[Cerebral toxoplasmosis developed after unrelated bone marrow transplantation for acute myeloid leukemia]

A 16-year-old boy received an unrelated bone marrow transplant while in second remission of acute myeloid leukemia. He suffered from severe oral mucosal complications and had difficulty taking oral drugs such as sulfamethoxazole/trimethoprim (ST). Engraftment was obtained on transplant day 35, and blurred vision and headache appeared around transplant day 60. Funduscopy revealed retinal hemorrhage and macular edema, and an MRI scan of the head revealed a nodular lesion in the left putamen. Toxoplasma gondii was detected by CSF PCR, and cerebral toxoplasmosis was diagnosed. Following therapy with ST and clindamycin, the patient was administered pyrimethamine, sulfadiazine, and leucovorin. Symptoms improved promptly, and CSF PCR was negative 45 days after the start of treatment. Since the prevalence of toxoplasma antibodies increases with age, it is crucial to avoid toxoplasma reactivation by ST after hematopoietic cell transplantation in postpubescent patients.

SPARC coordinates extracellular matrix remodeling and efficient recruitment to and migration of antigen-specific T cells in the brain following infection

Central nervous system (CNS) injury and infection can result in profound tissue remodeling in the brain, the mechanism and purpose of which is poorly understood. Infection with the protozoan parasite Toxoplasma gondii causes chronic infection and inflammation in the brain parenchyma. Control of parasite replication requires the continuous presence of IFNγ-producing T cells to keep T. gondii in its slowly replicating cyst form. During infection, a network of extracellular matrix fibers, revealed using multiphoton microscopy, forms in the brain. The origin and composition of these structures are unknown but the fibers have been observed to act as a substrate for migrating T cells. In this study, we show a critical regulator of extracellular matrix (ECM) remodeling, Secreted Protein, Acidic, Rich in Cysteine (SPARC), is upregulated in the brain during the early phases of infection in the frontal cortex. In the absence of SPARC, a reduced and disordered fibrous network, increased parasite burden, and reduced antigen-specific T cell entry into the brain points to a role for SPARC in T cell recruitment to and migration within the brain. We also report SPARC can directly bind to CCR7 ligands CCL19 and CCL21 but not CXCL10, and enhance migration toward a chemokine gradient. Measurement of T cell behavior points to tissue remodeling being important for access of immune cells to the brain and facilitating cellular locomotion. Together, these data identify SPARC as an important regulatory component of immune cell trafficking and access to the inflamed CNS.

Disruption of Purinergic Receptor P2X7 Signaling Increases Susceptibility to Cerebral Toxoplasmosis

Toxoplasmosis is a neglected disease that affects millions of individuals worldwide. Toxoplasma gondii infection is an asymptomatic disease, with lethal cases occurring mostly in HIV patients and organ transplant recipients. Nevertheless, atypical strains of T. gondii in endemic locations cause severe pathology in healthy individuals. Toxoplasmosis has no cure but it can be controlled by the proinflammatory immune response. The purinergic receptor P2X7 (P2X7) is involved in many inflammatory events and has been associated with genes that confer resistance against toxoplasmosis in humans. In vitro studies have reported parasite death after P2X7-receptor activation in various cell types. To understand the contribution of P2X7 during cerebral toxoplasmosis, wild-type and P2rx7 knockout mice were infected orally with T. gondii and their pathologic profiles were analyzed. We found that all P2rx7^-/- mice died 8 weeks after infection with an increased number of cysts and fewer inflammatory infiltrates in their brains. The cytokines interleukin-1β, interleukin-12, tumor necrosis factor-α, and reactive oxygen species were absent or reduced in P2rx7^-/- mice. Taken together, these data suggest that the P2X7 receptor promotes inflammatory infiltrates, proinflammatory cytokines, and reactive oxygen species production in the brain, and that P2X7 signaling mediates major events that confer resistance to cerebral toxoplasmosis.

Cerebral toxoplasmosis after haematopoietic stem cell transplantation

Toxoplasmosis is an opportunistic infection caused by the parasite Toxoplasma gondii. The infection is severe and difficult to diagnose in patients receiving allogeneic haematopoietic stem cell transplantation (HSCT). It frequently involves the central nervous system. The case is presented of cerebral toxoplasmosis in a 17-year-old youth with Fanconi anaemia treated with haematopoietic stem cell transplantation (HSCT).

Transventricular Mitral Commissurotomy in Critical Mitral Stenosis during Pregnancy

The management of a pregnant patient with mitral stenosis is a subject of debate with regards to the optimal type of treatment and the time of intervention. We performed trans-ventricular mitral commissurotomy (TVMC) either as an isolated procedure in the second trimester, or in combination with Cesarian section at term. We retrospectively analyzed our experience with TVMC during pregnancy and formulated a protocol for its management. Between January 1987 and April 2002, fifty one patients underwent TVMC for critical mitral stenosis during pregnancy. In 38 patients, elective TVMC was performed during the second trimester, while in 12, it was performed as an initial procedure along with Cesarian section at term. One patient had an emergency TVMC in the second trimester when she presented with intractable acute pulmonary edema. There were no maternal mortalities. Three patients who developed post-operative mitral regurgitation were managed conservatively. Another two patients who developed cerebral embolism with hemiplegia recovered completely without any neurological deficit. There was only one fetal death in a patient where TVMC was performed as an emergency procedure for acute pulmonary edema. We conclude that TVMC in pregnancy is a safe, cost effective alternative in critical mitral stenosis complicating pregnancy.

