Genetic characterization of Toxoplasma gondii from human and chicken isolates from Argentina.

This study aimed to determine the nPCR-RFLP genotypes of newly obtained T. gondii isolates from human congenital toxoplasmosis cases in Argentina and to determine their allelic profiles for virulence genes ROP18/ROP5. In addition, the ROP18/ROP5 profiles were also determined for previously characterized T. gondii samples. Isolation from congenital toxoplasmosis cases was carried out in mouse bioassay from two placentas (P1 and P2). Genotyping for the new human isolates was performed by nPCR-RFLP using 10 markers. The samples analyzed for ROP18/ROP5 included the two newly obtained isolates (from the congenital toxoplasmosis cases) and nine previously genotyped T. gondii DNA samples from humans and chickens. The results for P1 and P2 named as TgHm18-02Arg and TgHm19-01Arg showed ToxoDB genotypes #14 (non-archetypal) and #2 (clonal type III), respectively. Non-archetypal #14 has been isolated from human cases before in Argentina. However, this is the first report of T. gondii clonal type III in a human case in the country. The ROP18/ROP5 combination was detected in nine samples: 3/3 (n = 1), 4/3 (n = 4), 4/4 (n = 3), and 3-4/4 (n = 1). Notably, the 4/4 profile was identified for the first time and exclusively in T. gondii samples from Misiones province (which borders southern Brazil). Further studies are required to corroborate the regionalization of the ROP18/ROP5 profiles in Argentina.

Interferon-γ and IL-10 Release Assay for Patients with Ocular Toxoplasmosis.

Peripheral blood mononuclear cells (PBMC) from patients with ocular toxoplasmosis were challenged with total antigens from Toxoplasma gondii lysate (TATL) in a cytokine release assay (CRA), run during the inactive period of the disease. Increased interferon gamma (IFN-γ) levels were detected after PBMC stimulation with either ME49 reference strain (P = 0.0015) or local TgCkAr-11-9 isolate (P = 0.0012), as compared with those recorded under basal conditions. TATL from TgCkAr11-9 isolate induced a higher release of IFN-γ than ME49 strain in CRA from all tested patients (P = 0.02). The median value of IFN-γ release on TgCkAr-11-9 stimulation (26.03 pg/mL) allowed the classification of patients into high- or low-/non-IFN-γ releasers. Clinical correlations were established with both groups. The results obtained in this study suggest the need to include local strains when performing CRA with TATL.

Immune Mediators against Toxoplasma Gondii during Reactivation of Toxoplasmic Retinochoroiditis.

Purpose: The purpose of this article is to analyze possible associations between systemic and ocular cytokine levels and specific clinical ophthalmologic signs from patients with a reactivation of toxoplasmic retinochoroiditis (RTR). Methods: A total of 18 patients with an active RTR episode, 8 patients with inactive scars, and 14 control patients were included in the study. Serum samples and aqueous humor (AH) samples were analyzed for IFN (interferon)-γ, interleukin (IL)-10, and IL-6 levels by ELISA. Inflammation grade, location, and size of the retinochoroidal active lesion, sampling time, and time to resolution were recorded. Results: A significantly negative correlation between AH and serum levels of IFN-γ was detected (p < 0.05). Patients with an AH IFN-γ/IL-10 ratio lower than 1 were associated with the longest time to resolution and/or severe complications. Conclusion: Serum IFN-γ levels may be used as a prognostic marker for both time to resolution and the development of possible severe complications during a given RTR episode.

Regional Differences in the Clinical Manifestation of Ocular Toxoplasmosis Between the Center and Northeast of Argentina.

Purpose: To compare the clinical characteristics of patients with active episodes of ocular toxoplasmosis from three provinces, Misiones, Santa Fe, and Buenos Aires, Argentina. Methods: Patients with a diagnosis of ocular toxoplasmosis from three databases of four tertiary referral uveitis centers were reviewed. Collected data included presentation of the retinochoroiditis, location of the active lesions, associated inflammatory ocular signs and complications. Results: Three hundred thirty-four patients were included in this study. Bilateral involvement of the ocular disease occurred in 26 patients in Misiones (35.14%), 21 patients (12.8%) in Santa Fe, and 9 patients in Buenos Aires (9.4%) (p < 0.001). Extensive retinitis was observed in 49 patients (66.2%) in Misiones, 39 patients (23.8%) in Santa Fe, and 12 patients (12.5%) in Buenos Aires (p < 0.001). Conclusion: The results indicate that there are differences in the clinical characteristics of ocular toxoplasmosis in patients from Misiones, Santa Fe, and Buenos Aires.

Is reactivation of toxoplasmic retinochoroiditis associated to increased annual rainfall?

BACKGROUND: Reactivation of toxoplasmic retinochoroiditis is the most frequent form of uveitis in Misiones, Argentina. Fluctuations in the number of patients consulting with this type of uveitis were detected during the last decade. Since the province was consecutively exposed to rainy and dry periods over the last years, we decided to explore whether a relationship between reactivation of toxoplasmic retinochoroiditis and rain might be established according to the data registered during the 2004-2010 period. RESULTS: The frequency of toxoplasmic reactivation episodes increases when precipitation increases (mostly in second and fourth trimesters of each year). Analysis of the independent variables demonstrates that precipitation is a significant predictor of the frequency of reactivation episodes. Although registered toxoplasmic reactivations were more frequent during the third trimester of the year, the association between the third trimester and the reactivation episodes did not reach statistical significance. CONCLUSION: Prolonged and intense rainfall periods were significantly associated with the reactivation of toxoplasmic retinochoroiditis. Changes promoted by this climatic condition on both the parasite survival in the soil as well as a putative effect on the host immune response due to other comorbidities are discussed.