Vascular Endothelial Growth Factor-C Treatment Enhances Cerebrospinal Fluid Outflow during Toxoplasma gondii Brain Infection but Does Not Improve Cerebral Edema

Cerebral edema frequently develops in the setting of brain infection and can contribute to elevated intracranial pressure, a medical emergency. How excess fluid is cleared from the brain is not well understood. Previous studies have shown that interstitial fluid is transported out of the brain along perivascular channels that collect into the cerebrospinal fluid (CSF)-filled subarachnoid space. CSF is then removed from the central nervous system through venous and lymphatic routes. The current study tested the hypothesis that increasing lymphatic drainage of CSF would promote clearance of cerebral edema fluid during infection with the neurotropic parasite Toxoplasma gondii. Fluorescent microscopy and magnetic resonance imaging was used to show that C57BL/6 mice develop vasogenic edema 4 to 5 weeks after infection with T. gondii. Tracer experiments were used to evaluate how brain infection affects meningeal lymphatic function, which demonstrated a decreased rate in CSF outflow in T. gondii-infected mice. Next, mice were treated with a vascular endothelial growth factor (VEGF)-C-expressing viral vector, which induced meningeal lymphangiogenesis and improved CSF outflow in chronically infected mice. No difference in cerebral edema was observed between mice that received VEGF-C and those that rececived sham treatment. Therefore, although VEGF-C treatment can improve lymphatic outflow in mice infected with T. gondii, this effect does not lead to increased clearance of edema fluid from the brains of these mice.

TORCH Infections

Perinatal and neonatal infections are a significant cause of morbidity and mortality. As such, early recognition and workup when there is clinical concern is essential to supporting affected neonates. This article aims to focus specifically on the effects of toxoplasmosis, rubella, cytomegalovirus, herpes, and other agents (TORCH) infections, discussing epidemiology, diagnostics, and treatment if available. [Pediatr Ann. 2023;52(11):e400-e406.].

Knocking down of the DHFR-TS gene in Toxoplasma gondii using siRNA and assessing the subsequences on toxoplasmosis in mice

Toxoplasma gondii (T. gondii), an obligatory intracellular parasite, is the etiologic agent of toxoplasmosis. Dihydrofolate reductase-thymidylate synthase (DHFR-TS) is one of the most important enzymes in toxoplasma folic acid cycle. Due to the emergence of resistance in RH strain of T. gondii against pyrimethamine that acts via DHFR-TS inhibition and also the crucial role of small interference RNA (siRNA) technology in gene silencing, we aimed to use siRNA to knock down DHFR-TS gene expression in T. gondii as a therapeutic target against toxoplasmosis in a mouse model. Based on the DHFR-TS gene sequence, siRNA was designed. The siRNAs were transfected into the parasites by electroporation. Total RNA was extracted using RNX-Plus kit. The viability of parasite was assessed by methylthiazole tetrazolium (MTT). The survival time of mice challenged with siRNA-treated T.gondii were compared to the control group infected with the same amount of wild-type tachyzoites. The viability of siRNA-embedded parasites was 70.7% (29.3% decreased) compared to the wild-type parasite as control (P = 0.0001). The transcription level of siRNA-transfected parasites was reduced to 17.4% (82.6% inhibition) (P = 0.016). The in vivo assessment showed that the mean survival time of the mice inoculated with modified parasites was increased about 2 days after the death of all mice in the control group. The designed siRNAs in the current study were able to silence the DHFR-TS gene efficiently. This silencing led to a decrease in viability of the parasites and an increase in the survival time of the parasites-treated mice.

[The issue of certain infectious diseases of pregnant women in everyday practice Part I. Bacterial and parasitic infections]

AIM OF STUDY

Authors in their text are bringing the latest published findings on the impact of some of the most common infectious diseases on the course and outcome of pregnancies.

TYPE OF STUDY

Review.

RESULTS

Proposals and recommendations for examination, treatment, and management of infected pregnant womans, especially from the view of a primary contact gynecologist.

Toxoplasmosis presented as a submental mass: a common disease, uncommon presentation

Submental mass secondary to toxoplasmosis is not common in clinical work. A diagnosis of toxoplasmosis is rarely considered by physicians. Here we describe a 50-year-old woman presented with a progressive, painful, submental and left neck swelling for 1 month. After having obtained an insufficient evidence from the fine-needle biopsy, the patient finally received an excisional biopsy which highly indicated the possibility of lymphadenopathy consistent with toxoplasmosis. Diagnosis of toxoplasmosis was finally established by a combination of the pathological criteria, together with the positive serological finding. According to review the clinical presentations, pathological characteristics, diagnostic standard and treatment of this disease, the article aims to remind otolaryngologists who are evaluating a neck mass should be aware of the infectious cause of lymphadenopathy and the possibility of toxoplasmosis.

