that detect IgM, IgG, and Ag, particularly in cats coinfected with FIV.     

Prevalence of Toxoplasma gondii infection in cats in Georgia using enzyme-linked immunosorbent assays for IgM, IgG, and antigens

Serologic prevalence of Toxoplasma gondii infection was determined using enzyme-linked immunosorbent assays detecting immunoglobulin M (IgM), immunoglobulin G (IgG), and circulating T. gondii antigens (Ag) in 81 healthy cats and 107 cats with clinical signs referable to toxoplasmosis. A higher prevalence of infection was detected using the three assays together in healthy cats, clinically ill cats, and combined healthy and clinically ill cats than when IgG class antibody detection alone was used. IgM titers greater than or equal to 1:256 and IgG titers greater than or equal to 1:512 were present more frequently in cats with clinical signs of disease. Prevalence of present or prior infection as defined by these three assays combined increased with advancing age in both groups of cats.     

Effect of Feline Immunodeficiency Virus Infection on Toxoplasma gondii-specific Humoral and Cell-mediated Immune Responses of Cats with Serologic Evidence of Toxoplasmosis

Serum samples from 89 cats with serologic evidence of toxoplasmosis were identified by using an enzyme-linked immunosorbent assay (ELISA) that detected Toxoplasma gondii -specific immunoglobulin M (IgM) or T. gondii -specific immunoglobulin G (IgG). Concurrent feline immunodeficiency virus (FIV) infection was detected in 36 cats using an ELISA for detection of FIV-specific IgG. The majority of the cats in both the FIV-seropositive and FIV-seronegative groups were male and >5 years of age. FIV-seropositive cats were more likely to have T. gondii IgM titers without IgG ( P > 0.05) or any T. gondii IgM titer ( P > 0.05) than were FIV-seronegative cats. FIV-seronegative cats (1328) had a higher T. gondii IgG geometric mean titer than did FIV-seropositive cats (724) and were more likely to have T. gondii IgG titers 1:2048 than were FIV-seropositive cats ( P > 0.05). Cats with serologic evidence of both T. gondii and FIV infections had persistent T. gondii IgM titers for >12 weeks. Lymphoblast transformation in response to concanavalin A, T. gondii -specific intracellular antigens, and T. gondii -specific secretory antigens was compared in T. gondii seropositive and FIV-seronegative cats, cats with serologic evidence of T. gondii infection alone, and cats with serologic evidence of concurrent FIV and T. gondii infections. Lymphocytes from all but one cat in the FIV-seropositive group responded to concanavalin A. Whereas lymphocytes from FIV-seronegative cats with serologic evidence of toxoplasmosis responded to T. gondii -specific antigens, four of five of the FIV-seropositive cats with concurrent serologic evidence of toxoplasmosis did not.     

Comparison of Latex Agglutination, Indirect Hemagglutination, and ELISA Techniques for the Detection of Toxoplasma gondii-specific Antibodies in the Serum of Cats

The primary purpose of this study was to determine whether commercially available latex agglutination and indirect hemagglutination kits for the detection of Toxoplasma gondii-specific antibodies were capable of detecting T. gondii-specific immunoglobulin M (IgM) in the serum of cats. Serum samples from 35 cats containing either T. gondii-specific IgM, T. gondii-specific immunoglobulin G (IgG), or both were collected. Each serum sample was assayed using a latex agglutination kit, an indirect hemagglutination kit, an enzyme-linked immunosorbent assay (ELISA) for the detection of T. gondii-specific IgG, and an ELISA for the detection of T. gondii-specific IgM. When serum samples containing only T. gondii-specific IgM as determined by ELISA were assayed, the latex agglutination kit and the indirect hemagglutination kit detected antibodies in 33.3% and 13.3%, respectively. When T. gondii-specific IgG was present in a serum sample, the results from the latex agglutination kit, the indirect hemagglutination kit, and the IgG-ELISA were similar; however, there was a wide variation in titer magnitude results between the three assays. It was concluded that the latex agglutination kit and the indirect hemagglutination kit did not adequately detect T. gondii-specific IgM in feline serum.     

