Toxoplasmosis In Pregnancy Research Articles

A technique for dating toxoplasmosis in pregnancy and comparison with the Vidas anti-toxoplasma IgG avidity test

A comparative evaluation of 384 selected sera was performed using the Beckman Coulter Access and Abbott Axsym Toxo-IgG assays. The Axsym assay yields positive early results following infection, while the Access assay gives higher titres during chronic infection. The ratio between the two complementary tests, Axsym Toxo-IgG/Access Toxo-IgG (Ax/Ac), was compared with the Vidas anti-Toxoplasma IgG avidity index (AI). The Ax/Ac ratio decreased progressively as the time between infection and sampling increased. The mean Ax/Ac values (±SE) were 2.50 (±0.26), 2.14 (±0.13), 2.33 (±0.22), 1.34 (±0.09), 1.32 (±0.10), 0.92 (±0.08) and 0.74 (±0.07) for groups of sera sampled at 1, 2, 3, 4–5, 6–8, 9–12 and 13–24 months, respectively, after infection in pregnant women. These values were much smaller for cases with chronic infection (>24 months), i.e., 0.56 (±0.03), 0.44 (±0.04) and 0.53 (±0.04), respectively, for pregnant women and immunodepressed patients with and without reactivation. Taking a ratio of 1 as a threshold for recent infection, the patients in the groups sampled at 1, 2 and 3 months had Ax/Ac ratios >1 in 49/50 (98%), 53/55 (96.4%) and 36/36 (100%) cases, respectively. Thus, an Ax/Ac ratio of <1 in serum from a pregnant woman allows a recent infection (<3 months) to be excluded. This technique has the advantage of yielding positive results that develop much more rapidly than the AI, thereby helping to reassure large numbers of pregnant women and avoiding costly and unnecessary prophylactic treatment and follow-up.

Toxoplasmosis in pregnancy: often suspected, rarely convicted

Toxoplasmosis during pregnancy is uncommon and usually asymptomatic but can cause catastrophic fetal disease. It is often suspected because of non-specific symptoms or positive serological tests. However, false-positive toxoplasma IgM tests are common and confirmatory tests not always reliable. The risk of fetal infection increases as pregnancy progresses; it should be diagnosed or excluded by amniotic fluid PCR, especially early in pregnancy when the risk of severe damage is high. Prompt antibiotic therapy of maternal infection probably reduces fetal infection and disease, but its efficacy has not been confirmed by randomised controlled trials.

OC164: The role of targeted fetal ultrasound in women with acute toxoplasmosis in pregnancy

OC164: The role of targeted fetal ultrasound in women with acute toxoplasmosis in pregnancy

Ocular toxoplasmosis in pregnancy

To describe the course of ocular toxoplasmosis during pregnancy. This study was a retrospective, non-comparative case series of four pregnant women who were treated for ocular toxoplasmosis during pregnancy. All of the participants had severe and treatment-resistant toxoplasmic retinochoroiditis during pregnancy, leaving three of them with decreased visual acuity in spite of aggressive therapy. Delivery of the infant appeared to help the recovery in two patients. Pregnant state may provoke the recurrence of ocular toxoplasmosis.

Prevention of Toxoplasmosis in Pregnancy: Knowledge of Risk Factors

BACKGROUND: Infection with Toxoplasma gondii is common and usually asymptomatic, although it can have catastrophic consequences in a pregnant woman if passed to her developing fetus. Counseling of pregnant women about risk factor reduction may reduce the risk of congenital toxoplasmosis. This study was undertaken to assess and compare the knowledge of obstetricians and internists or family practitioners regarding well-established risk factors for toxoplasmosis infection. METHODS: The study surveyed 102 obstetricians, internists and family practitioners to assess their knowledge of risk factors for toxoplasmosis infection as well as their practices for primary prevention counseling of pregnant women. Responses were analyzed for differences. RESULTS: Obstetricians were more likely than internists or family practitioners to provide appropriate counseling on reducing the two most common risk factors for toxoplasmosis infection (undercooked meat consumption and gardening without gloves). However, over one quarter of all participants inappropriately advised pregnant women to avoid all cat contact. Obstetricians, internists and family practitioners were all likely to fail to identify undercooked meat consumption as the primary risk factor for toxoplasmosis transmission. CONCLUSIONS: Obstetricians appear to provide more appropriate counseling for primary prevention of toxoplasmosis than internists and family practitioners, but both groups of physicians inappropriately advised avoidance of all cat contact. Education of obstetricians, internists and family practitioners on risk factors for toxoplasmosis transmission is needed and may lower the rate of congenital toxoplasmosis as well as decrease the frequency of cat abandonment during pregnancy.