Congenital Toxoplasmosis: A Review

Acute infection of toxoplasmosis during pregnancy is detrimental to the developing fetus. In the United States, approximately 1 in 10,000 live births are affected by congenital toxoplasmosis. Although multifactorial in etiology, maternal infection is primarily attributed to the consumption of contaminated meat or water. Infection and transmission to the fetus may result in devastating neurologic impairment. Screening methods for all pregnant women should be implemented in routine prenatal care. This article will highlight the inherent dangers of congenital toxoplasmosis, while including general care of the fetus for prevention of transmission, medical management, and long-term outcomes.

Recommended management of Toxoplasma gondii infection in pregnant women and their children

Aforesaid recommendations for the management of T.gondii infection, elaborated by the group of experts, are intended for physicians of various specialties in order to standardize and facilitate diagnostic and therapeutic management. Early diagnosis of congenital toxoplasmosis, both symptomatic and asymptomatic, in neonatal period, initiation of adequate treatment and long-term, multispecialist monitoring, including multi-organ rehabilitation of children may prevent or reduce the complications of congenital toxoplasmosis. Health education, whose role is often underestimated, should be targeted mainly on girls and women at reproductive age as to prevent from infection during pregnancy.

[Toxoplasmosis: Epidemiology, Diagnosis, Treatment]

The up-to-date literature and original data on the epidemiology, diagnosis and treatment of toxoplasmosis are presented. Particular attention is paid to the parasite infection during pregnancy. Spiramycin is the drug of choice for acute toxoplasmosis in pregnant women.

[Prevention of congenital toxoplasmosis in a Buenos Aires hospital]

The prevention of congenital toxoplasmosis is based on providing information to women, serologic diagnosis and treatment of the infected mother and child. In this article we present the results of 12 years of implementation of a congenital toxoplasmosis prevention program in which we measured the mother's infection incidence rate, the transmission rate and the number and severity of infection in newborns. The study was performed on 12035 pregnant women in the period 2000-2011. The prevalence rate of antibodies against Toxoplasma gondii was 18.33% (2206/12035). Thirty-seven out of 9792 susceptible women presented acute infection and the mother's infection incidence rate was 3.78 per 1000 births. The transplacental transmission rate was 5.4% (2/37). Two newborns presented congenital toxoplasmosis infection, one had no clinical signs while the other presented strabismus and chorioretinitis. Thirty-five infected mothers and the two children with congenital infection were treated. The transmission rates obtained allow consider this prevention program as a valid resource to minimize the impact of congenital toxoplasmosis.

[Pulmonary toxoplasmosis in immunosuppressed patient]

Pulmonary toxoplasmosis occurs mainly in immunosuppressed patients and its diagnosis mainly relies upon biological confirmation of the parasite. We present the case of a 47 years patient in medullar aplasia after induction chemotherapy for acute lymphoblastic leukemia that developed pulmonary infiltrates of parasitic origin. The diagnosis of pulmonary toxoplasmosis was established after identification of the parasite in brochioloalveolar lavage fluid (BAL) and peripheral blood. Serological tests are of limited utility in immunosuppressed patients. We used classical methods for the diagnosis of parasitosis but they are being replaced by molecular methods. Polymerase Chain Reaction (PCR) allows a highly specific and sensitive diagnosis on any sample but it cannot be performed in any center.

[Knowledge and practices on toxoplasmosis in physicians attending pregnant women in Durango, Mexico]

OBJECTIVES

To determine the level of knowledge and practices about toxoplasmosis in physicians attending pregnant women in Durango, Mexico.

MATERIALS AND METHODS

One hundred physicians attending pregnant women in Durango,Mexico were surveyed. Of them, 67 were general practitioners, 17 family physicians, and 16 obstetricians. They were asked about (i) the parasite Toxoplasma gondii; (ii) general aspects about toxoplasmosis including clinical manifestations,diagnosis, treatment, and epidemiology; and (iii) their practices and experiences on toxoplasmosis.

RESULTS

From 66 to 89% (mean 78.5%) of physicians answered correctly about the parasite; 25 to 63% (mean 46.9%) answered correctly about clinical manifestations; and 36 to 45% (mean 40.5%) answered correctly about the serological diagnosis. Only 7% knew about the use of avidity test. Few physicians (23%) knew what medicaments are used against toxoplasmosis.From 12 to 86% (mean 40.3%) of participants answered correctly about transmission routes and only 7% got the right answer about susceptibility of infection. Fifty-nine percent of physicians never requested laboratory tests for detecting toxoplasmosis, and only 31% provide information for preventing infection to all their patients. Sixteen (16%) physicians had detected at least one case of Toxoplasma infection acquired during pregnancy.

