The probability of acquiring primary Toxoplasma infection in HIV-infected patients: results of an 8-year retrospective study

There is much hope that HIV-infected patients and AIDS patients can reckon with a prolonged survival in future. The increased survival of AIDS patients with positive Toxoplasma serology is not necessarily associated with an increased risk of developing Toxoplasma encephalitis. For HIV-infected patients with negative Toxoplasma serology, the probability of acquiring a primary Toxoplasma infection in highly endemic areas such as Germany had not been studied to date. One hundred eighty-three HIV-infected patients were followed up between 1987 and 1995 in a retrospective study. Within the cohort, 95% of the patients were male and 83% haemophiliacs. The initial (1987) and final (1995) prevalence rate of Toxoplasma antibodies was 33.3% and 36.6%, respectively. The annual rise of the primary infection rate was calculated as 0.41%. The dye test was used for the detection of Toxoplasma-specific antibodies. This assay proved to be reliable and stable during long-term observation. The rate of primary toxoplasmosis found in this long-term study was not higher than that of pregnant women in Germany. Chemoprophylactic measurements for seronegative HIV-infected patients are therefore not recommended, but regular serological screening to detect seroconverters is.

Recognition and management of toxoplasmosis

Toxoplasma gondii is a frequent cause of subclinical latent human infection and an important opportunistic pathogen that may cause severe disease in immunocompromised patients. Patients with AIDS who have antibodies to T. gondii should be considered at high risk for development of clinical disease (toxoplasmosis). Reactivation of latent infection in the central nervous system is a common HIV/AIDS-related complication in these patients. Typical presenting symptoms are headache, confusion, fever, and focal neurologic deficits. Routine serologic tests cannot distinguish active from latent infection. Neuroradiologic studies may be highly suggestive of toxoplasmic encephalitis, but the definitive diagnosis can be made only by demonstration of toxoplasma in brain tissue. The unique pathogenesis of toxoplasmic encephalitis in patients with AIDS necessitates intensive primary therapy followed by life long suppressive therapy. Clinical and radiographic improvement is usually rapid with appropriate treatment.

The investigation of toxoplasma infection associated with pregnancy

An audit was undertaken to determine case compliance with prenatal testing and investigation of infants for toxoplasma infection. Subsequently, the effect of enhanced reference unit Intervention was studied. The proportion of cases of toxoplasma infection associated with pregnancy completing an investigation programme was calculated. The effect of continued and short-term additional intervention was assessed and reasons for failure to comply were sought. The status of the child was established in 30% of cases when acute maternal toxoplasma infection was detected. Continuous reference unit intervention significantly improved case compliance to 45% over a 3-year period, but the effect was lost when the additional measures were withdrawn. Failure to complete the investigation procedure was associated with loss of patient-clinician contact and clinician/laboratory error. Enhanced intervention did not result in a significant improvement in compliance with the investigation programme for babies with clinical abnormality. The benefits of testing for toxoplasma infection associated with pregnancy are limited by failure to complete necessary investigations.

Pulmonary toxoplasmosis

With the advent of the human immunodeficiency virus (HIV) epidemic, the worldwide incidence of infections caused by Toxoplasma gondii has been rising. In this article I discuss the pathophysiology, diagnosis, and treatment of toxoplasma pneumonia. Basic research is now directed at the relationship of this organism to its host cells and how pharmacological or immunologic manipulation of that relationship may treat or prevent primary or recurrent infection. In addition to the standard diagnostic methods for T. gondii infection, newer methods using the tools of molecular genetics and immune complex staining are discussed. Although it is known that standard therapy for T. gondii pneumonia should use the synergistic combination of pyrimethamine and a sulfa-based antibiotic, optimal prophylactic antibiotic combinations and dosing schedules for recurrent infection are still being investigated. By stressing primary prevention and appropriate prophylaxis against T. gondii infection, the incidence of toxoplasma pneumonia in the immunocompromised host may be minimized.

