Toxoplasma gondii infection in advanced HIV infection

CD8 Encephalitis in HIV: A Review of This Emerging Entity

INTRODUCTION

Encephalitis is a life-threatening neurological condition with multiple causes in the setting of Human Immunodeficiency Virus (HIV). CD8 Encephalitis (CD8E) is a newly recognised condition which can present in an acute manner, with pertinent features including classical radiological findings with an intense brain parenchymal infiltration of CD8+ T cells. This review attempted to clarify the symptomatology, distribution and determinants of this condition, as well as to examine its vast unknowns.

METHODS

A literature review was undertaken in July 2022, utilising the PubMed and Google Scholar databases. Papers published between 2006-2022 were reviewed. Eighteen papers, totalling 57 patients, were found and analysed. Statistical analysis was undertaken using Chi-squared and Wilcoxon rank-sum tests as appropriate, with p < 0.05 deemed significant.

RESULTS

In this review, 57 patients were identified, with a female (61%, 34/56) and Black African (70%, 40/57) preponderance. Females were more likely to present with headache (p = 0.006), and headache was more likely to be present in those who died (p = 0.02). There was no statistically significant association between baseline CD4 count (p = 0.079) and viral load (p = 0.72) with disease outcome. Overall, 77% (41/53) of patients had classical imaging findings, including bilateral gadolinium-enhancing punctate and perivascular white matter lesions. However, many patients (23/57) required a brain biopsy as part of their diagnostic workup. Corticosteroid treatment was commonly prescribed in patients (64%, 35/55) and had a mortality benefit, with an overall survival in this group of 71% (p = 0.0008). In those who died, median survival was 5.5 months. In rare instances, recurrence of the disease was noted, which responded poorly to treatment.

DISCUSSION

CD8E represents a new and complex condition with few risk factors identified for its occurrence. The presenting symptoms are broad, but headache appears to be more common in females and more significantly associated with death. Though rare, CD8E is likely under-diagnosed, possibly due to overlapping features with other illnesses and lack of physician experience in its recognition and management. Corticosteroids demonstrate a clear mortality benefit, but more studies are required to determine their optimal dosing and duration, as well as the use of steroid-sparing agents. Further reviews should help to better determine the risk factors for the condition, as well as non-invasive biomarkers, to aid in diagnosis and help to predict poor prognosis and disease recurrence.

Blood biomarkers for HIV infection with focus on neurologic complications-A review

Although clinical examinations, neuroimaging, and cerebrospinal fluid analyses are the most important ways to evaluate the impact of HIV infection on the brain and in diagnosis of opportunistic infections, several blood biomarkers including HIV RNA concentrations, CD4 +T-cell count, and neurofilament light chain protein (NfL) concentration, along with tests for opportunistic infections can provide important information for clinical decisions.

Epidemiology, Pathophysiology, Diagnosis, and Management of Cerebral Toxoplasmosis

Toxoplasma gondii is known to infect a considerable number of mammalian and avian species and a substantial proportion of the world's human population. The parasite has an impressive ability to disseminate within the host's body and employs various tactics to overcome the highly regulatory blood-brain barrier and reside in the brain. In healthy individuals, T. gondii infection is largely tolerated without any obvious ill effects. However, primary infection in immunosuppressed patients can result in acute cerebral or systemic disease, and reactivation of latent tissue cysts can lead to a deadly outcome. It is imperative that treatment of life-threatening toxoplasmic encephalitis is timely and effective. Several therapeutic and prophylactic regimens have been used in clinical practice. Current approaches can control infection caused by the invasive and highly proliferative tachyzoites but cannot eliminate the dormant tissue cysts. Adverse events and other limitations are associated with the standard pyrimethamine-based therapy, and effective vaccines are unavailable. In this review, the epidemiology, economic impact, pathophysiology, diagnosis, and management of cerebral toxoplasmosis are discussed, and critical areas for future research are highlighted.

Infection with Toxoplasma gondii can promote chronic liver diseases in HIV-infected individuals

