Toxoplasma gondii: from animals to humans

SUMMARY We reviewed studies that reported results of systematic cytomegalovirus (CMV) screening on fetuses and/or liveborn infants. The overall birth prevalence of congenital CMV infection was 0.64%, but varied considerably among different study populations. About 11% of live-born infants with congenital CMV infection were symptomatic, but the inter-study differences in definitions of symptomatic cases limit the interpretation of these data. Non-white race, low socioeconomic status (SES), premature birth, and neonatal intensive care unit admittance were risk factors for congenital CMV infection. Birth prevalence increased with maternal CMV seroprevalence. Maternal seroprevalence accounted for 29% of the variance in birth prevalence between study populations. Maternal seroprevalence and birth prevalence were both higher in study populations that were ascertained at birth rather than in the prenatal period. Thus, timing of ascertainment should be considered when interpreting birth prevalence estimates. Birth prevalence was inversely correlated with mean maternal age, but this relationship was not significant when controlling for maternal seroprevalence. The rate of transmission to infants born to mothers who had a primary infection or a recurrent infection during pregnancy was 32% and 1.4%, respectively. Possible maternal primary infections (i.e. seropositive mother with CMV IgM) resulted in congenital infections about 20% of the time, but are likely to represent a mixture of primary and recurrent infections. In summary, CMV is a common congenital infection worldwide that can lead to permanent disabilities. There is an urgent need for interventions that can reduce the substantial burden of this often overlooked disease. Copyright # 2007 John Wiley & Sons, Ltd.

Review and meta‐analysis of the epidemiology of congenital cytomegalovirus (CMV) infection

Summary: The apicomplexan parasite Toxoplasma gondii was discovered a little over 100 years ago, but knowledge of its biological life cycle and its medical importance has grown in the last 40 years. This obligate intracellular parasite was identified early as a pathogen responsible for congenital infection, but its clinical expression and the importance of reactivations of infections in immunocompromised patients were recognized later, in the era of organ transplantation and HIV infection. Recent knowledge of host cell-parasite interactions and of parasite virulence has brought new insights into the comprehension of the pathophysiology of infection. In this review, we focus on epidemiological and diagnostic aspects, putting them in perspective with current knowledge of parasite genotypes. In particular, we provide critical information on diagnostic methods according to the patient's background and discuss the implementation of screening tools for congenital toxoplasmosis according to health policies.

https://hal.archives-ouvertes.fr/hal-00696903/document

Epidemiology of and Diagnostic Strategies for Toxoplasmosis

WHO Regional Office for Europe.

https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(14)62509-X/pdf

Toxoplasma gondii: transmission, diagnosis and prevention

We describe an outbreak of necrotizing enterocolitis (NEC) that occurred in the neonatal intensive care unit of our hospital. A total of 12 neonates developed NEC in June-July 1998. For two of them, twin brothers, the NEC turned out to be fatal. Enterobacter sakazakii, a known contaminant of powdered milk formula, was isolated from a stomach aspirate, anal swab, and/or blood sample for 6 of the 12 neonates. A review of feeding procedures revealed that 10 of the 12 patients were fed orally with the same brand of powdered milk formula. E. sakazakii was isolated from the implicated prepared formula milk as well as from several unopened cans of a single batch. Molecular typing by arbitrarily primed PCR (AP-PCR) confirmed, although partially, strain similarity between milk and patient isolates. No further cases of NEC were observed after the use of the contaminated milk formula was stopped. With this outbreak we show that intrinsic microbiological contamination of powdered milk formula can be a possible contributive factor in the development of NEC, a condition encountered almost exclusively in formula-fed premature infants. The use of sterilized liquid milk formula in neonatal care could prevent problems with intrinsic and extrinsic contamination of powdered milk formula.

Outbreak of Necrotizing Enterocolitis Associated with Enterobacter sakazakii in Powdered Milk Formula

A 10-year prospective study of sensorineural hearing loss in children with congenital cytomegalovirus infection.

Prenatal diagnosis of congenital toxoplasmosis: A multicenter evaluation of different diagnostic parameters

Two protocols for the extraction of cytomegalovirus (CMV) DNA and two methods for the amplification of CMV DNA in dried blood spots were evaluated for the retrospective diagnosis of congenital CMV infection. During the period from 1996 to 2006, a urine screening program detected 76 congenitally infected neonates. Stored Guthrie cards with blood from 55 cases and 12 controls were tested. Two spots of dried blood were cut from each card and evaluated in two centers. CMV DNA was extracted from a whole single spot. Center 1 used phenol-chloroform extraction and ethanol precipitation followed by a conventional PCR. Center 2 used the NucliSens easyMAG automated DNA/RNA extraction platform (bioMerieux) followed by a real-time PCR. For evaluation of the extraction method, DNA extracted from each blood spot was evaluated by the amplification method used by the collaborating center. The sensitivities were 66% for center 1 and 73% for center 2. None of the controls were positive. A sensitivity as high as 82% could be obtained by combining the most sensitive extraction method (the phenol-chloroform procedure) with the most sensitive PCR method (real-time PCR). The detection rate was not influenced by the duration of storage of the spots. The sensitivity was higher with blood from congenitally infected cases due to a primary maternal CMV infection, regardless of the protocol used. However, the difference reached significance only for the least-sensitive protocol (P = 0.036).

Evaluation of Different Cytomegalovirus (CMV) DNA PCR Protocols for Analysis of Dried Blood Spots from Consecutive Cases of Neonates with Congenital CMV Infections

Little is known about the best way to prevent congenital toxoplasmosis. Until recently, the major effort was directed at preventing the disease during pregnancy by the application of hygienic measures (primary prevention). With the advent of detecting congenital toxoplasmosis antenatally, another method for reducing the incidence of congenital toxoplasmosis becomes possible (secondary prevention). In this study, we evaluate these two methods for the prevention of congenital toxoplasmosis. For 12 consecutive years, we studied the incidence of congenital toxoplasmosis in 11,286 consecutive pregnant women. The impact of primary prevention was studied by measuring the reduction in seroconversion when hygienic measures were systematically applied. Primary prevention reduces the seroconversion rate during pregnancy by 63% (P = 0.013). The effect of secondary prevention was studied in 76 pregnant women at risk of delivering a child with congenital toxoplasmosis. Secondary prevention by means of serological screening combined with prenatal diagnosis detected congenital toxoplasmosis correctly in eight infected fetuses. Secondary prevention reduced the incidence of congenital toxoplasmosis an additional 40%. This reduction would predominantly be seen in the group of mildly to severely affected fetuses. From this study, the effectiveness of primary prevention is obvious. Health education on how to avoid toxoplasmosis during pregnancy should become standard obstetric care. Adequate serological screening and prenatal diagnosis can be helpful in reducing further the incidence of congenital toxoplasmosis. Whether or not screening for toxoplasmosis during pregnancy should be combined with primary prevention depends on the importance of congenital toxoplasmosis as a health problem in a given geographic area.

Anne Naessens

Papers

Outbreak of Necrotizing Enterocolitis Associated with Enterobacter sakazakii in Powdered Milk Formula

A 10-year prospective study of sensorineural hearing loss in children with congenital cytomegalovirus infection.

Prenatal diagnosis of congenital toxoplasmosis: A multicenter evaluation of different diagnostic parameters

Evaluation of Different Cytomegalovirus (CMV) DNA PCR Protocols for Analysis of Dried Blood Spots from Consecutive Cases of Neonates with Congenital CMV Infections

Evaluation of the possibilities for preventing congenital toxoplasmosis.