[Cerebral toxoplasmosis after umbilical cord blood transplantation diagnosed by the detection of anti-toxoplasma specific IgM antibody in cerebrospinal fluid]

Cerebral toxoplasmosis is a rare, potentially fatal, complication of hematopoietic cell transplantation. Early definitive diagnosis is very difficult and it may be associated with a poor prognosis. Herein, we describe a 60-year-old woman who developed cerebral toxoplasmosis after cord blood transplantation for myelodysplastic syndrome. During treatment with tacrolimus and methylprednisolone for relapsed grade 2 acute gut GVHD, fever and disturbance of consciousness occurred on day 210. Brain MRI showed multiple ring-enhancing nodular lesions in the thalamus, basal ganglia, brainstem, and subcortical white matter. Cerebrospinal fluid (CSF) assessment revealed elevations of both anti-to-xoplasma IgM and IgG, which were also elevated in serum, but no evidence of other infections or malignancies. Notably, the IgM level was higher in the CSF than in serum. Thus, cerebral toxoplasmosis was diagnosed. Soon after administration of oral sulfamethoxazole/trimethoprim and intravenous clindamycin in combination with short-term dexamethasone for the cerebral edema, her symptoms and signs began to improve. On day 229, both IgM and IgG titers in CSF had clearly decreased but remained essentially constant in serum. She was discharged without clinically significant neurological disorders. This case suggests that CSF specific anti-toxoplasma IgM titers might be useful for early diagnosis of cerebral toxoplasmosis after transplantation.

[Location of foci in cerebral toxoplasmosis in HIV-infected patients]

AIM

To analyze the data of magnetic resonance imaging (MRI) of the brain in its toxoplasmosis in HIV-infected patients.

SUBJECT AND METHODS

The clinical picture of cerebral toxoplasmosis was studied in 207 patients aged 18-76 years with Stage 4B HIV infection concurrent with the disease. Brain MRI using an Obraz-1 low-field (0.12 T) MRI scanner (Russia) was carried out in 115 (55.5%) patients. This investigation was conducted in 74 (65%) treated patients over time.

RESULTS

Brain T2-weighted and FLAR MRI scans most frequently revealed higher-signal polymorphic foci and T1-weighted MRI scans showed lower-signal ones predominantly involving the white matter or white-grey matter border. Perifocal edema was often recorded. Intravenous gadolinium contrast study indicated that these foci accumulated the contrast agent around the periphery following the target patterns. Sixty-four (86.5%) patients were observed to have significant positive changes: reductions in the number and sizes of foci and the area of perifocal edema; in 29 patients, the inflammatory foci changed into cysts as a favorable outcome of necrotizing encephalitis. The foci resolved completely only in 7% of the patients.

CONCLUSION

MRI is of great importance in intensive care, neurology, or neurosurgery units where patients with cerebral toxoplasmosis mimicking an acute cerebrovascular accident or a brain tumor are particularly frequently admitted to.

[Toxoplasmosis of the central nervous systems after allogeneic stem cell transplantation]

Toxoplasmosis is a rare opportunistic protozoal infection, which may occur in patients after hematopoietic stem cell transplantation. This disease originates almost exclusively from reactivation of latent infection in seropositive recipients. We present a case report of one patient with diagnosis of acute myeloid leukemia undergoing two allogeneic stem cell transplantations at two years interval. The second transplantation was complicated by the development of the toxoplasmic encephalitis in early posttransplant course. The initial neurological symptoms included diplopia caused by the paresis of right side motor branches of the 3rd and 6th cranial nerves due to a compressive lesion in basal ganglia. Patient suddenly deteriorated after an epileptic seizure followed by a loss of consciousness, bilateral ptosis and right side mydriasis. Prolonged sopor and bilateral mydriasis appeared because of the further lesion progression in basal ganglia and compression of the 3rd cranial nerve. After targeted therapy of Toxoplasma gondii the patient's clinical status improved and she regained consciousness. Unfortunately, examination of bone marrow later revealed the relapse of leukemia. We compared risk factors of the latent reactivation of infection in immunocompromised patients with published data. It is of interest that the toxoplasmosis of the brain developed in this patient after the second transplantation.

[Cerebral toxoplasmosis complicating an allograft with hematopoietic stem cells from peripheral blood]

We report the occurrence of a cerebral toxoplasmosis 52 days after a non-myeloablative allogeneic stem cell transplantation as treatment for acute myeloid leukemia.