Liver pathologies and infection with Toxoplasma gondii (Nicolle et Manceaux, 1908) are widespread among HIV-infected patients. However, a possible contribution of toxoplasmosis to the development of various forms of liver diseases in HIV-infected individuals has not yet been determined. This research is a retrospective cohort study. Medical cards of 907 HIV-positive patients, including 119 individuals who died, were studied. The patients were divided into two groups: 531 patients were seropositive to T. gondii and 376 seronegative. General liver pathology was more widespread among patients seropositive to T. gondii than in seronegative patients (63.1 ± 2.1% and 51.9 ± 2.6%, respectively, p < 0.001). The association of seropositive to T. gondii with general liver pathology is weak both in the whole cohort (Pearson's contingency coefficient C = 0.112), and among the deceased patients (C = 0.228). Chronic HBV-HCV coinfection was more common in the seropositive than in seronegative individuals as it was found both in entire cohorts (26.0 ± 1.9% and 18.6 ± 2.0%, respectively, p = 0.010) and in died patients (31.0 ± 5.5% and 14.6 ± 5.1%, respectively, p = 0.041). Toxoplasma gondii had a weak role in distributing of HBV-HCV coinfection between cohorts (C = 0.187). In both cohorts in patients with chronic hepatitis, regardless of its etiology, there was no significant difference in alanine transaminase activity (ALT). Cirrhosis of the liver occurred 4.5 times more often in deceased seropositive patients than in the entire seropositive cohort (23.9 ± 5.1 and 5.3 ± 2.0, respectively, p = 0.0006) whereas it no significantly increased in seronegative cohort (10.4 ± 4.4 against 4.8 ± 1.1, p > 0.05). In them T. gondii is weakly involved in cirrhosis formation (C = 0.168). Thus, in HIV-infected patients, T. gondii is a weak nonspecific adjunct that supports chronic liver inflammation and progression of cirrhosis, regardless of etiology, but does not influence the degree of hepatitis activity. The increased prevalence of HBV-HCV coinfection in patients seropositive for T. gondii may be related to their risk factor behaviour associated with uncontrolled blood contacts.

The prevalence of latent and acute toxoplasmosis in HIV-infected pregnant women: A systematic review and meta-analysis

OBJECTIVE

HIV in pregnancy is not only important for mother-to-child HIV transmission, but also it assumes additional importance because HIV increases susceptibility to opportunistic infections, leading to increased morbidity and mortality in mothers and neonates. Toxoplasmosis is one of the most important opportunistic infections in HIV-infected pregnant women. The present study was undertaken to assess the prevalence of latent toxoplasmosis (LT) and acute toxoplasmosis (AT) infection in HIV-infected pregnant women.

METHODS

PubMed/MEDLINE, Scopus, Web of Science, EMBASE and SciELO were searched to identify relevant studies. A random-effects model was used to estimate the overall and subgroup-pooled prevalences across studies. Heterogeneity between studies was assessed via the I² test.

RESULTS

A total of 14 articles that included 3256 subjects in nine countries met the inclusion criteria. The overall prevalence rates of LT and AT in HIV-infected pregnant women were 45.7% (95% CI, 32.3-59.7%) and 1.1% (95% CI, 0.4-3.2%), respectively. The findings indicate that, worldwide, approximately 559,000 and 13,450 HIV-infected pregnant women are affected by LT and AT, respectively. From this review, it is estimated that approximately 3432 babies annually could be born with congenital toxoplasmosis (CT) from HIV-infected pregnant mothers.

CONCLUSIONS

The present study indicates that a large number of HIV-infected mothers are affected by LT and AT. This can lead to adverse complications such toxoplasmic encephalitis in mothers and CT in neonates. Our results suggest a need for screening programs using well-validated diagnostic platforms for both LT and AT for all HIV-infected pregnant women.

Factors Associated With Poor Linkage to Human Immunodeficiency Virus Care Among Index Clients and Sex Partners Receiving Human Immunodeficiency Virus Assisted Partner Services in Kenya

INTRODUCTION

Human immunodeficiency virus (HIV) assisted partner services (aPS) has been recommended as a strategy to increase HIV case finding. We evaluated factors associated with poor linkage to HIV care among newly diagnosed HIV-positive individuals (index clients) and their partners after receiving aPS in Kenya.

METHODS

In a cluster randomized trial conducted between 2013 and 2015, 9 facilities were randomized to immediate aPS (intervention). Linkage to care-defined as HIV clinic registration, and antiretroviral therapy (ART) initiation were self-reported. Antiretroviral therapy was only offered to those with CD4 less than 500 during this period. We estimated linkage to care and ART initiation separately for index clients and their partners using log-binomial generalized estimating equation models with exchangeable correlation structure and robust standard errors.

RESULTS

Overall, 550 index clients and 621 sex partners enrolled, of whom 46% (284 of 621) were HIV-positive. Of the 284, 264 (93%) sex partners returned at 6 weeks: 120 newly diagnosed and 144 whom had known HIV-positive status. Among the 120 newly diagnosed, only 69% (83) linked to care at 6 weeks, whereas among the 18 known HIV-positive sex partners not already in care at baseline, 61% (11) linked. Newly diagnosed HIV-positive sex partners who were younger and single were less likely to link to care (P < 0.05 for all).

CONCLUSION

Only two thirds of newly diagnosed, and known HIV-positive sex partners not in care linked to care after receiving aPS. The HIV aPS programs should optimize HIV care for newly diagnosed HIV-positive sex partners, especially those who are younger and single.

