Central nervous system infections in individuals with HIV-1 infection

Prevalence of Toxoplasma gondii in HIV-Infected Individuals in Iran: A Systematic Review and Meta-Analysis

INTRODUCTION

Toxoplasma gondii is an obligate intracellular protozoan that can infect almost all warm-blooded animals, including humans. Patients with co-infection with toxoplasmosis and HIV have a 30-40% risk of developing toxoplasmosis encephalitis. This study aimed to describe the epidemiology and burden of Toxoplasma gondii in HIV-infected individuals in Iran.

METHODS

We searched the five English databases (Science Direct, PubMed, Scopus, Ovid, Embase, and Cochrane) and four Persian databases (Scientific Information Database (SID), Iran Medex, Iran Doc, and Magiran) with the terms of (Toxoplasma gondii OR "toxoplasmosis") AND (HIV OR "AIDS" OR immunodeficiency OR acquired immune deficiency syndrome) AND (Seroprevalence) AND (Seroepidemiologic Studies) AND (Elisa OR IgG) AND (PCR) AND (Iran) by two authors up to Feb 2021. Studies were included if they investigated people with HIV infection and presented data that allowed us to establish the prevalence of Toxoplasma gondii infection in Iran.

RESULTS

According to the inclusion/exclusion criteria, 15 studies were selected. A total number of 2275 HIV-infected individuals were tested and evaluated for toxoplasmosis from 2005 up to 2018 in different regions of Iran. The weighted overall prevalence of toxoplasmosis in HIV-infected individuals with Elisa was obtained using a random-effects model, which was estimated at 47% (95% CI = 31% - 62%). Also, the Weighted overall prevalence of toxoplasmosis in HIV-infected individuals with PCR was obtained using a random-effects model, which was estimated at 7% (95% CI = 3% - 12%).

CONCLUSION

According to the results of this study, it can be clearly understood that a large population of HIV patients living in Iran have toxoplasmosis. Therefore, due to the high susceptibility of these groups to toxoplasmosis, healthcare professionals must consider measures such as training in the ways of transmission and prevention of the infection to this high-risk group in order to reduce the risk of infection.

Cause of hospitalization and death in the antiretroviral era in Sub-Saharan Africa published 2008-2018: A systematic review

BACKGROUND

Worldwide despite the availability of antiretroviral therapy, human immunodeficiency virus/acquired immunodeficiency syndrome still causes morbidity and mortality among patients. In Sub-Saharan Africa, human immunodeficiency virus/acquired immunodeficiency syndrome remains a major public health concern. The aim of this study was to identify the causes of morbidity and mortality in the modern antiretroviral therapy era in Sub-Saharan Africa.

METHODS

We conducted a systematic review according to the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. We searched relevant studies from 3 databases which are Google Scholar, PubMed, and CINAHL. Two review authors independently screened titles, abstracts, and full-text articles in duplicate, extracted data, and assessed bias. Discrepancies were resolved by discussion or arbitration of a third review author. R software version 3.6.2 was used to analyze the data. Maximum values were used in order to show which disease was mostly spread out by looking at the highest prevalence reported. This systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO).

RESULTS

A total of 409 articles were obtained from the database search, finally 12 articles met the inclusion criteria and were eligible for data extraction. Among them, 3 were conducted in Nigeria, 2 were conducted in Uganda, 3 were conducted in South Africa, 1 in Gabon, 1 in Ethiopia, 1 in Ghana, and 1 in Burkina Faso. In most of the included studies, tuberculosis was the leading cause of hospitalization which accounted for between 18% and 40.7% and it was also the leading cause of death and accounted for between 16% and 44.3%, except in 1 which reported anemia as the leading cause of hospitalization and in 2 which reported wasting syndrome and meningitis respectively as the leading causes of death. Opportunistic malignancies accounted between for 1.8% to 5% of hospitalization and 1.2% to 9.8% of deaths.

CONCLUSIONS

Tuberculosis is the commonest cause of hospitalization and death in Sub-Saharan Africa, but it is always followed by other infectious disease and other non-AIDS related causes.

Clinical Signs and Laboratory Parameters as Predictors of Mortality among Hospitalized Human Immunodeficiency Virus-Infected Adult Patients at Tertiary Hospital in Surabaya

BACKGROUND: The morbidity and mortality rates due to human immunodeficiency virus (HIV) infection are still high despite various and advanced efforts in the management given for HIV/AIDS patients. AIM: This study proposed that clinical signs and laboratory parameters could be expected to predict the patient’s mortality. METHODS: This retrospective study was done by collecting 408 medical records of adult HIV/AIDS inpatients at a tertiary hospital in Surabaya from January 1, 2017, to December 31, 2019. Bivariate analysis using Chi-square test was carried out on nine variables, which were Glasgow Coma Scale (GCS) <15, hypotension, PaO2/FiO2 <400 mmHg, elevated liver enzymes, hemoglobin levels <10 mg/dl, platelet count <150,000/mm3, eGFR <60 ml/min/1.73 m2, albumin levels <3.5 mg/dl, and body mass index (BMI) <18.5 kg/m2. Variables which met the criteria would be included in the multivariate analysis using logistic regression. RESULTS: Based on bivariate analysis, mortality was found to be significantly associated with GCS <15, hypotension, PaO2/FiO2, elevated liver enzymes, platelet count <100,000 mm3, eGFR <60 ml/1.73kg/m2, albumin levels <3.5 mgdl, and BMI <18.5 kg/m2. However, based on multivariate analysis, there were five variables which were found to be able to independently predict the patients’ mortality, those were GCS <15 (OR 11.625), hypotension (OR 6.062), PaO2/FiO2< 400 mmHg (OR 7.794), eGFR <60 ml/min/1.73 m2 (OR 2.646), and albumin levels <3.5 mg/dl (OR 4.091). CONCLUSION: GCS <15, hypotension, PaO2/FiO2 <400 mmHg, eGFR <60 ml/1.73g/m2, and albumin levels <3.5 mg/dl were found as the independent risk factors which could predict the hospitalized HIV/AIDS patients’ mortality.

