Department of Biomedical Sciences and Pathobiology

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Examination of extraintestinal tissue cysts of Isospora belli
Lindsay, David S.; Dubey, Jitender P.; Toivio-Kinnucan, M. A.; Michiels, J. F.; Blagburn, B. L. (American Society of Parasitology, 1997-08)
Relapse is common in immunocompetent and immunosuppressed humans infected with Isospora belli and is believed to be associated with the presence of extraintestinal stages. In the present study, we examined this important stage in an AIDS patient using histological, immunohistological, histochemical, and ultrastructural methods to better understand the development and structure of this stage and to develop better means of detecting infections. Antisera made in rabbits to Isospora suis, Toxoplasma gondii, Hammondia hammondi, Sarcocystis neurona, Neospora caninum, and Caryospora bigenetica were tested against I. belli tissue cysts in the avidin-biotin peroxidase complex (ABC) immunohistological test. Most antisera reacted positively in the ABC test at dilutions of 1:100 but not at dilutions of 1:250. Some antisera to N. caninum and H. hammondi reacted positively at dilutions of 1:1,000 in the ABC test. Most reactive antisera stained the tissue cyst wall and not the enclosed zoite. Eight histochemical tests were examined and most were nonreactive with I. belli zoites or tissue cysts. Transmission electron microscopy revealed that the tissue cyst wall was composed of granular material and was directly beneath the parasitophorous vacuole membrane. Zoites were in the center of the tissue cysts and were surrounded by fibrillar material that appeared to originate from the zoite surface. Tubulelike structures were present in the granular tissue cyst wall and in the fibrillar material that surrounded the zoite. Zoites contained a crystalloid body. New findings in the present study consisted of identifying what are probably early tissue cysts that lack a developed tissue cyst wall, demonstrating that more than 1 tissue cyst can occupy a host cell, describing the distribution of micronemes and the shedding of zoite membranes, and identifying tubular structures in the inner tissue cyst wall and inner compartment.
Vaccination of mice with Neospora caninum: Response to oral challenge with Toxoplasma gondii oocysts
Lindsay, David S.; Lenz, S. D.; Dykstra, C. C.; Blagburn, B. L.; Dubey, Jitender P. (American Society of Parasitology, 1998-04)
Neospora caninum is a protozoan parasite that can cause severe disease in mammals. Two experiments were conducted to examine the effects of subcutaneous (s.c.) vaccination with Hank's balanced salt solution (HBSS), 1 x 10(5) N. caninum NC-1 strain tachyzoites or 1 x 10(5) Toxoplasma gondii TS-4 strain tachyzoites on challenge oral infections in mice with sporulated VEG strain T. gondii oocysts (1 x 10(3) oocysts exp. 1 and 5 x 10(3) oocysts exp. 2). An additional study, experiment 3, evaluated s.c. challenge with 2.5 x 10(3) tachyzoites of the highly virulent RH strain of T. gondii after vaccination with HBSS, NC-1 tachyzoites, or TS-4 tachyzoites. Mice vaccinated with NC-1 strain tachyzoites survived significantly (P < 0.05) longer than mice given HBSS in experiment 1, but not in experiments 2 and 3. Mice vaccinated with TS-4 strain tachyzoites survived significantly longer than HBSS-vaccinated mice in experiments 1, 2, and 3 and significantly longer than mice vaccinated with the NC-1 strain in experiments 2 and 3. Toxoplasma gondii tissue cyst numbers were significantly lower for mice vaccinated with TS-4 strain tachyzoites than mice vaccinated with HBSS or the NC-1 strain tachyzoites in experiment 1. No difference was observed in tissue cyst numbers in mice vaccinated with HBSS or NC-1 strain tachyzoites in experiment 1. No HBSS-vaccinated mice survived experiment 2, and the numbers of T. gondii tissue cysts were significantly lower for mice vaccinated with the TS-4 strain tachyzoites compared to NC-1 strain tachyzoites. No HBSS- or NC-1-vaccinated mice survived RH strain challenge in experiment 3. Results of these experiments indicate that infection with N. caninum provides some protection against fatal oral infection with T. gondii oocysts of a moderately pathogenic strain but not tachyzoites of a highly pathogenic strain. The protection provided bq N. caninum is much less than that provided by previous exposure to T. gondii, and the numbers of tissue cysts in the brains of mice are not significantly (P > 00.5) lowered.