Toxoplasmosis in kidney transplant recipients: report of six cases and review

Six patients with toxoplasmosis complicating renal transplantation are described, and 25 other reported cases are reviewed. The mean age of the 31 patients was 35.16 years. Most of the recipients (25 of 29) showed signs of toxoplasmosis within 3 months post-transplantation, with fever, neurological disturbances, and pneumonia as the main clinical features. Diagnosis was established at autopsy in 15 cases, by serology in 13 cases, and by direct examination, culture, or polymerase chain reaction of biological samples in 5 cases. Seventeen patients also had concomitant infections. The donor was the likely source of transmission to 10 recipients; reactivation was suspected in two cases. The source of transmission could not be determined for the remaining 19 patients. The mortality rate was 64.5%. Ten of the 11 patients given specific treatment survived, indicating that early diagnosis and therapy are essential.

Does human toxoplasmosis involve an imbalance in T1/T2 cytokines?

The T1 (interferon-gamma, interleukin-12, interleukin-2) and T2 (interleukin-4, interleukin-10, interleukin-6) cytokine groups constitute two polar responses of the immune system. The T1 group is a predominantly cellular response, while the T2 group response is mainly humoral. The hypothesis forwarded here links these subgroups of induced cytokines to the various clinical forms of human toxoplasmosis. Ocular toxoplasmosis in immunocompetent patients could be attributed to a T1 hyper-response, whereas congenital toxoplasmosis, toxoplasmic encephalitis (in immunodeficient patients) and active chronic toxoplasmosis (with persistent lymphadenophathy) would be characterized by a predominantly T2 response. Confirmation that this kind of immunological imbalance effectively underlies the various clinical forms of toxoplasmosis would open the way for a new range of treatments based on immunomodulation.

[Hodgkin's disease with concurrent infection of toxoplasmosis]

Hodgkin's disease (HD) is a specific type of malignant lymphoma characteristic of local and general lymphadenectasis. Aquired toxoplasmosis (AT) is one kind of lymphoadenopathy without fever and fatigue. When the two diseases coexist, clinical and pathological misdiagnosis may be made. This is the first male case of toxoplasmosis and Hodgkin's disease in China, diagnosed by surgical removal of the major part of the cervical and supraclavicular masses, detection of blood anti-toxoplasma gondii antibody, PCR analysis of toxoplasma gondii DNA, and pathological, ultrastructural and immunohistochemical studies of the tumour tissues. The patient treated by radiation and chemotherapy was abated.

Pulmonary toxoplasmosis in patients infected with human immunodeficiency virus: a French National Survey

We reviewed all cases of pulmonary toxoplasmosis (PT) that were documented by detection of Toxoplasma gondii in bronchoalveolar lavage fluid specimens during a French nationwide review of extracerebral toxoplasmosis in patients infected with human immunodeficiency virus (HIV). Only 64 cases of proven PT were recorded during the 33-month survey. The patients were similar to other patients with AIDS in terms of age, sex, and risk factors for HIV infection. PT occurred mainly in patients with advanced immunodeficiency (mean [+/- SD] CD4+ lymphocyte count, 40 +/- 75/mm3). Clinical features of PT usually include fever, cough and dyspnea; the associated radiological findings were mainly diffuse interstitial infiltrates. Serological data were uninformative. The treatment for PT was the same as that for cerebral toxoplasmosis. A clinical response was observed for 47% of patients, 23% of whom relapsed. Twenty-four patients (37%) died of toxoplasmosis, and 17 (27%) died of other causes. The median survival time was 150 days. We conclude that PT is an infrequent but severe infection in HIV-patients in France.

Toxoplasmosis of the spinal cord in a patient with AIDS: case report and review

We present the case of a patient whose acute myelopathy almost completely resolved with empirical therapy for toxoplasmosis, and we review thirteen previously reported cases of myelopathy thought to have been caused by Toxoplasma gondii in patients with AIDS. The most common symptoms and abnormal physical findings were motor loss (usually paraparesis), bilateral sensory loss, urinary bladder dysfunction, and local pain. The majority of patients had magnetic resonance images that showed abnormalities of the spinal cord and brain in association with positive serology for Toxoplasma. Therapy for toxoplasmosis, when administered soon after the onset of symptoms, has resulted in clinical and radiographic improvement in the conditions of patients with toxoplasmosis.