Anti-Toxoplasmic Immunoglobulin G Quantitation Correlates with Immunovirological Parameters of HIV-Infected Cameroonians

BACKGROUND

Toxoplasmosis is still a neglected common opportunistic infection in immunocompromised individuals, who are mainly people living with HIV (PLHIV) in whom reactivation of toxoplasmosis may occur with advanced HIV conditions in resource-limited settings (RLS).

OBJECTIVE

The objective was to assess the correlation between anti-toxoplasmic immunoglobulin G (anti-Toxo IgG) concentration and the immuno-virological status of PLHIV.

METHODS

A cross-sectional study was conducted in the year 2018 among 100 PLHIV aged ≥18 years in Yaounde-Cameroon. For each participant, anti-Toxo IgG, CD4-T lymphocytes, and plasma viral load (PVL) were measured using ELISA, flow cytometry, and real-time PCR, respectively.

RESULTS

Overall, 56% of the participants were seropositive for anti-Toxo IgG, while 33% were negative and 11% were equivocal. All (n=19) those with PVL>1000 copies/mL were seropositive to anti-Toxo IgG versus 52.85% (37/70) with PVL<1000 copies/mL; p<0.0001. Interestingly, all (n=11) those with severe immunodeficiency (T-CD4<200 cells/μL) were positive to anti-Toxo IgG versus 57.69% (45/78) with T-CD4>200 cells/μL; p<0.0001. Most importantly, PVL and anti- Toxo IgG concentration were positively correlated (r = 0.54; p<0.0001), while T-CD4 and anti- Toxo IgG concentration were negatively correlated (r = - 0.70; p<0.0001). Adjusting age, gender, immune status, and virological profile in logistic regression shows that only immune status was independently associated with the serological status of toxoplasmosis (p=0.0004).

CONCLUSION

In Cameroon, about half of PLHIV might be seropositive to anti-Toxo IgG, with decreasing immunity appearing as a risk of toxoplasmosis relapse. Thus, in the context of immunodeficiency, routine quantification of anti-Toxo IgG would alleviate the programmatic burden of this opportunistic infection in RLS with the generalized HIV epidemic.

Imaging in Differentiating Cerebral Toxoplasmosis and Primary CNS Lymphoma With Special Focus on FDG PET/CT

OBJECTIVE. The purpose of this article is to present a brief review of literature evaluating different imaging modalities with special focus on ¹⁸F-FDG PET/CT in differentiating cerebral toxoplasmosis and primary CNS lymphoma. CONCLUSION. Differentiating cerebral toxoplasmosis and primary CNS lymphoma is crucial in the care of patients with HIV infection. Delayed diagnosis can lead to considerable morbidity and mortality. The reference standard for diagnosis is biopsy and histopathologic examination. Biopsy has disadvantages due to its invasive nature and associated complications. Noninvasive imaging can be an alternative to biopsy for differentiation of toxoplasmosis and primary CNS lymphoma. Despite advances in MRI techniques, prophylaxis of opportunistic infection, and treatment of HIV infection, clinical situations continue to arise in which the diagnosis is not clear. In these instances, molecular imaging can be helpful.

Feline lymphoma in the nervous system: pathological, immunohistochemical, and etiological aspects in 16 cats

ABSTRACT: The pathological, immunohistochemical (IHC), and etiological features of lymphoma involving the nervous system (NS) in cats were analyzed through a retrospective study (2004-2017) in Rio Grande do Sul State, Brazil. The NS involvement was observed in 16 (12.2%) of 125 felines with lymphoma. Young cats were mainly affected, with a median of 24 months old. Most cases were secondary central NS lymphoma, whereas in three cats, the NS involvement was primary. IHC revealed 14 (87.5%) FeLV-positive, six FIV-positive, and one FeLV/FIV-negative cats. Distribution of feline lymphoma in the NS was 8/16 in the spinal cord, 7/16 in the brain, and 1/16 in the paravertebral nerves and ganglia (neurolymphomatosis). The lymphoma pattern in the spinal cord was exclusively extradural, often focal (6/8), and located in the lumbar (3/6), sacral (1/6), thoracic (1/6), and cervical segments (1/6). Brain neuroanatomical patterns were: leptomeningeal lymphomatosis (4/7), lymphomatous choroiditis (2/7), and intradural lymphoma (1/7). The feline with primary neurolymphomatosis presented a marked thickening of paravertebral nerves and ganglia from the sacral region. B-cell lymphoma (75%) was often diagnosed, and diffuse large B-cell lymphoma (DLBCL) (11/16) was the main subtype. T-cell lymphoma (25%) was less commonly observed and was classified as peripheral T-cell lymphoma (PTCL) (3/16) and T-cell lymphoblastic lymphoma (T-LBL) (1/16).

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

Cerebral toxoplasmosis is the most common cause of expansive brain lesions in people living with HIV/AIDS (PLWHA) and continues to cause high morbidity and mortality. The most frequent characteristics are focal subacute neurological deficits and ring-enhancing brain lesions in the basal ganglia, but the spectrum of clinical and neuroradiological manifestations is broad. Early initiation of antitoxoplasma therapy is an important feature of the diagnostic approach of expansive brain lesions in PLWHA. Pyrimethamine-based regimens and trimethoprim-sulfamethoxazole (TMP-SMX) seem to present similar efficacy, but TMP-SMX shows potential practical advantages. The immune reconstitution inflammatory syndrome is uncommon in cerebral toxoplasmosis, and we now have more effective, safe, and friendly combined antiretroviral therapy (cART) options. As a consequence of these 2 variables, the initiation of cART can be performed within 2 weeks after initiation of antitoxoplasma therapy. Herein, we will review historical and current concepts of epidemiology, diagnosis, and treatment of HIV-related cerebral toxoplasmosis.