Complete development of the porcine coccidium Isospora suis Biester, 1934 in cell cultures
Lindsay, David S.; Quick, D. P.; Steger, A. M.; Toivio-Kinnucan, M. A.; Blagburn, B. L. (American Society of Parasitology, 1998-06)
Development from inoculated sporozoites to unsporulated oocysts of Isospora suis Biester, 1934 is described in a swine testicular (ST) cell line. Sporozoites penetrated ST cells within 1 hr postinoculation (PI). Development was initially by endodyogeny to produce binucleate type I meronts and type I merozoites. Division by endodyogeny continued during the 13-day observation period and type I merozoites were the developmental stages most abundant at observation periods >3 days PI. Mutinucleate type II meronts and type II merozoites were first observed 7 days PI. Gamonts and oocysts were present 12 days PI. Oocysts did not sporulate in vitro. The ultrastructural features of stages were similar to those that occur in the pig host.
Characterization of temperature-sensitive strains of Neospora caninum in mice
Lindsay, David S.; Lenz, S. D.; Blagburn, B. L.; Brake, D. A. (American Society of Parasitology, 1999-02)
Temperature-sensitive (ts) strains of the Neospora caninum tachyzoites were selected by chemical mutagenesis and selection for growth at 32 C. Three ts strains and the parental, N. caninum wild-type strain, NC-1, were examined in the present study for their ability to cause disease in inbred BALB/c mice, outbred ICR mice, and chemically immunosuppressed ICR mice. In BALB/c mice, all 3 strains failed to induce clinical disease, whereas infection with the NC-1 strain caused central nervous system disease and death in some mice. No disease was observed in ICR mice inoculated with the 3 ts strains or the NC-I strain. All immunosuppressed ICR mice inoculated with the NC-1 strain died, whereas no immunosuppressed mice inoculated with the NCts-4 strain and only 1 of 5 mice inoculated with the NCts-8 and NCts-12 strains died. The NCts-4 and NCts-12 strains reverted to a wild-type phenotype when grown at 37 C. Vaccination of BALB/c mice with live, but not frozen NCts-8 strain tachyzoites induced significant (P < 0.05) protection following NC-1 strain challenge.
Development of Sarcocystis falcatula in cell cultures demonstrates that it is different from Sarcocystis neurona
Lindsay, David S.; Dubey, Jitender P.; Horton, K. M.; Bowman, D. D. (Cambridge University Press, 1999-03)
The development of Sarcocystis falcatula merozoites in bovine turbinate (BT) cell cultures is described and compared with development of Sarcocystis neurona merozoites. Merozoites of S. falcatula entered BT cell cultures and increased in size until 3 days post-inoculation when the nucleus of some merozoites developed lobes. Developing schizonts present at 4 days contained a lobed nucleus or appeared multinucleate. A single mature schizont was observed 4 days p.i. Schizonts were numerous 5 and 6 days p.i. Merozoites were produced from blastophores on the schizont. S. neurona merozoites developed to mature schizonts by 3 days p.i. in BT cells and a residual body was often present. Transmission electron microscopy revealed that S. falcatula merozoites possessed more micronemes than did S. neurona merozoites. Our study demonstrates that S. falcatula and S. neurona are not the same parasite.
Descriptions of two new species of coccidia (Protozoa : Eimeriidae) and redescriptions of Eimeria ivensae and Eimeria odocoilei from captive white-tailed deer, Odocoileus virginianus
Lindsay, David S.; Upton, S. J.; Hildreth, M. B. (American Society of Parasitology, 1999-12)
Two new species of Eimeria were observed in the feces of captive white-tailed deer fawns, Odocoileus virginianus, from Alabama. The first new species was easily recognized because of its small size. Sporulated oocysts are spherical, average 10.2 by 10.0 mu m, and lack a micropyle and oocyst residuum. Oocysts contain a polar granule and elongare-ellipsoidal sporocysts that measure 6.7 by 3.1 mu m. A Stieda body is present on the sporocysts. Oocysts were observed in the feces, and gamonts and oocysts were observed in the jejunum of a month-old fawn from Minnesota that died from enteritis due to this species. Oocysts of this small species were present in 5 of the 6 white-tailed deer fawns examined. Oocysts of a second new species are ellipsoidal and average 29.5 by 24.6 mu m. The oocyst encloses an oocyst residuum, polar granule, and elongate-ellipsoidal sporocysts that average 16.0 by 9.0 mu m. A Stieda body and substieda body are present an the sporocysts. Oocysts of the second new species were present in 4 of the 6 white-tailed deer fawns examined. Oocysts of E. ivensae are ovoid or flask-like and average 32.0 by 20.8 mu m The oocyst wall is rough, contains a micropyle, and encloses elongate-ellipsoidal sporocysts that average 16.5 by 7.8 8.8 mu m A Stieda body is present on the sporocysts. Oocysts of E. ivensae were present in 4 of the 6 white-tailed deer fawns. Oocysts of E. odocoilei are spherical or slightly subspherical and measure 24.7 by 21.5 mu m. They enclose ovoid sporocysts that average 12.7 by 8.8 mu m. A Stieda and substieda body are present on the sporocyst. Oocysts of E. odocoilei were present in 4 of the 6 white-tailed deer fawns.