Prevention of toxoplasmosis during pregnancy--an epidemiologic survey over 22 consecutive years.

Prevention of congenital toxoplasmosis is most often based on the results of a serological screening program in pregnant women followed by prenatal and postnatal treatment of women and their newborns when infection is already established during pregnancy or on cord blood (secondary prevention). Little effort has been made to study primary prevention of toxoplasmosis during pregnancy. To assess the possibilities of two different programs aimed at preventing the acquisition of toxoplasmosis during pregnancy. During the first study period (1979-1982) the natural incidence of toxoplasmosis in pregnancy was studied in 2986 pregnant women. In the second study period (1983-1990) the incidence of toxoplasmosis was studied in 8300 women. During this period, seronegative women received a written list of recommendations on how to avoid a toxoplasma infection during pregnancy. In the third study period (1991-2001) the incidence of toxoplasmosis was studied in 16,541 women. During this period, the prevention campaign consisted of a leaflet explaining a) toxoplasmosis as a disease and b) what measures should be taken to avoid toxoplasmosis during pregnancy. The third part of the campaign involved a reiteration of these recommendations during antenatal classes held around mid-gestation. The impact of the two prevention programs was studied by measuring the seroconversion rate in seronegative women. Twenty of 1403 seronegative women in the first period (1.43%), 19 of 3605 women in the second period (0.53%) and 8 of 8492 in the third period (0.09%) seroconverted during pregnancy. The first prevention campaign reduced the seroconversion rate by 63% (p<0.05 OR 2.729 95% CI 1.452-5.084). The second prevention program resulted in a reduction rate of 92% compared to the seroconversion rate in the first period (p<0.0001 OR 15.34 95% CI 6.741-34.89). Promotion of simple measures is very effective in the prevention of toxoplasmosis during pregnancy. Primary prevention should not only be based on education about preventive measures given by physicians, but these guidelines should be reiterated during antenatal classes and leaflets distributed containing written recommendations on the nature of the disease and its avoidance.

Testing for toxoplasmosis in pregnancy: a study of the routines in primary antenatal care.

The question of benefit of screening for antibodies against Toxoplasma gondii in pregnancy to prevent impairment in the infant has not been settled. Despite this, it is believed that such testing is common. The aim of this study was to describe the test routines and to identify factors associated with testing in primary antenatal care. Ulleval University Hospital, Oslo, Norway. All women who gave birth at Ulleval University Hospital, Oslo, Norway, in May 2000 were included. The number of antibody tests during pregnancy was obtained from the patient registry at the department of microbiology at the same hospital. 81% (361/446) had been tested for antibodies against Toxoplasma gondii during pregnancy. Women attending primary antenatal care at a specialist in obstetrics and gynaecology were most likely to be tested. Among women with no signs of prior toxoplasmosis, 35% (110/317) were tested only once. The majority of pregnant women are being tested for toxoplasmosis even though such testing has no documented preventive effect and has not been recommended.

Prevention of congenital toxoplasmosis in Slovenia by serological screening of pregnant women.

A programme for the prevention of congenital toxoplasmosis in Slovenia involving the screening of pregnant women for Toxoplasma infection is presented. Of 21,270 pregnant women screened for toxoplasmosis between, 1996 and the end of 1999, 13,987 (66%) were seronegative, 7,151 (34%) seropositive and 132 had primary infection; approximately 9/1,000 women were at risk of acquiring the primary infection. One hundred live-born infants of primary infected women were available for follow-up. Nine infected but asymptomatic children were born to mothers who were screened and treated in time and two congenitally infected babies were born to mothers in whom infection was detected too late in pregnancy and who therefore received no adequate treatment. It is suggested that the results obtained in this study outweigh the cost of screening for toxoplasmosis in pregnancy. Pregnant women should always be tested at the beginning of pregnancy and, in cases of seronegativity, should be re-tested in the second and third trimesters of the pregnancy. Toxoplasma primary infected pregnant women and neonates should be treated as soon as possible. However, long-term follow-up of children born to primary infected women would be necessary for an accurate evaluation of the effectiveness of the screening because of the possibility of late onset of symptoms.