Parasitic and fungal infections

Parasitic infections of the central nervous system (CNS) comprise a plethora of infectious agents leading to a multitude of different disease courses and thus diagnostic and therapeutic challenges. The prevalence of different pathogens is basically dependent on geographic and ethnic backgrounds, its infectious route frequently involving a third party, such as flies or domestic animals. The present review focuses on cerebral malaria due to Plasmodium falciparum infection, and Toxoplasma gondii encephalitis. Fungi produce a large variety of inflammatory conditions of the CNS with a variegated spectrum of signs and symptoms, which may involve the meninges and the brain parenchyma, where they produce cerebritis or abscesses and granulomatous lesions, respectively. Fungal CNS lesions are increasingly prevalent and diagnostically relevant due to increasing numbers of human immunodeficiency virus-positive patients, increasing numbers of patients reaching old age suffering from malignant tumors or decreased immunity, and finally the increasing use of established and new immunosuppressive treatments, which increase the susceptibility of patients to develop invasive mycoses. Fungi appear with characteristic morphotypes comprising hyphae, yeasts, and pseudohyphae. The mode by which fungi penetrate into the CNS, and the host/immune requirements are incompletely understood and remain a challenge for research.

Impact of the host on Toxoplasma stage differentiation

The unicellular parasite Toxoplasma gondii infects warm-blooded animals and humans, and it is highly prevalent throughout the world. Infection of immunocompetent hosts is usually asymptomatic or benign but leads to long-term parasite persistence mainly within neural and muscular tissues. The transition from acute primary infection towards chronic toxoplasmosis is accompanied by a developmental switch from fast replicating and metabolically highly active tachyzoites to slow replicating and largely dormant bradyzoites within tissue cysts. Such developmental differentiation is critical for T. gondii in order to complete its life cycle and for pathogenesis. Herein, we summarize accumulating evidence indicating a major impact of the host cell physiology on stage conversion between the tachyzoite and the bradyzoite stage of the parasite. Withdrawal from cell cycle progression, proinflammatory responses, reduced availability of nutrients and extracellular adenosine can indeed induce tachyzoite-to-bradyzoite differentiation and tissue cyst formation. In contrast, high glycolytic activity as indicated by increased lactate secretion can inhibit bradyzoite formation. These examples argue for the intriguing possibility that after dissemination within its host, T. gondii can sense its cellular microenvironment to initiate the developmental program towards the bradyzoite stage in distinct cells. This may also explain the predominant localization of T. gondii in neural and muscular tissues during chronic toxoplasmosis.

Seroprevalence of Toxoplasma gondii among HIV Patients in Jahrom, Southern Iran

Toxoplasma gondii is an important opportunistic agent especially in immunocompromised hosts and can cause significant morbidity and mortality. Hence, detection and monitoring of anti-Toxoplasma antibodies are of a great interest in HIV-infected patients. A study on the prevalence of toxoplasmosis and associated risk factors was carried out among HIV-infected patients in Jahrom, southern Iran. The prevalence of anti-Toxoplasma IgG antibodies was 21.1% in HIV-infected patients by ELISA. PCR was performed on all of the samples, and 1 of the blood samples was positively detected. Among the HIV patients, anti-Toxoplasma IgG antibodies were significantly higher in age group of 30-39 years old (P=0.05). The seroprevalence of toxoplasmosis in patients with CD4⁺<100 cells/μl was 33.3% that was significantly higher than the other groups (P=0.042) with or without IgG antibodies. The CD4⁺ count mean of seropositive patients was lower than that of seronegative patients. The seroprevalence of toxoplasmosis in patients with highly active antiretroviral therapy was significantly less than patients without therapy (P=0.02). In conclusion, this study showed low seroprevalence of latent toxoplasmosis among HIV-infected patients in the region and confirmed the need for intensifying prevention efforts among this high-risk population and also the risk of toxoplasmosis reactivation which could be important among this population.

A meta-analysis of HIV and heart rate variability in the era of antiretroviral therapy

BACKGROUND

Heart rate variability (HRV) has been used to assess autonomic dysfunction since the beginning of the HIV epidemic. Although autonomic failure was commonly detected in HIV and AIDS patients prior to the advent of antiretroviral therapy (ART), the effect of HIV on HRV in the current era of widespread ART availability is more ambiguous.

METHODS

A systematic search and review was conducted on cross-sectional observational and case-control studies published in the era of ART (1996-2015) that compared HRV between HIV + individuals treated with ART and HIV - controls. Eight out of the 20 studies identified, enrolling a total of 292 HIV + adults (mean age 38.7 years) and 201 HIV seronegative controls (mean age 35.1 years), were included in a meta-analysis based on stringent methodological criteria.

RESULTS

At rest, individuals with HIV showed lower HRV in the time (g) = -0.72, 95 % CI (-1.03 to -0.42) and low-frequency (LF) domain (g) = -0.51, (-0.81 to -0.21); markers of lower parasympathetic tone in the time (g) = -0.55, (-0.85 to -0.25) and high-frequency (HF) domain (g) = -0.42, (-0.71 to -0.12); and higher LF:HF ratio (g) = 0.46, (0.12-0.86) in the frequency domain, suggestive of parasympathetic withdrawal.

CONCLUSION

This meta-analysis confirmed, within a relatively young cohort of HIV + adults on ART, a general reduction in autonomic function with a shift toward sympathetic dominance. This shift may predispose HIV patients to early and elevated risk of arrhythmias, cardiac events, and accelerated HIV disease progression.

