HIV-Related Cerebral Toxoplasmosis Revisited: Current Concepts and Controversies of an Old Disease

A role for T-cell exhaustion in Long COVID-19 and severe outcomes for several categories of COVID-19 patients

Unusual mortality rate differences and symptoms have been experienced by COVID‐19 patients, and the postinfection symptoms called Long COVID‐19 have also been widely experienced. A substantial percentage of COVID‐19‐infected individuals in specific health categories have been virtually asymptomatic, several other individuals in the same health categories have exhibited several unusual symptoms, and yet other individuals in the same health categories have fatal outcomes. It is now hypothesized that these differences in mortality rates and symptoms could be caused by a SARS‐CoV‐2 virus infection acting together with one or more latent pathogen infections in certain patients, through mutually beneficial induced immune cell dysfunctions, including T‐cell exhaustion. A latent pathogen infection likely to be involved is the protozoan parasite Toxoplasma gondii, which infects approximately one third of the global human population. Furthermore, certain infections and cancers that cause T‐cell exhaustion can also explain the more severe outcomes of other COVID‐19 patients having several disease and cancer comorbidities.

Cerebral Toxoplasmosis, CMV and Bacterial Pneumonia with Decreasing CD4+ T-Cell Count as Results of Antiretroviral Therapy Discontinuation-A Case Report

Cerebral toxoplasmosis occurs mainly in immunocompromised hosts as a reactivation of latent Toxoplasma gondii infection. In the diagnostic process, magnetic resonance imaging (MRI), serum testing, and biopsy are used. We describe a case of a 43-year-old HIV-positive patient presenting with altered levels of consciousness, aphasia, and hemiparesis. The patient had a history of antiretroviral therapy discontinuation for about 3 years. MRI revealed lesions, suggesting cerebral toxoplasmosis and subacute hemorrhage, serum tests for Toxoplasma gondii were positive. Antiparasitics and glycocorticosteroids were administered. A decline in viral load and clinical improvement were observed, however CD4+ T-cell count continued to decrease. The patient’s state worsened, he developed CMV and bacterial pneumonia, which led to his death. What is crucial in the management of an HIV-infected patient is effective and continuous antiretroviral therapy. Discontinuation of the treatment may result in AIDS and lead to poor recovery of the CD4+ T-cell population, even after reimplementation of antiretroviral therapy and a decrease in viral load.

Differential diagnosis of brain lesions in a metastatic endometrial carcinosarcoma patient

The differential diagnosis of ring-enhancing brain lesions in a patient with metastatic malignancy may initially seem straightforward, and easily attributed to brain metastases. On rare occasions, the physician needs to avoid anchoring bias by re-evaluating the entire clinical context in which these ring-enhancing brain lesions are found. We report a case of cerebral toxoplasmosis mimicking brain metastases in a patient with metastatic cancer and without a prior history of human immunodeficiency virus. A 65-year-old lady with a recently detected relapse of her endometrial carcinosarcoma presented with a 2-week history of fever with no localising symptoms or signs of infection. The initial investigations were unremarkable. She had daily fever despite empirical broad-spectrum antibiotics. A positron emission tomography-computed tomography (PET-CT) was performed to evaluate the pyrexia of unknown origin, which showed metastatic deposits in the pelvis. A magnetic resonance imaging (MRI) of the brain was subsequently performed due to fluctuating mentation, which reported metastatic disease to the brain. Her pyrexia of unknown origin was attributed to malignancy-related fever. The medical oncologist was cautious about starting systemic treatment because the PET-CT had FDG-avid diffuse ground glass opacities in both lung fields, and requested for a bronchoscopic evaluation, which returned positive for Pneumocystis jirovecii. In light of this new finding, a multi-disciplinary discussion and a review of the brain MRI were undertaken, during which it was concluded that the likelihood of cerebral toxoplasmosis was much higher than brain metastases. She was treated with high dose trimethoprim-sulfamethoxazole for both P. jirovecii pneumonia and cerebral toxoplasmosis, with clinical and radiological improvement. This case highlights the importance of (a) clinical input in interpreting imaging findings, (b) entertaining the possibility of multiple concurrent pathologies explaining a patient’s symptoms, (c) being open to alternate diagnoses when new information surfaces even though the current working diagnosis is the most plausible and (d) multi-disciplinary communication when faced with diagnostic difficulty.

Hemichorea-Hemiballismus as a Presentation of Cerebritis from Intracranial Toxoplasmosis and Tuberculosis

Background

There is limited literature documenting hemichorea-hemiballism (HCHB) resulting from co-infection of toxoplasmosis and tuberculosis (TB) in acquired immunodeficiency syndrome (AIDS). Toxoplasmic abscess is the most common cause while TB is a rare etiology.