Varicella infection and toxoplasmosis in pregnancy

Varicella occurring in pregnancy can be dangerous for the fetus, the mother, and the newborn. The fetus may experience multiple system damage. The mother and newborn are at increased risk for varicella pneumonia with a 9% and 20% fatality rate, respectively. The recent introduction of the varicella vaccine will affect the occurrence of gestational infection. Toxoplasmosis is rarely dangerous for the pregnant woman, yet the fetus and newborn may be at risk for chorioretinitis, hydrocephalus, intracranial calcifications, and convulsions. The greatest challenge in the management of toxoplasmosis in pregnancy is diagnosis of the asymptomatic newborn before damage occurs. Strategies to prevent toxoplasmosis should be taught to every pregnant woman as part of parental care.

The potential role of azithromycin in the treatment of prophylaxis of toxoplasmosis

Infection with Toxoplasma gondii is the most common parasitic infection worldwide with an estimated prevalence of 1-2 billion people. The risk of developing severe toxoplasmosis is higher for immunocompromised individuals and fetuses of mothers who have acquired a primo-infection. The current therapy of choice for toxoplasmosis is the synergistic combination of pyrimethamine and sulphadiazine. This therapy is highly effective but its use is complicated in immuno-compromised individuals due to adverse secondary effects. In addition, since pyrimethamine is potentially teratogenic, its use is not recommended during early pregnancy. Clindamycin, a lincosaminide, in combination with pyrimethamine has been shown to be an acceptable therapeutic alternative in patients who are unable to tolerate pyrimethamine plus sulphadiazine. In the search for new, effective compounds with less adverse or toxic effects, recent efforts have focused on the new macrolides and the azalides. Here, the results of the investigations and, in particular, the theoretical considerations for the potential use of azithromycin in the therapy of toxoplasmosis in immunocompromised individuals are reviewed.

Infectious causes of hydrops fetalis

A variety of infectious agents have been associated with nonimmune hydrops fetalis, most notably parvovirus B19, cytomegalovirus, herpes simplex virus, Toxoplasma gondii, and Treponema pallidum. These agents produce hydrops through effects on fetal bone marrow, myocardium, or vascular endothelium. Knowledge of the epidemiology and clinical characteristics of maternal and fetal infection can be used to select a diagnostic approach. Etiologic diagnosis will guide prognosis and the selection of specific chemotherapy.

Limited value of cerebrospinal fluid for direct detection of Toxoplasma gondii in toxoplasmic encephalitis associated with AIDS

The diagnosis of acquired immunodeficiency syndrome-associated toxoplasmic encephalitis (TE), a typically focal disease resulting from reactivation of tissue cysts, relies mainly on indirect diagnostic methods. In a prospective study, we investigated the value of detection of Toxoplasma gondii in cerebrospinal fluid (CSF) by using the polymerase chain reaction and the mouse inoculation test. Twenty-four patients with 26 episodes of TE, 2 HIV-infected patients with primary acute Toxoplasma infection, and 38 HIV-infected control patients with latent Toxoplasma infection were investigated. Detection of T. gondii in CSF by both methods was possible in only 3 of the TE patients (11.5%), the remaining patients being negative with either of the methods. In contrast, T. gondii DNA was detected in both of the acutely infected patients, indicating that in primary acute toxoplasmosis parasites may easily be found in the CSF, whereas in the majority of TE cases in immunocompromised patients, T. gondii parasites do not gain access to the CSF drawn by lumbar puncture.