Gene Editing for Treatment of Neurological Infections

The study of neurological infections by viruses defines the field of neurovirology, which has emerged in the last 30 years and was founded upon the discovery of a number of viruses capable of infecting the human nervous system. Studies have focused on the molecular and biological basis of viral neurological diseases with the aim of revealing new therapeutic options. The first studies of neurovirological infections can be traced back to the discovery that some viruses have an affinity for the nervous system with research into rabies by Louis Pasteur and others in the 1880s. Today, the immense public health impact of neurovirological infections is illustrated by diseases such as neuroAIDS, progressive multifocal leukoencephalopathy, and viral encephalitis. Recent research has seen the development of powerful new techniques for gene editing that promise revolutionary opportunities for the development of novel therapeutic options. In particular, clustered regulatory interspaced short palindromic repeat-associated 9 system provides an effective, highly specific and versatile tool for targeting DNA viruses that are beginning to allow the development of such new approaches. In this short review, we discuss these recent developments, how they pertain to neurological infections, and future prospects.

Evolution of Cryptococcal Antigen Testing: What is new?

Over the last decade, an upsurge in both the frequency and severity of fungal infections due to the HIV/AIDS epidemic and the use of immunosuppressive therapy has occurred. Even diagnostic methods like culture and microscopy, which have low sensitivity and longer turn-around-times are not widely available, leading to delays in timely antifungal therapy and detrimental patient outcomes. The evolution of cryptococcal antigen (CrAg) testing to develop inexpensive and more sensitive methods to detect cryptococcal antigen is significant. These newer tests employ immunoassays as part of point-of-care platforms, which do not require complex laboratory infrastructure and they have the potential to detect early disease and reduce time to diagnosis of cryptococcal infection. Advocacy for widely available and efficacious life-saving antifungal treatment should be the only remaining challenge.

ISOLATION OF Cryptococcus neoformans FROM ENVIRONMENTAL SAMPLES COLLECTED IN SOUTHEASTERN NIGERIA

Cryptococcosis caused by Cryptococcus neoformans is the second most common fungal opportunistic pathogen and a life-threatening infection with serious clinical manifestations especially in HIV/AIDS and other immunocompromised patients. In Nigeria, HIV/AIDS infection has reached an alarming level. Despite this, information on the presence of this fungus in clinical and environmental samples is very scanty in Nigeria and many other parts of Africa. We set out to evaluate the presence of Cryptococcus neoformans or C. gattiiin pigeon droppings obtained from Southeastern Nigeria. One hundred and seventy-seven samples of pigeon droppings from six sample types were collected. The area covered comprised of ten cities and other locations spanning across five States in Nigeria. Using established techniques, Cryptococcus neoformans was isolated from 39 of the 177 (22.0%) samples overall. No C. gattiiwas isolated. Most of the isolates (32.4%) were recovered from dovecotes (11 of 34) followed closely by samples taken from markets (31.8%; seven of 22) and least from the church (4.0%; one of 25). The highest isolation rate (38.9%) was found in samples from Enugu-Ezike(seven of 23) while the least came from Afikpo and the other locations each with 9.1% isolation rate. This is the first large-scale screening of Cryptococcus neoformans from pigeon droppings in Nigeria. The ecological and epidemiological significance of these findings are discussed.

A Retrospective Cohort Study of Lesion Distribution of HIV-1 Infection Patients With Cryptococcal Meningoencephalitis on MRI: Correlation With Immunity and Immune Reconstitution

The objective of this paper is to correlate the MRI distribution of cryptococcal meningoencephalitis in HIV-1 infection patients with CD4 T cell count and immune reconstitution effect.A large retrospective cohort study of HIV patients from multi-HIV centers in China was studied to demonstrate the MRI distribution of cryptococcal meningoencephalitis and its correlation with the different immune status.The consecutive clinical and neuroimaging data of 55 HIV-1-infected patients with cryptococcal meningoencephalitis collected at multi-HIV centers in China during the years of 2011 to 2014 was retrospectively analyzed. The enrolled patients were divided into 2 groups based on the distribution of lesions. One group of patients had their lesions at the central brain (group 1, n = 34) and the other group of patients had their lesions at the superficial brain (group 2, n = 21). We explored their MRI characterization of brain. In addition, we also compared their CD4 T cell counts and immune reconstitution effects between the 2 groups based on the imaging findings.No statistical difference was found in terms of age and gender between the 2 groups. The medians of CD4 T cell counts were 11.67 cells/mm (3.00-52.00 cells/mm) in group 1 and 42.00 cells/mm (10.00-252.00 cells/mm) in group 2. Statistical difference of CD4 T cell count was found between the 2 groups (P = 0.023). Thirteen patients in group 1 (13/34) and 12 patients in group 2 (12/21) received highly active antiretroviral treatment (HAART). Patients of group 2 received HAART therapy more frequently than patients of group 1 (P = 0.021).Central and superficial brain lesions detected by MR imaging in HIV-1-infected patients with cryptococcal meningoencephalitis are in correlation with the host immunity and HAART therapy.

Development of primary central nervous system lymphoma associated with human immunodeficiency virus and JC virus infection

We report here a case of a 37-year-old man with human immunodeficiency virus (HIV) infection followed by JC virus (JCV) infection and primary central nervous system lymphoma (PCNSL). The patient had been infected with HIV type 1 due to blood products for hemophilia A during infancy. He had progression of nervous symptoms and was diagnosed with progressive multifocal leukoencephalopathy (PML) clinically at the age of 36, when his CD4-positive lymphocyte counts ranged between 350 and 450/μl. Oral mefloquine, intravenous methylprednisolone pulse therapy, and intravenous immunoglobulin were not effective for the PML, and the patient entered a vegetative state. Brain biopsy revealed JCV infection without pathological findings of PML. Eight months after the clinical diagnosis of PML, he developed respiratory failure and brain magnetic resonance imaging revealed a mass lesion in the brain stem. The patient died 19 months after the diagnosis of PML. Autopsy findings were compatible with PCNSL. EBV-encoded small RNA-1-positive cells were not detected. We present a case of JCV-positive PCNSL with HIV infection complicated with clinical PML.