Toxoplasmosis encephalitis following severe graft-vs.-host disease after allogeneic hematopoietic stem cell transplantation: 17 yr experience in Fukuoka BMT group

Toxoplasmosis is a rare but rapidly fatal complication that can occur following hematopoietic stem cell transplantation (HSCT). Over a 17-yr period at our institutions, a definite diagnosis of toxoplasmosis was made in only two of 925 allogeneic HSCT recipients (0.22%) and none of 641 autologous HSCT recipients. These two patients received a conventional conditioning regimen followed by transplantation from an HLA-matched donor; however, they developed severe graft-vs.-host disease, which required intensive immunosuppressive therapy. Despite prophylactic treatment with trimethoprim/sulfamethoxazole, their immunosuppressive state, as indicated by a low CD4(+) cell count, might have resulted in toxoplasmosis encephalitis. Rapid and non-invasive methods such as a polymerase chain reaction (PCR) test of their cerebrospinal fluid for Toxoplasma gondii and magnetic resonance imaging of the brain were useful for providing a definitive diagnosis and prompt therapy in these patients: one patient stabilized and survived after responding to treatment with pyrimethamine/sulfodiazine whereas the other died of bacterial infection. In addition, retrospective PCR analyses of the frozen stored peripheral blood samples disclosed that detection of T. gondii preceded the onset of disease, indicating routine PCR testing of peripheral blood specimens may be an early diagnostic tool. It should be noted that when patients receiving HSCT have an unexplained fever and/or neurological complications, PCR tests should be considered to avoid cerebral lesions and improve the outcome of the patients.

Atteintes du système nerveux central et infection par le VIH-1

Central nervous system complications are common in HIV-1 infected patients and occur either as a result of concomitant immunosuppression (opportunistic infections, lymphoma and tumors), as a primary manifestation of HIV infection, or as an adverse effect of therapy (immune restoration and toxicity). These complications contribute largely to patient morbidity and mortality. In the era of highly active antiretroviral therapy (HAART) these disease states have changed in presentation, outcome and incidence. We review in detail the epidemiology, pathogenesis, clinical features, diagnosis, and management of these disorders.

[The colorful clinical spectrum of cerebral toxoplasmosis in five HIV positive cases: what comes out of Pandora's box?]

In patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS), the most common cause of focal intracranial lesion is Toxoplasma gondii infection. T. gondii encephalitis is an easily and effectively treatable disease, with promising outcomes. T. gondii has the potential to form a focal infection niche anywhere in the central nervous system, thus allowing for a colorful clinical picture. In this report, we attempted to present five HIV/AIDS cases with central nervous system toxoplasmosis demonstrating five different neurological presentations. The ages, gender and clinical findings of the patients who were admitted to our Infectious Diseases Clinics were as follows; 35 years old male patient with delirium, 49 years old male patient with focal dystony, 32 years old female patient with facial paralysis and monoparalysis, 53 years old male patient with Wernicke syndrome, 32 years old male patient with epilepsy. Cerebral toxoplasmosis were diagnosed by clinical findings and imaging techniques. The patients were treated with trimetoprim-sulfametoxazol (TMP-SMZ) and haloperidol, only TMP-SMZ, clindamycin and daraprim, TMP-SMZ and levotiracetam, TMP-SMZ and phenytoin, respectively, with recovery in neurological and radiological symptoms. In conclusion, until proven otherwise, HIV/AIDS patients presenting with focal neurological complaints should be accepted as having central nervous system toxoplasmosis.

[Neurological manifestations of HIV-infection in the era of highly active antiretroviral therapy (HAART)]

After the introduction of highly active antiretroviral therapy (HAART) in 1996 the neurological manifestations of human immunodeficiency virus (HIV-1)-infection did not decline in incidence and prevalence like the other complications of immunodeficiency; in contrast, due to the longer survival times of HAART treated HIV-1-positive individuals, prevalence of virus associated neurological disease increased during the last years, as international studies underline. Therefore, clinicians and HIV-therapists should be able to diagnose HIV-1-associated neurological disease even in early stages. This article describes symptoms and signs, neuro-imaging and cerebrospinal fluid findings as well as therapy options in primary HIV-1-associated neurological disease like encephalo- and myelopathy and polyneuropathy. Furthermore, those opportunistic infections, caused by bacteria, viruses other than HIV and parasites emerging with manifest immunodeficiency and remaining to be relevant in the HAART era are presented from diagnostic, differential-diagnostic and therapeutic points of view. An extra paragraph describes the interaction of HAART with neurological/psychiatric standard therapies.

[Toxoplasma encephalitis in a patient receiving cyclosporine monotherapy for Behçet disease]

We report a 44-year-old woman with toxoplasma encephalitis that occurred during cyclosporine monotherapy for Behçet disease. She had been treated with cyclosporine for 8 years. She experienced headache and, nausea, and then consciousness disturbance developed. Brain MRI showed high-signal intensity lesions on T1-weighted MRI with Gd-enhancement in the left temporoparietal lobe, right thalamus and right frontal and temporal lobes. The pathological examination of the biopsied brain specimens suggested toxoplasma encephalitis. She improved rapidly after the administration of antibiotics for toxoplasma gondii. Anti-toxoplasma specific protein antibodies were positive in the serum and CSF, supporting a diagnosis of acute toxoplasmosis. Toxoplasma encephalitis due to cyclosporine mono-therapy has not been reported yet. The measurement of anti-toxoplasma specific protein antibodies may be useful for the early, accurate diagnosis of toxoplasmosis.

