Toxoplasmosis screening during pregnancy in France: Opinion of an expert panel for the CNGOF

Prenatal screening to prevent congenital toxoplasmosis as performed in France for several decades has been questioned in view of the decreasing incidence of this infection and the cost of testing. The French College of Obstetrics and Gynecology mandated a multidisciplinary panel of experts to perform a reassessment of the screening program in accordance with international good practice. In France, about 70% of pregnant women are not immune to T. gondii, and 0.2-0.25% become infected during pregnancy. The risk of maternal-fetal transmission of infection is on average 25-29% and depends greatly on the gestational age at seroconversion. In case of fetal transmission, the outcome is livebirth in 95% of cases, with latent congenital toxoplasmosis in 90% of cases and symptomatic forms in 10% of cases, of which 1/3 are severe and 2/3 moderate. Biological techniques have satisfactory performance regarding serologies for the diagnosis of maternal infections and PCR on amniotic fluid for the prenatal diagnosis of congenital toxoplasmosis. Primary prevention of toxoplasmosis is based on hygiene measures that are relatively simple, but poorly implemented. In case of maternal seroconversion, there is a strong case for prenatal prophylactic treatment as soon as possible (ideally within 3 weeks of seroconversion), spiramycin before 14 weeks of gestation (WG), and with a tendency to superiority of the pyrimethamine/sulfadiazine association over spiramycin beyond 14 W G, in order to reduce the risk of symptomatic congenital toxoplasmosis. In case of congenital toxoplasmosis, prompt initiation of treatment reduces the occurrence of cerebral signs and symptoms, as well as retinal lesions. Several medico-economic evaluations of the French toxoplasmosis screening program have been conducted including an individual cost-effectiveness approach with decision analysis which concluded on the profitability of prenatal screening as carried out in France (monthly surveillance of seronegative women, prenatal treatment in case of seroconversion, termination of pregnancy in severe forms). Though most international societies do not recommend systematic screening for mainly financial reasons, if congenital toxoplasmosis appears benign in France today, it is probably thanks to screening and the possibility of early treatment of fetuses and/or newborns. Thus, the panel recommends continuing for now the program in France for prevention of congenital toxoplasmosis.

Differential expression of genes in fetal brain as a consequence of maternal protein deficiency and nematode infection

Maternal dietary protein deficiency and gastrointestinal nematode infection during early pregnancy have negative impacts on both maternal placental gene expression and fetal growth in the mouse. Here we used next-generation RNA sequencing to test our hypothesis that maternal protein deficiency and/or nematode infection also alter the expression of genes in the developing fetal brain. Outbred pregnant CD1 mice were used in a 2×2 design with two levels of dietary protein (24% versus 6%) and two levels of infection (repeated sham versus Heligmosomoides bakeri beginning at gestation day 5). Pregnant dams were euthanized on gestation day 18 to harvest the whole fetal brain. Four fetal brains from each treatment group were analyzed using RNA Hi-Seq sequencing and the differential expression of genes was determined by the edgeR package using NetworkAnalyst. In response to maternal H. bakeri infection, 96 genes (88 up-regulated and eight down-regulated) were differentially expressed in the fetal brain. Differentially expressed genes were involved in metabolic processes, developmental processes and the immune system according to the PANTHER classification system. Among the important biological functions identified, several up-regulated genes have known neurological functions including neuro-development (Gdf15, Ing4), neural differentiation (miRNA let-7), synaptic plasticity (via suppression of NF-κβ), neuro-inflammation (S100A8, S100A9) and glucose metabolism (Tnnt1, Atf3). However, in response to maternal protein deficiency, brain-specific serine protease (Prss22) was the only up-regulated gene and only one gene (Dynlt1a) responded to the interaction of maternal nematode infection and protein deficiency. In conclusion, maternal exposure to GI nematode infection from day 5 to 18 of pregnancy may influence developmental programming of the fetal brain.

Pregnancy-associated malaria and malaria in infants: an old problem with present consequences

Albeit pregnancy-associated malaria (PAM) poses a potential risk for over 125 million women each year, an accurate review assessing the impact on malaria in infants has yet to be conducted. In addition to an effect on low birth weight (LBW) and prematurity, PAM determines foetal exposure to Plasmodium falciparum in utero and is correlated to congenital malaria and early development of clinical episodes during infancy. This interaction plausibly results from an ongoing immune tolerance process to antigens in utero, however, a complete explanation of this immune process remains a question for further research, as does the precise role of protective maternal antibodies. Preventive interventions against PAM modify foetal exposure to P. falciparum in utero, and have thus an effect on perinatal malaria outcomes. Effective intermittent preventive treatment in pregnancy (IPTp) diminishes placental malaria (PM) and its subsequent malaria-associated morbidity. However, emerging resistance to sulphadoxine-pyrimethamine (SP) is currently hindering the efficacy of IPTp regimes and the efficacy of alternative strategies, such as intermittent screening and treatment (IST), has not been accurately evaluated in different transmission settings. Due to the increased risk of clinical malaria for offspring of malaria infected mothers, PAM preventive interventions should ideally start during the preconceptual period. Innovative research examining the effect of PAM on the neurocognitive development of the infant, as well as examining the potential influence of HLA-G polymorphisms on malaria symptoms, is urged to contribute to a better understanding of PAM and infant health.

Congenital toxoplasmosis presenting with fetal atrial flutter after maternal ingestion of infected moose meat

Consumption of undercooked game meat during pregnancy is considered a risk factor for congenital toxoplasmosis, but cases definitively linking ingestion of infected meat to clinical disease are lacking. We report a confirmed case of congenital toxoplasmosis identified because of atrial flutter in the fetus and linked to maternal consumption of Toxoplasma gondii PCR-positive moose meat.