Neuropathological sequelae of Human Immunodeficiency Virus and apathy: A review of neuropsychological and neuroimaging studies

Apathy remains a common neuropsychiatric disturbance in the Human Immunodeficiency Virus (HIV-1) despite advances in anti-retroviral treatment (ART). The goal of the current review is to recapitulate findings relating apathy to the deleterious biobehavioral effects of HIV-1 in the post-ART era. Available literatures demonstrate that the emergence of apathy with other neurocognitive and neuropsychiatric symptoms may be attributed to neurotoxic effects of viral proliferation, e.g., aggregative effect of Tat and gp120 on apoptosis, transport and other enzymatic reactions amongst dopaminergic neurons and neuroglia. An assortment of neuroimaging modalities converge on the severity of apathy symptoms associated with the propensity of the virus to replicate within frontal-striatal brain circuits that facilitate emotional processing. Burgeoning research into functional brain connectivity also supports the effects of microvascular and neuro-inflammatory injury linked to aging with HIV-1 on the presentation of neuropsychiatric symptoms. Summarizing these findings, we review domains of HIV-associated neurocognitive and neuropsychiatric impairment linked to apathy in HIV. Taken together, these lines of research suggest that loss of affective, cognitive and behavioral inertia is commensurate with the neuropathology of HIV-1.

HIV-1 Tat inhibits phagocytosis by preventing the recruitment of Cdc42 to the phagocytic cup

Most macrophages remain uninfected in HIV-1-infected patients. Nevertheless, the phagocytic capacity of phagocytes from these patients is impaired, favouring the multiplication of opportunistic pathogens. The basis for this phagocytic defect is not known. HIV-1 Tat protein is efficiently secreted by infected cells. Secreted Tat can enter uninfected cells and reach their cytosol. Here we found that extracellular Tat, at the subnanomolar concentration present in the sera of HIV-1-infected patients, inhibits the phagocytosis of Mycobacterium avium or opsonized Toxoplasma gondii by human primary macrophages. This inhibition results from a defect in mannose- and Fcγ-receptor-mediated phagocytosis, respectively. Inhibition relies on the interaction of Tat with phosphatidylinositol (4,5)bisphosphate that interferes with the recruitment of Cdc42 to the phagocytic cup, thereby preventing Cdc42 activation and pseudopod elongation. Tat also inhibits FcγR-mediated phagocytosis in neutrophils and monocytes. This study provides a molecular basis for the phagocytic defects observed in uninfected phagocytes following HIV-1 infection.

Evaluation and treatment of chronic meningitis

Chronic meningitis is defined as an inflammatory cerebrospinal fluid (CSF) profile that persists for at least 1 month. The presentation often includes headache, nausea, vomiting, cranial neuropathies, symptoms of elevated intracranial pressure, or focal neurologic deficits. The most common etiologies of chronic meningitis fall into 3 broad categories: infectious, autoimmune, and neoplastic. Evaluation of the patient with suspected chronic meningitis should include a detailed history and physical examination as well as repeated CSF diagnostics, serologic studies, and biopsy of the brain or other abnormal tissue (eg, lymph node or lung), when indicated. Early identification of the etiology and rapid treatment are crucial for improving morbidity and mortality, but potential infectious and neoplastic conditions should be excluded prior to empirically starting steroids or immunosuppressive medications.

The EEG of tropical encephalopathies

In addition to encountering most of the conditions treated by clinicians in the West, clinicians in the tropics are faced with unique tropical encephalopathies. These are largely but not entirely infectious in nature. Despite the relatively low cost of EEG technology, it remains unavailable in many low-income tropical settings even at the tertiary care level. Where available, the EEG recordings and interpretation are often of unacceptable quality. Nonetheless, there are existing data on the EEG patterns seen in malaria and a number of tropical viral, bacterial, and parasitic infestations.

Viral encephalitis

While systemic viral infections are exceptionally common, symptomatic viral infections of the brain parenchyma itself are very rare, but a serious neurologic condition. It is estimated that viral encephalitis occurs at a rate of 1.4 cases per 100.000 inhabitants. Geography is a major determinant of encephalitis caused by vector-borne pathogens. A diagnosis of viral encephalitis could be a challenge to the clinician, since almost 70% of viral encephalitis cases are left without an etiologic agent identified. In this review, the most common viral encephalitis will be discussed, with focus on ecology, diagnosis, and clinical management.

HIV Associated Neurocognitive Disorders

Human immunodeficiency virus type 1 is associated with the development of neurocognitive disorders in many infected individuals, including a broad spectrum of motor impairments and cognitive deficits. Despite extensive research, the pathogenesis of HIV-associated neurocognitive disorders (HAND) is still not clear. This review provides a comprehensive view of HAND, including HIV neuroinvasion, HAND diagnosis and different level of disturbances, influence of highly-active antiretroviral therapy to HIV-associated dementia (HAD), possible pathogenesis of HAD, etc. Together, this review will give a thorough and clear understanding of HAND, especially HAD, which will be vital for future research, diagnosis and treatment.

Chronic and subacute meningitis

PURPOSE OF REVIEW

This article describes the background, clinical presentation, diagnosis, and treatment of selected etiologies of subacute and chronic meningitis. Key diagnostic considerations when evaluating a patient presenting with chronic inflammation of the CNS are discussed, and several specific infectious, neoplastic, and autoimmune etiologies are reviewed in detail.

RECENT FINDINGS

With recent advancement in serologic and CSF diagnostic testing, specific infectious, neoplastic, or autoimmune etiologies of chronic meningitis can be identified. Eliminating previous diagnostic uncertainty of chronic inflammation in the CNS has led to rapid and specific treatment regimens that ultimately improve patient outcomes. Recent advances in imaging have also aided clinicians in both their diagnostic approach and the detection of inflammatory complications such as hydrocephalus, hemorrhage, and ischemic stroke.

SUMMARY

Meningitis is defined as inflammation involving the meninges of the brain and spinal cord. Meningitis can be categorized as acute, subacute, or chronic based on duration of inflammation. This article focuses on the most common causes of subacute and chronic meningitis. Chronic meningitis is commonly defined as inflammation evolving during weeks to months without resolution of CSF abnormalities. Determining the time course of meningitis is important for creating a differential diagnosis. Most organisms causing acute meningitis rarely persist more than a few weeks. Although numerous etiologies of subacute and chronic meningitis have been identified, this article focuses on the most common etiologies: (1) infectious, (2) autoimmune, and (3) neoplastic.