Pyogranulomatous cystitis associated with Toxoplasma gondii infection in a cat after renal transplantation

CASE DESCRIPTION: An 8-year-old spayed female domestic shorthair cat was evaluated for azotemia and a suspected mass in the urinary bladder 6 weeks after receiving a renal transplant. Ultrasonography revealed a mass at the ureteroneocystostomy site, and the mass was excised. Both the donor and recipient cats were seronegative for Toxoplasma gondii-specific IgG antibodies prior to transplantation. CLINICAL FINDINGS: Histologic evaluation of the mass revealed lesions indicative of extensive necrotizing pyogranulomatous cystitis with numerous intralesional T gondii tachyzoites and bradyzoite cysts. TREATMENT AND OUTCOME: Treatment with clindamycin was initiated; however, the cat's clinical condition continued to decline, and it was euthanized 9 days after the mass was excised. Necropsy revealed T gondii cysts within the renal allograft and the transplanted ureter, with no evidence of systemic spread of organisms. CLINICAL RELEVANCE: Toxoplasmosis should be considered as a differential diagnosis for azotemia in feline renal transplant recipients regardless of the results of assays for T gondii antibodies in the serum of donors or recipients. This report illustrated the need for improved screening of donor and recipient cats and the importance of minimizing exposure to potential sources of T gondii after transplantation.     

Mitogen and antigen-specific induction of lymphoblast transformation in cats with subclinical toxoplasmosis.

Lymphoblast transformation in whole blood was assessed by 3H-thymidine incorporation after stimulation by concanavalin A and Toxoplasma gondii secretory and intracellular antigens in samples from cats with experimentally induced toxoplasmosis. Toxoplasma gondii-specific immunoglobulin M, immunoglobulin G, and circulating antigens were also measured throughout the study period. Lymphocytes from all cats were responsive to concanavalin A pre- and post-inoculation with T. gondii. Suppression of mitogen-stimulated lymphoblast transformation during the course of infection was not observed. Both the secretory and intracellular antigens stimulated lymphoblast transformation in many cats from Week 2 to Week 52 post-inoculation. Lymphoblast transformation was stimulated more frequently by intracellular antigens (66.25%) than by secretory antigens (48.75%). Lymphoblast transformation was not induced by T. gondii antigens in any cat prior to appearance of T. gondii-specific antibodies in serum or during the oocyst shedding period. Cats with persistent antigenemia had the most consistent lymphoblast transformation results induced by T. gondii-specific antigens.     

Effect of primary phase feline immunodeficiency virus infection on cats with chronic toxoplasmosis.

The effect of primary phase feline immunodeficiency virus (FIV) infection on clinical signs, hematological values, Toxoplasma gondii oocyst shedding, T. gondii-specific serology, T. gondii-specific cell-mediated immune responses, non-specific cell-mediated immune responses, and lymphocyte subpopulations from cats with experimentally induced chronic toxoplasmosis was studied. No significant clinical or hematologic abnormalities were noted following inoculation with FIV. T. gondii-specific IgM was significantly increased, concanavalin A, T. gondii tachyzoite antigen and T. gondii secretory antigen induction of lymphocyte transformation were significantly suppressed, and CD4+ cell numbers were significantly decreased following inoculation with FIV. The changes were attributed to FIV effects on the immune system and resultant activated toxoplasmosis.     

Seroprevalence of feline immunodeficiency virus, feline leukaemia virus and Toxoplasma gondii in stray cat colonies in northern Italy and correlation with clinical and laboratory data

Stray cat colonies in urban and rural areas of Lombardy, northern Italy, were surveyed for seroprevalence of feline immunodeficiency virus (FIV) antibodies, feline leukaemia virus (FeLV) antigen and Toxoplasma gondii IgG. Of 316 cats tested, 6.6% were positive for FIV and 3.8% were positive for FeLV infection; 203 cats were tested for T gondii IgG antibodies and a prevalence of 30.5% was detected. Statistical analysis tested the influence of provenience, age, gender, health status and laboratory results on seroprevalence and found male gender and adult age were risk factors for FIV infection. FIV-infected cats were more likely to have a decreased red blood cell count than FIV seronegative cats. No predictors were significantly associated with FeLV and T gondii seropositivity. Colony cats in this study posed a limited risk for retrovirus infection to pet cats allowed outdoors, whereas toxoplasmosis exposure was comparable with the worldwide data.     

