Identification of an atypical strain of toxoplasma gondii as the cause of a waterborne outbreak of toxoplasmosis in Santa Isabel do Ivai, Brazil.

Multilocus DNA sequencing has identified a nonarchetypal strain of Toxoplasma gondii as the causal agent of a waterborne outbreak in Brazil in 2001. The strain, isolated from a water supply epidemiologically linked to the outbreak, was virulent to mice, and it has previously been identified as BrI. Using a serologic assay that detects strain-specific antibodies, we found that 13 (65%) of 20 individuals who were immunoglobulin (Ig) M positive during the outbreak possessed the same serotype as mice infected with the purported epidemic strain. The remaining 7 individuals, plus additional IgM-negative, IgG-positive individuals, possessed 1 of 4 novel serotypes, the most common of which matched the serotype of mice infected with strains isolated from chickens foraging near the outbreak site. The latter strains likely reflect the genetic diversity of T. gondii circulating in highly endemic regions of Brazil. The serotyping assay proved a useful tool for identification of specific individuals infected with the outbreak agent.

Characteristics of untreated AIDS-related cytomegalovirus retinitis. I. Findings before the era of highly active antiretroviral therapy (1988 to 1994).

PURPOSE: To identify factors related to variations in the appearance of untreated AIDS-related cytomegalovirus (CMV) retinitis in severely immunodeficient individuals before the availability of highly active antiretroviral therapy (HAART) and to draw inferences regarding early events in the natural history of CMV retinitis based on clinical findings. DESIGN: Retrospective, observational case series. METHODS: We evaluated a series of 100 adult patients with AIDS and newly diagnosed CMV retinitis before the HAART era who were not being treated with specific anti-CMV therapy. Demographic factors, ophthalmic findings, and the influence of drug therapy (zidovudine, acyclovir) on lesion characteristics were evaluated. Lesion border opacity was scored using a four-point scale of severity. RESULTS: Lesions could be categorized by type (fulminant/edematous or indolent/granular) in only 66% of eyes. Severe lesion border opacity (4+) was related to presence of zone 1 lesions (P = .032) and greater extent of disease (P = .004). Acyclovir use was associated with less severe opacity (P = .029) and less zone 1 involvement (P = .016). Early lesions were adjacent to vessels in 73% of eyes; the fovea was involved in 13% of eyes. CONCLUSIONS: Lesion location and drug use that affects virus activity may influence the severity of lesion border opacity, a measure that may be more useful than lesion type in future clinical studies of CMV retinitis. In contrast to earlier concepts, CMV retinitis does not seem to be a fovea-sparing disease. Findings in this study can serve as a reference for investigations into possible changes in CMV retinitis since the introduction of HAART.

Characteristics of untreated AIDS-related cytomegalovirus retinitis. II. Findings in the era of highly active antiretroviral therapy (1997 to 2000).

PURPOSE: To describe host characteristics (use of highly active antiretroviral therapy [HAART]; CD4+ T-lymphocyte count; HIV ribonucleic acid [RNA] blood level) of people who were diagnosed with AIDS-related cytomegalovirus (CMV) retinitis after HAART became available and to investigate effects of HAART on ophthalmic findings. DESIGN: Retrospective, observational case series. METHODS: We collected demographic, medical, laboratory, and ophthalmic data for all patients with AIDS and newly diagnosed, untreated CMV retinitis from January 1997 through December 2000 at 10 sites in Los Angeles and Orange Counties, California. RESULTS: The proportions of Hispanic and African-American patients were equivalent to or greater than their prevalences in the AIDS and general populations of Los Angeles County. Most patients (n = 80; 63.5%) were known to be receiving HAART at the time of CMV retinitis diagnosis; only 22 patients (17.5%) were HAART-naïve. Median CD4+ T-lymphocyte count was 15 cells/microl and median HIV RNA blood level was 103,000 copies/ml for all patients, but in 10 patients, CMV retinitis developed despite good immunologic and virologic responses to HAART. When compared with HAART-naïve patients, HAART-failure patients with CMV retinitis had more asymptomatic disease (P = .073), better visual acuity in the better eye (P = .003), more bilateral disease (P = .007), less zone 1 involvement (P = .042), and lower lesion border opacity scores (P = .054). CONCLUSIONS: Most patients with AIDS and newly diagnosed CMV retinitis in an urban setting are HAART-experienced. HAART may influence characteristics of new CMV retinitis lesions at presentation, despite laboratory evidence of treatment failure, possibly because of residual CMV-specific immunity.