CONCLUSIONS

The physicians surveyed showed an incomplete knowledge about diagnosis and treatment of toxoplasmosis. Results are useful for optimal design of strategies in the medical education about toxoplasmosis.

Serological detection of Toxoplasma gondii in chronic renal failure patients and renal transplant recipients

Toxoplasma gondii antibodies were detected in 78 patients with renal disease by ELISA. Patients were classified according to the renal status; chronic renal failure patients not on haemodialysis (G1 = 19), chronic renal failure patients on regular haemodialysis (G2 = 30), renal transplant recipient (G3 = 29) and 13 normal controls. Anti-Toxoplasma IgG & IgM antibodies were 36.8% & 10.5% in renal failure patients not on haemodialysis, 56.7% &16.7% in patients on regular haemodialysis and 69% & 24.1% in renal transplant recipients versus 23.1% & 0% in controls with statistical significant difference for Toxoplasma IgG antibodies only. Anti-Toxoplasma IgG antibodies levels of G3 were lower than that of G1. It was observed that the more the exposure to dialysis, the more the risk of toxoplasmosis. It was found that 85.71% of renal transplant recipient seropositive cases for anti-Toxoplasma IgM antibodies were detected in one year post-transplantation and 14.28% of cases after the first year of transplantation.

A 10 month old infant with nystagmus and strabismus

This report present an infant with nystagmus, strabismus, salt and pepper and scars in funduscopy, calcification in Brain CT scan and high titer of Anti Toxoplasmosis antibody. A 10 month old infant that referred with nystagmus, strabismus after fever which appeared five months ago. In funduscopy of both eyes, salt and pepper and scars and in Brain CT scan multiple calcification were seen. The diagnosis of congenital Toxoplasmosis was established by positive serum Anti toxoplasma Ab (IgG) (> 400). Toxoplasmosis may present with only nystagmus and strabismus and physicians should consider this infection in the differential diagnosis of a abnormal eye movement.

[Recommendation for diagnostics and therapy of toxoplasmosis in persons with HIV infection]

Reactivation of latent toxoplasmosis is a serious complication in patients with deep immunodeficiency, but the disease has a good prognosis if early diagnosed and effectively treated. Definitive etiologic proof of the reactivation may be difficult and thus an empiric method (therapeutic trial) is used for confirmation of the diagnosis in clinical practice. The preferred therapy is a combination of pyrimethamine + sulfadiazine.

CpG oligonucleotides as adjuvant in therapeutic vaccines against parasitic infections

Immunostimulatory CpG DNA is recognized by cells of the innate immune system through Toll-like receptor 9 (TLR9). Synthetic CpG oligonucleotides (CpG-ODN) belong to the most potent vaccine adjuvants known today. This is due to their capacity not only to stimulate cells of the innate immune system but also to trigger effectively specific T- and B-lymphocyte responses. This unique quality seems to be superior in the induction of long-term effects and immunological memory. In addition to prophylactic vaccination, we showed that mice already infected with Toxoplasma gondii could be therapeutically vaccinated by the combined use of CpG-ODN and a bradyzoite antigen (BAG1 protein subunit). This treatment was effective against the infection and resulted in a long-term survival of the mice and reduced parasite burden in the brain. Different routes of CpG-ODN vaccine application including intranasal, oral or intraperitoneal delivery were compared with the classical subcutaneous application in two established experimental infection models of murine leishmaniasis and toxoplasmosis. Comparable effects were demonstrated for these modes of inoculation except for the oral uptake of uncoupled CpG-ODN, which resulted in a complete failure of treatment. Detailed studies were performed to optimize the time point of CpG-ODN application. The best results were obtained when the ODN were given within a few days around the infection, in contrast to former trials showing a time window of several weeks for significant oligonucleotide effects in non-infectious models. As CPG-ODN is a synthetic compound, it is not only available in high purity and reproducible quality, but can also be produced with different backbone modifications and sequence modifications. Combination of these possibilities resulted in new molecules that were highly effective as adjuvant in parasite infection models. Finally, our studies revealed not only that bacterial DNA is an effective vaccine adjuvants, but also that Leishmania DNA itself had immunostimulatory properties which are counteracted by a yet undefined inhibitory principle from living Leishmania.