Prevalence, Associated Factors, and Prognostic Determinants of AIDS‐Related Toxoplasmic Encephalitis in the Era of Advanced Highly Active Antiretroviral Therapy

BACKGROUND

Characteristics, associated factors, and survival probability of toxoplasmic encephalitis (TE) in the era of advanced highly active antiretroviral therapy (HAART) have not been fully clarified.

METHODS

Data for 205 individuals with acquired immunodeficiency syndrome (AIDS)-related TE were derived from the Italian Registry Investigative NeuroAIDS database, and the cases were studied longitudinally to evaluate prevalence, clinical characteristics, and survival. Moreover, the relationship between the occurrence of TE and exposure to antiretroviral therapy and to TE prophylaxis was evaluated.

RESULTS

With an overall prevalence of 26%, TE represented the most frequent neurological disorder in the cohort. Female sex, severe immunodeficiency, and absence of primary TE prophylaxis significantly increased the risk of TE, and previous exposure to antiretroviral therapy reduced the probability of disease occurrence. Thirty-six percent of patients who had received antiretroviral therapy developed TE, although in most of these cases, the patient experienced failure of antiretroviral therapy. Of note, 66% of patients who had experienced antiretroviral therapy did not receive prophylaxis for TE at TE diagnosis. The 1-year probability of that infection with human immunodeficiency virus (HIV) would progress or that death would occur after TE was 40% and 23%, respectively. Cognitive symptoms, low CD4(+) cell count, not receiving HAART after TE, and initiating HAART >2 months after TE diagnosis were all significantly associated with an increased probability of progression of HIV infection. Not receiving HAART after diagnosis negatively affected survival.

CONCLUSIONS

TE remains a highly prevalent disorder of the central nervous system, even in the late HAART era, particularly among severely immunosuppressed patients and in absence of prophylaxis. Considering that persons with TE have a high probability of early death, prophylaxis should be maintained in immunosuppressed patients who experience failure of antiretroviral therapy, and HAART should be initiated as soon as possible after TE diagnosis.

Toxopain-1 is critical for infection in a novel chicken embryo model of congenital toxoplasmosis

We tested the hypothesis that cathepsins and specifically toxopain-1, a cathepsin B, play a critical role in the pathogenesis of toxoplasmosis. We found that inhibiting the expression of toxopain-1-specific mRNA and protein by >60% significantly decreased the capacity of the parasites to multiply and invade in vitro. To relate these in vitro results to the role of toxopain-1 in pathogenesis in vivo, we developed a novel chicken embryo model of congenital toxoplasmosis. Inhibiting either toxopain-1 expression or specific cysteine proteinase activity significantly reduced congenital infection of chicken embryos, as determined by histopathology and by the number of parasites quantified by real-time PCR. Our new model provides key in vivo validation for the hypothesis that toxopain-1 is a potential drug target in Toxoplasma gondii and also provides a new animal model for rapid, inexpensive screening of antiparasitic compounds.

[Secondary diseases in patients with HIV infection: 15-year follow-up]

AIM

To analyse the results of a 15-year study of opportunistic diseases in AIDS patients.

MATERIAL AND METHODS

The spectrum of opportunistic diseases were made in AIDS patients in respect to clinical, laboratory and autopsy data for the periods: 1987-1992 (n = 27, 25 deaths--92.6%), 1993-1997 (n = 95, 58 deaths--61.8%), 1998-1999 (n = 70, 28 deaths--40%), 2000-2001 (n = 126, 31 deaths--24.6%), 2002 (n = 80, 32 deaths--40%).

RESULTS

The spectrum of opportunistic diseases in AIDS patients was determined for the above time periods and causes underlying these diseases have been determined.

CONCLUSION

Among opportunistic diseases associated with HIV infections most prevalent were the following: tuberculosis, cytomegaloviral infections, cerebral toxoplasmosis. Leading modern trends were identified: increasing morbidity of AIDS, tuberculosis, new AIDS cases at late stages with severe opportunistic diseases (2/3 of deaths).

Cerebral toxoplasmosis following etanercept treatment for idiophatic pneumonia syndrome after autologous peripheral blood progenitor cell transplantation (PBPCT)

Idiophatic pneumonia syndrome (IPS) is a term used to describe lung injury following hematopoietic stem cell transplantation (HSCT) without an infectious etiology. Diagnostic criteria include multilobar infiltrates on chest X-ray, clinical symptoms consistent with pneumonia and evidence of abnormal pulmonary physiology. The incidence after autologous transplantation is low (6%) but it has a high mortality (70-80%). Treatment with high-dose steroids has been used but the results are discouraging. Etanercept is a recombinant human soluble TNF receptor fusion protein that inhibits tumor necrosis factor alpha (TNFalpha) function. Recently, promising results have been obtained with etanercept for the treatment of acute and chronic GVHD after HSCT, but there is a little information regarding adverse effects. We report a case of IPS after autologous peripheral blood progenitor cell transplantation (PBPCT) successfully treated with etanercept. The patient developed cerebral toxoplasmosis immediately after etanercept treatment with a good outcome.