Case Description

We describe a 24-year-old male with AIDS-related HCHB as the presentation of cerebritis on the right subthalamic nucleus and cerebral peduncle from intracranial toxoplasma and TB co-infection. Antimicrobials and symptomatic therapy were given. Marked improvement was seen on follow-up.

Discussion

HCHB may be the initial presentation of intracranial involvement of this co-infection in the setting of AIDS and is potentially reversible with timely management.

Highlights

Hemichorea-hemiballismus (HCHB) may be an initial presentation of intracranial involvement of concomitant toxoplasmosis and tuberculosis causing focal cerebritis in the contralateral subthalamic nucleus and cerebral peduncle, particularly in the setting of human immunodeficiency virus infection.Acquired immunodeficiency syndrome-related HCHB is potentially reversible with timely diagnosis and treatment.

Cerebral toxoplasmosis with multiple hemorrhage lesions in an HIV infected patient: A case report and literature review

A 47-year-old man was admitted to a hospital for disturbance of consciousness. He was diagnosed with multiple hemorrhagic brain abscesses in bilateral hemispheres with human immunodeficiency virus (HIV) infection, and was transferred to our hospital for further examination and treatment. On admission, although he could respond to pain stimuli, he could not talk or communicate. His laboratory data on admission revealed CD4-positive T cell count of 67 cells/μL, and HIV1-RNA viral load of 5.6 × 10⁵ copies/mL. Both the serum IgG Toxoplasma gondii antibody and the cerebrospinal fluid polymerase chain reaction for Toxoplasma gondii DNA were positive. He was diagnosed with cerebral toxoplasmosis and HIV infection. His level of consciousness worsened, and the number of hemorrhagic lesions had increased in both hemispheres and the left thalamus on the computed tomography scan following two weeks of antitoxoplasma therapy. These newly discovered hemorrhagic lesions revealed in the CT had been found as the high intensity signal regions of initial fluid-attenuated inversion recovery magnetic resonance imaging. After five weeks of treatment, the hemorrhagic lesions gradually improved along with the patient's consciousness. Antiretroviral therapy was initiated six weeks following antitoxoplama therapy with reassurance that immune reconstitution inflammatory syndrome did not occur. After approximately four months of antitoxoplasma therapy, the patient was discharged into a group home with residual left hemiparesis on maintenance antitoxoplasma and antiretroviral therapy. Clinicians should recognize the delay of clinical and radiological improvement for hemorrhagic cerebral toxoplasmosis and patiently continue the antitoxoplasma therapy.

Cerebral toxoplasmosis and alcohol abuse in AIDS: dementia with multiple etiologies

Major neurocognitive disorder due to multiple etiologies, or dementia due to multiple etiologies (DME), is a term coined by the Diagnostic and Statistical Manual of Mental Disorders to refer to complex cases when multiple pathologies, such as Alzheimer's disease, Lewy Bodies, human immunodeficiency virus (HIV), vascular-related brain damage or frontotemporal lobar degeneration, are identified as contributing to neurocognitive impairment and/or behavioral alterations, based on patient's neuroimaging tests, laboratorial exams, associated symptomatology and medical history. In this study, we report the case of a 63-year-old male patient who presented with parkinsonism symptoms, aphasia and cognitive impairment on multiple domains after cerebral toxoplasmosis related to acquired immunodeficiency syndrome, vascular damage and a history of alcohol abuse. We discuss the neurocognitive and neurobehavioral variables that characterized this diagnosis, as well as the importance of the differential diagnosis of DME on the field of neuropsychology of aging and, especially, for individuals living with HIV infection.

The Use of Adjunctive Steroids in Central Nervous Infections

Central nervous system (CNS) infections continue to be associated with significant neurological morbidity and mortality despite various existing therapies. Adjunctive steroid therapy has been employed clinically to reduce inflammation in the treatment of CNS infections across various causative pathogens. Steroid therapy can potentially improve clinical outcomes including reducing mortality rates, provide no significant benefit, or cause worsened outcomes, based on the causative agent of infection. The data on benefits or harms of adjunctive steroid therapy is not consistent in outcome or density through CNS infections, and varies based on the disease diagnosis and pathogen. We summarize the existing literature on the effects of adjunctive steroid therapy on outcome for a number of CNS infections, including bacterial meningitis, herpes simplex virus, West Nile virus, tuberculosis meningitis, cryptococcal meningitis, Angiostrongylus cantonensis, neurocysticercosis, autoimmune encephalitis, toxoplasmosis, and bacterial brain abscess. We describe that while steroid therapy is beneficial and supported in pathogens such as pneumococcal meningitis and tuberculosis, for other diseases, like Listeria monocytogenes and Cryptococcus neoformans they are associated with worse outcomes. We highlight areas of consistent and proven findings and those which need more evidence for supported beneficial clinical use of adjunctive steroid therapy.