Detection of Toxoplasma gondii IgG antibodies in juvenile great grey kangaroos, Macropus giganteus giganteus.

Serial IgG antibody titers to Toxoplasma gondii from three juvenile great grey kangaroos (Macropus giganteus giganteus) with clinical signs consistent with toxoplasmosis were compared with titers from three clinically normal juveniles of similar age. The modified agglutination test was used to measure antibodies to T. gondii. Results demonstrated declining antibody titers to T. gondii in five of six animals. Antibody titers were similar in animals with and without clinical signs. This was interpreted as an indication that maternal IgG antibodies to T. gondii were transferred to juveniles, presumably in milk, rather than an indication of clinical disease. Therefore, clinicians should interpret Toxoplasma serology results in juvenile macropods cautiously.     

Serological survey of Toxoplasma gondii,feline immunodeficiency virus and feline leukaemia virus in urban stray cats in Belgium

Three hundred and forty-six serum samples taken between 1998 and 2000 from urban stray cats in the city of Ghent were tested for antibodies to Toxoplasma gondii and feline immunodeficiency virus (FIV), and antigens of feline leukemia virus (FeLV). Of these 346 samples, 243 (70.2 per cent) were seropositive for Tgondii. Thirty-nine cats (11.3 per cent) had antibodies against FIV and 13 (3.8 per cent) had circulating antigens of FeLV. Fewer of the female cats had FIV and heavier cats had a higher seroprevalence of FIV. Exact logistic regression showed that cats that were infected with FIV were more likely to be infected with T gondii (P = 0.04), and the cats with FIV had a higher titre of Tgondii antibodies than FIV-negative animals. However, FeLV was not associated with either T gondii or FIV.     

Prevalence of Toxoplasma gondii antibodies in dairy goats from 1982 to 1984

Serum samples from 1,000 dairy goats from northwest United States (1982 to 1984) were examined for Toxoplasma gondii antibodies by a modified agglutination test. Toxoplasma gondii antibody titers were less than 1.40 for 779 goats, 1.40 for 153 goats, and greater than or equal to 1:400 for 68 goats. Seroprevalence increased with age of goats; 3.7% of 54 six-month-old goats were seropositive (greater than or equal to 1:40) vs 17.8% of 218 one-year-old goats.     

Toxoplasma gondii infection in Blanford's fox (Vulpes cana)

Fatal toxoplasmosis was diagnosed in a Blanford's fox (Vulpes cana) from the United Arab Emirates. Toxoplasma gondii-like tachyzoites were found associated with necrosis in intestine, spleen, liver, kidneys, lungs, skeletal muscle, brain and heart. Protozoal tachyzoites reacted positively with T. gondii-specific polyclonal antibodies. Antibodies to T. gondii were detected in 10 of 12 V. cana assayed by the latex agglutination or the modified direct agglutination test.     

Diagnosis of recent Toxoplasma gondii infection in cats by use of an enzyme-linked immunosorbent assay for immunoglobulin M

Subclinical Toxoplasma gondii infection was induced in young and adult cats by oral administration of tissue cysts. An antibody-capture ELISA to detect anti-Toxoplasma IgM-class antibodies in the serum of cats was developed. The serologic response to experimental infection was followed in the 2 groups of cats by use of anti-Toxoplasma IgM and IgG detection. This study shows that anti-Toxoplasma IgM-class antibody titers develop early in the course of experimental infection in cats and that the combination of IgM- and IgG-class antibody titer measurement can aid in the detection of recent subclinical toxoplasmosis.     