Treatment of toxoplasmosis in pregnancy: concentrations of spiramycin and neospiramycin in maternal serum and amniotic fluid.

Toxoplasma infection during pregnancy is widely treated with oral spiramycin to reduce the risk of congenital toxoplasmosis in the infant. Failures of therapy have been observed, however. In this study, a sensitive high-performance liquid chromatography technique was used to measure concentrations of spiramycin and neospiramycin, one of the major metabolites of spiramycin, in maternal serum and amniotic fluid. Samples were obtained from 18 women who underwent amniocentesis for polymerase chain reaction (PCR) diagnosis of fetal infection 5-109 days following the prescription of spiramycin therapy (3 g/day). Concentrations of spiramycin and neospiramycin in both serum and amniotic fluid were highly variable, ranging from nondetectable values to 1 microg/ml. None of the concentrations measured were within the range reported to inhibit growth of the parasite in vitro. Consistent with previous reports, part of the observed variability in maternal and fetal drug concentrations could be explained by individual differences in several pharmacokinetic parameters: intestinal absorption, tissue distribution, cellular uptake, metabolism, transfer across the placenta, drug accumulation in fetal tissue, and maternal and fetal drug elimination. The heterogeneity of the data could also be related to differences in patient compliance with the medication prescribed. By addressing factors that could impair adequate treatment of toxoplasmosis during pregnancy, the data presented call for a larger-scale controlled study to determine individual and diurnal variations in maternal drug levels, patient compliance, and outcomes of the offspring. The activity of neospiramycin against Toxoplasma gondii should be assessed.

Treatments for toxoplasmosis in pregnancy.

Toxoplasmosis is a widespread parasitic disease and usually causes no symptoms. However, infection of pregnant women may cause congenital infection, resulting potentially in mental retardation and blindness in the infant. The objective of this review was to assess whether or not treating toxoplasmosis in pregnancy reduces the risk of congenital toxoplasma infection and improves infant outcomes. The Cochrane Pregnancy and Childbirth Group trials register was searched. An electronic search was performed using the key words 'congenital and toxoplasmosis' on the following databases: MEDLINE (1966-07/1997), Embase (1993-07/1997), Pascal (French) (1990-1997), Biological Abstracts (1993-1995) and the Cochrane Controlled Trials Register. There was also contact with experts in the field, including those in the European Research Network on Congenital Toxoplasmosis. Randomised controlled trials of antibiotic treatment versus no treatment of pregnant women with proven or likely acute Toxoplasma infection, with outcomes in the children reported. We also inspected relevant reports of less robust experimental studies in which there were (non randomly allocated) control groups, although it was not planned to include such data in the primary analysis. Reports of possibly eligible studies were scrutinised by two investigators. Out of the 2591 papers identified, none met the inclusion criteria. Despite the large number of studies performed over the last three decades we still do not know whether antenatal treatment in women with presumed toxoplasmosis reduces the congenital transmission of Toxoplasma gondii. Screening is expensive, so we need to evaluate the effects of treatment, and the impact of screening programmes. In countries where screening or treatment is not routine, these technologies should not be introduced outside the context of a carefully controlled trial.

Detection of Toxoplasma gondii in cured meats

Congenital toxoplasmosis is associated with acute maternal infection acquired during or shortly before the pregnancy. The mother's infection is initiated by the ingestion of one of the life forms of the parasite but the relative importance of the different sources of toxoplasmosis are not established. Recent epidemiological studies have confirmed ingestion of raw meats as a risk factor but also identified consumption of cured meats as being associated with acute toxoplasmosis in pregnancy. There is little existing information concerning the efficiency of commercial curing processes for inactivating Toxoplasma gondii. We sought to detect the presence of T. gondii in ready-to-eat cured meat samples by amplification of the parasite's P30 gene using the polymerase chain reaction (PCR). In addition, tissue culture was used in order to isolate viable parasites. Laboratory inoculated specimens were used to assess the sensitivity of each method. PCR was able to detect parasite contamination down to a level of 5×10 3 trophozoites/g while viable toxoplasma could be detected in tissue culture at a level of 10 3 trophozoites/g cured meat. The high salt content of some cured meats limited sensitivity of the PCR assay by inhibition of the polymerase enzyme and reduced the sensitivity of tissue culture due to osmotic pressure causing cytopathic effect. However viable T. gondii was detected in one out of 67 ready-to-eat cured meat samples. Our results highlight the need for improved methods for detecting toxoplasma contamination of food. Health implications of consuming cured meats in pregnancy require careful consideration.

