Importance of high IgG anti-Toxoplasma gondii titers and PCR detection of T. gondii DNA in peripheral blood samples for the diagnosis of AIDS-related cerebral toxoplasmosis: a case-control study

Seroepidemiological study on coinfection of toxoplasmosis and active tuberculosis in Northern Iran: a case control study

Coinfection of tuberculosis (TB) and human parasitic infections is common in developing countries. There is little information about the prevalence of Toxoplasma gondii (T. gondii) infection among TB patients in Iran. In this case-control study, anti-toxoplasma antibodies were measured by ELISA method in 100 patients with active tuberculosis and 100 healthy individuals who were matched in terms of sex, age, and place of residence. Anti-T. gondii IgG antibodies were diagnosed in 62% of TB patients (95% CI 53-71%) and 70% of control subjects (95% CI 62-78%). Anti-T. gondii IgM antibodies were found in 1% of both TB patients and control group. The seroprevalence of T. gondii infection was not significantly different between TB patients and healthy individuals (P > 0.05). None of the assessed sociodemographic and behavioral factors was recognized as a risk factor for toxoplasmosis in TB infected patients. Moreover, the level of anti-T. gondii IgG antibodies concentration in TB patients was significantly higher than in control subjects and revealed skewness towards humoral immune response in TB patients. Coinfection of toxoplasmosis and tuberculosis was prevalent but T. gondii infection was independent of active TB in this co-endemic area.

Human Toxoplasma gondii infection in Nigeria: a systematic review and meta-analysis of data published between 1960 and 2019

BACKGROUND

Over 70% of the worlds' population is infected by Toxoplasma gondii; a pathogen capable of causing cerebral toxoplasmosis in HIV patients and neonatal complications like miscarriage, chorioretinitis, hydrocephalus, cerebral calcification and foetal death in the third trimester of pregnancy. In spite of this, the burden of this zoonotic pathogen is poorly understood in Nigeria. The aim of the present study therefore, is to determine the burden of T. gondii among normal individuals, HIV patients and pregnant women as well as the distribution of the infection across Nigeria.

METHODS

Using the PRISMA guidelines, we conducted a systematic review and meta-analysis of data retrieved from six electronic databases (AJOL, Google Scholar, PubMed, Scopus, Science Direct and Web of Science). Pooled prevalence (PP) and heterogeneity were determined by the random-effects model and the Cochran's Q-test respectively. The quality of each study and publication bias were assessed by the 9 point Joanna Briggs Institute Critical Appraisal Instrument and the Egger's regression asymmetry test respectively, while the robustness of a pooled estimate was tested by the single study omission analysis.

RESULTS

Exactly 5834 of the 16,230 individuals examined for T. gondii infection by 50 studies across 17 Nigerian States were positive for the infection. Overall PP was 32.92% (95% CI: 27.89, 38.37), with a range of 14.41% (95% CI: 5.32, 33.54) to 86.82% (95% CI: 66.13, 95.69) across sub-groups. Pooled prevalence was significantly higher (p < 0.001) among pregnant women (40.25%; 95% CI: 33.19, 47.73) and HIV patients (31.68, 95% CI: 20.53, 45.41) than normal individuals (23.32, 95% CI: 17.25, 30.75). T. gondii prevalence declined by over 58% during the 59 years reviewed.

CONCLUSION

Toxoplasma gondii infection is moderately prevalent in Nigeria. Highest prevalence estimates were observed among pregnant women and in the south-south region. For effective control of the disease in Nigeria, a holistic approach involving on-farm, environmental, public health and animal components are suggested.

Disease of the Year 2019: Ocular Toxoplasmosis in HIV-infected Patients

Ocular toxoplasmosis (OT) may be an initial manifestation of acquired immunodeficiency syndrome (AIDS) in human immunodeficiency virus (HIV)-infected patients. OT has different clinical manifestations and can mimic other intraocular infections. Clinical findings may show single or multifocal retinochoroidal lesions or panuveitis. Atypical presentations are associated with extensive uni- or bilateral areas of retinal necrosis. OT lesions not associated with preexisting retinochoroidal scars are usually due to acquired rather than congenital infection. When CD4+ T cell counts are <100 c/uL, vitritis is frequently mild. Isolated anterior uveitis has been reported in single cases. Positive immunoglobulin M (IgM) antibodies are rare but their presence can support the diagnosis. As atypical presentations of OT are common, anterior chamber puncture for multiplex polymerase chain reaction amplification of infectious DNA should be considered, as early diagnosis and treatment can prevent massive tissue destruction and preserve vision. This review provides an overview of OT in HIV-infected patients.