Toxoplasma encephalitis in HIV/AIDS patients admitted to the Douala general hospital between 2004 and 2009: a cross sectional study

Background

It is estimated that about a third of the world’s population is chronically infected with Toxoplasma gondii. Toxoplasma encephalitis (TE), which occurs as a reactivation of quiescent chronic infection, is one of the leading causes of central nervous system (CNS) infection in AIDS. Its diagnosis in most centres still remains difficult. We opted to describe the clinical and radiological features of TE as well as in-hospital outcome and its associated factors.

Methods

We carried out a cross sectional study on the clinical case notes of adult patients admitted and treated for TE at the Douala General Hospital, Cameroon between January 1^st 2004 to December 31^st 2009.

Results

Of 672 patients admitted during the study period, 14.4% (97/672) had TE. The mean age was 36.9 ± 14.1 years and the median CD4 cell count was 68/mm³ (IQR): 43 – 103). Headache and fever were the most common presenting symptoms in 92.8% (90/97) and 87.6% (85/97) of patients. Annular contrast enhanced lesions were the most common brain scan finding in 81.4% (79/97) of patients. In-hospital mortality was 29.9% (29/97). Altered sensorium, presence of focal signs, neck stiffness and low CD4 cell count were factors associated with mortality. Adjusting for low CD4 count, altered sensorium remained strongly associated with fatality, adjusted odd ratio (AOR) 3.5 (95% CI 1.2 – 10.5).

Conclusion

Toxoplasma encephalitis is common among AIDS patients in Douala. Its high case fatality warrants adequate and compliant prophylactic therapy in severely immune depressed patients as well as early initiation of antiretroviral therapy in HIV-infected patients.

Central nervous system infections among individuals with and without end-stage renal disease

OBJECTIVES

Individuals with immunodeficiencies are at increased risk of central nervous system (CNS) infections. Data are limited on the risk of CNS infections in patients with end-stage renal disease (ESRD).

METHODS

We conducted a population-based, nationwide cohort study among ESRD patients from 1990 to 2009. Data on ESRD patients was obtained from the Danish Nephrology Registry database. Each ESRD patient was matched with up to 19 population controls. Using the National Hospital Registry we identified hospital admissions with CNS infection as primary discharge diagnosis.

RESULTS

The study included 13,374 ESRD patients and 245,397 population controls, providing 67,012 person-years and 2,237,237 person-years of observation, respectively. The overall incidence rate (IR) of first-time hospitalisation for CNS infection was 149 per 100,000 person-years (95%-confidence interval [CI], 123-181) among ESRD patients. The IR of CNS infection was comparable among dialysis and transplant patients. Compared to population controls, the incidence rate-ratio of first CNS infection was 5.58 (95%-CI, 4.47-6.91) for ESRD patients in general. The 30-day mortality following hospitalisation for CNS infections was 21% (95%-CI, 14-30) among ESRD patients and 13% (95%-CI, 10-16) among population controls.

CONCLUSIONS

ESRD patients have considerable excess risk and mortality from CNS infections, which is of great clinical and public health concern.

Toxoplasmosis

Toxoplasma gondii, an Apicomplexan, is a pathogic protozoan that can infect the central nervous system. Infection during pregnancy can result in a congenial infection with severe neurological sequelae. In immunocompromised individuals reactivation of latent neurological foci can result in encephalitis. Immunocompetent individuals infected with T. gondii are typically asymptomatic and maintain this infection for life. However, recent studies suggest that these asymptomatic infections may have effects on behavior and other physiological processes. Toxoplasma gondii infects approximately one-third of the world population, making it one of the most successful parasitic organisms. Cats and other felidae serve as the definite host producing oocysts, an environmentally resistant life cycle stage found in cat feces, which can transmit the infection when ingested orally. A wide variety of warm-blooded animals, including humans, can serve as the intermediate host in which tissue cysts (containing bradyzoites) develop. Transmission also occurs due to ingestion of the tissue cysts. There are three predominant clonal lineages, termed Types I, II and III, and an association with higher pathogenicity with the Type I strains in humans has emerged. This chapter presents a review of the biology of this infection including the life cycle, transmission, epidemiology, parasite strains, and the host immune response. The major clinical outcomes of congenital infection, chorioretinitis and encephalitis, and the possible association of infection of toxoplasmosis with neuropsychiatric disorders such as schizophrenia, are reviewed.

Global Molecular Epidemiology of Cryptococcus neoformans and Cryptococcus gattii: An Atlas of the Molecular Types

Cryptococcosis is a fungal disease affecting more than one million people per year worldwide. The main etiological agents of cryptococcosis are the two sibling species Cryptococcus neoformans and Cryptococcus gattii that present numerous differences in geographical distribution, ecological niches, epidemiology, pathobiology, clinical presentation and molecular characters. Genotyping of the two Cryptococcus species at subspecies level supplies relevant information to understand how this fungus has spread worldwide, the nature of its population structure, and how it evolved to be a deadly pathogen. At present, nine major molecular types have been recognized: VNI, VNII, VNB, VNIII, and VNIV among C. neoformans isolates, and VGI, VGII, VGIII, and VGIV among C. gattii isolates. In this paper all the information available in the literature concerning the isolation of the two Cryptococcus species has been collected and analyzed on the basis of their geographical origin, source of isolation, level of identification, species, and molecular type. A detailed analysis of the geographical distribution of the major molecular types in each continent has been described and represented on thematic maps. This study represents a useful tool to start new epidemiological surveys on the basis of the present knowledge.

Does introduction of thresholds in decision aids benefit the patient?: Comparison between findings-based and threshold-based diagnostic decision aids

PURPOSE

To assess how different diagnostic decision aids perform in terms of sensitivity, specificity, and harm.

