Serologic cross-reactivity between Sarcocystis neurona and Sarcocystis falcatula-like in experimentally infected Mongolian gerbils.

Sarcocystis neurona is the major cause of the equine protozoal myeloencephalitis (EPM) in the Americas and has opossums of the genus Didelphis as definitive hosts. Most isolates of Sarcocystis sp. shed by opossums in Brazil differ genetically from the known species of Sarcocystis. These Brazilian isolates behave similarly as Sarcocystis falcatula, which causes sarcocystosis in birds, and for this reason, have been classified as Sarcocystis falcatula-like. Genes coding for the immunodominant surface antigens SAG2, SAG3 and SAG4 of S. falcatula-like are similar to those from S. neurona. It is unknown the Sarcocystis species that causes EPM in Brazil, as S. neurona has never been genetically confirmed in Brazilian horses. All cases associated with EPM in Brazil were diagnosed by immunological tests, which are not specific for S. neurona infection. It is possible that S. falcatula-like may infect horses in Brazil. The aims of the current study were to test the susceptibility of gerbils (Meriones unguiculatus) to experimental infections with S. neurona and S. falcatula-like, and to investigate potential serologic cross-reactivity to these parasites by immunofluorescent antibody test (IFAT) and Western blot (WB). A total of 27 gerbils, distributed in five experimental groups (G1-G5), were employed in this work (G1: 4 negative controls; G2: 6 infected with S. neurona merozoites, G3: 6 infected with S. falcatula-like merozoites; G4 and G5 (5 and 6, respectively, infected with different doses of sporocysts). None of the 17 animals that seroconverted for the parasites in IFAT presented any visualized organism or Sarcocystis DNA in the examined tissues. No serologic cross-reactivity was observed using IFAT. However, sera from animals infected with S. falcatula-like and S. neurona presented the same pattern of antigenic recognition when S. neurona merozoites were used as antigen in WB, including reactivity to proteins of 30 and 16 kDa, regarded as specific markers for S. neurona-infected animals. Gerbils did not sustain infection by these parasites, although produced antibodies after inoculation. These results are suggestive that other animal species that are exposed to S. falcatula-like, including horses, may present serologic cross-reactivity to S. neurona in WB. IFAT was demonstrated to be more specific that WB for the detection of antibodies to S. falcatula-like and S. neurona in the experimental conditions of this study.

Prevalência de anticorpos anti-neospora caninum (Apicomplexa: Sarcocystidae) em bovinos leiteiros de propriedades rurais em três microrregiões no estado do Maranhão / Prevalence of anti-neospora caninum (Apicomplexa: Sarcocystidae) antibodies in dairy cattle in rural properties of three microrregions of Maranhão, Brazil

Objetivou-se, no presente estudo, pesquisar a prevalência de anticorpos anti-Neospora caninum em 812 amostras de soros sangüíneos de bovinos leiteiros procedentes de propriedades rurais de sete municípios das microrregiões de Itapecuru-Mirim, Médio Mearim e Presidente Dutra, estado do Maranhão, Brasil. Para o cálculo do tamanho da amostra, considerou-se um soroprevalência de 34,7 por cento para N. caninum, com erro máximo de 9,5 por cento e intervalo de confiança de 95 por cento. Para a detecção da presença de anticorpos da classe IgG, utilizou-se a técnica de Imunofluorescência Indireta (IFI), com ponto de corte 1:200, usando como antígeno, taquizoítos da cepa NC-1, mantida em cultura celular no Laboratório de Diagnóstico das Parasitoses dos Animais da Escola de Medicina Veterinária da UFBA. Do total de amostras analisadas, encontrou-se uma prevalência de 50,74 por cento. Os títulos variaram de 1:200 a 1:6400, assim distribuídos: 108 (26,21 por cento) amostras de soro apresentaram título de 1:200; 132 (32,04 por cento) 1:400; 94 (22,81 por cento) 1:800; 46 (11,16 por cento) 1:1600; 23 (5,58 por cento) 1:3200 e nove (2,18 por cento) com títulos de 1:6400. Dentre as microrregiões, a Itapecuru-Mirim apresentou o menor percentual de animais soropositivos (20,69 por cento) e Presidente Dutra o maior (47,66 por cento). Com relação à variável sexo, observou-se maior prevalência de sororreagentes nas fêmeas (46,80 por cento) do que nos machos (52,46 por cento). Não se verificou diferença significativa (P>0,05) para as variáveis microrregiões, sexo e idade. Conclui-se que os bovinos leiteiros das regiões estudadas estão expostos à infecção por N. caninum.

