Thierry Ancelle

Risk Factors for Toxoplasma Infection in Pregnancy: A Case-Control Study in France

Each year an estimated 4900 cases of primary Toxoplasma infection occur in pregnant women in France, a country with a high prevalence. Since 1992 all pregnant women at risk of Toxoplasma infection have been required to undergo monthly serological testing. This case-control study, the first of its kind in France, was undertaken to identify risk factors for Toxoplasma infection during pregnancy, with a view to improving primary prevention among non-immune pregnant women. A total of 80 pregnant women who seroconverted to Toxoplasma were matched with 80 pregnant women who had repeatedly negative tests. The women were interviewed by telephone, using a standardized questionnaire, to determine socio-demographic characteristics, exposure to possible risk factors and the type of information on prevention received during pregnancy. The risk factors for Toxoplasma infection included in a multivariate analysis were poor hand hygiene (OR = 9.9; 95%CI: 0.8-125), consumption of undercooked beef (OR = 5.5; 95%CI: 1.1-27), having a pet cat (OR =4.5; 95%CI: 1.0-19.9), frequent consumption of raw vegetables outside the home (OR = 3.1; 95%,CI: 1.2-7.7) and consumption of undercooked lamb (OR = 3.1; 95%CI: 0.85-14). Receipt of documentary advice on prevention was associated with a lower risk of infection. Prevention campaigns among pregnant women in France could be improved and should focus on eating habits, hand hygiene and cats.

Contributions of Immunoblotting, Real-Time PCR, and the Goldmann-Witmer Coefficient to Diagnosis of Atypical Toxoplasmic Retinochoroiditis

ABSTRACT Ocular toxoplasmosis is a major cause of posterior uveitis worldwide. The diagnosis is based mainly on ophthalmological examination. Biological diagnosis is necessary in atypical cases, and this requires aqueous humor sampling by anterior chamber paracentesis. We evaluated real-time PCR targeting the Toxoplasma gondii 529-bp repeat element, the Goldmann-Witmer coefficient (GWC), and immunoblotting for the diagnosis of toxoplasmic retinochoroiditis in 54 patients with atypical uveitis. The results of these biological tests, applied to paired aqueous humor-serum samples, were compared to the clinical findings. Combining either PCR or the GWC with immunoblotting increased the sensitivity to 73% or 70%, respectively. Together, PCR and the GWC had 80% sensitivity. If feasible, sensitivity can be increased by combining the three methods (85% sensitivity). The interval between symptom onset and anterior chamber paracentesis strongly influenced the detection of specific intraocular antibody synthesis. The sensitivity of the GWC increased from 45% to 56% when sampling was performed 10 days after symptom onset, and that of immunoblotting increased from 53% to 72% when puncture was performed 30 days after symptom onset. PCR analysis of aqueous humor samples detected toxoplasmic DNA in 55% of patients. In contrast to the results of immunoblotting and the GWC, the results of PCR were not influenced by the interval between symptom onset and paracentesis. PCR was more informative than the GWC and immunoblotting for immunocompromised patients. Acute necrotizing retinal lesions were significantly larger in PCR-positive patients, with a mean of 3.5 optic disc diameters, than in PCR-negative patients, with a mean of 1.5 optic disc diameters.

Detection of repetitive sequences ofTrichinella spiralis by the polymerase chain reaction in experimentally infected mice

Trichinosis remains a problem all over the world, especially in Western Europe. In fact, > 1,600 cases due to horsemeat consumption have been reported in France and Italy since 1975 (Ancelle etal. 1988; De Carneri et al. 1989). The conventional methods of diagnosing trichinosis in meat have been in use for more than a century. Trichinoscopy was introduced in 1863 and the digestion method was described in 1897 (reported in Zimmermann 1983). These methods are simple and easy to manage but they lack sufficient sensitivity and are not easily automated. Serological methods such as the enzyme-linked immunosorbent assay (ELISA) proved to be both sensitive and specific and adaptable to automation (Ruitenberg et al. 1976). However, experimental infection of horses has shown that the antibodies disappeared 16-20 weeks postinfection, although viable larvae were still present in the muscles (Soulb et al. 1989a). Detection of the specific DNA of Trichinella spiralis might be a more accurate method of detecting these parasites in chronically infected horses. In 1986, Klassen et al. described a 1.7-kb repetitive DNA sequence of T. s. spiralis that occurred in minimally dispersed, direct tandem arrays and had a copy number estimated at 2,800; it constituted 2% of the 2.5 x 108 bp haploid genome and was specific to strains usually isolated in pigs. Recently, this repetitive DNA fragment was cloned in plasmid pUC9 (pPra) and sequenced by de Vos et al. (1988). We decided to apply the polymerase chain reaction (PCR) described by Saiki et al. (1985) to the detection of a fragment of this repetitive sequence (pPra) in experimentally infected mice. DNA samples were extracted by a conventional procedure from (i) muscles of mice infected 2 months previously, (2) larvae obtained after chlorhydropeptic digestion of infected muscles and (3) non-infected mouse muscles. The two strains used in these experiments were iso-

Safety and Immunogenicity of Yellow Fever 17D Vaccine in Adults Receiving Systemic Corticosteroid Therapy: An Observational Cohort Study†

To assess the safety and immunogenicity of live attenuated yellow fever (YF) 17D vaccine in adults receiving systemic corticosteroid therapy.

