Spatial distribution of soil contaminated with Toxoplasma gondii oocysts in relation to the distribution and use of domestic cat defecation sites on dairy farms.

Little information is available on the relationship between the spatial distribution of zoonotic parasites in soil and the pattern of hosts' faeces deposition at a local scale. In this study, the spatial distribution of soil contaminated by the parasite Toxoplasma gondii was investigated in relation to the distribution and use of the defecation sites of its definitive host, the domestic cat (Felis catus). The study was conducted on six dairy farms with a high number of cats (seven to 30 cats). During regular visits to the farms over a 10month period, the cat population and cat defecation sites (latrines and sites of scattered faeces) on each farm were systematically surveyed. During the last visit, 561 soil samples were collected from defecation sites and random points, and these samples were searched for T. gondii DNA using real-time quantitative PCR. Depending on the farm, T. gondii DNA was detected in 37.7-66.3% of the soil samples. The proportion of contaminated samples at a farm was positively correlated with the rate of new cat latrines replacing former cat latrines, suggesting that inconstancy in use of a latrine by cats affects the distribution of T. gondii in soil. On the farms, known cat defecation sites were significantly more often contaminated than random points, but 25-62.5% of the latter were also found to be contaminated. Lastly, the proportion of positive T. gondii samples in latrines was related to the proximity of the cats' main feeding and resting sites on the farms. This study demonstrates that T. gondii can be widely distributed in farm soil despite the heterogeneous distribution of cat faeces. This supports the hypothesis that farms are hotspot areas for the risk of T. gondii oocyst-induced infection in rural environments.

[Characterization of specific IgG, IgM, IgA and IgE isotypes in profound candidiasis]. / Caractérisation des isotypes spécifiques IgG, IgM, IgA et IgE dans les candidoses profondes.

Enzyme-linked immunofiltration assay technique (Elisa) has been applied to the characterization of G, M, A and E anti-Candida antibodies isotypes specific to cell wall mannans in 201 sera from 126 patients. These sera were studied at the same time using Co-immunoelectrodiffusion and indirect immunofluorescence. In 18 of 21 patients with systemic candidiasis, Elisa demonstrated the presence of antimannan IgG antibodies in sera contemporary of Candida positive blood culture. These IgG were associated with antimannan IgM, A and E in 15 patients. In 37 patients colonized with Candida, used as negative controls, antimannan IgG were detected in 3 cases, and in 2 were associated with specific IgMs. The sensitivity and specificity of Elisa IgM and IgA in the diagnosis of systemic Candidiasis were 85.7% and 81%, respectively. The kinetic study shows that the different isotypes appeared most of the time simultaneously. The evolution of the 4 isotypes beyond the acute episode was variable and without correlation with the clinical status. The decrease of IgG was slower than the one of IgM, IgA or IgE. The systematic research, in at risk patients, of antimannan antibodies using Elisa required simple technology. A simple method should allow to aim at other functional antigens which could be used in a quantitative manner to determine the efficacy of the medical treatment.

Characterization of specific anti-Candida IgM, IgA and IgE: diagnostic value in deep-seated infections.

The proposed serological diagnosis of systemic Candida infections is based on a microplate immunocapture technique detecting IgM, IgA and IgE anti-Candida antibodies. Activity is revealed with a suspension of human erythrocytes sensitized with somatic antigen of Candida albicans, and is quantified on an automated plate reader. The sera were obtained from patients with deep-seated (n = 56) and superficial (n = 193) candidosis. We compared this immunological method with a combination of indirect immunofluorescence and co-immunoelectrodiffusion. The immunocapture method was more sensitive (80.4% vs. 48.2% with indirect immunofluorescence and 58.9% with co-immunoelectrodiffusion), and often provided the diagnosis at an earlier stage, with clear therapeutic advantages. The IgA isotype was a particularly valuable marker of deep-seated Candida infections.