Determination of the activity of diclazuril against Sarcocystis neurona and Sarcocystis falcatula in cell cultures
Lindsay, David S.; Dubey, Jitender P. (American Society of Parasitology, 2000-02)
Diclazuril is a benzeneacetonitril anticoccidial that has excellent activity against the extraintestinal stages of Toxoplasma gondii and Neospora caninum. It also is highly active against intestinal coccidia of poultry. The present study examined the efficacy of diclazuril in inhibiting merozoite production of Sarcocystis neurona and Sarcocystis falcatula in bovine turbinate cell cultures. Diclazuril inhibited merozoite production by more than 80% in cultures of S. neurona or S.falcatula treated with 0.1 ng/ml diclazuril and greater than 95% inhibition of merozoite production was observed when infected cultures were treated with 1.0 ng/ml diclazuril. Diclazuril may have promise as a therapeutic agent in the treatment of S. neurona-induced equine protozoal myeloencephalitis in horses and S. falcatula infections in birds.
Sarcocystis campestris from naturally infected 13-lined ground squirrels, Spermophilus tridecemlineatus tridecemlineatus, from Nebraska
Lindsay, David S.; McKown, R. D.; Dubey, Jitender P. (American Society of Parasitology, 2000-10)
Grossly visible sarcocysts were seen in the skeletal muscles of 1 of 12 13-lined ground squirrels, Spermophilus tridecemlineatus tridecemlineatus, collected in Nebraska. The tissue cyst wall was up to 5.0 mum thick and contained spikelike projections. Transmission electron microscopy of tissue cysts revealed they were similar to Sarcocystis campestris Cawthorn, Wobeser, and Gajadhar, 1983, previously known only from experimental infections in Richardson's ground squirrel Spermophilus richardsonii. Prominent electron-dense bodies were observed lining the microfilaments present in the spikelike projections of the sarcocyst wall. This is the first report of S. campestris in a natural intermediate host and the first report of this parasite outside of Saskatoon, Canada.
The South American opossum, Didelphis marsupialis, from Brazil as another definitive host for Sarcocystis speeri Dubey and Lindsay, 1999
Dubey, Jitender P.; Kerber, C. E.; Lindsay, David S.; Kasai, N.; Pena, H. F. J. (Cambridge University Press, 2000-12)
The North American opossum, Didelphis virginiana, is a definitive host for at least 3 species of Sarcocystis: S. falcatula Stiles 1983, S. neurona Dubey, Davis, Speer, Bowman, de Lahunta, Granstrom, Topper, Hamir, Cummings, Suter 1991, and S. speeri Dubey and Lindsay 1999. In order to identify species of Sarcocystis in the South American opossum, D. marsupialis, Sarcocystis sporocysts from the intestines of a naturally infected opossum (D. marsupialis) from Brazil were fed to 4 gamma-interferon knockout (KO) mice, a nude mouse, and 2 budgerigars (Melopsittacus undulatus). All 4 KO mice became ill and 1 died 42 days post-feeding (p.f.) of sporocysts, 1 was killed 44 days p.f. because of neurological signs, and 2 were killed 52 and 53 days p.f, because of abnormal gaits. Numerous sarcocysts were seen in the skeletal muscles of all 4 KO mice and they were structurally identical to S. speeri seen in KO mice fed sporocysts from D. virginiana from the United States and D. albiventris from Argentina. The nude mouse was killed 41 days p.f. because it appeared weak; schizonts were seen in sections of its liver and sarcocysts were seen in sections of skeletal muscles. Sarcocystis speeri was cultured in bovine turbinate cells inoculated with liver homogenate from this mouse. Sarcocystis neurona was not demonstrable in tissues of mice. The tale budgerigars remained asymptomatic and S. falcatula was not found in their tissues when they were killed 29 days p.i. This is the first report of S. speeri from D. marsupialis.