Different strains of Toxoplasma gondii induce different cytokine responses in CBA/Ca mice

To investigate the role that cytokines may have in the development of toxoplasmic encephalitis (TE), the levels of gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), interleukin-12 (IL-12 ]p40[), IL-10, IL-6, IL-4, and IL-2 in serum were examined in CBA/Ca mice infected with a type II strain (ME49 or FORT) of Toxoplasma gondii. These strains caused severe (ME49) or mild (FORT) TE in CBA/Ca mice. From weeks 1 to 8 of infection, the levels of IL-6, IL-10, IL-12, IFN-gamma, and TNF-alpha in serum were significantly higher in the ME49-infected mice than in the FORT-infected mice, suggesting a role for these cytokines in the severity of TE in CBA/Ca mice. Since the ME49 and FORT strains are of the same type, our results suggest a role for the parasite in the development of severe TE through the increased production of proinflammatory cytokines and indicate that not all type II strains cause TE.

Toxoplasmosis in bone marrow transplantation: a report of two cases and systematic review of the literature

Toxoplasma infection represents a rare but often fatal complication in bone marrow transplant (BMT) recipients. We report two cases of toxoplasmosis: one of successfully treated cerebral toxoplasmosis after peripheral blood stem cell transplantation, and a fatal case of pulmonary toxoplasmosis in a BMT recipient. We have systematically reviewed the 110 published cases of toxoplasmosis following BMT. We analyzed the pre-transplant and clinical features of BMT recipients developing toxoplasmosis, together with the diagnostic procedures used and treatment given. By univariate and multivariate statistical analysis we analyzed the risk factors for diagnosis (during life vs post-mortem) and Toxoplasma-related mortality. Ante-mortem diagnosis was made in 47% of cases. Site of infection (P = 0.02; odds ratio 10.8), presence of symptoms at onset (P = 0.01) and conditioning regimen (P = 0.04) were factors influencing whether the diagnosis was made before or after death. Overall mortality rate was 80% and that attributed to toxoplasmosis was 66%. Variables influencing outcome were: site of infection (P = 0.02; odds ratio 5.28), day of onset (P = 0.04) and conditioning regimen (P = 0.04). Underlying disease (P = 0.02; odds ratio 9.45), among patients diagnosed before death, was the most significant factor influencing outcome.

Risk factors for toxoplasmic encephalitis in HIV-infected patients: a case-control study in Brazil

A case-control study to identify the risk factors for toxoplasmic encephalitis (TE) among HIV-infected patients with latent Toxoplasma gondii infection was performed in a teaching hospital in south-eastern Brazil. Although the subjects were all positive for serum IgG antibodies to Toxoplasma, some (the cases) developed TE during routine follow-up at the hospital whereas others (the controls) did not. Adjusted odds ratios (aOR) were estimated by multiple logistic regression after controlling for potential confounders. Only 46 (22%) of the 210 cases but 93 (45%) of the 205 controls were on prophylactic regimens with co-trimoxazole [aOR = 0.30; 95% confidence interval (CI) = 0.15-0.60]. Subjects with fewer than 100 (aOR = 37.09; CI =7.49-183.67) or between 100 and 200 CD4 cells/microl (aOR = 10.20; CI =2.00-51.90) were at substantially increased risk of developing TE than those with >400 CD4 cells/microl. Although the results of preliminary, unadjusted data analysis indicated that male sex and homosexual or bisexual activity might be additional risk factors, these associations were not found to be statistically significant by multiple regression analysis. In conclusion, no risk factors for TE other than low CD4 cell counts and failure to receive prophylaxis were found among HIV-infected Brazilian patients with past exposure to Toxoplasma. Seropositive patients with CD4 cell counts above 100/microl (the point at which specific prophylaxis is usually recommended) but below 200/microl might also benefit from effective anti-TE prophylaxis.

Involvement of apoptosis and interferon-gamma in murine toxoplasmosis

PURPOSE

A murine toxoplasmosis model has been developed that results in central nervous system (CNS) and ocular inflammation characterized by encephalitis with numerous brain tissue cysts and milder inflammation with rare tissue cysts in the eye after 4 weeks of Toxoplasma gondii infection. In this model IFN gamma and inducible nitric oxide (iNO) are protective against T. gondii infection. In this study, the role of apoptosis in the pathogenesis of toxoplasmosis was investigated.