Congenital toxoplasmosis: efficacy of maternal treatment with spiramycin alone.

The evidence supporting an additional benefit of a combined regimen of pyrimethamine-sulfonamides compared with spiramycin alone in the secondary prevention of congenital toxoplasmosis was critically evaluated. We reviewed the series of cases published in the English literature on antiparasitic treatment of acute toxoplasmosis infection in pregnancy, using spiramycin until fetal infection is documented, then using cycles of spiramycin alternated with combined pyrimethamine-sulfonamide therapy. We then compared the occurrence of overt disease among infected offspring (both severe, represented by ophthalmologic or cerebral abnormalities, and mild occurrences, represented by asymptomatic intracranial calcifications and retinal scars without visual impairment) between the published case series and our consecutive series of cases treated during a 10-year period (January 1986-December 1995) with spiramycin alone. The prevalence of fetal infection in our series was 7.8% (12/154), similar to that reported after alternated regimens (7.0%). The rate of overt disease among infected fetuses is not different after treatment with alternated regimens than after continuous antibiotic spiramycin therapy [23% (19/82) vs. 10% (1/10); relative risk, 2.3; 95% confidence interval, 0.4, 47.0]. The pharmacokinetics of the drugs used may account for this finding. The treatment of acute toxoplasmosis in pregnancy with an alternated antibiotic regimen of pyrimethamine-sulfonamide is not more efficacious at preventing overt neonatal disease than treatment with continuous spiramycin alone.

Immunopathogenesis of Toxoplasmosis in Pregnancy

The immunopathogenesis of toxoplasmosis during pregnancy is not completely understood. This paper will try to discuss the most frequently asked questions about the immunopathogeny of congenital toxoplasmosis: differential virulence of Toxoplasma isolates, genetic susceptibility to infection, facilitation of placental transfer, models of congenital toxoplasmosis, and transmission in seropositive hosts. Most published data suggest a role of the genetic background of the host and of the parasite. Models of congenital toxoplasmosis have been evaluated, but it appears that the conclusion drawn would be barely appropriate to understand the pathogenesis in pregnant women.

Immunopathogenesis of toxoplasmosis in pregnancy

The immunopathogenesis of toxoplasmosis during pregnancy is not completely understood. This paper will try to discuss the most frequently asked questions about the immunopathogeny of congenital toxoplasmosis: differential virulence of Toxoplasma isolates, genetic susceptibility to infection, facilitation of placental transfer, models of congenital toxoplasmosis, and transmission in seropositive hosts. Most published data suggest a role of the genetic background of the host and of the parasite. Models of congenital toxoplasmosis have been evaluated, but it appears that the conclusion drawn would be barely appropriate to understand the pathogenesis in pregnant women. Infect. Dis. Obstet. Gynecol. 5:121–127, 1997. © 1997 Wiley-Liss, Inc.

Screening for toxoplasmosis in pregnancy: what is the evidence of reducing a health problem?

Toxoplasma gondii is a parasite which may give rise to congenital infection. Screening pregnant women for antibodies against toxoplasmosis is being debated in many countries. The preventive impact of toxoplasmosis screening of pregnant women depends on the magnitude of disease caused by congenital toxoplasmosis (incidence x transmission rate to fetus x diseased proportion of infected children), on the one hand, and the preventable proportion of disease (sensitivity of the screening test x efficacy of the treatment x compliance), on the other. In this study the preventive impact of screening pregnant women for toxoplasmosis antibodies is assessed by letting the value for these variables change within reasonable limits. To obtain information on these variables, relevant publications were reviewed in the Medline database from 1983 to February 1996 and the Cochrane Pregnancy and Childbirth Database. References in review articles on congenital toxoplasmosis were also studied. The literature review showed that no population based prospective studies of the natural history of toxoplasmosis infection during pregnancy, nor any randomised controlled trials of the efficacy of antiparasitic treatment, had been carried out. In the empirical studies which have been performed the values of most variables show considerable differences. According to these values, the estimates in this study of the impact of toxoplasmosis screening in pregnancy may range from 0 to 40 children in whom disease is preventable per 100,000 pregnant women susceptible to toxoplasmosis infection. Sufficient scientific evidence is not yet available to propose screening for toxoplasmosis in pregnant women, and efforts should be made to provide such knowledge. Also, the magnitude of the negative impact of screening, such as induced abortion of healthy fetuses, anxiety in women with false positive screening tests, and side effects of treatment, has not been sufficiently examined.