Central nervous system infection with Toxoplasma gondii

Central nervous system infection by Toxoplasma gondii, or Toxoplasma encephalitis, is the most common cause of brain mass lesions in human immunodeficiency virus (HIV)-infected patients. It usually presents as one or more brain abscesses, but it can also cause a diffuse encephalitis or ventriculitis. Individuals who are Toxoplasma immunoglobulin G-seropositive, who have peripheral blood CD4+ T-cell concentrations below 200/μL, are not on antiretroviral therapy, and are not taking trimethoprim-sulfamethoxazole to prevent Pneumocystis pneumonia, are at particular risk for Toxoplasma encephalitis. Neuroimaging typically shows round, isodense or hyperdense lesions in the hemispheric gray-white junction, deep white matter, or basal ganglia that enhance with contrast in a ring, nodular, or homogeneous pattern. In appropriate patients, response to an empiric treatment trial can establish the diagnosis. Immune reconstitution inflammatory syndrome is uncommon in HIV-infected patients treated for Toxoplasma encephalitis and combination antiretroviral therapy is an integral part of toxoplasmosis treatment.

In vitro observation of the stage conversion of transgenic Toxoplasma gondii RH strain expressing dual fluorescent proteins

Toxoplasma gondii converts from tachyzoites to bradyzoites after acute infection and thus survives the attack of the host immune responses. In this study, we observed the conversion of tachyzoites to bradyzoites in cell cultures using a transgenic T. gondii RH strain. The transgenic parasites continuously express yellow fluorescent protein (YFP) but only express red fluorescent protein (RFP) at the bradyzoite stage. Red fluorescent bradyzoite-containing cysts were found in transgenic parasite infected cells cultured with atmospheric CO2 supply, indicating the successful induction of the stage conversion. In cell culture with alkalic medium (pH 8.1) and atmospheric CO2 supply, only part of the YFP-expressing parasites in a cyst express RFP marker, suggesting the asynchronous development of T. gondii in vitro. This study provides a possibility for further studies of the gene expression profile during stage conversion and the genes involved.

Possible link between Toxoplasma gondii and the anosmia associated with neurodegenerative diseases

Toxoplasma gondii is an intracellular protozoan infecting 30% to 50% of global human population. Recently, it was suggested that chronic latent neuroinflammation caused by the parasite may be responsible for the development of several neurodegenerative diseases manifesting with the loss of smell. Studies in animals inoculated with the parasite revealed cysts in various regions of the brain, including olfactory bulb. Development of behavioral changes was paralleled by the preferential persistence of cysts in defined anatomic structures of the brain, depending on the host, strain of the parasite, its virulence, and route of inoculation. Olfactory dysfunction reported in Alzheimer's disease, multiple sclerosis, and schizophrenia was frequently associated with the significantly increased serum anti-T gondii immunoglobulin G antibody levels. Damage of the olfactory system may be also at least in part responsible for the development of depression because T gondii infection worsened mood in such patients, and the olfactory bulbectomized rat serves as a model of depression.

Toxoplasma gondii: sexual transmission in mice

This study was performed to evaluate sexual transmission of Toxoplasma gondii in mice. RH strain tachyzoites were intraperitoneally inoculated into 10 Balb/C male mice and after 48 h, their semen were collected from epididymis and examined by giemsa staining and PCR. Twenty Balb/C female mice mated with four infected male mice four times and any mating time was 48 h whilst 20 female control mice mated with four uninfected male mice for 8 days. Female mate choice was assessed using a three-chambered cage. Four female mice were placed in a central chamber and in one side of it, two infected male mice were kept and in other side, two naïve male mice were placed. Due each quarter, every of the female movement was reported and then the female was replaced to middle chamber. Besides on the detection of DNA and whole parasite in semen, no abortion and death was seen in female mice. Pregnancy was seen only 4 out of 20 female mice which mated with infected males while 17 pregnancies were seen from 20 control female mice (P value = 0.0001). No statistical significant was seen in female mate choice between naïve male (45 movement) and infected male (36 movement). This study showed that toxoplasmosis could not transmit to female mice and their offspring due to mating and the parasite had not effect on female mate choice. It seems that infected male mice cannot entirely mate with females due to reduction of male weapon and body size, physiological vigor and energy.

Ocular toxoplasmosis II: clinical features, pathology and management

The term, ocular toxoplasmosis, refers to eye disease related to infection with the parasite, Toxoplasma gondii. Recurrent posterior uveitis is the typical form of this disease, characterized by unilateral, necrotizing retinitis with secondary choroiditis, occurring adjacent to a pigmented retinochoroidal scar and associated with retinal vasculitis and vitritis. Multiple atypical presentations are also described, and severe inflammation is observed in immunocompromised patients. Histopathological correlations demonstrate focal coagulative retinal necrosis, and early in the course of the disease, this inflammation is based in the inner retina. For typical ocular toxoplasmosis, a diagnosis is easily made on clinical examination. In atypical cases, ocular fluid testing to detect parasite DNA by polymerase chain reaction or to determine intraocular production of specific antibody may be extremely helpful for establishing aetiology. Given the high seroprevalence of toxoplasmosis in most communities, serological testing for T. gondii antibodies is generally not useful. Despite a lack of published evidence for effectiveness of current therapies, most ophthalmologists elect to treat patients with ocular toxoplasmosis that reduces or threatens to impact vision. Classic therapy consists of oral pyrimethamine and sulfadiazine, plus systemic corticosteroid. Substantial toxicity of this drug combination has spurred interest in alternative antimicrobials, as well as local forms of drug delivery. At this time, however, no therapeutic approach is curative of ocular toxoplasmosis.