The effects of malaria and intermittent preventive treatment during pregnancy on fetal anemia in Malawi

BACKGROUND

Fetal anemia is common in malarious areas and is a risk factor for infant morbidity and mortality. Malaria during pregnancy may cause decreased cord hemoglobin (Hb) and fetal anemia among newborns. Intermittent preventive treatment during pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is protective against malaria but may also affect hematopoiesis and contribute to fetal anemia.

METHODS

Peripheral, placental, and cord blood were examined for malaria parasitemia and Hb concentration in a cross-section of 3848 mothers and infants delivered at Queen Elizabeth Central Hospital in Blantyre, Malawi between 1997 and 2006. Unconditional linear and logistic regressions were performed with multiple imputation for missing covariates to assess the associations between malaria, IPTp with SP, and fetal anemia.

RESULTS

The overall prevalence of fetal anemia was 7.9% (n = 304). Malaria parasitemia at delivery was associated with an adjusted decrease in cord Hb of -0.24 g/dL (95% confidence interval [CI], -.42 to -.05). The adjusted prevalence odds ratio for the effect of malaria on fetal anemia was 1.41 (95% CI, 1.05-1.90). Primigravidae who did not take IPTp had infants at highest risk for fetal anemia, and density of parasitemia was correlated with the decrease in cord Hb. There was no significant association between SP use and cord Hb or fetal anemia.

CONCLUSIONS

Malaria during pregnancy, but not IPTp, decreases cord Hb and is a risk factor for fetal anemia in Malawi. Intermittent preventive treatment during pregnancy with SP may continue to be safe and effective in preventing malaria during pregnancy and fetal anemia despite development of SP resistance.

[Effect of congenital infection by Trypanosoma cruzi on intrauterine development and the fetal-neonatal immune response]

In congenital infection by Trypanosoma cruzi, morbidity and mortality vary from asymptomatic cases to severe clinical forms of the disease. It has been found that there is no specific clinical profile in newborns infected by T. cruzi, since during intrauterine development diverse pathological changes take place, causing alterations in the serological and parasitological profiles. Some intrinsic factors of the host, such as: the placental barrier and the ability of both, mother and fetus, to develop a specific immune response to control parasite multiplication, could be involved in such differences. Another possibility includes the genetic polymorphism of T. cruzi, since it is considered that strains of greater virulence can cross the placenta more easily and are more pathogenic to the fetus and/or the neonate.

[Cases of Toxoplasma gondii infection in foetus's and toxoplasmic encephalitis in immunosupressed patients confirmed by PCR method in NIPH - NIH, 2009-2010]

The results of molecular tests for Toxoplasma gondii infection carried out in NIPH-NIH were presented in the light of current data on diagnostics and epidemiology of toxoplasmosis. Between January 2009 and December 2010 four cases of active toxoplasmosis were confirmed using PCR targeting the 529-bp repeat element of Toxoplasma gondii. Intrauterine infection was found in 3 out of 180 (1.7%) examined women. Toxoplasmic encephalitis was confirmed in one patient who was a liver transplant recipient. T. gondii was not detected in cerebrospinal fluid of 19 out of 20 examined patients with encephalitis. The cases of intrauterine toxoplasmosis diagnosed in 2009-2010 make 57.1% of all cases diagnosed in the last decade. In 2001-2010 toxoplasmic encephalitis was detected in two patients out of 45 examined. The choice of tests and interpretation of the results are important elements of T. gondii infection diagnosis and require cooperation between clinicians and laboratory diagnosticians. Establishing reference center for toxoplasmosis in Poland would contribute towards the improvement of standards of diagnostics and treatment of cases of congenital infections and the infection in immunosuppresed patients.

[Detection of Trypanosoma cruzi DNA in the placenta and fetuses of mice with Chagasic acute infection]

The objective of the present study was to detect the presence of Trypanosoma cruzi DNA in the placenta and fetal tissues of NMRI mice (Mus musculus) inoculated with 22 x 10(3) trypomastigotes metacyclic of the M/HOM/BRA/53/Y strain by intraperitoneal route. Mice were pregnant in the acute phase of the infection. The course of patent parasitemia by T. cruzi was evaluated before mating and during pregnancy. At day twenty of gestation, animals were sacrificed and the fetuses and their placentas were removed to evaluate T. cruzi infection. Samples of fetal placenta, heart and skeletal muscle were fixed in 10%, formalin, included in paraffin and stained with hematoxilin and eosin (HE). The histopathological study of sections of fetal tissues revealed inflammatory infiltrates with mononuclear and polymorphonuclear cells and without parasitism in these tissues. The amplification of T. cruzi DNA by Polymerase Chain Reaction (PCR) showed a positive reaction in 18% of placental tissue of pregnant infected mice. The samples of heart and skeletal muscle of the fetuses of mothers infected with T. cruzi did not show the presence T. cruzi DNA. The placenta and skeletal muscle of the fetuses analyzed by Peroxidase anti Peroxidase inmunostaining showed T. cruzi antigens in those tissues. Negative results by PCR in fetal tissues might be related with the virulence and tropism associated with the biological and genetic characteristic Of the T. cruzi strain used in the experimental infection of female mice.

Fetus-in-fetu: Parasite or Neoplasm?

INTRODUCTION

Fetus-in-fetu is a rare congenital fetiform mass whose etiology is still controversial. We report two cases of fetus-in-fetu. CASE 1: A fetal retroperitoneal cystic tumor including two masses was detected by ultrasonography at 26 gestational weeks. The masses showed distinctive structures resembling a vertebral axis and were prenatally diagnosed as fetus-in-fetu. A resected specimen revealed two fetiform masses. CASE 2: An intracranial tumor with hydrocephalus was detected by ultrasonography at 19 gestational weeks. The pregnancy was terminated, and a postmortem examination revealed six fetiform masses with immature teratoma.

DISCUSSION

The tumors may possibly consist of parasitic monozygotic diamniotic twins or highly differentiated teratomas.