METHODS

C57BL/6 (wild-type mice), B6MRL/lpr, and B6MRL/gld (defective Fas or FasL expression, respectively) mice were infected intraperitoneally with 20 to 30 tissue cysts of the ME-49 strain of T. gondii. Mice were killed at days 0, 14, or 28 after infection. The eyes and brains were harvested for histologic, immunohistochemical, and molecular studies. Analysis included immunostaining for Fas, FasL, Bcl-2, and Bax; in situ apoptosis detection (TUNEL assay); RT-PCR amplification for IFN gamma; and measurement of ocular nitrite levels. The control mice were naïve mice of each strain that received no inoculation or injection.

RESULTS

Wild-type mice appeared to constitutively express apoptotic molecules at higher levels in the eye than in the brain. Consequently, during T. gondii infection, apoptosis was greater in the eyes than in the brain. Untreated naïve lpr and gld mice showed no expression of Fas and FasL, respectively. After infection, a slightly higher number of tissue cysts (lpr, 11.8 +/- 2.4; gld, 10.3 +/- 3.4) were found in the brains of the mutants than in the control animals (8.8 +/- 2.9). However, no significant differences between the number of apoptotic cells, inflammatory scores, or number of tissue cysts were noted in the eyes. IFN gamma mRNA in control mice was detected at day 28 after infection, whereas in both mutants, mRNA production occurred earlier, at day 14. Ocular nitrite levels were higher in lpr and gld mice than in wild-type mice.

CONCLUSIONS

No significant difference in the degree of ocular inflammation and apoptosis was detected between the wild-type and Fas or FasL mutant mice. However, there was an earlier and subjectively greater expression of IFN gamma in the brain and eye and a higher level of nitrite in the ocular tissue of mutant strains than in the wild type. Multiple factors are likely to be involved in the pathogenesis of ocular toxoplasmosis.

Toxoplasmosis, a severe complication in allogeneic hematopoietic stem cell transplantation: successful treatment strategies during a 5-year single-center experience

Toxoplasmosis is a rare but often fatal complication that occurs after patients undergo allogeneic hematopoietic stem cell transplant. At our institution, toxoplasmosis was diagnosed in 8 of 301 patients who received stem cell transplants. Disseminated toxoplasmosis with a rapid fatal course was observed in 2 patients. Six patients had cerebral toxoplasmosis diagnosed on the basis of neurological signs and observation of the patients' mental confusion, seizures, and typical lesions (which were assessed by computed tomography, magnetic resonance imaging, or both). Seroconversion of antitoxoplasma immunoglobulin and a discovery of toxoplasma deoxyribonucleic acid in the cerebrospinal fluid (confirmed by use of polymerase chain reaction) were documented in all patients. Treatment consisted of clindamycin therapy (for 2 patients) and of pyrimethamine-clindamycin therapy, sulfadiazine therapy, or both (for 5 patients). Patients showed improvement after therapy, as assessed by clinical and radiological means. Three of 8 patients survive-1 without any residual neurological symptoms and 2 with minimal neurological symptoms.

MRI of intracranial toxoplasmosis after bone marrow transplantation

Toxoplasma encephalitis was confirmed by biopsy in three patients with bone marrow (BMT) or peripheral blood stem-cell transplantation (PBSCT). All had MRI before antimicrobial therapy. The intensity of contrast enhancement was very variable. One patient had one large, moderately enhancing cerebral lesion and several smaller almost nonenhancing lesions. The second had small nodular and haemorrhagic lesions without any enhancement. The third had late cerebral toxoplasmosis and showed multiple lesions with marked contrast enhancement. The moderate or absent contrast enhancement in the two patients in the early phase of cerebral toxoplasmosis may be related to a poor immunological response, with a low white blood cell count in at least one patient. Both received higher doses of prednisone than the patient with late infection, leading to a reduced inflammatory response. In patients with a low leukocyte count and/or high doses of immunosuppressive therapy, typical contrast enhancement may be absent.

Cerebral toxoplasmosis - a late complication of allogeneic haematopoietic stem cell transplantation

Toxoplasma gondii infection reactivation predominantly occurs among patients after allogeneic haematopoietic stem cell transplantation. Mostly, reactivation occurs during first 3 months after transplant, especially when risk factors are present. We report a case of late cerebral toxoplasmosis reactivation, which was probably triggered by a brief course of corticosteroids, administered for chronic graft-versus-host disease (cGVHD). In the presence of risk factors, such as cGVHD, prophylactic treatment for toxoplasmosis should be reinstituted; Trimethoprim-sulfamethoxasole most probably prevented earlier reactivation of toxoplasmosis in our patient.

Chorea in patients with AIDS

OBJECTIVE

To describe differing etiologies and possible anatomoclinical correlates of choreic movements in a series of AIDS patients.

METHODS

We analyzed the clinical records and neuroimaging data of 5 consecutive AIDS patients who developed choreic movements at our center from January, 1994 to December, 1996.

RESULTS

There were 2 cases of focal choreic dyskinesias, 1 of right hemichorea, and 2 of generalized chorea. Onset was acute and febrile in 1 case, and subacute in the other 4. In 1 patient the chorea was the AIDS onset symptom; in another choreic movements were the first neurological symptom following AIDS diagnosis; in 2 patients AIDS had a neurological onset other than chorea; and in the fifth patient buccofacial dyskinesias appeared following the development of bacterial encephalitis.