Serodiagnosis of acute toxoplasmosis in macropods

The sera of 34 Australian macropods, the brains of which had been bioassayed for Toxoplasma gondii, were used to establish that a titre greater than 1/32 was significant for a direct agglutination test against toxoplasmosis. In addition, the concentration of 2-mercaptoethanol required to destroy the IgM fraction of macropod serum was confirmed in a modified direct agglutination test. To further validate the tests, the serological responses of three eastern grey kangaroos (Macropus giganteus) dosed orally with T. gondii oocysts and one M. giganteus injected with T. gondii cysts were studied. The tests were then used to investigate a diagnosis of acute toxoplasmosis in four Tasmanian pademelons (Thylogale billardierii) clinically suspected of acquiring toxoplasmosis naturally. One hundred and fifty-one Bennett's wallabies (Macropus rufogriseus rufogriseus) and 85 T. billardierii were also tested to determine the prevalence of acute toxoplasmosis of macropods in the wild. Four percent of M. r. rufogriseus and 1.2% of T. billardierii possessed T. gondii-specific IgM in their sera.     

The influence of feeding and maintenance system on occurrence of Toxoplasma gondii infections in dogs

Serum samples of 113 dogs visiting "outpatient clinics", 52 dogs kept in shelters and 35 animals from a military dog training centre were examined for Toxoplasma gondii specific antibodies using a latex agglutination test. Significant differences in seroprevalences were found between dogs from the training centre (8.6% of positive results) and the other populations examined (40.7% of positive seroreagents in animals visiting outpatient clinics and 44.2% in the group from shelters, respectively). Among clinic patients, dogs fed raw meat were significantly more frequently seropositive (65.2%) than those eating only commercial dry feed or cooked meat (25.7%). No statistically significant differences were noted in males compared to females and in pure breed dogs compared to crossbreed dogs. The antibodies were usually found in low titres under 60 IU/ml (69.6% of positive results). High titres (120-480 IU/ml) were detected in 2 of 3 dogs with clinical toxoplasmosis. In these dogs IFAT T. gondii specific IgM were detected and a favourable response to antiprotozoal treatment was observed. All the dogs with medium and high titres were given raw meat. Age and the presence of cats did not seem to have any influence on T. gondii seroprevalence. Neospora caninum specific antibodies in low titres ranging from 1:20-1:320 were found in 7 (9.7%) of 72 T. gondii positive seroreagents.     

A survey for Toxoplasma gondii antibodies in deer and other wildlife on a sheep range.

Blood samples were obtained from native mammals and birds on a sheep range (Hopland Field Station) in northern California. Serums were tested for antibodies to Toxoplasma gondii by the indirect hemagglutination test. Of 382 deer that were tested from 1964 to 1973, 77 (20%) were seropositive for T gondii. Among 36 serums representing 6 species of wild carnivores (badgers, bobcats, coyotes, foxes, raccoons, and skunks), 18 (50%) were seropositive. All of the 5 bobcats tested were seropositive, with antibody titers ranging from 1:65,536. The testing of 175 serums from small wild mammals indicated antibody prevalence of 8% among jackrabbits, 6% among brush rabbits, and 2% among squirrels. None of the native mice tested was seropositive for T gondii. Of 120 native birds tested, 6 (5%) were seropositive. Of the resident domestic species of animals tested, antibodies were found in 1 of 7 domestic cats, 1 of 5 feral cats, 1 of 2 dogs, and 54 (13%) of 405 sheep.     

Prevalence of IgG antibodies to Encephalitozoon cuniculi and Toxoplasma gondii in cats with and without chronic kidney disease from Virginia