Discovering disease associations by integrating electronic clinical data and medical literature

Electronic health record (EHR) systems offer an exceptional opportunity for studying many diseases and their associated medical conditions within a population. The increasing number of clinical record entries that have become available electronically provides access to rich, large sets of patients' longitudinal medical information. By integrating and comparing relations found in the EHRs with those already reported in the literature, we are able to verify existing and to identify rare or novel associations. Of particular interest is the identification of rare disease co-morbidities, where the small numbers of diagnosed patients make robust statistical analysis difficult. Here, we introduce ADAMS, an Application for Discovering Disease Associations using Multiple Sources, which contains various statistical and language processing operations. We apply ADAMS to the New York-Presbyterian Hospital's EHR to combine the information from the relational diagnosis tables and textual discharge summaries with those from PubMed and Wikipedia in order to investigate the co-morbidities of the rare diseases Kaposi sarcoma, toxoplasmosis, and Kawasaki disease. In addition to finding well-known characteristics of diseases, ADAMS can identify rare or previously unreported associations. In particular, we report a statistically significant association between Kawasaki disease and diagnosis of autistic disorder.

Discontinuation of maintenance therapy against toxoplasma encephalitis in AIDS patients with sustained response to anti-retroviral therapy

Discontinuation of maintenance therapy against toxoplasma encephalitis (TE) for individuals infected with human immunodeficiency virus (HIV) who are receiving successful anti-retroviral therapy is considered safe. Nevertheless, there are few published studies concerning this issue. Within the setting of the Swiss HIV Cohort Study, this report describes a prospective study of discontinuation of maintenance therapy against TE in patients with a sustained increase of CD4 counts to > 200 cells/microL and 14% of total lymphocytes, and no active lesions on cerebral magnetic resonance imaging (MRI). In addition to clinical evaluation, cerebral MRI was performed at baseline, and 1 and 6 months following discontinuation. Twenty-six AIDS patients with a history of TE agreed to participate, but three patients (11%) could not be enrolled because they still showed enhancing cerebral lesions without a clinical correlate. One patient refused MRI after 6 months while clinically asymptomatic. Among the remaining 22 patients who discontinued maintenance therapy, one relapsed after 3 months. During a total follow-up of 58 patient-years, there was no TE relapse among the patients who had remained clinically and radiologically free of relapse during the study. Thus, discontinuation of maintenance therapy against TE was generally safe, but may fail in a minority of patients. Patients who remain clinically and radiologically free of relapse at 6 months after discontinuation are unlikely to experience a relapse of TE.

Temporary restoration of immune response against Toxoplasma gondii in HIV-infected individuals after HAART, as studied in the hu-PBMC-SCID mouse model

We studied immune reconstitution against the parasite T. gondii in HIV-infected patients treated for 1 years with highly active antiretroviral therapy (HAART). We used SCID mice, humanized with peripheral blood mononuclear cells (PBMC) from patients, which were then infected with T. gondii cysts. Mice humanized with PBMC from patients before the start of HAART were highly susceptible to infection. In contrast, mice humanized with PBMC from patients who had received HAART for 6 months displayed higher survival rates, correlating with lower intracerebral parasite loads. However, this resistance was lost during follow up because mice humanized with PBMC from patients treated with HAART for 12 months survived for no longer than mice that had not been humanized. Specific lymphocyte proliferation assays showed that the increase in proliferative response depended on treatment duration and that HAART induced changes in IFN-gamma secretion in the presence of Toxoplasma antigens. Thus, our results indicate partial immune reconstitution against T. gondii in HIV-infected patients following HAART, possibly due to changes in the patterns of specific IFN-gamma production and redistribution of functional memory CD4+ cells.

Molecular diagnosis of toxoplasmosis

Toxoplasmosis is an anthropozoonotic disease endemic world-wide, caused by the apicomplexan Toxoplasma gondii. Although the course of infection is generally benign, it can cause significant morbidity and mortality in the developing fetus and in immunocompromised individuals. Biological diagnosis classically relies upon serology and direct detection of the parasite by inoculation to laboratory animals. In the past decade, the use of the polymerase chain reaction (PCR) has made a significant improvement in both the prenatal diagnosis of congenital toxoplasmosis and the detection of acute disease in the immunocompromised patient. Nevertheless, like many 'in-house' PCR assays, the PCR-Toxoplasma suffers from lack of standardization and variable performance according to the laboratory. A wide variety of primers has been used in different assays, but few comparative tests have been performed. Moreover, in contrast to other parasitic diseases, PCR-Toxoplasma has not yet attained a sufficient level of sensitivity, regardless of the clinical condition considered. These drawbacks are discussed, together with the undoubted gain that PCR has brought to this difficult diagnosis.

