Partial protection against tissue cysts formation in pigs vaccinated with crude rhoptry proteins of Toxoplasma gondii

A vaccine containing crude Toxoplasma gondii rhoptry proteins incorporated in the immunostimulating complexes (ISCOM) adjuvant was tested in pigs for protecting against tissue cyst formation. For this, 38 mixed breed pigs were divided into four groups, G1 (vaccinated challenged, n=10) received two doses (100 microg/dose) of the rhoptry vaccine at days 0 and 21, G2 (vaccinated challenged, n=10) received viable tachyzoites (7 x 10(7)) of the RH strain at day 0, G3 (unvaccinated challenged, n=10) and G4 (unvaccinated unchallenged, n=8). Pigs were challenged with 4 x 10(4) VEG strain oocysts 57 days later. The G1 pigs produced high IgG antibody levels in the indirect enzyme-linked immunosorbent assay (ELISA) after the second dose of rhoptry vaccine, but were not clinically protected against a high dose oocyst challenge. Partial protection was observed in G1 at the chronic phase of infection, when compared with G3. Pigs in group 2 developed high antibody levels and were protected against clinic signs. T. gondii was not detected in two (G1) and three (G2) pigs by mouse bioassay. The results indicate partial protection in pigs vaccinated with a rhoptry vaccine.     

First isolation and molecular characterization of Toxoplasma gondii from finishing pigs from São Paulo State, Brazil

Toxoplasma gondii infection is widely prevalent in humans in Brazil. Among the food animals, pigs are considered the most important meat source of T. gondii for infection in humans. In the present study, we report the first isolation of viable T. gondii from finishing pigs in Brazil. Antibodies to T. gondii were found in 49 (17%) of 286 pigs prior slaughter using the modified agglutination test (MAT) at a serum dilution of 1:25. Attempts were made to isolate T. gondii from 28 seropositive pigs. Samples of heart, brain, and tongue from each pig were pooled, digested in acid pepsin, and bioassayed in five mice per pig. Viable T. gondii was isolated from seven pigs; all isolates were lethal for mice. Restriction fragment length polymorphism on products of SAG2 locus amplified by PCR revealed that two isolates were Type I and five were Type III. The results indicate that phenotypically and genetically T. gondii isolates from pigs from Brazil are distinct from isolates of T. gondii from pigs in the USA.     

Prevalence of Neospora caninum antibodies and factors associated with their presence in dairy cattle of the north of Paraná state, Brazil

To determine the prevalence of Neospora caninum antibodies and associated factors, blood sera from 623 female dairy cattle from 23 farms in the north of the state of Paraná, Brazil, were analyzed by means of the indirect immunofluorescent-antibody test (IFAT > or = 25). Serum samples from 134 dogs living on the same farms also were tested for N. caninum antibodies (IFAT > or = 50), and the presence of dogs was associated with the prevalence of N. caninum antibodies in cattle. The overall seroprevalence in cattle was 14.3%, mainly in animals over 24 months of age. Seroprevalence in Holsteins (15.1% of 558) was greater than in mixed-breed cattle (7.7% of 65). Age (> or =24 months) of cattle, feeding silage and/or concentrate produced on the farm were associated; antibodies were found in 21.6% of dogs; and the presence of dogs was associated with the prevalence of N. caninum antibodies in cattle.     

Prevalence of anti-Neospora caninum antibodies in dogs from urban, periurban and rural areas of the city of Uberlândia, Minas Gerais--Brazil