Kidney disease is a common and serious condition in domestic cats. There are numerous causes of kidney disease including parasitic infection. Encephalitozoon cuniculi is a microsporidian parasite that develops in the kidneys of rabbits and causes chronic renal disease. Little has been reported concerning E. cuniculi in cats and no serological studies on this parasite in cats have been conducted in the United States to date. The present study explored the possibility that E. cuniculi is an unrecognized contributor to the high prevalence of kidney disease observed in cats. A serological survey was conducted to determine the prevalence of IgG antibodies to spores of E. cuniculi in cats with and without a diagnosis of chronic kidney disease (CKD) according to the International Renal Interest Society (IRIS) staging system. Likewise, samples were examined for IgG antibodies to Toxoplasma gondii, a common well studied protozoan of cats. Plasma and sera were obtained from 232 feline patients at the Virginia-Maryland Regional College of Veterinary Medicine teaching hospital. With the investigators blinded to the renal status of test subjects, samples were screened via indirect immunofluorescent antibody assay (IFA). Thirty-six of the 232 cats met the IRIS staging system criteria for CKD. Antibodies to E. cuniculi were found in 15 of the 232 samples, which included 4 of the 36 cats with CKD. Sera from cats serologically positive to E. cuniculi did not react to spores of E. intestinalis or E. hellem when examined in the IFA. Antibodies to T. gondii were found in 63 of the 232 samples, which included 10 of the 36 cats with CKD. The prevalence of antibodies in cats with CKD to either protozoan was not significantly different (P>0.05) from the cats without CKD in the study. Collectively the results do not support the hypothesis that either E. cuniculi or T. gondii play a significant etiologic role in the occurrence or progression of CKD in cats.     

Epidemiologic investigation of seroprevalence of antibodies to Toxoplasma gondii in cats and rodents

OBJECTIVE: To provide an epidemiologic investigation of the seroprevalence of antibodies to Toxoplasma gondii in populations of cats and wild rodents in Rhode Island and to address the possible epidemiologic role of wild rodents in the spread of toxoplasmosis. ANIMALS: 200 cats and 756 small wild rodents. PROCEDURE: Serum samples were obtained from 84 cats in animal shelters and 116 cats in veterinary hospitals. Serum samples were also obtained from 756 small wild rodents from multiple sites in Rhode Island. Sera from rodents and cats were assayed for antibodies to Tgondii by use of the modified agglutination test RESULTS: Overall, 42% (84/200) of cats had serum antibodies to Tgondii. Seroprevalence was not significantly different between stray (50%; 42/84) versus client-owned (36%; 42/116) cats, between male (43%; 40/94) versus female (42%; 39/93) cats, or between indoor (26%; 7/27) versus outdoor (39%; 35/89) cats. Seroprevalence rate of trapped rodents was 0.8% (6/756). Six rodents captured in Washington County accounted for of the seropositive rodents. Four of 6 of the seropositive rodents were trapped at a single site in Washington County (an abandoned barn). Five stray cats, known to have resided at the same site in Washington County as 4 of the seropositive rodents, were also found to be seropositive for antibodies to T gondii. CONCLUSIONS AND CLINICAL RELEVANCE: Seroprevalence rate in rodents was not correlated with the seroprevalence rate in cats. Stray cats, especially those known to be feral, may be more likely to perpetuate the cat-mouse cycle of T gondii than client-owned cats.     

Serological survey of Toxoplasma gondii, Dirofilaria immitis, Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) infections in pet cats in Bangkok and vicinities, Thailand

The seroprevalence of Toxoplasma gondii, Dirofilaria immitis (heartworm), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) infections was examined using serum or plasma samples from 746 pet cats collected between May and July 2009 from clinics and hospitals located in and around Bangkok, Thailand. The samples were tested for heartworm, FIV, and FeLV using a commercial ELISA. Of the 746 samples, 4.6% (34/746) were positive for heartworm antigen, 24.5% (183/746) had circulating FeLV antigen, and 20.1% (150/746) had antibodies against FIV. In addition, the first 348 submitted samples were tested for T. gondii antibodies using a modified agglutination test (MAT, cut off 1:25); 10.1% (35/348) were seropositive. Of the 348 cats sampled for all four pathogens, 11, 10, and 1 were positive for T. gondii antibodies and FIV antibodies, FeLV antigen, or D. immitis antigen, respectively. Of the 35 T. gondii-seropositive cats, 42.9% (15/35) were co-infected with at least one of the other three pathogens. The presence of antibodies to FIV was significantly associated with both age and gender, while FeLV antigen presence was only associated with age. In the case of FIV, males were twice as likely to be infected as females, and cats over 10 years of age were 13.5 times more likely to be infected than cats less than 1 year of age. FeLV antigen was more common in younger cats, with cats over 10 years of age being 10 times less likely to be FeLV positive than cats under 1 year of age. This is the first survey for these four pathogens affecting feline health in Thailand.