Oocyst excretion in dogs fed mouse brains containing tissue cysts of a cloned line of Neospora caninum
Lindsay, David S.; Ritter, D. M.; Brake, D. (American Society of Parasitology, 2001-08)
Neospora caninum is an apicomplexan parasite that causes neonatal neuromuscular disease in dogs and abortions in cattle. Bovine neosporosis is a major production problem worldwide. The parasite is transmitted to cattle via oocysts excreted by dogs or by transplacental transmission. Dogs are the only proven definitive host for N. caninum. One of 3 dogs fed mouse brains containing tissue cysts of a wild-type N. caninum strain CK0160SC3B (CKO) excreted oocysts in its feces. Two of 3 dogs fed mouse brains containing tissue cysts from a cloned line of the CKO strain excreted N. caninum oocysts in their feces. The results indicate that a single N. caninum tachyzoite contains all the genetic information needed to produce the asexual and sexual cycles in the canine intestine.
The gamma interferon knockout mouse model for Sarcocystis neurona: Comparison of infectivity of sporocysts and merozoites and routes of inoculation
Dubey, Jitender P.; Lindsay, David S.; Kwok, O. C. H.; Shen, S. K. (American Society of Parasitology, 2001-10)
The dose-related infectivity of Sarcocystis neurona sporocysts and merozoites. of 2 recent isolates of S. neurona was compared in gamma interferon knockout (KO) mice. Tenfold dilutions of sporocysts or merozoites were bioassayed in mice, cell culture, or both. All 8 mice, fed 1,000 sporocysts, developed neurological signs with demonstrable S. neurona in their tissues. Of 24 mice fed low numbers of sporocysts. (100, 10, 1), 18 became ill by 4 wk postinoculation, and S. neurona was demonstrated in their brains; antibodies (S. neurona agglutination test) to S. neurona and S. neurona parasites were not found in tissues of the 6 mice that were fed sporocysts and survived for >39 days. One thousand culture-derived merozoites of these 2 isolates were pathogenic to all 8 mice inoculated subcutaneously (s.c.). Of the 24 mice inoculated s.c. with merozoites. numbering 100, 10, or 1, only 3 mice had demonstrable S. neurona infection; antibodies to S. neurona were not found in the 21 mice that had no demonstrable organisms. As few as 10 merozoites. were infective for cell cultures. These results demonstrate that at least 1,000 merozoites are needed to cause disease in KO mice. Sarcocystis neurona sporocysts were infective to mice by the s.c. route.
Prevalence of agglutinating antibodies to Neospora caninum in raccoons, Procyon lotor
Lindsay, David S.; Spencer, J.; Rupprecht, C.; Blagburn, B. L. (American Society of Parasitology, 2001-10)
Neospora caninum is an apicomplexan parasite that causes neonatal neuromuscular disease in dogs and abortions in cattle. Dogs are the only proven definitive host. Little is known about the prevalence of antibodies to this parasite in wildlife. Sera from 99 raccoons (Procyon lotor) were examined for agglutinating antibodies to N. caninum using the modified agglutination test employing formalin-fixed tachyzoites as antigen. Raccoons originated in Florida (n=24, collected in 1996), New Jersey (n=25, collected in 1993), Pennsylvania (n=25, collected in 1999), and Massachusetts (n=25, collected in 1993 and 1994). Ten (10%) had antibodies to AT. caninum; 9 had titers of 1:50, and 1 (1%) had a titer of 1:100. The present study indicates that raccoons have minimal exposure to N. caninum. The sera were also tested for agglutinating antibodies to Toxoplasma gondii and 46 (46%) were positive; 16 had titers of 1:50, 8 had titers of 1:100, and 22 had titers of greater than or equal to1:500.
Use of molecular probes to assess geographic distribution of Pfiesteria species
Rublee, Parke A.; Kempton, Jason W.; Schaefer, Eric F.; Allen, Irving C.; Harris, Janera; Oldach, David W.; Bowers, Holly; Tengs, Torstein; Burkholder, JoAnn M.; Glasgow, H. B. (US Department of Health and Human Sciences, Public Health Science, 2001-10-01)
We have developed multiple polymerase chain reaction (PCR)-based methods for the detection of Pfiesteria sp. in cultures and environmental samples. More than 2,100 water and sediment samples from estuarine sites of the U.S. Atlantic and gulf coasts were assayed for the presence of Pfiesteria piscicida Steidinger & Burkholder and Pfiesteria shumwayae Glasgow & Burkholder by PCR probing of extracted DNA. Positive results were found in about 3% of samples derived from routine monitoring of coastal waters and about 8% of sediments. The geographic range of both species was the same, ranging from New York to Texas. Pfiesteria spp. are likely common and generally benign inhabitants of coastal areas, but their presence maintains a potential for fish and human health problems. Key words: molecular probes, PCR, Pfiesteria, toxic dinoflagellates.