Diagnosis of congenital toxoplasmosis: pre- and post-natal evaluation in Sicilian (Italy) epidemiological area. Preliminary data

To evaluate the usefulness of conventional serological methods with western blot assay (WB) in congenital toxoplasmosis diagnosis, we prospectively enrolled in a clinical and serological follow-up all pregnant women with Toxoplasma gondii infection and their offspring, referred to us from October 2004. Western blot and standard serological test were performed on sera collected from mother during pregnancy and from mother and child at birth, at postpartum month 1-3-6-9 and 12. At this point in time, 22 pregnant women and 14 infants have completed the follow-up. 4 newborns were infected and 2 had specific toxoplasmosis anomalies at the birth. In mothers without seroconversion, the WB performed during pregnancy demonstrates the highest accordance with postnatal follow-up whereas in 1 case the negative result of PCR analysis was not confirmed by postnatal observation. The detection of anti-T gondii IgG against 8 kDa accessory antigenic band and against the accessory band included between 35 and 40 kDa band in immunoblot assay was useful for diagnosis of acute phase but did not improve the evaluation of comparative postnatal profile. Althougth few infants have concluded the postnatal follow-up, the preliminary results showed a greater value of using a IgM and IgA WB test than other standard method for the early diagnosis of toxoplasmosis at birth also in child born to treated mothers. The comparative anti-T gondii IgG immunoblot profile of mother and child permitted us to reduce the time of ruling out infection in newborns born to mothers with probable or possible infection and/or when prenatal diagnosis is negative or not performed.

Toxoplasma gondii infection in horses. A review

This review updates those written by Dubey and Beattie in 1988 (1988a) and by Tenter et al in 2000, on pathological and epidemiological aspects of Toxoplasma infection in horses. Under natural conditions, seroprevalence may variate from 0% up to 90%. This wide variation may be due to the sensitivity of the serological methods, to the age of animals, to the geographical area, and even to the hygienic condition of the farms and farm management. With few exceptions, horses are considered one of the less sensitive specie to the pathogenic effect of Toxoplasma gondii. In fact, neither under experimental nor under natural condition a genuine pathologic picture related to the toxoplasmic infection has been described. In one occasion the organism has been isolated from an eye condition and in others a connection between a higher frequency of unspecified pathological conditions and a positive response to serological test for Toxoplasma has been speculated. Diaplacental transmission and the following abortion have been only occasionally reported, and at least in one case in a quite trustworthy way, therefore it must be considered possible, though rare. Although infection of humans due to the consumption of horse meat has never been reported, the existence of a possible risk arouses by the demonstration of the presence of parasite stages in either naturally or experimentally infected horses, which resulted to be infective for mice and/or cats.

[Contribution of the real time PCR in antenatal diagnosis of congenital toxoplasmosis]

BACKGROUND

The antenatal diagnosis of congenital toxoplasmosis rests in Tunisia on ultrasonography coupled with biological explorations. Among these explorations the search of Toxoplasma gondii by means of real time PCR in amniotic fluid is the examination of choice.

AIM

We report the results of 33 parturients for which the biological examinations allowed to retain the notion of perigravidic or pergravidic toxoplasmic infection.

METHODS

They were 13 patients having a seroconversion during the pregnancy, 19 having anti-toxoplasmic IgM with a low or intermediate index of avidity and a patient having presented a symptomatic anteconceptional primary infection. The ADN was extracted by means of the Kit (Qiagen). Genic amplification by PCR TaqMan targeted a portion of 71 pairs of bases of the B 1 gene.

RESULTS

The PCR was positive among 9 patients (27.3%). They were a patient having presented a symptomatic toxoplasmosis during the pregnancy, 4 patients having consulted only in the 2nd quarter and for which the index of avidity was intermediate and 4 patients having presented seoconversions of 1st (n=1) of 2nd (n=2) or 3rd trimester. Among these patients, 2 had a medical interruption of pregnancy. The 7 others were put under pyrimethamine sulfadiazine. The neonatal assessment practised at 5 new-born babies was negative in all the cases. The PCR was negative for 24 patients. 18 pregnancies were followed. The neonatal serology was negative. The follow-up of 13 newborn child showed the disappearance of the antitoxoplasmic IgG between the 6th and 12th month.

Malaria in pregnancy: what can the social sciences contribute?

Building on existing knowledge from social science work on malaria, the authors propose two models for studying social science aspects of malaria in pregnancy.

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.

[Lesions in cross-breed pregnant cows, experimentally infected with Sarcocystis cruzi (Hasselmann, 1923) Wenyon, 1926 (Apicomplexa: Sarcocytidae)]

To identify pathologic alterations, sixteen cows, in the last 3 months of gestation, all cross-breed, Holstein x Zebu, serum positive for Sarcocystis, were selected and divided into four groups of four animals each. The first group was considered as control and the other three groups were experimentally infected with 1x10(4) (2nd group), 5x10(4) (3rd group) and 1x10(5) (4th group) sporocysts obtained from dog's feces. The gross lesions in the cows were consisted of pale mucous membranes, paleness of the skeletal striated muscle and enlargement of lymph nodes, heart, liver, spleen and lungs. In the aborted fetus, the most prominent gross lesion were excess of fluid in peritoneal and thoracic cavities, and petecheas in the surface of intercostal muscles, thymus and spleen. On histological sections, no parasitic form was found in the tissues of the fetus, placenta or uterine tissue of the exposed cows. However, meronts, young and mature cysts of S. cruzi were observed in striated muscle. In the aborted fetus, hemorrhage, was the main histological lesion observed in brain, cerebellum and kidneys.

Diagnosis of fetal infections

PURPOSE OF REVIEW

The purpose of this review is to present recent developments in the prenatal diagnosis of the most clinically relevant congenital infections.

RECENT FINDINGS

Immunoglobin G avidity testing can help to differentiate between recent or prior infection. A combination of tests, including serology, avidity and polymerase chain reaction, may be necessary to improve accuracy of diagnosis. The interval between exposure to an infectious agent and prenatal testing can be critical to the interpretation of the test result.

