Saemi Ogassawara

Seroprevalence of Toxoplasma gondii in captive neotropical felids from Brazil

Seroprevalence of Toxoplasma gondii was determined in 865 captive neotropical felids from 20 states from Brazil, sampled from September 1995 to April 1997. Sera were tested by the modified agglutination test (MAT) using formalin-fixed whole tachyzoites and mercaptoethanol. Antibodies (MAT> or =1:20) to T. gondii were found in 472 of 865 (54.6%) cats: in 45 of 99 (45.9%) jaguarundis (Herpailurus yagouaroundi), in 97 of 168 (57.7%) ocelots (Leopardus pardalis), in 68 of 131 (51.9%) oncillas (L. tigrinus), in 35 of 63 (55.5%) margays (L. wiedii), in 1 of 8 (12.5%) Pampas-cat (Oncifelis colocolo), in 9 of 12 (75.0%) Geoffroys-cat (O. geoffroyi), in 134 of 212 (63.2%) jaguars (Panthera onca), and in 83 of 172 (48.2%) pumas (Puma concolor). Antibody titers were: 1:20 in 27 felids, 1:25 in 142 felids, 1:40 in 6 felids, 1:50 in 292 felids, and > or =1:500 in 5 felids. The high seroprevalence of T. gondii antibodies found in the present study suggested a widespread exposure of neotropical cats to T. gondii in zoos in Brazil. The results warrant an investigation on the mode of exposure and oocyst shedding by neotropical cats.

OCCURRENCE OF CATTLE SARCOCYSTIS SPECIES IN RAW KIBBE FROM ARABIAN FOOD ESTABLISHMENTS IN THE CITY OF SAO PAULO, BRAZIL, AND EXPERIMENTAL TRANSMISSION TO HUMANS

Fifty samples of raw kibbe from 25 Arabian restaurants in the city of São Paulo, Brazil, were examined for the presence of bovine Sarcocystis species, using light and electron microscopy, and for infectivity to humans. Sarcocysts were found in all 50 samples. Based on cyst wall structure, S. hominis (94%), S. hirsuta (70%), and S. cruzi (92%) were identified (mostly as mixed infections). Different raw kibbe samples, positive for S. hominis in fresh preparations, were offered as a meal for 7 human volunteers. Six volunteers (85.7%), 2 of whom developed diarrhea, excreted sporocysts in feces. The prepatent period lasted 10–14 (12 ± 1.8) days and the patent period lasted 5–12 (8.8 ± 1.1) days.

Cross-Reactions between Toxocara canis and Ascaris suum in the diagnosis of visceral larva migrans by western blotting technique

Visceral larva migrans (VLM) is a clinical syndrome caused by infection of man by Toxocara spp, the common roundworm of dogs and cats. Tissue migration of larval stages causes illness specially in children. Because larvae are difficult to detect in tissues, diagnosis is mostly based on serology. After the introduction of the enzyme-linked immunosorbent assay (ELISA) using the larval excretory-secretory antigen of T. canis (TES), the diagnosis specificity was greatly improved although cross-reactivity with other helminths are still being reported. In Brazil, diagnosis is routinely made after absorption of serum samples with Ascaris suum antigens, a nematode antigenically related with Ascaris lumbricoides which is a common intestinal nematode of children. In order to identify T. canis antigens that cross react to A. suum antigens we analyzed TES antigen by SDS-PAGE and Western blotting techniques. When we used serum samples from patients suspected of VLM and positive result by ELISA as well as a reference serum sample numerous bands were seen (molecular weight of 210-200 kDa, 116-97 kDa, 55-50 kDa and 35-29 kDa). Among these there is at least one band with molecular weight around 55-66 kDa that seem to be responsible for the cross-reactivity between T. canis and A. suum once it disappears when previous absorption of serum samples with A. suum antigens is performed.

Influence of soil texture in the recovery of Toxocara canis eggs by a flotation method

In epidemiological surveys, the evaluation of soil contamination by Toxocara canis eggs requires a quick and easy method for the isolation of parasite eggs from soil samples. The efficiency of flotation methods is influenced by sample size, soil texture, degree of soil contamination, pretreatment, flotation solutions and time of flotation. This investigation was designed to evaluate the influence of soil texture in the recovery of T. canis eggs with the centrifugal flotation technique of Dada (Dada, B.J.O., 1979. A new technique for the recovery of Toxocara eggs from soil. J. Helminthol., 53: 141-144). Four types of soil (clay silt, sandy, silty clay and sand) were artificially contaminated with T. canis eggs (200 eggs per gram). Zinc sulphate (specific gravity 1.20) and sodium dichromate (specific gravity 1.35) were used as flotation solutions. Twenty replicated examinations were performed for each type of soil and flotation solution. There was a statistically significant difference in the results depending on soil type. The highest recovery percentages were observed in soils rich in sand (62.5% for sand and 38.0% for sandy soil). Differences were also observed with different flotation solutions. Sodium dichromate solution was more efficient for recovering T. canis eggs, regardless of the soil texture.

TOXOPLASMA GONDII ANTIBODIES IN EXOTIC WILD FELIDS FROM BRAZILIAN ZOOS

Abstract Serum samples from 37 captive exotic felids in 12 zoos from six Brazilian states were assayed for antibodies to Toxoplasma gondii by the modified agglutination test using formalin-fixed whole tachyzoites. Titers greater than or equal to 1:20 were considered positive. Antibodies to T. gondii were found in 24 of 37 (64.9%) felids, including one European lynx (Lynx lynx), two jungle cats (Felis chaus), two servals (Leptailurus serval), two tigers (Panthera tigris), three leopards (Panthera pardus), and 14 of 27 lions (Panthera leo). This is the first serologic analysis for T. gondii infection in exotic wild felids from Brazilian zoos.

TOXOCARIASIS: SEROLOGICAL DIAGNOSIS BY INDIRECT ANTIBODY COMPETITION ELISA

Toxocariasis is caused by infection of man by Toxocara canis and Toxocara cati larvae, the common roundworm of dogs and cats. Because larvae are difficult to detect in tissues, diagnosis is mostly based on serology. Non specific reactions are observed mainly due to cross-reactivity with Ascaris sp antigens. This investigation aimed at developing and evaluating an indirect antibody competition ELISA (IACE) employing a specific rabbit IgG anti-Toxocara canis excretory-secretory antigens as the competition antibody, in order to improve indirect ELISA specificity performed for toxocariasis diagnosis. For that, the rabbit IgG was previously absorbed by Ascaris suum adult antigens. Sensitivity and specificity of IACE were first evaluated in 28 serum samples of mice experimentally infected with T. canis embryonated eggs. Adopting cut-off value established in this population before infection, sensitivity and specificity were 100% after 20 days post-inoculation. For human population IACE was evaluated using sera from 440 patients with clinical signs of toxocariasis and the cut-off value was established with 60 serum samples from apparently healthy individuals. Using as reference test the indirect ELISA performed by Adolfo Lutz Institute, sensitivity was 60.2%, specificity was 98% and concordance was 77.3%. Repeatability of IACE was evaluated by the inter-reactions variation coefficient (2.4%).