Outcome of Toxoplasmosis Acquired during Pregnancy following Treatment in Both Pregnancy and Early Infancy

OBJECTIVES

Congenital toxoplasmosis is associated with clinical dilemmas as untreated infants may have a guarded prognosis and as treatment may induce severe side effects. The aim of this study was to investigate the outcome of infants born to mothers with toxoplasmosis acquired during pregnancy, following administration of appropriate regimens both during pregnancy and early infancy.

STUDY DESIGN

All 35 infants, born to mothers with toxoplasmosis acquired during pregnancy, and referred to the major Neonatal Department in Crete, Greece, during the 7-year period 1997-2003 were included. All neonates were evaluated soon after birth and on a regular follow-up.

RESULTS

Almost all mothers received spiramycin from diagnosis through labor and 2 received pyrimethamine and sulfadiazine. At birth, infants had IgG antibody titers ranging from 1/1,350 to 1/109,350. All infants initially received pyrimethamine, sulfadiazine and folinic acid but in only 4 cases treatment was continued beyond the second month of life. Transient neutropenia was commonly observed. A follow-up period of 1.2-8.2 years did not reveal any remarkable sequelae.

CONCLUSIONS

Our findings suggest that effective treatment both during pregnancy and early infancy is safe and may contribute to a good outcome of infants born to mothers with toxoplasmosis acquired during pregnancy.

Intraglandular toxoplasmosis of the parotid gland pre- or postoperative diagnosis?

Toxoplasmosis is an ubiquitous protozoan infection, caused by the coccidian Toxoplasma gondii. It usually presents clinically with lymphadenopathy, mainly in the head and neck region. However, in the English literature, very scarce cases of intraparotid Toxoplasma exist, none having been diagnosed preoperatively. In this article, we present 2 cases of intraglandular parotid toxoplasmosis, one diagnosed postoperatively and the other preoperatively. We also review the relevant literature concerning Toxoplasma infection of the parotid gland.

[Parasitic infection in immunocompromised patients]

Several parasites are responsible for life threatening infections in immunocompromised patients. They occur in patients with a profound immunodeficiency affecting the T-cell mediated immunity. In AIDS patients, opportunistic infections are highly prevalent in those with CD4 lymphocyte counts < 200/mm3. Most of these parasites are intracellular protozoa. Severe parasitic infections in immunocompromised hosts either results from the reactivation of a previously acquired infection, such as toxoplasmosis, or from a primary acquired infection which manifests more severely because of the immune defect: this is the case for intestinal protozoa, such as Cryptosporidium, microsporidia, Cyclospora and Isospora belli which can be the cause of severe chronic diarrhea and for visceral leishmaniasis. Strongyloides stercoralis is the only helminth responsible for disseminated infection in immunocompromised patients. For each parasite, recommendations for preventing infection or specific chemoprophylaxis are efficient for prevention of opportunistic infections. Immune reconstitution also proved very efficient to reduce their incidence during VIH infection.

[Toxoplasmic infection in pregnancy. Report of 12 cases]

The toxoplasmosis is a protozoal infection which is capable to induce an infection. Often fatal in the newborn babies infected by transplacental way, thus, the discovery of a toxoplasmic seroconversion during the follow up of the pregnant women had posed to the obstetrician some problems in the manegement. We reported 12 observations of toxoplasmic seroconversion during pregnancy with literature review.

Congenital toxoplasmosis—prenatal aspects of Toxoplasma gondii infection

Toxoplasma gondii (T. gondii) is the cause of toxoplasmosis. Primary infection in an immunocompetent person is usually asymptomatic. Serological surveys demonstrate that world-wide exposure to T. gondii is high (30% in US and 50-80% in Europe). Vertical transmission from a recently infected pregnant woman to her fetus may lead to congenital toxoplasmosis. The risk of such transmission increases as primary maternal infection occurs later in pregnancy. However, consequences for the fetus are more severe with transmission closer to conception. The timing of maternal primary infection is, therefore, critically linked to the clinical manifestations of the infection. Fetal infection may result in natural abortion. Often, no apparent symptoms are observed at birth and complications develop only later in life. The laboratory methods of assessing fetal risk of T. gondii infection are serology and direct tests. Screening programs for women at childbearing age or of the newborn, as well as education of the public regarding infection prevention, proved to be cost-effective and reduce the rate of infection. The impact of antiparasytic therapy on vertical transmission from mother to fetus is still controversial. However, specific therapy is recommended to be initiated as soon as infection is diagnosed.