CONCLUSION

Chorea was associated with cerebral toxoplasmosis in 2 patients, progressive multifocal leukoencephalopathy in 1, subacute HIV encephalopathy in another, and was probably iatrogenic in the last. Chorea is not unusual in AIDS, however the causes are variable and careful neuroradiological and clinical evaluation is required to identify them. AIDS-related disease should be considered in young patients presenting with chorea without a family history of movement disorders.

Central nervous system toxoplasmosis in acquired immunodeficiency syndrome: An emerging disease in India

With the incidence of patients infected with human immuno-deficiency virus (HIV) increasing in India, the central nervous system (CNS) manifestations of the disease will be seen more frequently. The CNS may be primarily afflicted by the virus or by opportunistic infections and neoplasms secondary to the immune suppression caused by the virus. In India, although mycobacterium tuberculosis has been reported to be the most common opportunistic infection, toxoplasmosis may become as common owing to the ubiquitous nature of the protozoan. Since an empirical trial of medical therapy without histopathological diagnosis is recommended, the true incidence of this condition may remain under estimated. The role of ancillary tests such as radiology and serology in the initial diagnosis of this condition remain crucial. This report highlights two patients who were diagnosed to have acquired immuno-deficiency syndrome (AIDS) only after the biopsy of the intracranial lesion was reported as toxoplasmosis. Presently all patients for elective neurosurgery are tested for HIV antigen. The management protocol to be followed in a known patient with AIDS presenting with CNS symptoms is discussed in detail. The value of ancillary tests is also reviewed.

[Non-Hodgkin's lymphoma with Toxoplasma encephalitis]

A 62-year-old man was admitted to our hospital due to fever and systemic lymph-node swelling on June 9, 1998. He was given a diagnosis of non-Hodgkin's lymphoma (diffuse mixed T cell lymphoma) with involvement of mediastinum and para-aortic lymph nodes, pleura, peritoneum, and bone marrow. After diagnosis, combined chemotherapy (CHOP regimen) was started. On day 11, the patient's consciusness level suddenly deteriorated. A brain computed tomographic scan showed no abnormal findings. A cytospin smear of cerebrospinal fluid disclosed tachyzoides (Toxoplasmic bodies), thus yielding a diagnosis of Toxoplasma encephalitis. Oral sulfadoxine pyrimethamine rapidly alleviated the patient's consciousness disturbance. One month later, a cytospin smear and RT-PCR analysis of cerebrospinal fluid detected no tachyzoides. Complete remission of lymphoma was achieved after 2 courses of CHOP therapy. Toxoplasma encephalitis should be considered a potential cause of consciousness disturbance in immunocompromised hosts, such as patients with malignant lymphoma. Cytospin smears of cerebrospinal fluid are a useful tool for the early diagnosis of Toxoplasma encephalitis.

Opportunistic CNS infection after bone marrow transplantation

We retrospectively identified opportunistic CNS infections in 655 patients who had undergone allogeneic, syngeneic or autologous BMT or PBSCT between 1990 and 1997. Twenty-seven patients (4%) developed CNS infections. All CNS infections occurred in allogeneic BMT or PBSCT patients. The most common CNS infections were toxoplasma encephalitis (74%) and cerebral aspergillosis (18%). Furthermore, we identified one patient with candida encephalitis and one patient with viral encephalitis. Overall mortality of patients with opportunistic CNS infection was 67%. There were two different groups of toxoplasma encephalitis with a different appearance on MR imaging. The first group showed edema, but no gadolinium enhancement, whereas the second group exhibited typical MRI appearances with the exception of frequent hemorrhagic transformation. The first group had a significant shorter latency between BMT and onset of CNS infection (mean 45 days vs 180 days, P = 0.02), a significant higher daily dose of corticosteroids as treatment for graft-versus-host disease (GVHD) (P = 0.01), more severe GVHD and a higher mortality (71% vs 36%). This study shows that the most common CNS infections in our patient population are toxoplasma encephalitis and cerebral aspergillosis, that there are two distinct subgroups of toxoplasma encephalitis and that CNS infections occur after allogeneic BMT only.

Attachment ligands of viable Toxoplasma gondii induce soluble immunosuppressive factors in human monocytes

Previous studies have demonstrated that surface antigen proteins, in particular SAG-1, of Toxoplasma gondii are important to this parasite as attachment ligands for the host cell. An in vitro assay was developed to test whether these ligands and other secretory proteins are involved in the immune response of human cells to toxoplasma. Human monocytes were infected with tachyzoites in the presence of antiparasite antibodies, and their effect on mitogen-induced lymphoproliferation was examined. The presence of antibody to either parasite-excreted proteins (MIC-1 and MIC-2) or surface proteins (SAG-1 and SAG-2) during infection neutralized the marked decrease seen in mitogen-induced lymphoproliferation in the presence of infected monocytes. Conversely, antibodies to other secreted proteins (ROP-1) and cytoplasmic molecules had no effect on parasite-induced, monocyte-mediated downregulation. Fluorescence microscope analysis detected microneme and surface antigen proteins on the monocyte cell surface during infection. These results suggest that microneme and surface antigen proteins trigger monocytes to downregulate mitogen-induced lymphoproliferation.

