Epidemiology of neonatal infections

Eye anomalies: seasonal variation and maternal viral infections

INTRODUCTION

Eye anomalies, including anophthalmos and microphthalmos (absent eye and small eye), are common features in congenital infection syndromes such as rubella. Influenza, Coxsackie virus, and Parvovirus are less well-established teratogens. We report an ecologic analysis of anophthalmia/microphthalmia prevalence in England in relation to temporal variation in these infections using routine infection data.

METHODS

The national (England) anophthalmos/microphthalmos register holds details of 406 babies (excluding chromosomal anomalies) born 1988-1994. Weekly infection data were obtained from the U.K. Public Health Laboratory Service and Royal College of General Practitioners Weekly Returns Service. We assigned cases and births an estimated exposure based on the population infection counts in the gestational weeks known to be critical for ocular development. We calculated the rate ratio of anophthalmos/microphthalmos prevalence for infection in the 90th percentile compared with the 10th percentile by Poisson regression.

RESULTS

There was a positive association between severe anophthalmos/microphthalmos prevalence and Parvovirus B19 (rate ratio = 1.26; 95% confidence interval = 1.00-1.58) and for influenza (1.41; 1.08-1.84). Coxsackie virus showed a negative association with any anophthalmos/microphthalmos (0.75; 0.58-0.98) and with severe cases (0.66; 0.46-0.95).

CONCLUSIONS

This analysis provides suggestive evidence for a teratogenic role of influenza and Parvovirus in anophthalmos/microphthalmos. The role of maternal infections in congenital anomaly etiology is worthy of further investigation.

Congenital toxoplasmosis

Toxoplasma gondii, a parasite, has three modes of transmission: oral intake of raw or undercooked meat or contaminated fruits and vegetables, ingestion of materials contaminated with cat feces, and transplacental infection. The focus of this article is congenital toxoplasmosis, which is transmitted to the fetus across the placenta. When primary infection of the mother occurs during pregnancy, there is a 40 percent chance of fetal infection; rate of transmission and severity of infection are related to gestational age at the time of infection. The brain and retina are often affected, and there can be a wide range of clinical disease. Amniocentesis or cordocentesis provides the most accurate diagnosis. At birth, 80-90 percent of infants with congenital toxoplasmosis are asymptomatic. But further testing may reveal retinal and central nervous system abnormalities, and there is a risk of long-term sequelae. Chorioretinitis, hydrocephalus, intracranial calcifications, and convulsions are the typical presentation of classic congenital toxoplasmosis. Serology is the most common method of diagnosing neonatal infection, but more complex tests are also utilized. The prognosis for the untreated infant is poor; however, when antibiotic therapy is started early, the rate of sequelae is reduced significantly.

Clinical algorithms for the screening of pregnant women for STDs in Libreville, Gabon: which alternatives?

OBJECTIVE

Sexually transmitted diseases (STDs) remain one of the major public health problems in the developing world. To implement a systematic screening of STDs among pregnant women in Libreville, Gabon, a preliminary cross sectional study on STD prevalence and risk factors was performed in antenatal clinics. A score, integrating risk factors and elementary clinical signs for the screening of STDs, showed higher performances compared with hierarchical algorithms. The prospective validation of this score based on six criteria (risk factors and simple clinical signs) was done in 1994-5. The sensitivity (76.7%), compared with results from other studies, was acceptable for diagnosing cervical infection (Neisseria gonorrhoeae and/or Chlamydia trachomatis) but the specificity was low (50.6%). In addition, the diagnostic values for diagnosing vaginal infection (Trichomonas vaginalis and/or Candida albicans) were poor. We then proposed to evaluate an alternative flowchart for the screening of cervical and vaginal infections.

METHODS

In this study, 646 pregnant women were enrolled. Each woman was interviewed and examined by a physician and then was subjected to reference laboratory examinations. An algorithm in two steps, combining a risk assessment score at the beginning of a hierarchical process, followed by a second step more specifically applied to a limited number of women, was developed and evaluated.

RESULTS

The prevalence rate was 11.3% for cervical infection and 39.5% for vaginal infection. The first step of the algorithm, applied to all pregnant women, is based on four criteria (age, marital status, dyspareunia, coloured vaginal discharge). It allows classification of the women into three classes: high, low, and intermediate risk of cervical infection. Only the patients with intermediate risk were submitted to further investigations including speculum and microscopic examination, and subsequently chlamydial antigen detection. This flowchart was 83.6% and 81.2% sensitive and 63.4% and 62.7% specific for predicting cervical infection and vaginal infection, respectively.

CONCLUSION

Similar strategies using simple rapid tests for chlamydial and gonococcal infection would certainly constitute a good diagnostic tool. This theoretical model needs to be evaluated prospectively, not only to confirm their diagnostic value but also to evaluate their feasibility, reliability and acceptability, as well as their cost effectiveness.

Urine sample used for congenital toxoplasmosis diagnosis by PCR

The diagnosis of toxoplasmosis in congenitally infected infants can be difficult; serology is unreliable, and diagnosis must be based on the combination of symptomatology and direct demonstration of the parasite. Four infants suspected of having Toxoplasma gondii infection were studied by serological analysis, tissue culture, and PCR determination. T. gondii was isolated from the urine of one patient. The parasite was detected by PCR in the blood and cerebrospinal fluid of three infants and in the urine in all patients. Because nested PCR proved to be a sensitive, relatively rapid, and specific method and because it can be applied to a variety of different clinical samples, PCR can be a valuable technique for the identification of T. gondii infections in children. The present study indicates that PCR examination of urine, a fluid never before used for diagnosis in this age group, may be valuable in diagnosing cases of congenital toxoplasmosis.