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.

Congenital toxoplasmosis: prevention, screening and treatment

Congenital toxoplasmosis is an established cause of abortion, neonatal disease and ocular defects presenting in later life. Preventative options include health education, immunization and screening of pregnant women and infants with appropriate management of cases found to be at risk. Screening requires a knowledge of the disease, the test, the treatment and the administration of the proposed programme. Treatment can be directed towards the acutely infected mother, the infected fetus or infant and the patient with an acute exacerbation of ocular toxoplasmosis following congenital infection. Harm-benefit assessment of screening programmes designed to prevent congenital toxoplasmosis has produced conflicting results. Further research is required into the incidence of acute toxoplasmosis in pregnancy and subsequent congenital infection, the frequency of neonatal handicap, precise tests for the diagnosis of recent maternal infection and the presence of congenital toxoplasmosis and improved treatment of the infection.

Serological screening for toxoplasmosis in pregnancy in Slovenia.

In the period from 1981 to 1994, serological screening for toxoplasmosis was carried out in 20,953 pregnant women in Slovenia. Seropositivity among pregnant women was found to have decreased from 52% in the 1980s to 37% in the recent period, 1991-94, while during the same period the incidence of suspected primary infections acquired in pregnancy rose from 0.33% to 0.75%. These latest figures ought to promote an informed debate on the possible need for obligatory serological screening of pregnant women in Slovenia for toxoplasmosis.

Toxoplasmosis in pregnancy.

Acute acquired toxoplasma infection in a pregnant woman may result in a tragic outcome for her offspring. Transmission to the fetus has been limited almost solely to those women who acquire the infection during gestation; the dictum has been that women infected before conception are at virtually no risk unless they are severely immunocompromised by drugs they receive during pregnancy. Recently, increasing numbers of pregnant women who are coinfected with human immunodeficiency virus (HIV) and Toxoplasma gondii and whose immune deficiencies cause reactivation of the latent T. gondii infection, leading to dual infection of the offspring, have been recognized. All of these events occur in the setting of a preventable infection and disease. Recent studies in Western European countries have defined the prevalence of toxoplasma infection among pregnant populations and the incidence of congenital transmission. Similar timely studies have not been done in the United States. Routine serological screening of women during pregnancy, although it can successfully detect the acute acquired infection and thereby allow treatment intended to prevent infection of the fetus, is not conducted in the United States. Since the vast majority of infected newborns have subclinical infection at birth, they go undetected; if not treated, most suffer the unfortunate sequelae of this congenital infection. Thus, whereas screening is mandatory in countries such as France and Austria, in the United States a single serum sample-often obtained either late in the first trimester or during the second or third trimester-is the only source of information on whether the fetus is at risk.

Models for prediction of the frequency of toxoplasmosis in pregnancy in situations of changing infection rates.

Estimation of the number of women infected during pregnancy with Toxoplasma gondii from seroconversion or seroprevalence data meets with various difficulties. Because of the high risk of transmission of the infection to the fetus such infections are however a major concern in pregnancy-related health planning. The expected annual percentage of pregnant women infected with Toxoplasma was calculated using models with varying assumptions with regard to the infection rate, assumed to be independent of age but dependent on calendar time. Three situations were studied: a stable situation, a sudden fall in the infection rate and a gradually declining (slower or faster) infection rate over the lifetime of the pregnant women. With a constant infection rate, a maximum number of affected pregnancies occurs at a yearly infection rate of 4%. In countries with a strongly decreasing annual infection rate, estimates based on data on the relation between age and seropositivity related to only one period of time tend to overestimate the number of affected pregnancies by as much as 60%. In countries in transition from high to low infection rates, it is likely that the influence of decreasing immunity will, at least temporarily, more than outweigh the influence of the falling infection rates, resulting in a higher number of infected pregnant women. The models used can also describe situations with age-dependent variation in the infection rate, and may well apply to other infectious diseases relevant to pregnancy.