SUMMARY

This review reinforces the need for accurate testing to guide appropriate counseling and individual fetal risk assessment. The findings of viral-specific antibodies or sonographic abnormalities do not accurately predict the severity or outcome of fetal infection. Further research is necessary to determine the pathogenesis of transplacental viral transmission and thereby allow us to target prevention strategies.

Fetal brain infections

INTRODUCTION

Congenital infections can cause severe brain damage. As a result, it is very important to identify them early in their course so that treatment can be administered to the mother, if possible. The role of imaging is to determine the presence, if any, and the extent of brain damage in the infected fetus. Although MRI is most commonly used as an adjunct to sonography, when clinical suspicion is high in the setting of a normal ultrasound or to better define abnormalities detected by ultrasound, MRI is routinely used in toxoplasmosis seroconversion to definitively rule out brain lesions, even when the ultrasound scan is considered normal. MRI is also used serially throughout the pregnancy to check for the development of brain abnormalities; medical treatment results in excellent clinical outcome if the brain is normal.

DISCUSSION

This article describes the indications, techniques, and findings that will allow proper use of fetal MRI in the setting of congenital infections.

Additional evaluation of undiagnosed bovine abortion cases may reveal fetal neosporosis

Diagnosis of Neospora caninum associated bovine abortion is often made by histological examination of fetal tissues, although this procedure is not very sensitive. One hundred and forty-four undiagnosed bovine abortion cases were evaluated for N. caninum associated bovine abortion using a revised diagnostic protocol. As a result, 12 (8.3%) of these previously undiagnosed bovine abortion cases were definitively diagnosed as N. caninum positive. The 12 new positive cases included 7 that had exhibited histological lesions, and 5 that had not exhibited histological lesions when examined prior to this study. None of the 12 cases had been immunohistochemically (IHC) stained prior to this study. Also, IHC staining implemented during this research revealed tachyzoites without associated histological lesions in at least 1 tissue from 69 (47.9%) of 144 aborted bovine fetuses, and positive IHC staining of cytoplasmic N. caninum antigen in macrophages in at least 1 tissue from 44 (30.6%) of 144 aborted bovine fetuses. These results demonstrate the necessity for more aggressive evaluation of bovine fetuses for neosporosis.

Fetal Toxoplasma infection after oocyst inoculation of pregnant rats

Six groups totalling 53 Wistar rats were fed 10(4)oocysts from one of six different Toxoplasma strains at 15 days of pregnancy. The overall transplacental transmission rate was 51%. This varied between 10% and 80%, dependent on the strain used. The strains of Toxoplasma which are more pathogenic for mice were transmitted transplacentally more frequently than the strains of intermediate or low pathogenicity. There were no statistically significant differences in the rate of congenital transmission of Toxoplasmain rats fed oocysts (present work) or cysts (previous work).

Transplacental toxoplasmosis in a reindeer (Rangifer tarandus) fetus

Toxoplasma gondii infection was diagnosed in a full term stillborn reindeer (Rangifer tarandus) fetus. The fetus had encephalitis and placentitis associated with T. gondii. Tissue cysts were identified histologically in sections of brain and tachyzoites were present in placenta and the myocardium. Protozoa in the brain, heart, and placenta stained positively with T. gondii antibodies, but not with Neospora caninum antibodies in an immunohistochemical test. The dam of the fetus had a 1:12,800 titer to T. gondii in the modified agglutination test employing whole tachyzoites and mercaptoethanol. This is the first confirmed report of T. gondii infection in reindeer.

Isolation of viable Toxoplasma gondii from naturally infected aborted bovine fetuses

Neospora caninum and Toxoplasma gondii are related parasites. The former is a common cause of abortion in dairy cattle. The latter has not been conclusively demonstrated in bovine fetuses. During the course of attempts to isolate N. caninum from aborted fetuses, T. gondii was isolated from 2 aborted fetuses, 1 from Portugal and 1 from the United States. Both isolates were made by bioassay of fetal brains in mice. The fetus from Portugal was about 5 mo in gestational age, and the fetus from the United States was a full-term stillborn.

Fetal infection with Neospora caninum in dairy and beef cattle in Belgium

Neospora caninum is a protozoan parasite, which causes fetal and neonatal mortality in livestock and companion animals. In 224 abortions in Belgian cattle, different diagnostic methods were used to demonstrate infection, and the presence of N. caninum. An indirect fluorescent antibody test (IFAT) was used to analyze fetal and maternal sera and immunohistochemistry (IHC) was performed when lesions consistent with neosporosis were observed in the brain, heart or liver. Twenty dairy cattle sera out of 70 (29%) and 13 beef cattle sera out of 93 (14%) were positive by IFAT. A positive titer to N. caninum was found in seven and three fetuses born to beef and dairy cows, respectively. Lesions consistent with N. caninum infection were observed in 17 fetuses. Of nine positive beef fetuses, five were confirmed by IHC while, all but one dairy fetus were confirmed using the same technique. Age had no influence on the serological status of the mother (P = 0.486) whereas husbandry system had a borderline influence (P = 0.082). However, a strong association (P = 0.004) between the level of antibodies in the dam and the occurrence of lesions in the fetus was observed and lesions were more prominent in dairy than in beef fetuses. Additionally, the distribution of intra-cerebral lesions was more extensive in dairy than in beef fetuses (P < 0.0001). Age and serological status of the fetus were found to influence the occurrence of lesions in beef fetuses (both P < 0.001) but no such significant relationships could be demonstrated in dairy fetuses. The study indicated that N. caninum must be considered as an important cause of bovine abortion in Belgium.