In Brazil there are few reports on the prevalence of anti-Neospora caninum antibodies in dogs from urban, periurban and rural areas. Serum samples from 450 dogs, 300 from urban, 58 from periurban and 92 from rural areas, were tested for the detection of anti-N. caninum IgG antibodies using IFAT: indirect fluorescent antibody test (IFAT, > or =50). Antibodies were observed in 63 (14%) of the 450 serum samples analyzed, with 32 (10.7%) in dogs coming from the urban area, 11 (18.9%) from the periurban area and 20 (21.7%) from the rural area. Statistical differences were seen between the occurrences in animals from the urban area and those of the rural area (P = 0.01). The antibody titers found were: 1:50 in 20 dogs, 1:100-1:800 in 41 dogs, and 1:3200 in two dogs. In the female dogs, a smaller prevalence of dogs with antibodies was observed in those from the urban area (7.5%) in comparison with those of the rural (21.0%) (P = 0.05) and periurban (23.3%) (P = 0.01) areas. There were growing levels of antibody prevalence with the increase in age of the dogs in all three areas studied. Although this increase was not significant, it indicates a tendency towards more infections with age, suggesting post-natal exposure to N. caninum. However, a significant difference (P = 0.05) was observed in the occurrence of anti-N. caninum antibodies in dogs with ages = 2 years in urban (13.1% urban) versus rural environments (27.1% rural). Among the other age brackets studied the difference was not significant. The results confirm the presence of N. caninum in the region and reveal the important role of dogs in the parasite's epidemiology.     

Seroprevalence of Coxiella burnetii antibodies in wild deer populations in eastern Australia

Coxiella burnetii causes significant reproduction losses in livestock and the disease Q fever in humans. Transmission of C. burnetii is facilitated by the stability of the bacterium in the environment and the susceptibility of a variety of host species to infection. Consequently, inter-species transmission occurs frequently through either direct or indirect contact. Wildlife may represent reservoirs of C. burnetii and could therefore be a source of infection for domestic animals. Understanding the prevalence of C. burnetii infections at the wildlife-livestock interface is important for disease control. This study aimed to investigate the extent of C. burnetii exposure in wild deer in eastern Australia. Serum samples were obtained from 413 wild deer from seven regions in four eastern Australian states from 2017 to 2020. Antibodies were detected using a commercial Q fever antibody kit validated for ruminants. Seroprevalence of C. burnetii antibodies in deer was determined and true prevalence estimated, for each region. The overall seroprevalence of C. burnetii antibodies in wild deer was 3.4% (14 seropositive of 413 deer sampled) with true prevalence estimated to be 4.3% (95% credible interval: 0.6%, 10.9%). Seropositive deer were identified only in Queensland (7/108 seropositive) and northern New South Wales (7/120 seropositive). This geospatial distribution is consistent with seropositivity in other animal species and indicative of the level of C. burnetii in the environment. The low seroprevalence suggests that wild deer are unlikely to be a major reservoir species for C. burnetii in eastern Australia but may still be implicated in inter-species transmission cycles.     

Biologic and genetic comparison of Toxoplasma gondii isolates in free-range chickens from the northern Pará state and the southern state Rio Grande do Sul, Brazil revealed highly diverse and distinct parasite populations

The prevalence of Toxoplasma gondii in 84 free-range chickens (34 from the northern Pará state, and 50 from Rio Grande do Sul, the southern state) from Brazil, South America was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 39 (46.4%) of 84 chickens with titers of 1:10 in one, 1:20 in two, 1:40 in four, 1:80 in seven, 1:160 in five, 1:320 in six, 1:640 in eight and > or =1:1280 in six. Hearts and brains of 45 chickens with titers of 1:20 or less were pooled and fed to two T. gondii-free cats. Hearts and brains of 39 chickens with titers of 1:10 or higher were bioassayed in mice. Feces of cats were examined for oocysts. One cat fed tissues from 31 chickens with titers of less than 1:10 from Rio Grande do Sul shed T. gondii oocysts. T. gondii was isolated by bioassay in mice from 33 chickens with MAT titers of 1:20 or higher. All infected mice from 10 isolates died of toxoplasmosis. All 34 isolates (15 from Pará, 19 from Rio Grande do Sul) were genotyped using 11 genetic markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, a new SAG2 and Apico. Eleven genotypes were revealed for Pará isolates and seven genotypes for Rio Grande do Sul. No genotype was shared between the two geographical locations. These data suggest that T. gondii isolates are highly diverse and genetically distinct between the two different regions in Brazil that are 3500 km apart.