The objective in the present study was to research the prevalence of anti-Neospora caninum in 812 samples of blood serum of dairy cattle from farms of seven municipalities of microrregions of Itapecuru-Mirim, Middle Mearim and President Dutra, state of Maranhão, Brazil. For the calculation of sample size, it was considered a seroprevalence of 34.7 percent for N. caninum, with a maximum error of 9.5 percent and a confidence interval of 95 percent. To detect antibodies, it was used the technique of Indirect Immunofluorescence (IFI), with the cut-off of 1:200, using as antigen, tachyzoites strain NC-1, maintained in cell culture in the Laboratory of Diagnosis of Parasitism of the Animals, School of Veterinary Medicine of the Federal University of Bahia, Brazil. Of the total samples, it was obtained a prevalence of 50.74 percent. The titles ranged from 1:200 to 1:6400, distributed as follows: 108 (26.21 percent) serum samples showed title of 1:200; 132 (32.04 percent) 1:400; 94 (22.81 percent) 1:800; 46 (11.16 percent) of 1:1600; 23 (5.58 percent) of 1:3200 and nine (2.18 percent) with titers of 1:6400. Among the microrregiões the Itapecuru-Mirim showed the lowest percentage of animals seropositive (20.69 percent) and President Dutra the largest (47.66 percent). It was observed higher prevalence of seropositives in females (46.80 percent) than in males (52.46 percent). There was no significant difference (P> 0.05) for the microrregions variables, sex and age. Concluded that the dairy cattle of the regions studied are exposed to infection by N. caninum.

Toxoplasma gondii and Neospora caninum in sparrows (Passer domesticus) in the Northeast of Brazil.

Toxoplasma gondii is a cosmopolitan protozoan parasite of warm-blooded animals that causes high rates of infection in mammals and birds. Sparrows (Passer domesticus) are synantropic birds which are distributed worldwide. They serve as intermediate hosts for the parasite but are quite resistant to toxoplasmosis. The aims of this study were to determine the frequency of T. gondii infection in sparrows using serologic and molecular tests, and to investigate related parasites, such as Neospora caninum and Hammondia sp., using a nested PCR for Toxoplasmatinae DNA followed by sequence analysis of the PCR amplicons. A total of 293 sparrows were trapped at the states of Bahia and Pernambuco, Brazil. Tissues of 40 animals were available for molecular tests. Antibodies to T. gondii were found in 1.02% (3/293) of animals using a hemagglutination test, with titers ranging from 1:32 to 1:128. Toxoplasmatinae DNA was detected in 10/40 (25%) sparrows; after nucleotide sequencing, T. gondii was confirmed in 7/40 (17.5%) birds and N. caninum in 3/40 (7.5%) animals. Sparrows from Brazil were confirmed as intermediate hosts of T. gondii, that reinforces the potential importance of these birds on the transmission of the parasite to cats and other animals that may predate sparrows. In addition, N. caninum was detected for the first time in sparrows. To the authors' knowledge, this is the first wild synantropic bird species identified as intermediate host of N. caninum. These findings seem to have a great epidemiologic impact because of the cosmopolitan distribution of sparrows and due to their increasing population in urban and rural areas.

Detection of Hammondia heydorni and related coccidia (Neospora caninum and Toxoplasma gondii) in goats slaughtered in Bahia, Brazil.

Hammondia heydorni is a coccidian parasite with an obligatory two host life cycle, with dogs and foxes as definitive hosts, and a number of intermediate hosts, including goats. While infection by this parasite seems to be unassociated with any clinical signs, infection by the closely related parasites Neospora caninum and Toxoplasma gondii can result in abortion, stillbirths and low yielding in caprine herds. The aim of this work was to investigate the frequency of goats infected with H. heydorni using a nested PCR, specific to Toxoplasmatinae internal transcribed spacer 1 (ITS1) of the rDNA, followed by sequencing of the purified PCR fragments. The same molecular techniques were used to determine the frequencies of N. caninum and T. gondii-infected animals. A total frequency of 13.72% (14/102) was obtained for Toxoplasmatinae DNA in goat tissues. After sequencing the PCR products from all positive tissues, a frequency of 3.92% (4/102), 1.96% (2/102) and 7.84% (8/102) were obtained for H. heydorni, N. caninum and T. gondii, respectively. All sequences shared 98-100% identity with sequences from other strains of these coccidia present in GenBank. To the authors' knowledge, this is the first report of H. heydorni DNA in tissues from naturally infected intermediate hosts.