Comparative study between elisa IgG, IgM and PCR in diagnosing and studying toxoplasmosis in Qualyobia Governorate, Egypt

ELISA IgG, IgM antibodies and PCR for toxoplasmosis were performed on 55 women with complicated gestation and their babies. Besides, ELISA IgG and IgM were applied on 27 uncomplicated gestation (mothers & babies) and 152 randomly selected individuals. Seropositivity to specific IgG antibodies was 36.4%, 59.2% and 57.9% and for IgM was 27.3%, 7.4% and 10.5% in complicated gestation. uncomplicated gestation and random population respectively. PCR was positive in 20%, 50% and 60% of mothers with abortion, premature deliveries and deliveries of babies with congenital anomalies respectively. 55.5% and 40% were found seropositive for IgG from normal full term babies and abnormal babies. 13% of abnormal babies were IgM positive and 46.6% were PCR positive from the same group.

Laboratory diagnosis of Toxoplasma gondii infection and toxoplasmosis

For the past 40 years, the Toxoplasma Serology Laboratory at the Palo Alto Medical Foundation Research Institute (TSL-PAMFRI) has been dedicated to the laboratory diagnosis of Toxoplasma gondii infection and toxoplasmosis. TSL-PAMFRI is the "brain child" of Jack S. Remington. Jack's ceaseless devotion to objectivity and uncompromising excellence has made TSL-PAMFRI the Toxoplasma reference laboratory for the Centers for Disease Control and Prevention, the US Food and Drug Administration, and health care providers and clinical laboratories in the United States and other countries. Jack's leadership and vision created, defined, and significantly contributed to the development of laboratory methods for the diagnosis of the infection and diseases caused by T. gondii. A summary of the laboratory tests currently available at TSL-PAMFRI for the diagnosis of infection and disease caused by the parasite is presented here.

[Detection of congenital toxoplasmosis in utero with a polymerase chain reaction on amniotic fluid]

To establish a prenatal diagnosis of congenital toxoplasmosis the PCR test was done on amniotic fluids from 47 women suspected of primary Toxoplasma infection during pregnancy. Fragments of Toxoplasma B1 gene were found in 5 examined samples. Positive tests were confirmed by mouse inoculation or by serologic testing of newborns. It was concluded that the PCR performed on amniotic fluid should be recommended for the prenatal diagnosis of congenital toxoplasmosis, however, negative results of the test can not rule out congenital infection.

Prenatal toxoplasmosis diagnosis from amniotic fluid by PCR

Toxoplasmosis is one of the most common infections all over the world. Most cases are asymptomatic, except in immunosuppressed individuals and fetuses, which can be seriously damaged. Prenatal diagnosis should be made as soon as possible since treatment of the mother can minimize fetal sequelae. Our aim in this study was to test the polymerase chain reaction technique (PCR) in 86 samples of amniotic fluid from women who seroconverted during pregnancy. DNA was amplified using external primers and, in a second step, internal primers, in a nested PCR system. Samples were also inoculated into mice and the newborn were evaluated by T. gondii serology, skull x-ray, transfontanel ultrasound, fundoscopic examination, lumbar puncture and clinical examination. PCR was positive in seven cases and negative in 79. Among PCR-positive cases, two were negative by inoculation into mice and by clinical evaluation; among PCR-negative ones, three had clinical evidence of toxoplasmosis and one was positive after inoculation into mice. PCR showed values of sensitivity = 62.5% and specificity = 97.4%; the values of inoculation into mice where 42.9% and 100%, respectively. Although PCR should not be used alone for prenatal diagnosis of congenital toxoplasmosis, it is a promising method and deserves more studies to improve its efficacy.

Neosporosis in Mexican dairy herds: lesions and immunohistochemical detection of Neospora caninum in fetuses

Of 211 aborted bovine fetuses collected from Mexican dairy herds between January 1996 and March 1999, 73 showed microscopical lesions consistent with neosporosis. Of these 73 fetuses, 58 (79%) showed lymphocytic myocarditis, 39 (53%) showed microgliosis and multifocal necrosis in the brain, 39 (53%) showed lymphocytic hepatitis, and 19 (26%) showed lymphocytic myositis. Immunohistochemical examination of brain, myocardium and liver from 53 of the same 73 fetuses demonstrated Neospora caninum antigens in 41 (77%), of which 19 (46%) gave positive results in one of the three sites, 15 (37%) in two, and seven (17%) in three. The results indicated the presence of neosporosis in a number of the main dairy farming regions of Mexico.

Naturally-occurring Neospora caninum infection in an adult sheep and her twin fetuses

Neospora caninum tissue cysts were found in the brains of surgically delivered twin fetuses at 119 days of gestation. In the brains of both fetuses, there was an inflammatory reaction involving perivascular cuffings of mononuclear cells, glial nodules. The dam of these fetuses died because of metritis. Histopathological examination of the ewe revealed N. caninum tissue cysts and focal gliosis with mononuclear cell cuffings. A N. caninum-specific DNA fragment was detected in a brain homogenate of the ewe by the polymerase chain reaction method. This is the first report of N. caninum infection in twin ovine fetuses and in an adult sheep.

Transplacental transmission of Toxoplasma gondii in minipigs infected with strains of different virulence

Infections with the zoonotic protozoan Toxoplasma gondii during pregnancy can result in severe fetal infections. To investigate the use of pigs as animal models for congenital toxoplasmosis, tachyzoites of 5 T. gondii strains, with low to intermediate virulence in mice, were intravenously inoculated into pregnant minipig gilts. Two strains caused abortions of uninfected fetuses following severe disease of the mothers. One strain caused no disease in the gilts but slightly elevated anti-T. gondii antibodies in 2 of 9 fetuses. One strain produced clinical disease with 4 mummified fetuses and 2 full-term, congenitally infected piglets in 1 gilt and no clinical disease but elevated specific fetal antibodies in both piglets of the other gilt. Infection with the fifth strain (SVS-O14), which was considered apathogenic to both pigs and mice based on the clinical course of this and previous experiments, resulted in significant numbers of congenitally infected piglets, as indicated by production of anti-T. gondii antibodies in all 12 fetuses; the parasite was identified in 3 of these fetuses. This pattern of infection indicates that pigs infected with SVS-O14 (or a similar strain) are relevant animal models for studies of transplacental transmission and pathogenesis of congenital toxoplasmosis.

