Restoration of Toxoplasma gondii-specific immune responses in patients with AIDS starting HAART

Latent toxoplasmosis is associated with neurocognitive impairment in young adults with and without chronic HIV infection

We evaluated the impact of latent toxoplasmosis (LT) on neurocognitive (NC) and neurobehavioural functioning in young adults with and without chronic HIV infection, using a standardised NC test battery, self-reported Beck Depression Inventory, Frontal System Behavior Scale, MINI-International Neuropsychiatric Interview and risk-assessment battery. 194 young adults (median age 24years, 48.2% males) with chronic HIV infection (HIV+) since childhood and 51 HIV seronegative (HIV-) participants were included. HIV+ individuals had good current immunological status (median CD4: 479 cells/μl) despite a low CD4 nadir (median: 93 cells/μl). LT (positive anti-Toxoplasma IgG antibodies) was present in one third of participants. The impairment rates in the HIV- with and without Toxo were not significantly different (p=0.17). However, we observed an increasing trend (p<0.001) in impairment rates with HIV and LT status: HIV-/LT- (6.1%); HIV-/LT+ (22%), HIV+/LT- (31%), HIV+/LT+ (49%). In a multivariable analysis using the entire study group there were main effects on cognition for HIV and also for LT. Within the HIV+ group LT was associated with worse performance globally (p=0.006), in memory (p=0.009), speed of information processing (p=0.01), verbal (p=0.02) and learning (p=0.02) domains. LT was not associated with depressive symptoms, frontal systems dysfunction or risk behaviors in any of the groups. HIV participants with lower Toxoplasma antibody concentration had worse NC performance, with higher GDS values (p=0.03) and worse learning (p=0.002), memory (p=0.006), speed of information processing (p=0.01) T scores. Latent Toxoplasmosis may contribute to NC impairment in young adults, including those with and without chronic HIV infection.

Relevance of and New Developments in Serology for Toxoplasmosis

Toxoplasmosis is a widespread parasitic disease caused by the intracellular parasite Toxoplasma gondii with a wide spectrum of clinical outcomes. The biological diagnosis of toxoplasmosis is often difficult and of paramount importance because clinical features are not sufficient to discriminate between toxoplasmosis and other illnesses. Serological tests are the most widely used biological tools for the diagnosis of toxoplasmosis worldwide. This review focuses on the crucial role of serology in providing answers to the most important questions related to the epidemiology and diagnosis of toxoplasmosis in human pathology. Notwithstanding their undeniable importance, serological tools need to be continuously improved and the interpretation of the ensuing results remains complex in many circumstances.

Toxoplasma encephalitis in an HIV-infected patient on highly active antiretroviral therapy despite sustained immune response

Toxoplasma encephalitis (TE) is usually diagnosed in advanced stages of HIV infection when the CD4+ count is <100–200 cells/µl. A 55-year-old woman with HIV/AIDS, well controlled on antiretroviral therapy (ART), CD4+ count in the 300 cells/μl range for >1 year presented with acute onset of headache, nausea and vomiting. She had been on her current ART regimen consisting of raltegravir, co-formulated emtricitabine/tenofovir and etravirine for three years and had been off Pneumocystis prophylaxis for 10 months (trimethoprim-sulfamethoxazole). Brain MRI showed multiple ring-enhancing, supratentorial and infra-tentorial parenchymal lesions suspicious for metastases. She had no other evidence of metastatic disease in her body. The possibilities of TE and primary CNS lymphoma were considered but deemed unlikely given the high CD4+ count. A brain biopsy demonstrated Toxoplasma tachyzoites. There was no evidence of lymphoma or carcinoma. Anti-toxoplasma treatment yielded good initial clinical and radiographic responses. While on TE maintenance therapy, she developed similar symptoms. Repeat MRI showed progression of lesions. Further work-up including CSF Epstein-Barr virus PCR and SPECT Th 201 imaging was not conclusive for CNS lymphoma. The patient’s clinical condition deteriorated and she died. We postulate that functional immunological dysfunction is a possible mechanism by which our patient developed TE despite demonstrating sustained immune response on ART.

Therapy and prophylaxis of opportunistic infections in HIV-infected patients: a guideline by the German and Austrian AIDS societies (DAIG/ÖAG) (AWMF 055/066)

INTRODUCTION

There was a growing need for practical guidelines for the most common OIs in Germany and Austria under consideration of the local epidemiological conditions.

MATERIALS AND METHODS

The German and Austrian AIDS societies developed these guidelines between March 2010 and November 2011. A structured Medline research was performed for 12 diseases, namely Immune reconstitution inflammatory syndrome, Pneumocystis jiroveci pneumonia, cerebral toxoplasmosis, cytomegalovirus manifestations, candidiasis, herpes simplex virus infections, varizella zoster virus infections, progressive multifocal leucencephalopathy, cryptosporidiosis, cryptococcosis, nontuberculosis mycobacteria infections and tuberculosis. Due to the lack of evidence by randomized controlled trials, part of the guidelines reflects expert opinions. The German version was accepted by the German and Austrian AIDS Societies and was previously published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF; German Association of the Scientific Medical Societies).

CONCLUSION

The review presented here is a translation of a short version of the German-Austrian Guidelines of opportunistic infections in HIV patients. These guidelines are well-accepted in a clinical setting in both Germany and Austria. They lead to a similar treatment of a heterogeneous group of patients in these countries.

Incidence and clinical and immunological characteristics of primary Toxoplasma gondii infection in HIV-infected patients

OBJECTIVES

To determine the incidence and laboratory characteristics of primary Toxoplasma gondii infection in HIV-infected individuals.

