Toxoplasmosis is one of the leading parasitic diseases worldwide. Some data suggest that chronic acquired toxoplasmosis could be linked to behavioral alterations in humans. The parasite infects neurons, forming immunologically silent cysts. Cerebral microcirculation homeostasis is determinant to brain functions, and pathologic states can alter capillarity or blood perfusion, leading to neurodegeneration and cognitive deficits. Albino mice were infected with Toxoplasma gondii (ME49 strain) and analyzed after 10, 40, and 180 days. Infected mice presented decreased cerebral blood flow at 10 and 40 days post infection (dpi), which were restored at 180 dpi, as shown by laser speckle contrast imaging. Intravital microscopy demonstrated that infection led to significant capillary rarefaction, accompanied by neuroinflammation, with microglial activation and increased numbers of rolling and adherent leukocytes to the wall of cerebral capillaries. Acetylcholine-induced vasodilation was altered at all time points, and blood brain barrier permeability was evident in infected animals at 40 dpi. Infection reduced angiogenesis, with a decreased number of isolectin B4-stained blood vessels and a decrease in length and branching of laminin-stained capillaries. Sulfadiazine reduced parasite load and partially repaired microvascular damages. We conclude that T. gondii latent infection causes a harmful insult in the brain, promoting neuroinflammation and microcirculatory dysfunction in the brain, with decreased angiogenesis and can contribute to a neurodegenerative process.

Toxoplasma gondii is a zoonotic agent of great importance in veterinary and public health. The aim of this study was to identify T. gondii by IHC (immunohistochemistry) in different sheep tissues and to determine if an association exists between the results obtained by this method and those obtained by the Modified Agglutination Test (MAT). Tissue specimens of twenty-six sheep seroreactive for T. gondii were selected for histopathological evaluation. The presence of T. gondii was investigated in brain, liver and heart samples by IHC and a possible anti-T. gondii antibody cross reactions with other parasites. McNemar's, Chi-square and Fisher's Exact Tests were applied for the statistical analysis of the results. The analysed tissues showed at least one of the following histopathological changes: mild-to-moderate congestion, focal polymorphonuclear inflammatory infiltrate and multifocal or focal mononuclear inflammatory infiltrate. Sarcocystis spp. were identified in the histological sections from both the heart and diaphragm tissues of 88.5% (23/26) of the animals. A total of 46.2% (12/26) of the T. gondii seroreactive sheep was also positive for T. gondii by IHC in at least one organ (brain, liver or heart). The liver IHC-positivity for T. gondii was statistically equivalent to the global individual IHC-positivity, according to McNemar's test. In addition, IHC allowed the detection of T. gondii in infected animals regardless of the titration observed in the MAT. The statistical difference observed between the three organs when comparing the low titration group, suggested that the heart might be the most suitable organ to detect T. gondii infection by IHC. The IHC results in this study revealed that almost half of MAT positive animals could serve as potential sources of infection for humans because bradyzoites were identified in different tissues, regardless of the MAT titration.

Five Toxoplasma gondii isolates (TgPgBr1–5) were isolated from hearts and brains of pigs freshly purchased at the market of Campos dos Goytacazes, Northern Rio de Janeiro State, Brazil. Four of the five isolates were highly pathogenic in mice. Four genotypes were identified. Multi-locus PCR-DNA sequencing showed that each strain possessed a unique combination of archetypal and novel alleles not previously described in South America. The data suggest that different strains circulate in pigs destined for human consumption from those previously isolated from cats and chickens in Brazil. Further, multi-locus PCR-RFLP analyses failed to accurately genotype the Brazilian isolates due to the high presence of atypical alleles. This is the first report of multi-locus DNA sequencing of T. gondii isolates in pigs from Brazil.

Feces were collected from 125 sheep between January and December 2007, on ten farms in the State of Rio de Janeiro, Brazil, and examined for the presence of Cryptosporidium. Ninety samples were collected from lambs 2 to 6 months of age, and 35 were from sheep over 12 months of age. All samples were subjected to molecular analysis by polymerase chain reaction (nested PCR) in two steps of the SSU rRNA. Two samples (1.6%) from the lambs were positive, and after sequencing were identified as Cryptosporidium ubiquitum. This species has been reported worldwide and it is considered a zoonotic pathogen since it has been found and in several animal species and humans. However, because of the low frequency of C. ubiquitum found, the risk for public health in this region may not be high.