Serology for Toxoplasma in Immunocompromised Patients: Still Useful?

Toxoplasmosis represents one of the most common comorbidity factors in solid organ or hematopoietic stem cell transplant recipients as well as in other immunocompromised patients. In the past decades, availability and performance of molecular tools for the diagnosis or the exclusion of toxoplasmosis in these patients have greatly improved. However, if accurately used, serology remains a complementary and essential diagnostic tool for physicians and medical parasitologists for the prevention and management of toxoplasmosis in immunocompromised patients as well. It is required for determination of the immunological status of patients against Toxoplasma. It also helps diagnose and monitor complex cases of opportunistic Toxoplasma infection in immunocompromised patients. New perspectives are available to further enhance their yield and ease of use.

Duffy blood group system and ocular toxoplasmosis

Duffy blood group phenotypes [Fy(a + b-), Fy(a-b+), Fy(a + b+), Fy(a-b-)], characterized by the expression of Fy^a, and Fy^b antigens, are present in red blood cells. Therefore, we hypothesize that the non-hematopoietic expression of these antigens might influence cell invasion by T. gondii. 576 consecutive patients from both genders were enrolled. The presumed OT clinical diagnosis was performed. Duffy phenotyping was performed by hemagglutination in gel columns and for the correct molecular characterization Fy(a-b-) phenotype, using PCR-RFLP. Anti-T. gondii IgG antibodies were detected by ELISA. Chi-square, Fisher's exact tests were used to compare the proportions. OT was present in 22.9% (n = 132) and absent in 77.1% (n = 444) of patients. The frequencies of anti-T. gondii IgG antibodies were higher in OT (127/132, 96.2%) than those without this disease (321/444, 72.3%) (p < .0001). None of the Duffy antigens or phenotypes were associated with T. gondii infection (χ2: 2.222, GL: 3, p = .5276) as well as the risk of OT (χ2: 0.771, GL: 3, p = .8566). Duffy blood group system phenotypes and their antigens do not constitute risk factors for infection by T. gondii infection and the development of OT.

Temporal expression of Toxoplasma stage-specific genes in brain tissue: coincidence with parasitological and histopathological findings in mice models

In the intermediate hosts, tachyzoites of T. gondii predominate in the acute stage while bradyzoites persist inside tissue cysts with the potential for reactivation. The two stages exhibit different metabolic and antigenic characters. The present study aimed to investigate temporal expression of Toxoplasma SAG1 and BAG1 genes in the brain tissue and the coincident parasitological and histopathological findings in mice models of toxoplasmosis. The study included group A: mice infected with RH strain and sacrificed 7 days post-infection (p.i.); group B: mice infected with RH strain and treated with sulfamethoxazole-trimethoprim (30 mg/kg/day and 150 mg/kg/day respectively) 24 h p.i. until sacrificed at days 5, 10, or 20 post-treatment; group C: mice infected with ME-49 strain and sacrificed at days 7, 27, 47, or 67 p.i; and group D: mice infected with ME-49 strain and received dexamethasone daily starting at day 68 p.i. and scarified at days 6 or 10 post-treatment. All mice were inspected daily for abnormal physical signs. Peritoneal exudate and brain homogenate were examined for detection of Toxoplasma stages. Brain sections were examined histopathologically. SAG1 and BAG1 gene expression was evaluated using reverse transcription real-time polymerase chain reaction and the ΔΔCt method. Results revealed that marked BAG1 upregulation is consistent with detection of Toxoplasma cysts and degenerative changes while predominance of tachyzoites and inflammatory infiltrate is compatible with SAG1 upregulation. The study sheds light on the potential for using stage-specific gene expression pattern as markers for evaluation of toxoplasmosis disease progression in clinical settings.