Adverse reactions to cotrimoxazole in HIV-infected patients: predictive factors and subsequent HIV disease progression

The relationship between the onset of adverse events to cotrimoxazole in HIV-infected patients and the subsequent development of toxoplasmosis, other AIDS-defining events and survival was studied in 592 French patients who first received cotrimoxazole during the Delta trial. Low CD4+ cell count at cotrimoxazole introduction was the only factor associated with the onset of adverse reactions. The occurrence of toxoplasmosis and first AIDS-defining events were significantly and independently linked to a low CD4+ cell count at cotrimoxazole introduction (p < 0.0001) and to previous cotrimoxazole withdrawal for adverse events (p = 0.004 and p < 0.0001, respectively), but not to previous cotrimoxazole withdrawal for reasons other than adverse events, as compared to patients who did not discontinue taking cotrimoxazole during this survey. The survival rate was significantly shorter among both patients who stopped taking cotrimoxazole for adverse events and for other reasons (p = 0.03 and p = 0.0001, respectively), as compared to patients who continued to take cotrimoxazole.

Incidence and risk factors for toxoplasmic encephalitis in human immunodeficiency virus-infected patients before and during the highly active antiretroviral therapy era

The occurrence of toxoplasmic encephalitis (TE) was studied among 19,598 and 17,016 patients enrolled in the French Hospital Database on human immunodeficiency virus whose CD4 cell counts decreased to < or =200x10(6) cells/L before (1992-1995) or after (1996-1998) the availability of highly active antiretroviral therapy, respectively. The incidence of TE decreased from 3.9 cases per 100 person-years in the first period (95% confidence interval [CI], 3.7-4.1) to 1.0 cases per 100 person-years in the second period (95% CI, 0.9-1.1). After adjustment for known risk factors for TE, patients who received cotrimoxazole prophylaxis had a lower risk of TE (adjusted relative hazard, 0.6 and 0.5, respectively, for the first and second periods; P < .001). For patients treated with cotrimoxazole at inclusion, discontinuation of cotrimoxazole increased the risk of TE in both periods (adjusted relative hazard, 4.8 and 4.2, respectively; P < .001). Among patients whose CD4 cell counts increased to > 200 x 10(6) cells/L while undergoing highly active antiretroviral therapy, the incidence of TE was 0.1 cases per 100 person-years (95% CI, 0.0-0.2) and was not increased by discontinuation of cotrimoxazole.

Twice-weekly pyrimethamine-sulfadoxine effectively prevents Pneumocystis carinii pneumonia relapse and toxoplasmic encephalitis in patients with AIDS

OBJECTIVE

To evaluate the safety and efficacy of a fixed 25mg pyrimethamine--500mg sulfadoxine combination plus 15mg folinic acid given twice weekly for the prevention of relapses of Pneumocystis carinii pneumonia (PCP) and primary episodes of toxoplasmic encephalitis.

METHODS

Ninety-five HIV-infected patients with successfully treated PCP and without history of toxoplasmic encephalitis were enrolled between January 1990 and October 1995 in a single-arm open-label prospective study. No patient was receiving highly active antiretroviral treatment, including protease inhibitors or non-nucleoside reverse transcriptase inhibitors, while on study medication. Efficacy was analysed on an "as-treated" basis.

RESULTS

Five patients (5.3%) suffered a PCP relapse while on study medication, three of whom had been non-compliant. No relapse occurred in the first year. Probabilities of freedom from relapse were 0.96 after 24 months and 0.90 after 36 months. Of 69 patients positive for anti-toxoplasma IgG antibodies, one (1.5%) developed cerebral lesions compatible with toxoplasmic encephalitis after 50 months. Cutaneous allergic reactions were observed in 16 patients (16.8%) resulting in permanent discontinuation in six patients (6.3%). Two patients (2.1%) developed serious adverse reactions (Stevens-Johnson syndrome), both of whom had continued prophylaxis despite progressive hypersensitivity reactions.

CONCLUSIONS

The prophylactic regimen used is effective in preventing PCP relapses and toxoplasmic encephalitis. The regimen appears to be safe. Severe adverse events can likely be prevented by discontinuation of prophylaxis at the time allergic reactions are noted. Rechallenge frequently results in tolerance of the regimen. Efficacy and safety compare favourably with previously studied regimens. This simple prophylactic regimen may provide a convenient alternative for patients unable to tolerate approved regimens.