Toxoplasma gondii causes toxoplasmosis, a worldwide disease. Experimentation with pigs is necessary for the development of new therapeutic approaches to human diseases. BR-1 mini pigs were intramuscularly infected with T. gondii with tachyzoites (RH strain) or orally infected with cysts (ME-49 strain). Haematology and serum biochemistry were analysed and buffy coat cells were inoculated in mice to determine tachyzoite circulation. No alterations were observed in erythrocyte and platelet values; however, band neutrophils increased seven days after infection with ME-49. Serology of the mice inoculated with pig blood leucocytes revealed circulating ME-49 or RH strain tachyzoites in the pigs' peripheral blood at two and seven or nine days post-infection. The tachyzoites were also directly observed in blood smears from the infected pigs outside and inside leucocytes for longer periods. Alanine-aminotransferase was high at days 21 and 32 in the RH infected pigs. After 90 days, the pigs were euthanised and their tissue samples were processed and inoculated into mice. The mice serology revealed the presence of parasites in the hearts, ileums and mesenteric lymph nodes of the pigs. Additionally, cysts in the mice were only observed after pig heart tissue inoculation. The infected pigs presented similar human outcomes with relatively low pathogenicity and the BR-1 mini pig model infected with ME-49 is suitable to monitor experimental toxoplasmosis.

Toxoplasmosis is an important cause of abortion in sheep and a zoonotic risk to humans, leading to significant hazards to health and to economic losses. This study examined the seroprevalence and associated risk factors for infection with Toxoplasma gondii in 379 sheep from 12 flocks in Rio de Janeiro state, Brazil. Using the modified agglutination test (MAT), 202 (53.3 %) of 379 were seropositive with titers of 1:25 in 65, 1:50 in 40, 1:100 in 23, 1:200 in 11, 1:400 in 36, 1:800 in 7, 1:1,600 in 1, and 1:3,200 or higher in 19 sheep. The most significant factors associated with T. gondii seropositivity in sheep were age, gender, and veterinary care. Finding of T. gondii antibodies in 97 of the 202 sheep in titers of 1:100 or higher is indicative of persistently infected animals. This high level of seropositivity requires urgent control measures to reduce impact on animal productivity and public health.

Pigs may represent a source of Cryptosporidium sp. infection to humans. The objective of this study was to identify the Cryptosporidium species present in pigs from the State of Rio de Janeiro, Brazil, and verify what risks pigs represent in the transmission of human cryptosporidiosis, because there is no such information to date in Brazil. Ninety-one samples of pig feces were collected from 10 piggeries in 2 municipalities located in the north and northwest regions of the State of Rio de Janeiro, Brazil. A nested polymerase chain reaction (PCR) protocol to amplify an 830-bp fragment of the small subunit rDNA (SSU rRNA) gene was followed by sequencing of all positive PCR samples. Two samples (2.2%) were Cryptosporidium sp. positive and were identified as pig genotype type II (PGII). This genotype has been observed in an immunocompetent person, in cattle without pigs nearby, and from a potential human source. Its potential for zoonotic transmission is little known and should be rigorously studied.

Toxoplasma gondii is a parasite considered one of the major causes of reproductive problems in sheep. Furthermore, the presence of the agent in ram semen urges the possibility of sexual transmission in this species. The aim of this study was to evaluate if ram's frozen semen spiked with T. gondii tachyzoites would be able to cause infection in sheep by laparoscopic artificial insemination (AI). Nine ewes tested seronegative to anti-T. gondii antibodies by the modified agglutination test (MAT) were superovulated and inseminated to collect embryos. Animals were divided into two groups: G1 (n = 5), ewes inseminated with semen containing 4 × 10 tachyzoites; and G2 (n = 4), ewes inseminated with tachyzoite-free semen (control group). To confirm infection, ewe's blood samples were collected on days -14, -7, 0, 7, 14, 21, 28, 35, 49 and 57 after AI for analysis by MAT and PCR. Tissue samples of these ewes were also collected for histopathology and immunohistochemistry (IHC). Seven days after AI, all ewes of group G1 had specific antibodies to T. gondii, while those of G2 were negative. Toxoplasma gondii DNA was detected in the blood of one ewe and parasites were observed in tissues of all five animals inseminated with contaminated semen, indicating that semen freezing protocol does not affect T. gondii transmission by artificial insemination in sheep.