[Detection of Toxoplasma gondii DNA in the autopsy cases of abnormal birth and teratosis by polymerase chain reaction]

Toxoplasma gondii DNA in the autopsy tissues of 72 cases of the premature, stillbirth and congenital malformation was detected using polymerase chain reaction (PCR). The specific amplified products were found in 9 cases, i.e. one case of premature, 3 cases of stillbirth, one case of hydrocephalus and 4 cases of other teratosis. The positive rate was 12.5%. Ten control samples were negative. The results showed that Toxoplasma gondii infection was present in the disease cases. The finding indicates that the infection of Toxoplasma gondii may be one of the main causes of the abnormal birth and the congenital teratosis.

Prenatal diagnosis of congenital toxoplasmosis transmitted by an immunocompetent woman infected before conception. Reims Toxoplasmosis Group

We report a rare case of congenital toxoplasmosis transmitted by an immunocompetent woman infected before conception. Active toxoplasmosis was suspected due to persistent lymphadenitis with specific IgM, IgA, IgE antibodies. Prenatal diagnosis based on amniocentesis and fetal blood sampling at 24 weeks' amenorrhoea was positive on amniotic fluid, and fetal infection was confirmed after termination. In our opinion such cases need the same monitoring as when seroconversion occurs during the first trimester. A pregnancy-free interval of six to nine months is recommended after proven patent toxoplasmosis seroconversion.

Double maternal seroconversion to cytomegalovirus and Toxoplasma gondii

BACKGROUND

We report the first case of a double maternal seroconversion for Toxoplasma gondii (TG) and cytomegalovirus (CMV) diagnosed during pregnancy.

CASE

One case is reported of a female patient referred for seroconversion in response to TG in the 27th week of gestation. A search for foetal involvement revealed signs of non-specific foetal infection without any TG-related lesions. Tests were carried out for another foeto-maternal infectious disease and maternal seroconversion in response to CMV was discovered with virus in the amniotic fluid. The foetus developed hydrocephalus and intracranial calcifications and the pregnancy was terminated at the parents' request. CMV-induced multiple organ involvement without any signs of Toxoplasma gondii-related involvement were noted in the foetus.

CONCLUSIONS

This case indicates that a search should be made for another infectious disease likely to involve the foetus when non-specific signs of infection in the foetus are present, even though maternal seroconversion has been recognized.

Neospora caninum identification in an aborted bovine fetus in Spain

Neospora caninum tachyzoites were identified in areas of the cerebrum with lesions of non-suppurative encephalitis in an aborted bovine fetus in Spain.

Experimental porcine neosporosis

Six gilts were inoculated intramuscularly with 2.5x10(6) tachyzoites of Neospora caninum on three different days of gestation to study the pathogenic effect of Neospora infection in pigs, including possible transplacental transmission. The gilts were euthanized 59, 30, and 9/10 days postinoculation (p.i.), corresponding to days 107, 102/106 and 110/111 of pregnancy. With the exception of one animal (euthanized day 9 p.i.) all gilts seroconverted as measured by the indirect, fluorescent antibody test (IFAT). Neosporosis with multifocal intralobular necrotizing hepatitis was seen in the two gilts inoculated 9/10 days before euthanasia. The uterus of one gilt inoculated 59 days before euthanasia revealed granulomatous and focal necrotizing endometritis with a corresponding multifocal necrosis of the trophoblasts of two fetuses. Transplacental neosporosis was indicated in the two fetuses by strongly elevated Neospora IFAT titres in pleural fluid and by the presence of multifocal necrotizing encephalitis and hepatitis together with non-suppurative myocarditis, pneumonitis, nephritis and hepatitis. Furthermore, N. caninum was re-isolated in cell culture from one of these fetuses. A third fetus from the same gilt revealed only disseminated, pinpoint necroses in the liver. Immunohistochemically, N. caninum tachyzoites were detected in association with histopathological changes in the liver and the endometrium of the gilts, and in the brain, liver, and allantochorion of the three fetuses.

In utero transmission of Pneumocystis carinii sp. f. oryctolagi

Although vertical transmission of Pneumocystis in human or animal hosts has often been suspected, no evidence demonstrating this infection route has been furnished until now. This widespread parasite is constantly found in the lungs of rabbits, which spontaneously develop a benign pneumocystosis at weaning. However, the infection source, the method of entry of Pneumocystis organisms into the rabbit and when this mammal is infected, remain to be known. As a few parasites have been microscopically observed and detected by PCR in the lungs of rabbits at birth, in utero Pneumocystis infection has been hypothesized. The presence of Pneumocystis was therefore carefully assessed in 16 pregnant does, their embryos and fetuses by using several detection methods. Pneumocystis was detected by PCR in maternal blood, embryos, amniotic fluid and fetuses. The parasite was also revealed histologically and by immunofluorescence in fetal and maternal lungs and in placentas. The results suggest that vertical transmission of P. carinii sp. f. oryctolagi occurs as early as at the 10th day of pregnancy.

Prenatal diagnosis and treatment of congenital Toxoplasma gondii infections: an experimental study in rhesus monkeys

The efficacy of treatment in fetuses in whom congenital Toxoplasma gondii infection has ben established has been investigated using rhesus monkeys as a model for humans. A polymerase chain reaction has been developed for the detection of Toxoplasma gondii. Using this polymerase chain reaction congenital infection can be established within 2 days of receiving an amniotic fluid sample. The polymerase chain reaction has subsequently been used to monitor the effect of treatment on fetal infection. The results show that early treatment with the combination of pyrimethamine and sulfadiazine was clearly effective in reducing the number of parasites in the infected fetus. The parasite was no longer detectable in the amniotic fluid 10 to 13 days after treatment was started. Spiramycin, on the other hand, has to be administered for at least 3 weeks to achieve the same effect. Moreover, pharmacokinetic studies revealed that spiramycin does not reach the brain. Pyrimethamine and sulfadiazine are able to pass the blood-brain barrier. Pyrimethamine appears to accumulate in the brain tissue and reaches concentrations which are also effective in vitro.