[Acute toxoplasmic perimyocarditis in a 67-year-old HIV-negative woman--a case report]

Acquired toxoplasmosis is a widespread parasitic disease caused by an obligate intracellular protozoan, Toxoplasma gondii. Humans are infected by consuming undercooked or raw meat containing tissue cysts or by ingesting oocysts in food or water contaminated with feline faeces. Most cases of Toxoplasma gondii infections in immunocompetent individuals are asymptomatic. Although acquired toxoplasmosis is usually a mild infection, it may be life-threatening in immunocompromised patients. In this report we present a 67-year-old HIV-negative woman with acute toxoplasmic perimyocarditis, heart failure and with a history of ischemic heart disease, hypertension and dyslipidemia. The diagnosis was based on clinical characteristics, echocardiographic examinations, elevated inflammatory markers and the presence of IgM and IgG antibodies against Toxoplasma gondii. We conclude that Toxoplasma gondii infection should be considered in each case of perimyocarditis with concomitant, significant diagnostic and therapeutic problems, especially in immunocompromised patients. This paper also reviews differential diagnosis of elevated CA 125 serum levels in postmenopausal women.

Alpha CD 2 mAb treatment safely attenuates adoptive transfer colitis

Increased proliferation, defective apoptosis, and cytokine dysregulation of T lymphocytes are thought to be important for the pathogenesis of inflammatory bowel disease. Since these phenomena can be corrected by alpha CD 2 mAb, we asked whether CD2 directed immunotherapy safely prevents and/or ameliorates adoptive transfer colitis. Colitis was induced by transfer of CD4(+) T cell blasts to syngenic RAG 1(-/-) mice or CD 45 RB(high) CD4(+) T cells to SCID mice. The alpha CD 2 mAb 12-15 or rat IgG was given, starting either initially or upon first signs of colitis. Disease activity was assessed by clinical monitoring, microscopic scoring, hemoccult, endoscopy, and blood count analysis. Cytokine production of stimulated LPL was measured by ELISA and cell proliferation by [(3)H]-thymidine incorporation. Parasite control was analyzed in a murine model of infection with Toxoplasma gondii. The alpha CD 2 mAb significantly increased mean survival time when starting at transfer of blasts (survival >35 days: alpha CD 2 69% vs 0% of controls, P<0.001). In the SCID colitis model hematochezia and macroscopic colitis were delayed. When used in established T-cell blast colitis, the benefit was less pronounced, even in combination with dexamethasone (mean survival+/-s.e.m.: alpha CD 2+dexa: 13.5+/-2.9 vs dexa+IgG: 6.3+/-1.0, P<0.05). In the preventive experiment the alpha CD 2 mAb markedly reduced IL-2 secretion and T-cell proliferation. The immune response towards Toxoplasma gondii was not impaired. These studies show for the first time that CD2 directed immunotherapy can attenuate or delay adoptive transfer colitis and ameliorate established colitis. Most likely inhibition of IL-2 secretion and T-cell proliferation are responsible for these effects. Still, immune defence towards T. gondii is maintained.

Treating opportunistic infections among HIV-exposed and infected children: recommendations from CDC, the National Institutes of Health, and the Infectious Diseases Society of America

In 2001, CDC, the National Institutes of Health, and the Infectious Diseases Society of America convened a working group to develop guidelines for therapy of human immunodeficiency virus (HIV)-associated opportunistic infections to serve as a companion to the Guidelines for Prevention of Opportunistic Infections Among HIV-Infected Persons. In recognition of unique considerations related to HIV infection among infants, children, and adolescents, a separate pediatric working group was established. Because HIV-infected women coinfected with opportunistic pathogens might be more likely to transmit these infections to their infants than women without HIV infection, guidelines for treating opportunistic pathogens among children should consider treatment of congentially acquired infections among both HIV-exposed but uninfected children and those with HIV infection. In addition, the natural history of opportunistic infections among HIV-infected children might differ from that among adults. Compared with opportunistic infections among HIV-infected adults, which are often caused by reactivation of pathogens acquired before HIV infection when host immunity was intact, opportunistic infections among children often reflect primary acquisition of the pathogen and, among children with perinatal HIV infection, infection acquired after HIV infection has been established and begun to compromise an already immature immune system. Laboratory diagnosis of opportunistic infections can be more difficult with children. Finally, treatment recommendations should consider differences between adults and children in terms of drug pharmacokinetics, dosing, formulations, administration, and toxicities. This report focuses on treatment of opportunistic infections that are common in HIV-exposed and infected infants, children, and adolescents in the United States.