In vitro anti-Toxoplasma gondii antibody production by peripheral blood mononuclear cells in the diagnosis and the monitoring of toxoplasmic encephalitis in AIDS-related brain lesions

The spontaneous secretion in vitro of anti-Toxoplasma gondii antibodies by peripheral blood mononuclear cells was assessed in 69 patients with AIDS-related brain lesions. The sensitivity and specificity of this assay in the diagnosis of toxoplasmic encephalitis (TE) were found to be 85.4% and 92.8%, respectively. Twenty-four patients with TE were observed during 1-year follow-up after initiation of anti-Toxoplasma treatment and classified on the basis of their clinical and radiologic responses as sustained responders (SR; n = 11), incomplete responders (IR; n = 7) or transient responders (TR; n = 6). In vitro anti-T. gondii antibody secretion decreased as early as the first month after initiation of treatment and disappeared within the year in SRs, persisted in IRs, and decreased but rebounded at relapse in the TR patients. In vitro anti-T. gondii antibody, which reflects immune system activation by parasitic antigens, could be a surrogate marker of TE in AIDS patients.

Toxoplasma encephalitis in AIDS patients in São Paulo during 1988 and 1991. A comparative retrospective analysis

We conducted a retrospective analysis of Toxoplasma encephalitis patients from Instituto de Infectologia Emílio Ribas, the main AIDS hospital of São Paulo, Brazil, during two different stages of the HIV epidemics, in 1988 (38 patients) and 1991 (33 patients). There were AIDS-related demographic differences, but the clinical presentation and diagnostic efficiency were similar, usually based on tomography and clinical response to therapy, with a clear distinction from other CNS infections, based on clinical and laboratory findings. Specific serologic studies were performed less often in 1991, with a high frequency of therapy change. The direct acute death rate from Toxoplasma encephalitis was high during both periods, i.e. 8/38 in 1988 and 10/33 in 1991. The direct acute death rate for the patients from the two periods as a whole was 25.4% (18/71), related to the time of HIV infection, absence of fever and presence of meningeal irritation at presentation, blood leukocytes higher than 10,000/mm3 and blood lymphocytes lower than 350/mm3. Toxoplasma encephalitis is a preventable disease when adequate prophylactic therapy is used and is relatively easy to treat in diagnosed HIV patients. Unfortunately, this severe and deadly disorder is the HIV diagnostic disease in several patients, and our data support the need for careful management of these patients, especially in those countries with a high toxoplasmosis prevalence where AIDS is concurrent with economic and public health problems.

Human immunodeficiency virus infection, Part II

The acceptance of highly active antiretroviral therapy (HAART) among patients and health care providers has had a dramatic impact on the epidemiology and clinical characteristics of many opportunistic infections associated with human immunodeficiency virus (HIV). Previously intractable opportunistic infections and syndromes are now far less common. In addition, effective antibiotic prophylactic therapies have had a profound impact on the risk of patients developing particular infections and on the incidence of these infections overall. Most notable among these are Pneumocystis carinii, disseminated Mycobacterium avium complex, tuberculosis, and toxoplasmosis. Nevertheless, infections continue to cause significant morbidity and mortality among patients who are infected with HIV. The role of HAART in many clinical situations is unquestioned. Compelling data from clinical trials support the use of these therapies during pregnancy to prevent perinatal transmission of HIV. HAART is also recommended for health care workers who have had a "significant" exposure to the blood of an HIV-infected patient. Both of these situations are discussed in detail in this article. In addition, although more controversial, increasing evidence supports the use of HAART during the acute HIV seroconversion syndrome. An "immune reconstitution syndrome" has been newly described for patients in the early phases of treatment with HAART who develop tuberculosis, M avium complex, and cytomegalovirus disease. Accumulating data support the use of hydroxyurea, an agent with a long history in the field of myeloproliferative disorders, for the treatment of HIV. Newer agents, particularly abacavir and adefovir dipivoxil, are available through expanded access protocols, and their roles are being defined and clarified.

Changing disease patterns in focal brain lesion-causing disorders in AIDS

OBJECTIVES

To assess temporal trends of the different disorders causing focal brain lesions (FBL) in HIV-infected patients and to examine the reliability of the U.S. Centers for Disease Control and Prevention (CDC) criteria for presumptive diagnosis of toxoplasmic encephalitis (TE) for the years 1991 to 1996.

DESIGN/METHODS

A prospective, monocenter study. Percentages of occurrence of the different FBL-causing disorders for each year were calculated. Temporal trends were analyzed by chi2 test for linear trend and multivariate polytomous nonordinal logistic regression. The positive predictive value (PPV) of the CDC's presumptive criteria for the diagnosis of TE (recent onset of a focal neurologic abnormality consistent in intracranial disease or a reduced level of consciousness, evidence on brain imaging of a lesion having mass effect or the radiographic appearance of which is enhanced by injection of contrast medium, and serum antibody to toxoplasmosis) was calculated using contingency tables for each calendar year.

