Keywords
serology
molecular diagnosis
people living with HIV
diagnostic performance
Kinshasa
How to Cite
Abstract
Introduction
Toxoplasmosis is a major public health concern in sub-Saharan Africa, particularly among people living with HIV (PLHIV), owing to the severe neurological complications and high mortality associated with the disease. Diagnosis primarily relies on detecting anti-Toxoplasma gondii antibodies or amplifying parasitic DNA via polymerase chain reaction (PCR).
Purpose
To evaluate and compare the diagnostic performance—including sensitivity, specificity, predictive values, diagnostic accuracy, and inter-test agreement—of serological and molecular methods for detecting toxoplasmosis among PLHIV in Kinshasa.
Methods
A descriptive cross-sectional study with an analytical component was conducted from October 2025 to January 2026 across public referral health centers in Kinshasa. A total of 71 PLHIV presenting with clinical signs suggestive of toxoplasmosis were enrolled. Anti-T. gondii IgG antibodies were detected using the Enzyme-Linked Fluorescent Assay (ELFA) on the Mini VIDAS system. Conventional PCR targeting the 529-bp repetitive element of T. gondii was performed on leukocyte DNA extracted using the PureLink Viral RNA/DNA Mini Kit and served as the reference method.
Results
IgG serology was positive in 32.4% (n=23) of participants, whereas PCR detected T. gondii DNA in 39.4% (n=28). Cross-tabulation revealed 19 true positives, 39 true negatives, 4 false positives, and 9 false negatives (seronegative/PCR-positive discordance: 12.7%). Diagnostic methods showed a statistically significant association (χ2=23.94,p<.001; Fisher’s exact test p<.001; OR=19.38,95% CI [4.93,98.49]). IgG serology demonstrated a sensitivity of 67.9% (95% CI [49.3%,82.1%]), specificity of 90.7% (95% CI [77.9%,96.2%]), positive predictive value of 82.6% (95% CI [63.2%,96.2%]), and negative predictive value of 81.3% (95% CI [68.1%,89.4%]). The overall diagnostic accuracy was 81.7% (95% CI [70.7%,89.8%]), with a Cohen’s kappa coefficient of 0.60 (95% CI [0.39,0.82]), indicating moderate agreement. Females constituted 59.2% (n=42) of the sample (female-to-male ratio of 1.4:1). The mean age was 44±12 years (range: 18–75 years), with the 36–45 age group being the most represented (28.2%).
Conclusion
Compared to IgG serology, PCR demonstrated superior diagnostic sensitivity for detecting active toxoplasmosis in immunocompromised patients. While PCR serves as a critical reference tool, serological and molecular modalities provide complementary clinical insights and should be integrated into combined diagnostic algorithms for PLHIV.
References
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Copyright (c) 2026 Lukoki, Y. M., Booto, G. I., Losenga, L. O., Tshinguta, C. L., Bongenya, B. I., Kamangu, E. N.