METHODS

Four diagnostic decision aids were compared, as applied to a simulated patient population: a findings-based algorithm following a linear or branched pathway, a serial threshold-based strategy, and a parallel threshold-based strategy. Headache in immune-compromised HIV patients in a developing country was used as an example. Diagnoses included cryptococcal meningitis, cerebral toxoplasmosis, tuberculous meningitis, bacterial meningitis, and malaria. Data were derived from literature and expert opinion. Diagnostic strategies' validity was assessed in terms of sensitivity, specificity, and harm related to mortality and morbidity. Sensitivity analyses and Monte Carlo simulation were performed.

RESULTS

The parallel threshold-based approach led to a sensitivity of 92% and a specificity of 65%. Sensitivities of the serial threshold-based approach and the branched and linear algorithms were 47%, 47%, and 74%, respectively, and the specificities were 85%, 95%, and 96%. The parallel threshold-based approach resulted in the least harm, with the serial threshold-based approach, the branched algorithm, and the linear algorithm being associated with 1.56-, 1.44-, and 1.17-times higher harm, respectively. Findings were corroborated by sensitivity and Monte Carlo analyses.

CONCLUSION

A threshold-based diagnostic approach is designed to find the optimal trade-off that minimizes expected harm, enhancing sensitivity and lowering specificity when appropriate, as in the given example of a symptom pointing to several life-threatening diseases. Findings-based algorithms, in contrast, solely consider clinical observations. A parallel workup, as opposed to a serial workup, additionally allows for all potential diseases to be reviewed, further reducing false negatives. The parallel threshold-based approach might, however, not be as good in other disease settings.

Morbidity and Mortality Patterns of Hospitalised Adult HIV/AIDS Patients in the Era of Highly Active Antiretroviral Therapy: A 4-year Retrospective Review from Zaria, Northern Nigeria

Background. This study, undertaken in major tertiary hospital in northern Nigeria, examined the morbidity and mortality patterns of hospitalised adult HIV/AIDS patients in the HAART era. Methods. Between January 2006 and December 2009, admission records and causes of deaths of hospitalised medical HIV-infected patients were retrieved and analysed according to antiretroviral (ART) status. Results. Of the 207 HIV/AIDS patients reviewed, majority were newly diagnosed (73.4%), and most were hospitalised and died from various AIDS-defining illnesses, mainly disseminated tuberculosis and sepsis. Immune-inflammatory-reconstitution-syndrome, ART-toxicity and ART-failure, contributed to morbidity and mortality in patients receiving ART. Sixty six (31.9%) patients died, with higher mortality in males and in those with lower CD4-cell count, lower PCV, and shorter hospital stay. However, hospital stay ≤3 days and severe anaemia (PCV < 24%) were independent predictors of mortality. Conclusion. In the current HAART era, late presentation and tuberculosis continue to fuel the HIV/AIDS pandemic in Africa, with emerging challenges due to ART-related complications.

A comparison of seriously ill patients with or without AIDS requiring prolonged mechanical ventilation

PURPOSE

The aim of this study was to compare differences in underlying diagnoses, weaning outcomes, discharge disposition, and survival in prolonged mechanical ventilator (PMV)-dependent patients with and without AIDS.

METHODS

Ninety consecutive AIDS patients requiring PMV were retrospectively matched with 90 clinically similar non-AIDS patients to form matched cohorts to determine differences in their outcomes.

RESULTS

AIDS patients had more acute diagnoses requiring PMV, whereas non-AIDS patients had more chronic diagnoses (P < .001). Weaning outcomes were alike with 31 (35%) AIDS and 37 (41%) non-AIDS patients successfully weaned. More AIDS patients went home, and fewer, to nursing facilities (P = .04). In each cohort, successfully weaned patients had significantly longer survival than their unweaned counterparts (all P < .001). Successful weaning reduced the risk of death in AIDS and non-AIDS patients (hazard ratios, 0.29 and 0.20; 95% confidence intervals, 0.17-0.50 and 0.11-0.36, respectively; all P < .001).

CONCLUSIONS

AIDS had little effect on weaning success or survival. Successful weaning increased survival regardless of a diagnosis of AIDS. The AIDS patients had more home discharges and fewer to nursing facilities, which likely resulted from the AIDS patients having more acute illnesses leading to PMV than the non-AIDS patients.

Toxoplasma gondii and the blood-brain barrier

Infection with the protozoan parasite Toxoplasma gondii is characterized by asymptomatic latent infection in the central nervous system and skeletal muscle tissue in the majority of immunocompentent individuals. Life-threatening reactivation of the infection in immunocompromized patients originates from rupture of Toxoplasma cysts in the brain. While major progress has been made in our understanding of the immunopathogenesis of infection the mechanism(s) of neuroinvasion of the parasite remains poorly understood. The present review presents the current understanding of blood-brain barrier (patho)physiology and the interaction of Toxoplasma gondii with cells of the blood-brain barrier.

IL-23 in infections, inflammation, autoimmunity and cancer: possible role in HIV-1 and AIDS

The growing family of interleukin (IL)-12-like cytokines produced by activated macrophages and dendritic cells became the important players in the control of infections, development of inflammation, autoimmunity and cancer. However, the role of one of them-heterodimer IL-23, which consists of IL12p40 and the unique p19 subunit in HIV-1 infection pathogenesis and progression to AIDS, represent special interest. We overviewed findings of IL-23 involvement in control of peripheral bacterial pathogens and opportunistic infection, central nervous system (CNS) viral infections and autoimmune disorders, and tumorogenesis, which potentially could be applicable to HIV-1 and AIDS.