Usefulness and limitations of polymerase chain reaction in the etiologic diagnosis of neurotoxoplasmosis in immunocompromised patients

The objective of the present study was to assess the performance and the best indication of the polymerase chain reaction (PCR) for the detection of Toxoplasmosis gondii DNA in cerebrospinal fluid (CSF) from patients with suspected neurotoxoplasmosis. CSF samples were collected from 79 patients for amplification of the T. gondii genome (gene B1) by two PCR techniques (nested and real time). Twenty-seven of the 79 patients were classified as probable cases of neurotoxoplasmosis on the basis of clinical criteria, neuroimaging and therapeutic response. PCR showed high sensitivity (86.6%) when performed in CSF samples which were collected up to the seventh day of specific toxoplasmosis treatment. There was no positive test after 1 week of treatment. These results suggest the usefulness of PCR for the diagnosis of cerebral toxoplasmosis, and support the first week as the window for the best performance of toxoplasmosis PCR in CSF.

IgG4 specific to Toxoplasma gondii excretory/secretory antigens in serum and/or cerebrospinal fluid support the cerebral toxoplasmosis diagnosis in HIV-infected patients

Cerebral toxoplasmosis is the most common neurological opportunistic disease manifested in HIV infected patients. Excretory/secretory antigens (ESA) are serological markers for the diagnosis of reactivation of the infection in HIV-infected patients with cerebral toxoplasmosis. Immunosuppressed patients develop high antibody titers for ESA. However, little is known about the humoral response for these antigens. The present study analyzed the profile of antibody recognition against ESA in comparison with tachyzoite lysate antigen (TLA) in 265 sera and 270 cerebrospinal fluid (CSF) samples from infected patients with Toxoplasma gondii and or HIV and in sera of 50 healthy individuals. The samples of sera and CSF were organized in 8 groups. The sera sample groups were: Group I - Se/CT/AIDS (patients with cerebral toxoplasmosis/AIDS) with 58 samples; Group II - Se/ONinf/AIDS/PosT (patients with AIDS/other neuroinfections/positive toxoplasmosis) with 49 samples; Group III - Se/ONinf/AIDS/NegT (patients with AIDS/other neuroinfections/negative toxoplasmosis) with 58 samples; Group IV - Se/PosT/NegHIV (individuals with asymptomatic toxoplasmosis/negative HIV) with 50 samples and Group V - Se/NegT/NegHIV (healthy individuals/negative toxoplasmosis and HIV) with 50 samples. The CSF sample groups were: Group VI - CSF/CT/AIDS (patients with cerebral toxoplasmosis/AIDS) with 99 samples; Group VII - CSF/ONinf/AIDS/PosT (patients with AIDS/other neuroinfections/positive toxoplasmosis) with 112 samples, and Group VIII - CSF/ONinf/AIDS/NegT (patients with AIDS/other neuroinfections/negative toxoplasmosis) with 59 samples. Levels of IgM, IgA, IgE, IgG and subclasses were determined by ELISA against TLA and ESA antigens. IgM, IgA or IgE antibodies against ESA or TLA were not detected in sera from patients with toxoplasmosis suggesting that all patients were in chronic phase of the infection. High levels of IgG1 against TLA were found in sera samples from groups I, II and IV and in CSF samples from groups VI and VII; whereas IgG2, IgG3 and IgG4 levels were not detected in the same sera or CSF sample groups. However, patients from groups I and VI, that had tachyzoites circulating in blood and CSF respectively, produced a mix of IgG1 and IgG4 antibodies against ESA. IgG2 against ESA were predominant in serum from patients with the latent (non-active) T. gondii infection/HIV negative and in CSF samples from patients with other neuroinfections and positive toxoplasmosis (groups IV and VII, respectively). IgG4 levels against ESA were found to be significantly (P<0.05 and P<0.005) higher in patients with cerebral toxoplasmosis (groups I and VI, respectively) in comparison with groups II, IV and VII. This data suggest that IgG4 can be valuable for supporting the diagnosis of focal brain lesions, caused by T. gondii infection, in HIV-infected patients. This approach might be useful, mainly when molecular investigation to detect parasites is not available.