Prevalence of latent toxoplasmosis and serological diagnosis of active infection in HIV-positive patients.
The seroprevalence of latent Toxoplasma gondii infection was determined in a cohort of 715 HIV-positive patients followed up at an HIV outpatient clinic. Using indirect immunofluorescence and direct agglutination assays for detecting IgG, the prevalence of anti-Toxoplasma gondii antibodies was shown to be 50%. During a four-year period, clinically apparent acute toxoplasmosis occurred in 47 patients (43 with cerebral, 3 with ocular and 1 with bone marrow toxoplasmosis) among the 360 patients positive for anti-Toxoplasma gondii IgG and in one patient (with cerebral toxoplasmosis) among the 355 patients who were serologically negative. A significant rise in IgG levels could be shown during acute toxoplasmosis episodes in only 30% of patients, compared with 3% of patients without active toxoplasmosis. During acute toxoplasmosis, IgM antibodies were detected in only two patients (6%) by an immunosorbent agglutination assay and in one (3%) by an enzymatic immunocapture assay. Specific IgA was detected by a non-enzymatic immunocapture assay in six patients (18%) during acute episodes. The very high predictive value (99.7%) of a negative IgG test remains the best serological parameter for excluding an acute episode of toxoplasmosis in HIV-positive patients.
Zufferey
J
J
Institute of Microbiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Sugar
A
A
Rudaz
P
P
Bille
J
J
Glauser
M P
MP
Chave
J P
JP
D000208:Acute Disease; D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002452:Cell Count; D015331:Cohort Studies; D006679:HIV Seropositivity / Q000150:complications*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D015994:Incidence; D008297:Male; D008875:Middle Aged; D014123:Toxoplasmosis / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000276:immunology*
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D007075:Immunoglobulin M