Workshop summary: food safety: meat- and fish-borne zoonoses

In this workshop, J.P. Dubey (USA), Th. Hiepe (Germany), and P. Deplazes (Switzerland), were invited speakers. The main areas covered were toxoplasmosis, microsporidiosis, trematode infections, taeniosis/cysticercosis and trichinellosis. The public health and economic impact of meat- and fish-borne parasitic zoonoses is considerable in terms of morbidity and even mortality in humans as well as in losses due to reduced productivity in animals and condemnation of parasitised meat and fish. In this context, the increasing demands of consumers for meat and fish free of pathogens and chemical residues has to be considered. Among the parasitic zoonoses some are widespread and frequent, for example toxoplasmosis. About 30-50% of women of child-bearing age are at risk of acquiring the infection during pregnancy with the potential of prenatal infection and severe disease of the foetus. In addition, toxoplasmosis plays an increasing role as an AIDS-associated infection. There are some recent indications that Toxoplasma infections acquired by adults by ingestion of sporulated oocysts may be more pathogenic than cyst-induced infections. In such cases, eye lesions are quite frequent and were previously thought to be predominantly acquired by prenatal infection (J.P. Dubey, USA). Fish- or crustacean-borne trematodes (species of Clonorchis, Opisthorchis, Paragonimus, intestinal flukes) infect about 39 million people, and about 550 millions are at risk (WHO, 1995). Other zoonotic infections are less frequent but may cause severe and lethal diseases, for example Taenia solium cysticercosis.

Diagnosis of bovine fetal Neospora infection with an indirect fluorescent antibody test

Fetal fluids from 138 spontaneously aborted bovine fetuses were examined for the presence of antibodies against Neospora antigens by means of an indirect fluorescent antibody test (IFAT). The fetuses were divided into group 1, consisting of 74 fetuses with confirmed or presumptive fetal neosporosis, and group 2, consisting of 64 fetuses with either no aetiological diagnosis, presumptive diagnoses of non-Neospora infections or non-infectious diseases, or fetuses with confirmed diagnoses of other fetal diseases. Thirty-seven of the 74 fetuses in group 1 had detectable titres of antibody to Neospora; approximately 21 per cent of the fetuses between three and five months gestation, 56 per cent of these between six and seven months gestation, and 93 per cent of these between eight and nine months gestation, had detectable titres of antibody. Only one of the 64 fetuses in group 2 had a detectable titre of antibody to Neospora.

Evaluation of abortions in cattle attributable to neosporosis in selected dairy herds in California

OBJECTIVE

To estimate the minimum rate of abortion attributable to infection with Neospora sp in selected California dairy herds.

DESIGN

Prospective study.

ANIMALS

Twenty-six dairy herds containing 19,708 cows were studied. Fourteen herds had a history of abortions attributable to neosporosis, and 12 were herds in which neosporosis had not been identified as a cause of abortions.

PROCEDURE

During a 1-year period, all available aborted fetuses were submitted to veterinary diagnostic laboratories to determine the cause of abortion. Reproductive records of cows that aborted were reviewed.

RESULTS

Neospora sp infection was the major cause of abortion identified (113/266 abortions, 42.5%). The majority (232/266, 87.2%) of the aborted fetuses were submitted from herds with a history of abortions attributable to neosporosis, and Neospora sp infection was identified as the causative agent in 101 of 232 (43.5%) of the abortions from these herds. Fewer aborted fetuses were submitted from the 12 herds that did not have a history of abortion attributable to Neospora sp; however, neosporosis was confirmed as a cause of abortion in 6 of these 12 herds and was identified as the causative agent in 12 of 34 (35.3%) abortions from these herds. The disease was widespread throughout the state (19/26 herds in our study). Available reproductive histories of cows that had abortions attributed to neosporosis were evaluated, and 4 cows were identified that twice aborted Neospora-infected fetuses.

CLINICAL IMPLICATIONS

Abortion attributable to Neospora sp infections can be expected to be a continuing major cause of abortion in dairy herds with a history of neosporosis as well as in dairy herds that have a history of sporadic abortions, but for which Neospora sp infections have not been previously identified as a cause of abortion. Subsequent pregnancies in cows that abort a Neospora sp-infected fetus also are at risk of infection, suggesting that the immunity provided by an initial infection is inadequate to prevent repeat infection or that cows can be persistently infected with Neospora sp.

Prenatal infection with Setaria marshalli (Boulenger 1921) in cattle

A full year's epidemiological study was conducted in Japan on prenatal infection with Setaria marshalli in cattle. A total of 65 bovine fetuses of abattoir origin, both male and female of 2-9 months of age, were examined postmortem. Results showed that S. marshalli adult worms were detected in the peritoneal cavity of six bovine fetuses of 7-9 months of age during the months of October-December, but not in fetuses of any age during the months of January-September. Infection was not detected in any fetuses under the age of 7 months at any given month of the year. This is the first observation to demonstrate prenatal S. marshalli infection in fetuses. Since S. marshalli has not been detected in cattle older than 2 years, it is speculated that prenatal infection is the common type, while postnatal infection is rather uncommon. Considering fetal age and the seasonal factor, a fetus of age 4-5 months would most frequently develop prenatal infection in the June-August period, when mosquitoes are active as vectors. It is concluded, therefore, that S. marshalli prenatal infection develops during the middle stage of fetal life in summer.