Neurologic cytomegalovirus complications in patients with AIDS: retrospective review of 13 cases and review of the literature

Neurological disorders caused by Cytomegalovirus (CMV) in patients with Acquired Immunodeficiency Syndrome (AIDS) are rarely reported in the Highly Active Antiretroviral Therapy (HAART) period. The objective of this study was to describe the main clinical and laboratory features of patients with CMV-related neurological complications in HIV-infected patients admitted to a referral center in São Paulo, Brazil. CMV disease requires the identification of the virus in the cerebrospinal fluid (CSF) using Polymerase Chain Reaction (PCR). Thirteen cases were identified between January, 2004 and December, 2008. The median age of patients was 38 years and nine (69%) were men. At admission all patients were aware of their HIV status and only four (31%) patients were on HAART. Patients who were not on antiretroviral therapy before admission received HAART while inpatients. CMV disease was the first AIDS-defining illness in eight (62%) patients. The neurologic syndromes identified were diffuse encephalitis (n = 7; 62%), polyradiculopathy (n = 7; 54%), focal encephalitis (rhombencephalitis) (n = 1; 8%), and ventriculo-encephalitis (n = 1; 8%). Seven (54%) patients presented extra-neural CMV disease and four (31%) had retinitis. The median of CD4+ T-cell count was 13 cells/µL (range: 1-124 cells/µL). Overall in-hospital mortality was 38%. Eight patients used ganciclovir or foscarnet (in-hospital mortality: 50%) and five patients used ganciclovir and foscarnet (in-hospital mortality: 20%). None of the patients fulfilled the diagnosis criteria of immune reconstitution inflammatory syndrome. Four patients were lost to follow-up, and three patients presented immune recovery and discontinued secondary prophylaxis. Although infrequent, distinct neurological syndromes caused by CMV continue to cause high mortality among AIDS patients. Survival depends upon the use of effective antiviral therapy against CMV and the early introduction of HAART.

The changing epidemiology of HIV-infected patients in the intensive care unit

With the introduction of highly active antiretroviral therapy (HAART), HIV has become a chronic disease. As HIV-infected patients are aging, they are at increased risk for comorbid diseases. These non-AIDS related diseases account for a growing proportion of intensive care unit (ICU) admissions in HIV-infected patients in recent studies. HIV-infected patients still present to the ICU with HIV-related conditions such as Pneumocystis jirovecii pneumonia (PCP), but these conditions are becoming less common. Respiratory failure remains the most common indication for ICU admission. Immune reconstitution inflammatory response syndrome and toxicities related to HAART may also result in ICU admission. While ICU survival has improved since the earliest era of the HIV epidemic, hospital mortality for HIV-infected patients admitted to the ICU remains around 30%. Risk factors for ICU mortality include poor functional status, weight loss, more than one year between HIV diagnosis and ICU admission, lower serum albumin, higher severity of illness, need for mechanical ventilation, and respiratory failure-particularly if due to PCP and accompanied by pneumothorax. The impact of HAART on ICU outcomes is unclear. HAART administration in the ICU can be challenging due to limited delivery routes, concern for viral resistance and medication toxicities. There are no data to determine the safety or efficacy of HAART initiation in the ICU. Future studies are needed to address the role of age, associated comorbidities and impact of HAART on outcomes of HIV-infected patients admitted to the ICU.

Progressive multifocal leukoencephalopathy as an AIDS-defining condition in a patient with high CD4+ T-lymphocyte count

We present the case of a 31-year-old man with acute manifestation of progressive multifocal leukoencephalopathy (PML) as an AIDS-defining disease. The patient presented with a three-day history of neurological disease, brain lesions without mass effect or contrast uptake and a slightly increased protein concentration in cerebrospinal fluid. A serological test for HIV was positive and the CD4+ T-cell count was 427/mm³. Histological examination of the brain tissue revealed abnormalities compatible with PML. The disease progressed despite antiretroviral therapy, and the patient died three months later. PML remains an important cause of morbidity and mortality among HIV-infected patients.

HIV-associated tuberculous meningitis--diagnostic and therapeutic challenges

HIV-associated tuberculous meningitis (TBM) poses significant diagnostic and therapeutic challenges and carries a dismal prognosis. In this review, we present the clinical features and management of HIV-associated TBM, and compare this to disease in HIV-uninfected individuals. Although the clinical presentation, laboratory findings and radiological features of TBM are similar in HIV-infected and HIV-uninfected patients, some important differences exist. HIV-infected patients present more frequently with extra-meningeal tuberculosis and systemic features of HIV infection. In HIV-associated TBM, clinical course and outcome are influenced by profound immunosuppression at presentation, emphasising the need for earlier diagnosis of HIV infection and initiation of antiretroviral treatment.

Toxoplasmosis not transmitted by cat bite, but high prevalence of antibodies to Toxoplasma gondii in patients bitten by their own cat

The aims of the study were to investigate the prevalence of antibodies to Toxoplasma gondii in a group of patients bitten by cats, and also to determine if toxoplasmosis can be transferred by cat bite. Seventy-two patients who attended the emergency wards at 3 hospitals in Stockholm, Sweden, due to infection by cat bite, were investigated for specific IgM and IgG antibodies to T. gondii in the acute phase, as well as in the convalescent phase about 2 weeks later. Specific IgG antibodies to T. gondii (> or =8 IU/ml) were found in 17/72 patients (24%) in the acute phase. No case of seroconversion occurred. Patients who were bitten by their own cat had positive antibody titres to T. gondii significantly more often than those bitten by a foreign cat; 30% and 5%, respectively (p = 0.02). This suggests that regular contact with cats may contribute to the transmission of the parasite.

Toxoplasma gondii infection and cerebral toxoplasmosis in HIV-infected patients

Cerebral toxoplasmosis is a major cause of morbidity and mortality among HIV-infected patients, particularly from developing countries. This article summarizes current literature on cerebral toxoplasmosis. It focuses on: Toxoplasma gondii genetic diversity and its possible relationship with disease presentation; host responses to the parasite antigens; host immunosupression in HIV and cerebral toxoplasmosis as well as different diagnostic methods; clinical and radiological features; treatment; and the direction that studies on cerebral toxoplasmosis will likely take in the future.