Incidence of toxoplasmosis in 5532 pregnant women in Crete, Greece: management of 185 cases at risk

OBJECTIVES

To study the incidence of toxoplasmosis in pregnant women in Crete and to test a designed protocol for handling those at risk of delivering congenitally infected infants.

STUDY DESIGN

Pregnant women were screened serologically over a period of 5 years. Cases with suspected acute toxoplasmosis were treated, peripheral blood (PB), and amniotic fluid (AF) tested by polymerase chain reaction (PCR) and culture, and fetuses monitored by ultrasonography. The absence of congenital infection in infants was confirmed by serology and clinical evaluation.

RESULTS

Of the 5532 pregnant women followed, 70.57% remained seronegative, 29.45% were seropositive, and there was direct evidence of seroconversion in six cases. Acute toxoplasmosis was suspected in 185 cases, maternal parasitemia was detected in five cases and positive amniotic fluid in one case. Congenital infection was excluded in all infants followed, based on the absence of ultrasound findings in utero, lack of clinical symptoms at birth, negative Western blotting (WB) at birth and 3 months later, and descending serology for a year.

CONCLUSION

Overall, 29.45% of the pregnant women followed were seropositive, 3.3% with suspected acute toxoplasmosis, and in 0.02% cases there was evidence of maternofetal transmission. The protocol tested allowed differentiation between acute and latent toxoplasmosis, safe management of the cases at risk and assisted in avoidance of unwarranted pregnancy terminations.

Séroconversion toxoplasmique chez la femme enceinte

INTRODUCTION

Since 1992 France has been running a toxoplasmosis prevention program based on the serological detection of infections during pregnancy. In the absence of a consensus, the seroconversions discovered are managed in different ways, varying from one centre to another.

OBJECTIVE

To describe the habits of the specialised centres in France and propose means to reduce the heterogeneity.

METHODS

A survey using a questionnaire mailed to the centres of parasitology in France specialised in the management of toxoplasmosis seroconversion during pregnancy.

RESULTS

All the 30 centres surveyed replied. Five of them do not provide recommendations for treatment and were excluded from analysis. The attitudes of the 25 other centres varied greatly with regard to the indications for therapeutic abortion and amniocentesis, treatment protocols with pyrimethamine and sulfamides, as well as in the frequency of sonographical monitoring.

CONCLUSION

In the absence of National guidelines, the management of seroconversions discovered during the prenatal prevention of congenital toxoplasmosis program is left to the discretion of the specialised centre. This results in variations from one town to the next. This heterogeneity underlines the lack of knowledge on the most efficient and acceptable means of preventing and treating congenital toxoplasmosis. In order to improve this situation, the French parasitologists have launched a program of consensual meetings aimed at harmonising the treatment protocols and identifying the points that require further studies.

Toxoplasmosis

Toxoplasma gondii is a protozoan parasite that infects up to a third of the world's population. Infection is mainly acquired by ingestion of food or water that is contaminated with oocysts shed by cats or by eating undercooked or raw meat containing tissue cysts. Primary infection is usually subclinical but in some patients cervical lymphadenopathy or ocular disease can be present. Infection acquired during pregnancy may cause severe damage to the fetus. In immunocompromised patients, reactivation of latent disease can cause life-threatening encephalitis. Diagnosis of toxoplasmosis can be established by direct detection of the parasite or by serological techniques. The most commonly used therapeutic regimen, and probably the most effective, is the combination of pyrimethamine with sulfadiazine and folinic acid. This Seminar provides an overview and update on management of patients with acute infection, pregnant women who acquire infection during gestation, fetuses or infants who are congenitally infected, those with ocular disease, and immunocompromised individuals. Controversy about the effectiveness of primary and secondary prevention in pregnant women is discussed. Important topics of current and future research are presented.

Opportunistic infections of the CNS in patients with AIDS: diagnosis and management