Anti-toxoplasma, antioxidant and cytotoxic activities of Pleopeltis crassinervata (Fée) T. Moore hexane fraction

The apicomplexan parasite Toxoplasma gondii (T. gondii) causes toxoplasmosis in humans. Pyrimethamine and sulfadiazine that are the drugs of choice to treat the disease, produce severe side effects as well as failure treatments because of drug resistance; thus, novel anti-Toxoplasma compounds are needed and natural compounds can be a good source to obtain them, as medicinal plants have been used to control other apicomplexan parasites. Pleopeltis crassinervata (P. crassinervata) is a fern used in some rural areas of Mexico to treat among other malaises, mouth ulcers, gastrointestinal problems and parasites. Therefore, the efficacy of extracts and fractions obtained from P. crassinervata fronds was evaluated on the viability of T. gondii RH strain tachyzoites by the Stytox green method. RH is the prototypical type 1 Toxoplasma strain, isolated for the first time from the brain of a patient boy named R. H. Its phytochemical profile, MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, Hep-2 cytotoxicity and antioxidant activity by ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods, were also assessed. Hexane fraction exhibited the highest anti-Toxoplasma activity with an IC50 of 16.90 µg/mL. This fraction did not show antioxidant activity and contained at least 2 terpenoid type compounds with retention factor (Rf) of 0.75 and 0.86. The fraction was not toxic to the host cells in doses up to 50 µg/mL. P. crassinervata frond hexane fraction seems to be a good candidate to obtain possible anti-Toxoplasma compounds. This study is the first to report the biological, antioxidant and cytotoxic activity of P. crassinervata fern.

Plasma extracellular microRNAs are related to AIDS/cerebral toxoplasmosis co-infection

This study investigated the potential of five miRNA candidates for cerebral toxoplasmosis/HIV co-infection (CT/HIV) biomarkers. miR-155-5p, miR-146a-5p, miR-21-5p, miR-125b-5p and miR-29c-3p were tested in 79 plasma divided into groups: 32 CT/HIV patients; 27 individuals with asymptomatic toxoplasmosis (AT); and 20 individuals seronegative for toxoplasmosis (NC). From each was collected peripheral blood/EDTA for laboratory diagnosis. Blood cells for DNA extractions (molecular diagnosis), plasma for RNA extractions (gene expression) and ELISA (serological diagnosis). miRNA expression was performed by qPCR, and values were expressed in Relative Quantification (RQ). Among the five miRNAs, miR-21-5p and miR-146a-5p were up-expressed in CT/HIV group when compared with AT and NC groups. RQ means for miR-21-5p and miR-146a-5p in CT/HIV group were 3.829 and 2.500, while in AT group, were 1.815 and 1.661, respectively. Differences between 3 groups were statistically significant (Kruskal-Wallis ANOVA test), as well as CT/HIV and AT groups (Mann-Whitney test). Plasma of CT/HIV and AT groups expressed similar levels of miR-29c-3p, miR-155-5p and miR-125b-5p. As NC group was different of CT/HIV and AT groups, differences between three groups were statistically significant (Kruskal-Wallis ANOVA test). No difference was shown between CT/HIV and AT groups (Mann-Whitney test). These results suggest the host miRNAs modulation by Toxoplasma gondii.

Serum IgG Anti-Toxoplasma gondii Antibody Concentrations Do Not Correlate Nested PCR Results in Blood Donors

Background:Toxoplasma gondii infects millions of individuals worldwide. This protozoan is food and water-borne transmitted but blood transfusion and organ transplantation constitute alternative forms for transmission. However, the influence of IgG anti-T. gondii antibodies in molecular analysis carried out in peripheral blood still remain unclear. This study aimed to investigate the serum IgG anti-T. gondii antibody concentrations correlate Nested PCR results in blood donors.

Methods: 750 blood donors were enrolled. IgM and IgG anti-T. gondii antibodies were assessed by ELISA (DiaSorin, Italy). Nested PCR was performed with primers JW62/JW63 (288 bp) and B22/B23 (115 bp) of the T. gondii B1 gene. The mean values of IgG concentration were compared for PCR positive and PCR Negative blood donors using the t-test or Mann-Whitney according to the normal distribution (p-value ≤ 0.05).

Results: 361 (48.1%) blood donors presented positive serology as follow: IgM⁺/IgG⁻: 5 (0.6%); IgM⁺/IgG⁺: 21 (2.8%); IgM⁻/IgG⁺: 335 (44.7%) and 389 (51.9%), negative serology. From 353 blood donors with positive serology tested, the Nested PCR was positive in 38 (10.8%) and negative in 315 (89.2%). There were no differences statistically significant between the mean values of serum IgG anti-T. gondii antibody concentrations and the Nested PCR results.

Conclusions: In conclusion, our data show that variations in the serum IgG anti-T. gondii antibody concentrations do not correlate T. gondii parasitemia detected by Nested PCR in chronically infected healthy blood donors.