Incidence and risk factors of toxoplasmosis in a cohort of human immunodeficiency virus-infected patients: 1988-1995. HEMOCO and SEROCO Study Groups

The incidence of cerebral and extracerebral toxoplasmosis among 1,699 HIV-infected patients followed in the SEROCO and HEMOCO cohorts (1988-1995) was studied. It increased from 0.7 per 100 person-years in 1988 to 2.1 per 100 person-years in 1992, as a result of the increasing prevalence of patients with CD4 cell counts below 200/microL. It decreased thereafter to 0.2 per 100 person-years in 1995, while the proportion of patients receiving specific prophylaxis was increasing. A Toxoplasma antibody titer of >150 IU/mL was an important predictor of toxoplasmosis (adjusted relative risk [aRR], 3.6 [95% confidence interval, 2.1-6.0]), independent of a CD4+ cell count of <200/microL (aRR, 20.8) and specific prophylaxis (aRR, 0.2 [0.1-0.3]). The median CD4+ cell count was 389/microL at the time the antibody titer was first noted to be >150 IU/mL, while the median CD4 cell count at onset of toxoplasmosis was 58/microL. Thus, disease was diagnosed 10 days to 74 months after the rise in Toxoplasma antibody titers. While the risk factors for development of toxoplasmosis remain incompletely defined, the importance of specific prophylaxis for patients with low CD4 cell counts and high Toxoplasma antibody titers is supported by these findings.

Successful treatment of cerebral toxoplasmosis in a marrow transplant recipient: contribution of a PCR test in diagnosis and early detection

We report successful treatment of cerebral toxoplasmosis in an unrelated donor marrow transplant recipient. The clinical diagnosis was confirmed by polymerase chain reaction (PCR) amplification for T. gondii-DNA performed both on cerebrospinal fluid and blood leukocytes. Retrospective testing of stored blood samples demonstrated positive leukocyte PCR signal detected up to 52 days prior to onset of clinical symptoms. This case highlights the value of PCR in the diagnosis and early detection of cerebral toxoplasmosis.

[Efficacy and good tolerance of cotrimoxazole as treatment of cerebral toxoplasmosis in AIDS]

OBJECTIVE

Non-viral opportunistic infections involving the central nervous system in AIDS patients most commonly result from toxoplasmic encephalitis (TE). Combination pyremethamin (pyr)/sulfadiazine (sulf) is the mainstay treatment for TE, but many patients experience severe adverse events occasionally requiring discontinuation of this antitoxoplasmic medication. This investigation assessed the effects of an open, prospective trial of alternative trimethroprim/sulfamethoxazole: cotrimoxazole (CTX) therapy for TE in AIDS patients.

PATIENTS AND METHODS

The subjects were 18 AIDS patients with a first presumptive attack of TE (Group 1) and 9 relapsing patients, including 6 out of Group 1 (Group 2). We gave CTX as a therapy at the dose of 960 mg four times a day for 48 hours, then 960 mg three times a day for two weeks, followed by 960 mg twice daily until computed tomography showed complete disappearance of active TE lesions. Life-long maintenance therapy consisted to CTX 960 mg daily.

RESULTS

Group 1: Seventeen patients improved clinically and achieved complete resolution on computed tomography scars over a mean period of 33 days (range: 21-56). Only one patient was withdrawn from the study at day 18 due to a severe skin rash. Neither serious hematologic nor liver toxicity were observed. Under maintenance therapy, 7 patients relapsed after an average duration of 15.5 months. Relapses were precipitated either by poor compliance (5/7) or erronenous CTX protocol (2/7). Group 2: There were 15 relapses affecting 9 patients who were treated successfully with CTX. CTX was discontinued in one relapsing patient who experienced a Stevens-Johnson syndrome on day 13. This patient had previously experienced cutaneous intolerance to sulfadiazine.

CONCLUSION

A relative low dose regimen of CTX appears to be strongly efficient and safe treatment for toxoplasmic encephalitis in AIDS. Such a study is of particular interest for developing countries where TE is highly prevalent, given the wide availability of CTX which could be proposed as an economic first line therapy.

Post-transplant cerebral toxoplasmosis diagnosed by magnetic resonance imaging

Cerebral toxoplasmosis is a rare late complication in allogeneic bone marrow transplanted patients. Neuroradiological findings may suggest the correct diagnosis. We report a patient in whom cerebral magnetic resonance imaging (MRI) showed a lesion characteristic of toxoplasmosis. Anti-toxoplasma treatment led to clinical and radiological improvement. MRI seems to be a valid tool for detection and follow-up of cerebral toxoplasmosis.

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.