The CNS is the second most commonly affected organ in patients with AIDS. Many opportunistic infections may involve the brain, but the four most frequent conditions are toxoplasmosis, progressive multifocal leukoencephalopathy (PML), cryptococcosis and cytomegalovirus infection. Although the incidence of these infections among patients with AIDS has decreased in the past years as a consequence of the introduction of highly active antiretroviral therapy (HAART), they remain a major cause of morbidity and mortality in this patient group. This article summarises the clinical manifestations, diagnostic procedures and management strategies for these four conditions. The clinical manifestations are nonspecific and depend on the type and location of the lesions. In clinical practice, the diagnosis of these entities is made with noninvasive methods. Imaging studies, especially magnetic resonance imaging, are very useful for the diagnosis of toxoplasmic encephalitis and PML, although their usefulness for the diagnosis of cryptococcal meningitis and cytomegalovirus infections is lower. The presence of multiple ring-enhancing lesions with surrounding oedema and mass effect is characteristic of toxoplasmosis. The response to antitoxoplasmic therapy, which is usually observed within the first 2 weeks, is also used for diagnostic purposes. Molecular methods applied to the CSF are essential for the diagnosis of PML and cytomegalovirus infections. In addition, the quantification of viral DNA of both JC virus (the causative agent of PML) and cytomegalovirus has prognostic implications and may serve to evaluate the response to therapy. Cryptococcosis may be easily diagnosed by CSF stains and cultures, as well as by the detection of the cryptococcal capsular polysaccharide antigen in the blood and, especially, the CSF. Effective treatments are available for toxoplasmosis and cryptococcosis, although adverse effects are common and some patients may not respond to therapy. In contrast, there is no specific treatment for PML, and the efficacy of anticytomegalovirus therapy is poor and the toxicity significant. HAART has improved the outcome of patients with AIDS who have infections of the CNS, and the initiation of this therapy is mandatory for all patients with such infections, particularly in those conditions for which effective therapy is not available. Lifelong secondary prophylaxis with agents for the opportunistic infections was necessary before the HAART era because the risk of recurrence was very high if only induction therapy was administered. However, today, the discontinuation of secondary prophylaxis in patients treated with HAART who have stably reached a certain immune reconstitution is possible.

[Toxoplasma infections in early pregnancy: consequences and management]

OBJECTIVE

To assess the consequences for the fetus of maternal toxoplasma infection acquired during the first 8 weeks of gestation and to set guidelines on how to manage these maternal infections.

METHODS

Data were prospectively analyzed on 360 pregnancies followed-up in our department due to a toxoplasma infection during the 8 first weeks of pregnancy. Estimates of the risk of fetal infection were based on all cases, including those which could not be followed up until infection was ruled out or confirmed. Severity of infection was estimated based on ultrasound findings during pregnancy, neonatal and long-term postnatal clinical, neurological and ophthalmologic work up.

RESULTS

Out of the 360 included women, 336 gave birth to a live born child: 7 (2%) were infected, 302 (90%) were free of infection and follow-up was insufficient to conclude about the 27 (8%) remaining infants. The estimated risk of fetal infection ranged between 2 and 10% based on live born children and between 3 and 14% when the 24 interrupted pregnancies were included. At their last clinical evaluation at 70 months of age, all 7 children, including the 2 who had inactive peripheral eye lesions and the one who had a unique intracranial calcification were free of any ophthalmologic or neurological impairment.

CONCLUSION

Our study confirms that in the event of a maternal infection during the first 8 weeks of pregnancy the risk of fetal infection is low and results mainly in a spontaneous termination of pregnancy. Future parents should be assured that conversely to a common opinion, the prognosis of congenital toxoplasmosis in live-born children is good. For these early maternal infections as for those acquired later, we recommend immediate treatment with spiramycin, monthly ultrasound surveillance, amniocentesis and treatment with pyrimethamine and sulphamides if the PCR is positive. Abortion should be restricted to cases with ultrasound lesions

Central nervous system infections in individuals with HIV-1 infection

Opportunistic infections of the central nervous system (CNS) are common complications of advanced immunodeficiency in individuals with human immunodeficiency virus type 1 (HIV-1) infection. Neurological disease is the first manifestation of acquired immunodeficiency syndrome (AIDS) in 10% to 20% of symptomatic HIV-1 infection. Prompt diagnosis and treatment of such disorders is critical. Also, in the era of highly active antiretroviral therapy (HAART), these disease states have changed in presentation and epidemiology. Therefore, we review the epidemiology, pathogenesis, clinical features, diagnosis, and management of five common central nervous system disorders in individuals with HIV-1 infection: toxoplasma encephalitis, primary central nervous system lymphoma, cryptococcal meningitis, cytomegalovirus encephalitis, and progressive multifocal leukoencephalopathy.

Toxoplasmosis, an overview with emphasis on ocular involvement

Toxoplasmosis is a common parasitic zoonosis and an important cause of abortions, mental retardation, encephalitis, blindness, and death worldwide. Although a large body of literature has emerged on the subject in the past decades, many questions about the pathogenesis and treatment of the disease remain unanswered. This review aims to provide an overview of the current insights regarding the causative parasite and the mechanisms leading to symptomatic infection with emphasis on ocular toxoplasmosis.