METHODS

This retrospective study was conducted between 1988 and 2012 on a cohort of 1130 HIV-infected patients at the AIDS Center Prague. Toxoplasma serology, standard laboratory parameters, and health status were evaluated at 3-6-month intervals for all patients.

RESULTS

The total person-time of follow-up of patients at risk of Toxoplasma seroconversion was 3046.3 years; there were 14 primary T. gondii infections, yielding an incidence rate of 0.0046 (95% confidence interval 0.0027-0.0078). Most of the subjects were clinically asymptomatic, but in one case seroconversion was accompanied by transient cervical lymphadenopathy. The CD4+ T-lymphocyte count geometric mean increased from 418 (95% confidence interval 303-579) cells/μl before seroconversion to 501 (95% confidence interval 363-691) cells/μl after seroconversion (p = 0.004), while other parameters (CD8+ T-lymphocytes, natural killer cells, viral load, beta2-microglobulin, total immunoglobulins) remained unchanged. As compared to the control group, patients with primary toxoplasmosis had higher initial levels of total immunoglobulins IgA and IgG and a tendency to higher CD8+ T lymphocyte counts.

CONCLUSIONS

Neither the incidence nor the course of the primary Toxoplasma infection was influenced by the immune status of the patients. Immune parameters of patients with primary Toxoplasma infection did not differ from those of the controls.

Activity of antiretroviral drugs in human infections by opportunistic agents

Highly active antiretroviral therapy (HAART) is used in patients infected with HIV. This treatment has been shown to significantly decrease opportunist infections such as those caused by viruses, fungi and particularly, protozoa. The use of HAART in HIV-positive persons is associated with immune reconstitution as well as decreased prevalence of oral candidiasis and candidal carriage. Antiretroviral therapy benefits patients who are co-infected by the human immunodeficiency virus (HIV), human herpes virus 8 (HHV-8), Epstein-Barr virus, hepatitis B virus (HBV), parvovirus B19 and cytomegalovirus (CMV). HAART has also led to a significant reduction in the incidence, and the modification of characteristics, of bacteremia by etiological agents such as Staphylococcus aureus, coagulase negative staphylococcus, non-typhoid species of Salmonella, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. HAART can modify the natural history of cryptosporidiosis and microsporidiosis, and restore mucosal immunity, leading to the eradication of Cryptosporidium parvum. A similar restoration of immune response occurs in infections by Toxoplasma gondii. The decline in the incidence of visceral leishmaniasis/HIV co-infection can be observed after the introduction of protease inhibitor therapy. Current findings are highly relevant for clinical medicine and may serve to reduce the number of prescribed drugs thereby improving the quality of life of patients with opportunistic diseases.

Immune-recovery posterior uveitis associated with inactive isolated toxoplasmic retinochoroiditis in a patient with human immunodeficiency virus

PURPOSE

To report a case of severe panuveitis in a patient with human immunodeficiency virus that developed after inactivation of toxoplasmic retinochoroiditis. The patient also developed cerebral toxoplasmosis.

METHODS

A patient with human immunodeficiency virus who developed immune-recovery posterior uveitis in the context of inactive toxoplasmic retinochoroiditis underwent complete ophthalmologic evaluation, polymerase chain reaction of the aqueous humor, diagnostic vitrectomy, and cerebral ancillary testing.

RESULTS

Polymerase chain reaction-confirmed toxoplasmic retinochoroiditis healed with appropriate treatment, but 2 months later coinciding with systemic immune restoration, the brain lesions worsened and immune-recovery panuveitis caused decreased visual acuity. Diagnostic vitrectomy confirmed only inflammatory cells.

CONCLUSION

Immune-recovery panuveitis caused by cytomegalovirus retinitis is well documented, but we found only one published case caused by toxoplasma. Immune-recovery panuveitis should not be ruled out despite the absence of previous cytomegalovirus retinitis. A patient with human immunodeficiency virus who has had an intraocular opportunistic infection, despite resolution, must be followed-up by an ophthalmologist in collaboration with an infectious disease specialist to prevent blindness.

Parasitic infections in HIV infected individuals: diagnostic & therapeutic challenges

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leishmaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection.

Varicella-zoster virus-specific cell-mediated immune responses in HIV-infected adults

The incidence of herpes zoster remains high in HIV-infected patients despite the use of combined antiretroviral therapy (cART). We wished to assess varicella-zoster virus (VZV)-specific cell-mediated immune (CMI) responses in HIV-infected adults on cART. VZV-specific CMI responses were assessed using lymphocyte proliferative responses, cytokine production (IL-2, TNF-α, and IFN-γ), and interferon-γ ELISPOT assays in 103 HIV-infected adults and 30 healthy controls. HIV-infected patients were analyzed according to their current and nadir CD4 cell count and their use of cART. A multivariate analysis was performed to identify factors associated with VZV-specific CMI responses. HIV-infected patients had lower VZV-specific CMI responses than healthy controls. Patients with a CD4 T cell count <100/μL had almost no detectable responses whereas those with a current CD4 T cell count >300/μL and suppressed viral replication on cART had responses similar to those of healthy controls. In multivariate analysis, factors significantly associated with VZV-specific CMI responses were the absence of a previous AIDS-defining event and higher CD4 cell counts, in particular central and effector memory CD4 T cell counts. HIV-infected patients with a history of AIDS or low CD4 cell counts have impaired VZV-specific CMI responses, and remain at risk for herpes zoster.