The role of cytokines in toxoplasmosis

Infection with Toxoplasma gondii is normally asymptomatic, but as a consequence of the AIDS epidemic the incidence of symptomatic disease and especially toxoplasmic encephalitis (TE) has grown in frequency. The high frequency of adverse reactions to conventional therapeutic regimens for toxoplasmosis highlight the need to develop new strategies for the management of this disease. The importance of cytokines in resistance against T. gondii has been shown primarily in murine models of toxoplasmosis and a number of cytokines (e.g., IFN-gamma, TNF-alpha, IL-2 and IL-12) have been proposed for trials in patients with TE. One mechanism by which these cytokines produce their effects is through stimulation of macrophages and/or NK cells. However, there are problems with immunological intervention in immunocompromised patients with TE since the infection is present primarily in the central nervous system (CNS), an immunoprivileged site, and because certain cytokines may down regulate the immune response. While much valuable information has been obtained from studies conducted in immunocompetent strains of mice their relevance to an immunocompromised host is unknown. The development of genetically altered mice with immune deficiencies offers promising new models that may allow for more rational development of new treatment regimens.

Management strategies for infectious diseases in pregnancy

This review presented the clinical manifestations, diagnostic and therapeutic options, and preventive strategies for several congenital infections. The infections discussed show the spectrum of modes of vertical transmission and severity of fetal disease encountered, in addition to the successes and limitations of the current medical interventions. Further improvements in diagnostic techniques and therapies for managing the infected fetus are likely to occur during the next decade. Similarly, the widespread adaptation of new and sensitive diagnostic assays, such as the polymerase chain reaction, is likely to further improve our ability to identify infectious agents as the primary cause of certain abnormal fetal conditions. Where specific diagnostic tests and therapies have proven successful in preventing or treating fetal infections, universal screening programs should be given serious consideration. Of paramount importance, however, is the active research on the development of preventive interventions designed to prevent maternal infections and vertical transmission. Although specific immunotherapies, vaccines, and drug therapies hold great promise for controlling the spread of some infections, it cannot be overemphasized that some serious infectious complications of pregnancy may be avoided by simple preconception or early antenatal maternal counseling.

Toxoplasmosis in individuals with AIDS

Toxoplasmosis remains an important complication of AIDS. Recent advances in both diagnosis and treatment have decreased the immediate mortality. New innovations in prophylaxis will ultimately decrease incidence of this disease.

[Toxoplasmosis in pregnancy. Prevention, diagnosis, and therapy]

Toxoplasmosis is a worldwide health problem. Infection of a pregnant woman can result in severe fetal morbidity or in subclinical neonatal infection; most subclinical cases will develop ocular and neurological sequelae. Fetal infection and clinical outcome is related to when in pregnancy toxoplasmosis was acquired. The risk of transmission increases from 14% in the first trimester to 29% in the second and 59% in the third. Conversely, clinical damage decreases from about 80% in the first to 10% in the third trimester, but up to 50% of patients with subclinical congenital toxoplasmosis will develop neurologic and ocular sequelae. Congenital toxoplasmosis can be prevented by identification of non immune women at the beginning of pregnancy, by giving information on how to avoid the infection and by a serological follow-up until the delivery. Serological follow-up is based on repeated testing for specific IgG and IgM, but other serologic methods are necessary to differentiate between acute and chronic infections and possibly on a single serum sample. Procedures to detect fetal infection are ultrasound examination, cordocentesis and amniocentesis; prenatal diagnosis relies on demonstration of toxoplasma in fetal blood or amniotic fluid by mouse inoculation. Very promising results have recently obtained by the PCR-method applied to amniotic fluid samples. All strongly suspected cases of acquired toxoplasmosis in pregnancy have to be treated.

Viruses, bacteria, and protozoans in pregnancy: a sample of each

This article only touches the surface of a very broad subject. As mentioned before, the microorganisms covered were chosen with the practitioner in mind. The reader will note that many of the syndromes discussed have subtle presentations with overlapping symptomatology or essentially no symptoms at all. Clinicians therefore must maintain a high degree of suspicion when faced with such infectious complications of pregnancy.