Effects of specific monoclonal antibodies to dense granular proteins on the invasion of Toxoplasma gondii in vitro and in vivo

Although some reports have been published on the protective effect of antibodies to Toxoplasma gondii surface membrane proteins, few address the inhibitory activity of antibodies to dense granular proteins (GRA proteins). Therefore, we performed a series of experiments to evaluate the inhibitory effects of monoclonal antibodies (mAbs) to GRA proteins (GRA2, 28 kDa; GRA6, 32 kDa) and surface membrane protein (SAG1, 30 kDa) on the invasion of T. gondii tachyzoites. Passive immunization of mice with one of three mAbs following challenge with a lethal dose of tachyzoites significantly increased survival compared with results for mice treated with control ascites. The survival times of mice challenged with tachyzoites pretreated with anti-GRA6 or anti-SAG1 mAb were significantly increased. Mice that received tachyzoites pretreated with both mAb and complement had longer survival times than those that received tachyzoites pretreated with mAb alone. Invasion of tachyzoites into fibroblasts and macrophages was significantly inhibited in the anti-GRA2, anti-GRA6 or anti-SAG1 mAb pretreated group. Pretreatment with mAb and complement inhibited invasion of tachyzoites in both fibroblasts and macrophages. These results suggest that specific antibodies to dense-granule molecules may be useful for controlling infection with T. gondii.

Seroprevalence of varicella zoster virus, parvovirus B19 and Toxoplasma gondii in a Melbourne obstetric population: implications for management

At an antenatal clinic at a Melbourne obstetric hospital, 308 women were questioned about a known past history of infection with varicella zoster virus (VZV), human parvovirus B19 and Toxoplasma gondii. Immunoglobulin G (IgG) concentrations were determined for the 3 infectious agents and a recalled history of infection was compared with the presence of specific antibody. Exactly 66% of women recalled being infected with chickenpox (VZV) and 94% showed serological evidence of past exposure. Although 64% of women had parvovirus specific IgG, only one gave a definite history of past parvovirus infection. None of the 23% of women with evidence of previous exposure to Toxoplasma gondii recalled a past infection. The proportion of antenatal women at risk in this study was used to estimate the potential burden of disease from congenital infections in Australia and to examine implications for management of pregnancies complicated by these 3 infections.

Preventing congenital toxoplasmosis

SCOPE OF THE PROBLEM

Toxoplasmosis is caused by infection with the protozoan parasite Toxoplasma gondii. Acute infections in pregnant women can be transmitted to the fetus and cause severe illness (e.g., mental retardation, blindness, and epilepsy). An estimated 400-4,000 cases of congenital toxoplasmosis occur each year in the United States. Of the 750 deaths attributed to toxoplasmosis each year, 375 (50%) are believed to be caused by eating contaminated meat, making toxoplasmosis the third leading cause of foodborne deaths in this country.

ETIOLOGIC FACTORS

Toxoplasma can be transmitted to humans by three principal routes: a) ingestion of raw or inadequately cooked infected meat; b) ingestion of oocysts, an environmentally resistant form of the organism that cats pass in their feces, with exposure of humans occurring through exposure to cat litter or soil (e.g., from gardening or unwashed fruits or vegetables); and c) a newly infected pregnant woman passing the infection to her unborn fetus. RECOMMENDATIONSFOR PREVENTION: Toxoplasma infection can be prevented in large part by a) cooking meat to a safe temperature (i.e., one sufficient to kill Toxoplasma); b) peeling or thoroughly washing fruits and vegetables before eating; c) cleaning cooking surfaces and utensils afterthey have contacted raw meat, poultry, seafood, or unwashed fruits or vegetables; d) pregnant women avoiding changing cat litter or, if no one else is available to change the cat litter, using gloves, then washing hands thoroughly; and e) not feeding raw or undercooked meat to cats and keeping cats inside to prevent acquisition of Toxoplasma by eating infected prey.

RESEARCH AGENDA

Priorities for research were discussed at a national workshop sponsored by CDC in September 1998 and include a) improving estimates of the burden of toxoplasmosis, b) improving diagnostic tests to determine when a person becomes infected with Toxoplasma, and c) determining the applicability of national screening programs.

CONCLUSION

Many cases of congenital toxoplasmosis can be prevented. Specific measures can be taken by women and their health-care providers to decrease the risk for infection during pregnancy and prevent severe illness in newborn infants.

[Toxoplasma gondii]

The authors offered a general view on Toxoplasma gondii from the historical, taxonomic, biological and epidemiological point of view. They also studied the problems of pathogenesis, pathology, clinics, diagnosis, as well as therapy and prevention. (Tab. 1, Ref. 9)