[Congenital toxoplasmosis: transmission to the fetus of a pre-pregnancy maternal infection]

It has been established that maternal immunity developing before conception protects the fetus from congenital toxoplasmosis. We observed a case of congenital toxoplasmosis consecutive to a maternal toxoplasma infection that had preceded pregnancy. A woman with normal immune system developed toxoplasmosis 2 months before conceiving. No treatment was given to this prepregnancy seroconverted patient. At 25 weeks of amenorrhoea, the ultrasound examination showed a fetal cerebral ventricular dilatation. Amniocentesis and cordocentesis showed fetal toxoplasmosis infection. Fetopathologic examination confirmed the diagnosis of cerebral toxoplasmosis. The pathophysiology of maternal-fetal toxoplasma transmission and the role played by maternal immunodeficiency are discussed. This exceptional case-report showed the difficulties of the management in patients with 3-month pre-pregnancy toxoplasmosis and its practical implications.

A case of Neospora associated bovine abortion in Sweden

Neospora caninum is a recently recognized protozoan organism that causes fatal neuromuscular disease in dogs and abortions and stillbirths in cattle and other animals (Dubey & Lindsay 1993). The parasite is morphologically similar and phylogenetically very closely related to the cyst-forming coccidium Toxoplasma gondii (Ellis et al. 1994, Holmdahl et al. 1994). This group of parasites has a two-host life cycle principally involving a carnivorous definitive host and a herbivorous or omnivorous intermediate host. However, with N. caninum, there is as yet no knowledge of any definitive host harbouring sexual stages of the parasite. The only known route of transmission is vertical from mother to foetus (Dubey & Lindsay 1993).

Prenatal diagnosis of congenital toxoplasmosis with a polymerase-chain-reaction test on amniotic fluid

BACKGROUND

Congenital infection with Toxoplasma gondii can produce serious sequelae. However, there is little consensus about screening during pregnancy, and the tests used to establish a prenatal diagnosis of toxoplasmosis are complex and slow. We evaluated a simpler approach that is based on a polymerase-chain-reaction (PCR) test.

METHODS

Prenatal diagnostic tests, including ultrasonography, amniocentesis, and fetal-blood sampling, were performed in 2632 women with T. gondii infection acquired during pregnancy. In 339 consecutive women, a competitive PCR test for T. gondii was performed on amniotic fluid, and its results were compared with those of conventional diagnostic tests. The PCR test targets the B1 gene of T. gondii, uses an internal control, and can be completed in a day. Positive tests were confirmed by serologic testing of newborns or by autopsy in terminated pregnancies.

RESULTS

Overall, the risk of fetal infection was 7.4 percent, but it increased sharply with gestational age. Congenital infection was demonstrated in 34 of 339 fetuses by conventional methods, and the PCR test was positive in all 34. In three other fetuses, only the PCR test gave positive results, and follow-up testing confirmed the presence of congenital toxoplasmosis. The PCR test gave one false negative result but no false positive results. The PCR test performed better than conventional parasitologic methods (sensitivity, 97.4 vs. 89.5 percent; negative predictive value, 99.7 vs. 98.7 percent).

CONCLUSIONS

For the prenatal diagnosis of congenital T. gondii infection, an approach based on a PCR test performed on amniotic fluid is rapid, safe, and accurate.

Experimental reproduction of bovine fetal Neospora infection and death with a bovine Neospora isolate

Studies were conducted to determine the pathogenic potential of the recently isolated bovine Neospora protozoa (BPA-1) for the bovine fetus. Cows chosen for study had Neospora titers < 160 using an indirect immunofluorescent antibody (IFA) test. Four experimental groups were studied. In group 1, 2 fetuses were inoculated in utero at 118 days gestation with culture-derived Neospora tachyzoites. A pregnant control cow was housed in the same pen, observed daily and screened serologically for evidence of exposure to Neospora. In group 2, 2 cows were infected with Neospora tachyzoites at 138 or 161 days gestation, and 1 control cow was given uninfected cell culture suspension simultaneously at 154 days gestation. Groups 3 (85 days gestation) and 4 (120 days gestation) each consisted of 2 cows infected with Neospora tachyzoites and 1 control cow given uninfected material at the same stage of gestation. Dead fetuses were surgically removed from the infected cows in group 1 on postinfection day (PID) 17. The histopathology was compatible with protozoal fetal infection, and protozoa were identified by immunohistochemistry. Viable fetuses were removed surgically from cows in group 2 on PID 28-30. The histopathology was compatible with protozoal fetal infection, protozoa were identified by immunoperoxidase techniques, and Neospora tachyzoites were reisolated in vitro from tissues of the 2 infected fetuses. In groups 3 and 4, the control fetus and 1 infected fetus were removed surgically between PID 26 and PID 33. The remaining infected cows were observed until fetal death or abortion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Neospora infection in an aborted fetus in British Columbia

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[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.

Congenital toxoplasmosis: an experimental study in rhesus monkeys for transmission and prenatal diagnosis

This paper describes a rhesus monkey model to study congenital transmission and the prenatal diagnosis of Toxoplasma gondii infection. Transmission to the fetus was investigated after maternal infection in the second (Day 90) or third trimester (Day 130) of pregnancy. A parasitemia was induced and lasted for about 10 days as proven by mouse inoculation and nested PCR on whole blood samples and peripheral blood mononuclear cells. Transmission of T. gondii was proven in 4 of 9 (44%) fetuses in the second trimester and in 3 of 9 fetuses in the third trimester of gestation. Six of the 7 proven fetal infections could be diagnosed antenatally. Postnatally, 4 additional fetuses that most likely were congenitally infected were found, although this could not formally be proven. The mothers of these 4 fetuses were infected in the third trimester. If we accept this group as being antenatally infected, an overall transmission rate is found of 11 of 18 cases (61%). This rate is similar to that found in humans. This is the first description of a monkey model for congenital toxoplasmosis, that is suitable to study the approach of antenatal diagnosis and the effectivity of treatment, with obvious relevance for Toxoplasma infections in humans.