Sarcocystis neurona infections in sea otter (Enhydra lutris): Evidence for natural infections with sarcocysts and transmission of infection to opossums (Didelphis virginiana)
Dubey, Jitender P.; Rosypal, A. C.; Rosenthal, B. M.; Thomas, N. J.; Lindsay, David S.; Stanek, J. F.; Reed, S. M.; Saville, W. J. A. (American Society of Parasitology, 2001-12)
Although Sarcocystis neurona has been identified in an array of terrestrial vertebrates, recent recognition of its capacity to infect marine mammals was unexpected. Here, sarcocysts from 2 naturally infected sea otters (Enhydra lutris) were characterized biologically, ultrastructurally, and genetically. DNA was extracted from frozen muscle of the first of these sea otters and was characterized as S. neurona by polymerase chain reation (PCR) amplification followed by restriction fragment length polymorphism analysis and sequencing. Sarcocysts from sea otter no. 1 were up to 350 mum long, and the villar protrusions on the sarcocyst wall were up to 1.3 mum long and up to 0.25 mum wide. The villar protrusions were tapered towards the villar tip. Ultrastructurally, sarcocysts were similar to S. neurona sarcocysts from the muscles of cats experimentally infected with S. neurona sporocysts, Skeletal muscles from a second sea otter failed to support PCR amplification of markers considered diagnostic for S. neurona but did induce the shedding of sporocysts when fed to a laboratory-raised opossum (Didelphis virginiana). Such sporocysts were subsequently fed to knockout mice for the interferon-gamma gene, resulting in infections with an agent identified as S. neurona on the basis of immunohistochemistry, serum antibodies, and diagnostic sequence detection. Thus, sea otters exposed to S. neurona may support the development of mature sarcocysts that are infectious to competent definitive hosts.
Isolates of Sarcocystis falcatula-like organisms from South American opossums Didelphis marsupialis and Didelphis albiventris from Sao Paulo, Brazil
Dubey, Jitender P.; Lindsay, David S.; Rosenthal, B. M.; Kerber, C. E.; Kasai, N.; Pena, H. F. J.; Kwok, O. C. H.; Shen, S. K.; Gennari, S. M. (American Society of Parasitology, 2001-12)
Isolates of Sarcocystis falcatula-like organisms from South American opossums were characterized based on biological and morphological criteria. Sporocysts from intestinal scrapings of 1 Didelphis marsupialis and 8 Didelphis albiventris from Sao Paulo, Brazil. were fed to captive budgerigars (Melopsittacus undulants). Budgerigars fed sporocysts from all 9 isolates became ill and S. falcatula-like schizonts were identified in sections of their lungs by immunohistochemical staining. Sarcocystis falcatula-like organisms were cultured from lungs of budgerigars fed sporocysts from D. marsupialis and from lungs of budgerigars fed sporocysts from 3 of 8 D. albiventris. The 33/54 locus amplified by polymerase chain reaction from culture-derived merozoites contained both a HinfI endonuclease recognition site previously suggested to diagnose S. falcatula and a DraI site thought to diagnosed S. neurona. Development of the isolate from D. marsupialis was studied in cell cultured its schizonts divided by endopolygeny, leaving a residual body. Morphological and genetic variation differentiated this Sarcocystis isolate originating in D. marsupialis from the Cornell 1 isolate of S. falcatula. This is the first report of a S. falcatula infection in the South American opossum. D. marsupialis.
Prevalence of antibodies to Neospora caninum in white-tailed deer, Odocoileus virginianus, from the southeastern United States
Lindsay, David S.; Little, Susan E.; Davidson, W. R. (American Society of Parasitology, 2002-04)
Serum samples from 305 white-tailed deer (Odocoileus virginianus) from 14 states in the southeastern United States were examined for antibodies to Neospora caninum using a direct agglutination test. Positive a,agglutination titers were found in 145 (48%) of the white-tailed deer examined: 21 (7%) had titers of 1:25, 92 (30%) had titers of 1:50, and 32 (10%) had titers of greater than or equal to1:500. These findings that antibodies to N. caninum are common in white-tailed deer support the concept that a sylvatic cycle might exist for this economically important parasite of domestic cattle.
