Ocular Involvement Following an Epidemic of Toxoplasma gondii Infection in Santa Isabel do Ivaí, Brazil.
OBJECTIVE
To investigate ocular involvement (prevalence, incidence, lesion characteristics) following postnatally acquired infection with an "atypical" genotype of Toxoplasma gondii during a well-characterized 2001 outbreak in Santa Isabel do Ivaí, Brazil, attributed to a contaminated municipal reservoir.


METHODS
Prospective longitudinal cohort study.


METHODS
We performed ophthalmic examinations on 290 of 454 individuals with serologic evidence of T gondii infection during the epidemic (positive IgM antibody tests). Prevalence of ophthalmic findings (intraocular inflammatory reactions [including transient, isolated retinal whitening without clinically apparent retinal necrosis] and necrotizing retinochoroiditis) at initial examination (baseline) and incidence of new findings during 10.5 months of follow-up were calculated. Cumulative risks of ophthalmic events were determined (Kaplan-Meier technique).


RESULTS
Ocular involvement was present in 33 of 288 IgM+ individuals (11.5%) at baseline, including 17 with focal retinal whitening only and 13 with necrotizing retinochoroiditis. Incidence of new ocular involvement was estimated to be 1.73 events per 100 person-months (PM); cumulative risk at 10.5 months was 30.1%. Incident necrotizing retinochoroiditis was more common among those with focal retinal whitening at baseline (6.7/100 PM) than among those with no ocular involvement at baseline (1.11/100 PM; hazard ratio 6.07 [1.94-19.01]; P < .0001).


CONCLUSIONS
Waterborne infection with an atypical genotype of T gondii is associated with substantial risk of ocular involvement. Lesions may continue to develop during the first year after infection. The increased risk of late necrotizing retinochoroiditis associated with isolated focal retinal whitening at presentation suggests the early presence of parasites in the retina, despite initial lack of observable retinal necrosis.
Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil; Clínica Silveira, Erechim, Rio Grande do Sul, Brazil.
Claudio
C
Silveira
Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
Cristina
C
Muccioli
Ocular Inflammatory Disease Center, Stein Eye Institute and the Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California. Electronic address: uveitis@jsei.ucla.edu.
Gary N
GN
Holland
Division of Parasitic Diseases and Malaria, Center for Global Health, United States Centers for Disease Control and Prevention, Atlanta, Georgia.
Jeffrey L
JL
Jones
Ocular Inflammatory Disease Center, Stein Eye Institute and the Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California.
Fei
F
Yu
Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
Adam
A
de Paulo
Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil.
Rubens
R
Belfort
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000913:Antibodies, Protozoan / Q000097:blood; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D002825:Chorioretinitis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000469:parasitology; D015331:Cohort Studies; D004196:Disease Outbreaks; D019353:Endemic Diseases; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005493:Folic Acid Antagonists / Q000627:therapeutic use; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D002955:Leucovorin / Q000627:therapeutic use; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011739:Pyrimethamine / Q000627:therapeutic use; D016036:Seroepidemiologic Studies; D013411:Sulfadiazine / Q000627:therapeutic use; D014122:Toxoplasma / Q000276:immunology / Q000302:isolation & purification*; D014126:Toxoplasmosis, Ocular / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology* / Q000469:parasitology; D014867:Water / Q000469:parasitology; D014881:Water Supply
D000913:Antibodies, Protozoan; D000981:Antiprotozoal Agents; D005493:Folic Acid Antagonists; D007075:Immunoglobulin M; D014867:Water; D013411:Sulfadiazine; D002955:Leucovorin; D011739:Pyrimethamine