RESULTS

A highly significant decline of the risk of TE and an increase of the probability of patients to take anti-Toxoplasma prophylaxis were observed. A threefold but statistically not significant augmented risk of diagnosing both primary central nervous system lymphoma (PCNSL) and progressive multifocal leucoencephalopathy (PML) has been registered for 1996 compared with 1991. Among FBL showing contrast enhancement, the increased finding of PCNSL over the years studied was significant. The probability of other FBL-causing disorders, such as focal viral encephalitis sustained by cytomegalovirus or herpes simplex virus, increased significantly over the years studied. Multivariate analysis confirmed that the year of diagnosis of FBL had a significant effect on the risk reduction of TE. The PPV of the CDC's criteria for the presumptive diagnosis of TE dropped from 100% for the year 1991 to 39% in the year 1996. A similar result was obtained in calculating the PPV of presumptive criteria only among patients without previous primary prophylaxis.

CONCLUSIONS

Because of the significant decrease of TE and the increase of PCNSL empiric anti-Toxoplasma therapy no longer seems appropriate as a first-line approach to all HIV-positive patients with FBL. Especially in the case of a finding of FBL by contrast enhancement, new diagnostic strategies should be employed to identify the underlying disorder rapidly and accurately.

Evaluation of the Eiken latex agglutination test for anti-Toxoplasma antibodies and seroprevalence of Toxoplasma infection among factory workers in Addis Ababa, Ethiopia

Sera from 170 factory workers aged 18-45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti-Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti-Toxoplasma antibodies was 80.0% (95% confidence interval 73.9-86.1%). The sensitivity and specificity of the Eiken latex agglutination test were 96.3% and 97.1%, respectively, showing its validity for the detection of anti-Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74.2% versus 83.3%, P > 0.05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected (P < 0.001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti-Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.

Intention-to-treat vs. on-treatment analyses of clinical trial data: experience from a study of pyrimethamine in the primary prophylaxis of toxoplasmosis in HIV-infected patients. ANRS 005/ACTG 154 Trial Group

Randomized clinical trials analyzed by the intent-to-treat approach provide unbiased comparisons among treatment groups. To avoid dilution of treatment effect, many people also perform an analysis by treatment actually received, although this method may introduce bias into the results. This paper presents several approaches used for analyzing data of a recent trial and the difficulties encountered in interpreting the results of each approach. The ANRS 005/ACTG 154 Study was a double-blind, placebo-controlled, randomized, international (French, U.S., and Spanish) multicenter trial designed to assess the effectiveness of pyrimethamine for the primary prophylaxis of cerebral toxoplasmosis (CT) in HIV-infected patients with advanced immunodeficiency. In the intention-to-treat analysis, the cumulative probability of CT at 1 year did not differ significantly between the pyrimethamine arm (11.9%) and the placebo arm (13.1%), Hazard Ratio (HR) = 0.94 (95% Confidence Interval (CI) = 0.62-1.42), whereas an on-treatment analysis resulted in a significant difference: 4.2% in the pyrimethamine arm and 12.4% in the placebo arm, HR = 0.44 (95% CI = 0.24-0.80). The data showed a significant interaction between compliance and treatment outcome; and side effects were more frequently cited as reasons for compliance violations in the pyrimethamine group. Several different analytic approaches (censoring data at the time patients discontinued the study medication only for selected reasons) failed to explain the disparity between the estimation of effect of pyrimethamine by the intention-to-treat and on-treatment analyses. This experience led us to believe that comparing the results of both analyses was the best method to convince clinicians that intention-to-treat was the only interpretable analysis. We were concerned that even if pyrimethamine had a beneficial effect, it was very difficult (1) to quantify and (2) to apply to clinical practice unless one could predict the occurrence of study drug discontinuation for each patient at the time of treatment assignment. Although exploratory analyses may yield clinically relevant information and useful clarifications in the evaluation of treatments, intention-to-treat remains the only interpretable analysis of clinical trials.

[Epidemiologic characteristics of cerebral toxoplasmosis in 399 HIV-infected patients followed between 1983 and 1994]

OBJECTIVE

To describe the epidemiological characteristics of toxoplasmic encephalitis in HIV-infected patients with a more than 12-year follow-up.

METHODS

From a data base of 1,628 AIDS subjects hospitalized from 1983 to 1994, we studied the epidemiological characteristics of 399 patients with toxoplasmic encephalitis. Diagnosis of toxoplasmic encephalitis was based on the association of central neurological disorders, typical lesions on CT scan or MRI, and favorable outcome under appropriate toxoplasmosis therapy.

RESULTS

Four hundred sixty-four cases of toxoplasmic encephalitis were reported in 399 patients (24.5% of the patients with AIDS). The overall incidence was 20.5 per 100 patients-year. Toxoplasmic encephalitis was the first AIDS defining event in 51% of the cases and revealed HIV infection in 13% of the cases. In the remaining 49%, the mean delay from AIDS diagnosis to toxoplasmic encephalitis was 13 months (range: 1-71 months). At the time of diagnosis, mean CD4 count was 44/mm3 (range: 0-408/mm3). Antibodies to Toxoplasma gondii were found in 97% of the cases. Before the first episode of toxoplasmic encephalitis, 58% of the patients were given antiretroviral therapy (mean: 17.8 months; range: 1-64 months). Of the 399 patients with toxoplasmic encephalitis, 366 (92%) did not receive any primary toxoplasmosis prophylaxis. Among them, 205 (56%) did not receive any drug prophylaxis, and 161 (44%) had Pneumocystis carinii pneumonia prophylaxis alone (aerosolized pentamidine). Thirty-three failures were observed (8%) with cotrimoxazole: 14 cases (3%) were considered to have irregular compliance. Sixty-five relapses were observed in 52 patients. At the end of the study 334 patients had died (84%). The median survival was 11.4 months (95% confidence interval, range: 10.4-12.4 months).