Comment réduire le coût du dépistage de la toxoplasmose chez la femme enceinte

BACKGROUND A program of systematic serology screening for toxoplasmosis during pregnancy has been running in France since 1978. The program involves monthly follow-ups for all non-immune pregnant women. Due to the steady decline in the seroprevalence of toxoplasmosis, the cost of the program is steadily increasing. Current screening is based on the detection of IgG and IgM isotypes. The aim of this work was to estimate the benefit of replacing combined dosage of two isotypes, by an alternative strategy that detects total anti-Toxoplasma immunoglobulins. METHODS The rate of decreasing seroprevalence and the increasing burden on serological examinations was measured in a study population of pregnant women who were checked for toxoplasmosis by the parasitology laboratory of the Cochin Hospital, Paris. The increase in screening costs was estimated for the all-pregnant women and the expected benefits stemming from simply measuring total anti-Toxoplasma immunoglobulins compared to the double IgG-IgM assay were estimated. RESULTS Between 1987 and 2008, the seroprevalence of toxoplasmosis measured at the Cochin hospital dropped from 70.8% to 48.6% with a 1.77% annual rate of decline. This downward trend is similar to that observed by the national perinatal surveys performed in 1995 and in 2003. As the number of non-immune women to follow-up each month is constantly increasing, the proportion of negative tests issued reached 87.6% in 2008. Extrapolating these results to the whole of France, we estimated that the number of required screening tests perform was increasing by 93,000 units per year with an additional associated cost of one million euros. Various alternative scenarios of antibody detection are proposed that could save between 40.2% and 48.4% of current screening costs. CONCLUSION Replacement of combined dosage of IgG and IgM isotypes by determination of just total Ig would significantly reduce costs of toxoplasmosis screening for pregnant women, without effecting either the general strategy, or proven efficiency of the national program.

Longer incubation times for yeast fungemia: importance for presumptive treatment

Isolation rates of Candida glabrata at ≤2 days were 8.9% and 34.8% at >2 days; for Cryptococcus neoformans, they were 0.9% and 8.6%, respectively (1741 fungemia analyzed). An incubation time >2 days supports candins as presumptive treatment for C. glabrata, keeping in mind the risk of Cryptococcus fungemia.

Le diagnostic de la trypanosomose humaine africaine

Resume La trypanosomose humaine africaine a Trypanosoma brucei gambiense ou T.b. rhodesiense, qui sevit exclusivement en Afrique, est tres rarement observee en Europe chez des voyageurs ou des migrants (quelques cas annuels). L’incubation peut etre longue et variable. La maladie debute par une phase lymphatico-sanguine ou predominent fievre et adenopathies cervicales, suivie quelques mois plus tard d’une phase meningo-encephalitique comportant de nombreux symptomes neurologiques et psychiatriques. L’evolution, sans traitement, aboutit a la cachexie et un coma conduisant a la mort du patient. Les traitements, souvent toxiques, different selon la phase. Le diagnostic de la maladie, difficile a evoquer, doit donc etre complete par un diagnostic de phase. Il est oriente par un syndrome inflammatoire (VS et CRP elevees), une plasmocytose avec vacuoles (cellules de Mott) et une forte elevation des IgM seriques. Le diagnostic direct de la premiere phase se fait par mise en evidence du trypanosome dans le suc ganglionnaire, ou dans le sang, par frottis, goutte epaisse ou apres concentration par centrifugation en tube capillaire (test de Woo), ou passage en micro-colonne echangeuse d’ions. Dans la seconde phase, le diagnostic est evoque devant un titre eleve d’IgM dans le LCR, une cytorachie elevee et une proteinorachie superieure a 450 mg/L. Il est confirme par la decouverte de trypanosomes dans le LCR apres double centrifugation. Il existe de nombreuses methodes de diagnostic serologique (immunofluorescence, ELISA…). La technique la plus utilisee sur le terrain est le CATT en raison de sa simplicite. Les techniques de biologie moleculaire sur le sang et le LCR (PCR, LAMP) sont maintenant applicables et permettent encore d’augmenter la sensibilite.