Prevalence of agglutinating antibodies to Sarcocystis neurona in skunks (Mephitis mephitis), raccoons (Procyon lotor), and opossums (Didelphis virginiana) from Connecticut
Mitchell, S. M.; Richardson, D. J.; Cheadle, M. A.; Zajac, Anne M.; Lindsay, David S. (American Society of Parasitology, 2002-10)
Equine protozoal myeloencephalitis is the most important protozoan disc a 6 of horses in North America and is usually caused by Sarcocystis neuronal Natural cases of encephalitis caused by S. neurona have been reported in skunks (Mephitis mephitis) and raccoons (Procyon lotor). Opossums (Didelphis spp.) are the only known definitive host. Sera from 24 striped skunks, 12 raccoons, and 7 opossums (D. virginiana) from Connecticut were., examined for agglutinating antibodies to S. neurona using the S. neurona agglutination test (SAT) employing formalin-fixed merozoites as antigen. The SAT was validated for skunk sera using pre- and postinfection serum samples from 2 experimentally infected skunks. Of the 24 (46%) skunks 11 were positive, and all 12 raccoons were positive for S. neurona antibodies. None of the 7 opossums was positive for antibodies to S. neurona. These results suggest that exposure to sporocysts of S. neurona by intermediate hosts is high in Connecticut. The absence of antibodies in opossums collected from the same areas is most likely because of the absence of systemic infection in the definitive host.
Toxoplasmosis in three species of native and introduced Hawaiian birds
Work, T. M.; Massey, J. G.; Lindsay, David S.; Dubey, Jitender P. (American Society of Parasitology, 2002-10)
Toxoplasma gondii was found in endemic Hawaiian birds, including 2 nene geese (Nesochen sandvicensis), 1 red-footed booby (Sula sula), and an introduced bird, the Erckels francolin (Francolinus erckelii). All 4 birds died of disseminated toxoplasmosis; the parasite was found in sections of many organs, and the diagnosis was confirmed by immunohistochemical staining with anti-T. gondii-specific polyclonal antibodies. This is the first report of toxoplasmosis in these species of birds.
Comparable growth of Tritrichomonas mobilensis in two commercially available culture media
Boggild, A. K.; Sundermann, C. A.; Estridge, B. H.; Lindsay, David S. (American Society of Parasitology, 2002-10)
The investigation reported herein was undertaken to determine which medium is more practical for the axenic laboratory culture of trichomonads. The growth of Tritrichomonas mobilensis was monitored in 2 different types of commercially available growth media. Although Roswell Park Memorial Institute (RPMI) 1640 medium is typically used as a mammalian cell culture medium, it was found to support the growth of trichomonads as well as the American Type Culture Collection (ATCC) medium 745 under similar conditions. Environmental variables, such as temperature and pH, known to affect the success of trichomonad cultures were controlled. The mean generation times (MGTs) of T. mobilensis in the log phase of growth were 5.1 and 4.9 hr for RPMI 1640 and ATCC medium 745, respectively. A stationary phase of zero growth was reached more quickly in the ATCC medium 745 cultures, and in both media a phase of rapid attrition followed this period of static growth. In assessing the practicality of the media, total cell amplification, as well as factors such as cost, case of preparation, and storage capacity, were considered.
Prevalence of antibodies to Neospora caninum and Sarcocystis neurona in sera of domestic cats from Brazil
Dubey, Jitender P.; Lindsay, David S.; Romand, D. H. S.; Thulliez, P.; Kwok, O. C. H.; Silva, J. C. R.; Oliveira-Camargo, M. C.; Gennari, S. M. (American Society of Parasitology, 2002-12)
Antibodies to Neospora caninum and Sarcocystis neurona were determined in serum samples of 502 domestic cats from Brazil using direct agglutination tests with the respective antigens. Antibodies to S. neurona were not found in 1:50 dilution of any serum in the S. neurona agglutination test, suggesting that domestic cats from Sao Paulo city were not exposed to S. neurona sporocysts from opossums. Antibodies to N. caninum were found in 60 (11.9%) of 502 cats with titers of 1:40 in 36 cats, 1:80 in 18 cats, 1:160 in 5 cats, and 1:800 in 1 cat using the Neospora agglutination test (NAT). Antibodies to N. caninum were confirmed by Western blotting in the sera of 10 cats with NAT titers of 1:80 to 1:800; this finding suggests that at least 10 cats had N. caninum-specific antibodies confirmed by 2 tests. This is the first documentation of natural exposure of cats to N. caninum.

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