CONCLUSIONS

Toxoplasmic encephalitis incidence has decreased since the introduction of appropriate drug prophylaxis.

Cotrimoxazole is effective as primary prophylaxis for toxoplasmic encephalitis in HIV-infected patients: a case control study

In a case-control study, prophylaxis with cotrimoxazole for toxoplasmic encephalitis (TE) in HIV-infected patients was evaluated. Cotrimoxazole had been given as PCP prophylaxis. 20 patients with TE were identified and 72 matching control cases were found. All patients had IgG-antibodies to Toxoplasma gondii and CD4+ T-cell counts < or = 100/microliter. The use and duration of cotrimoxazole prophylaxis were recorded. It was found that among the patients with TE, none had used cotrimoxazole for > 70% of the observation time, and that the 1-y incidence was 0% in the control group vs. 41% in those patients without sufficient cotrimoxazole use. The conclusion is that cotrimoxazole is effective as primary prophylaxis for TE, even in a dose of 480 mg daily.

Effects of 2',3'-dideoxyinosine on Toxoplasma gondii cysts in mice

The activity against Toxoplasma gondii of 2',3' dideoxyinosine (ddI), an anti-human immunodeficiency virus drug, was examined in an in vitro and in vivo study. Cell cultures infected with a strain known to cause chronic infections were used to show the dose-dependent effect of this drug compared with spiramycin and sulfadiazine. When a dose of 4 microg/ml was used, no infected THP-1 cells or parasites were found after 60 h of incubation. An electron-microscopic study confirmed that after 12 h at 1 microg/ml, the few parasites observed were severely altered. The treatment of chronically infected mice 3 months postinfection showed that a 30-day treatment with 2 mg of ddI/ml induced a significant reduction in the number of T. gondii cysts in the cerebral tissue. These cysts were not viable, as confirmed by immunofluorescence and reinfection experiments. These experiments suggest a possible role for ddI in the treatment of toxoplasmosis, and this possibility deserves further investigation.

Toxoplasmose chez les patients immunodéprimés. Apport à la connaissance de l'infection toxoplasmique

Toxoplasmosis can be a severe infection in immunosuppressed patients. In these patients it can present as collected encephalitis, diffuse hypoxemic pneumopathy, or disseminated infection with fatal outcome. These presentations are observed mainly in HIV-infected patients, and less frequently in bone-marrow transplanted, or heart or heart and lung transplanted patients, or in patients given long term steroids or immunosuppressive therapy. The disease is due most often to the reactivation of latent persistent forms of the parasite at a moment of depression of host defense mechanisms, with local reactivation, and/or hematogenous dissemination. In some cases, the disease is favored by an insufficient protective response after primary infection. Treatment, based on the pyrimethamine-sulfadiazine combination should be continued as long as a profound immunosuppression is present. Prevention is based on recommendations to avoid acquisition of the parasite for seronegative patients, and on chemoprophylaxis, using cotrimoxazole as first line regimen, in patients already infected with Toxoplasma gondii.

Primary care of the HIV patient: standard practice and new developments in the era of managed care

It is easy when taking care of the patient with AIDS to lose sight of the whole person and become focused on the details of micromanagement, distracted by the array of new therapies, and overwhelmed by the financial risks of the disease. It is therefore critical that a healing and respectful relationship is developed with patients and they are engaged in the decisions regarding their care. Physicians must also continue the search for new therapies and struggle to ensure that patients have access to state-of-the-art treatment. In this, the primary care physician plays a critical role, through identifying study centers, becoming an investigator in expanded access programs, and using referrals to clinical trials to provide new therapies to patients and improve understanding of HIV treatment. Finally, quality of life must be at the forefront of physicians' medical conscience. Ultimately, the physician must know when the best treatment he of she can offer is the assurance of a dignified and comfortable death.

Quantitative competitive PCR with bronchoalveolar lavage fluid for diagnosis of toxoplasmosis in AIDS patients

Of 121 AIDS patients, 12 (10%) had Toxoplasma gondii DNA detected by competitive PCR in their bronchoalveolar lavage samples. Quantitation of the PCR results showed a correlation between the parasite burden and the serum lactic dehydrogenase titer. Quantitative competitive PCR could be useful to assess the diagnosis and the severity of pulmonary toxoplasmosis.