Excessive Perinatal Mortality in a Small Town Associated with Evidence of Toxoplasmosis

Robertson, J. S.

doi:10.1136/bmj.2.5192.91

Cited by 17 publications

(3 citation statements)

References 11 publications

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“…Even new procedures-for example, the No prospective survey, however de-taking of a Papanicolau smear from the tailed, could hope to cover all these cervix with a wooden curette in early matters, not to mention other possible pregnancy-may conceivably have a deleteteratogens, such as symptomless maternal rious effect (this procedure disturbs the toxoplasmosis (Robertson 1960) or even delicate mechanism of the cervical canal Listeria monocytogenes infection. and plug).…”

Section: (V) the Records Of 'Interesting Cases'mentioning

confidence: 99%

Clinical Pitfalls in Retrospective and Prospective Drug Teratogenicity Studies

Carter¹,

Wilson²

1963

Develop Med Child Neuro

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SUMMARY 1. A brief description is given of one method of retrospective inquiry into drug terato‐genesis, using general practitioner records (perhaps the best source of information). 2. The disadvantages of retrospective studies are discussed. 3. It is suggested that two measures of ‘teratogenic effect’ may be helpful: the malformation rate per se; and the ‘pregnancy wastage rate’. The pregnancy wastage rate may be most useful when only a small number of mothers can be found who have had the drug in question in early pregnancy. 4. Although prospective studies have many advantages, the speed with which retrospective studies give a rough answer is of great importance. It should be possible without undue delay to divide drugs commonly prescribed in pregnancy into two main groups: teratogens and non‐teratogens (at dosage levels usual in practice). It may also be possible to assess very approximately the degree of risk for each teratogenic drug. 5. Prospective studies of drug teratogenicity will suffer from the disadvantage that during the first trimester, doctors may now be unwilling to prescribe drugs, and patients to take them, unless they are absolutely necessary. Retrospective studies, with records from the period before the profession and public became aware of the dangers of drugs in early pregnancy, may be a much richer source of information. 6. The aetiology of many malformations may be multifactorial, and the interplay of causes (including drugs) may be complex. 7. There is a place for both retrospective and prospective surveys concerned with teratogenic drugs. RÉSUMÉ Pièges rencontrés dans les études cliniques sur la tératogénicité des médicaments Les auteurs donnent une brève description d'une méthode d'enquête rétrospective sur la tératogénèse de médicaments en s'aidant des notes des praticiens (probablement la meilleure source d'information). Les inconvénients des études rétrospectives sont discutés. On a suggéré l'intérêt que peuvent présenter deux mesures de l'action tératogène: le taux de malformations proprement dit et le ‘gaspillage de grossesse’. Le taux de ‘gaspillage de grossesse’ peut être le plus utile lorsqu'on ne dispose que d'un petit nombre de mères ayant pris le médicament en question au début de leur grossesse. Bien que les études prospectives aient de nombreux avantages, la rapidité avec laquelle les études rétrospectives donnent une réponse approximative revêt une grande importance. Il devrait être possible sans trop de délai de diviser les médicaments prescrits couramment pendant la grossesse en deux groupes: tératogènes et non tératogènes (aux doses habituellement prescrites). Il peut être possible également d'estimer très approximativement le degré de risque pour chaque médicament. Les études prospectives sur la tératogénèse des médicaments vont rencontrer des difficultés du fait que pendant le premier trimestre de la grossesse les docteurs pourraient être maintenant peu disposés à prescrire des médicaments, et les patientes peu disposées à les prendre s'ils ne sont pas absolument néc...

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Section: (V) the Records Of 'Interesting Cases'mentioning

confidence: 99%

Clinical Pitfalls in Retrospective and Prospective Drug Teratogenicity Studies

Carter¹,

Wilson²

1963

Develop Med Child Neuro

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“…Fair (1959), using the skin test in a large series in America, reached the same conclusion. In view of evidence of the prevalence of toxoplasmosis in Lincolnshire (Beattie, 1957;Robertson, 1960Robertson, , 1962, it was decided to examine all subnormals in hospitals in the county.…”

Section: %mentioning

confidence: 99%

Toxoplasma skin- and dye-test surveys of severely subnormal patients in Lincolnshire

Robertson

1965

J. Hyg.

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Of 918 severely subnormal patients in mental deficiency hospitals in Lincolnshire 917 were tested by the toxoplasmin skin tests, forty-nine out of 265 patients were dye tested because of a positive skin test or other indication. All patients in another group of 655 subnormals were dye tested, and comparison of these results with those of groups from the normal population showed that in children there was an excess of about 20% of dye-test positivity among the subnormals—a figure identical with that found by Thalhammer in Vienna.The excess of positives became progressively less with increasing age and by middle age the incidence was the same in subnormals as among blood donors in the county. It is suggested that this indicates that patients in hospital are exposed to a lower risk of acquiring infection and that the higher incidence among adult males than among adult female defectives is due to the fact that more of them go out to work, many of them on farms. This factor could also explain the lower incidence of positivity in adult mongols and epileptics who are less commonly employable.Possible explanations of the higher incidence among subnormal than among control children are discussed. Although it is tempting to assume that it indicates that some may be cases of congenital toxoplasmosis, the lack of gradient between child mongols, child epileptics and other subnormal children does not support this hypothesis. The numbers of mongol and epileptic children were too small to give statistically significant results. It is possible that the home environments of severely subnormal children exposed them to a higher risk of infection than did the homes of the control children and that the observed excess of dye and skin-test positivity may be due to increased incidence of acquired infection before their admission to hospital.It was found that there was reasonable concordance between the dye test at a titre of 1/8 and skin sensitivity reactions exceeding 7 mm. in diameter, but poor agreement if 10 mm. was taken as the criterion of positivity.Despite the lesser sensitivity of the skin test, the pattern of the results was the same as that observed in the dye-test survey, and the value of the skin-test for epidemiological surveys was confirmed.

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“…The Medical Officer of Health had noted the persistently high perinatal mortality for this area for the years (Robertson, 1960) and had suggested that this might be due to toxoplasmosis on account of the unusually high rate of positive reactions to the Toxoplasma dye test of Sabin & Feldman (1948). He had also noted that in the 2-4 years age group the conversion from positive to negative occurred during the late summer; this, he believed, might indicate a mosquito-borne infection since the population of mosquitoes was abnormally high.…”

Section: Introductionmentioning

confidence: 99%

The survival ofToxoplasmain infected mosquitoes

Chapman

Ormerod

1966

J. Hyg.

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1. An incomplete field study in Lincolnshire, England, suggested that toxoplasmosis might be transmitted from pig to man by mosquitoes. Although the results were inconclusive they suggested the experimental work recorded in this paper.2. Trophozoites of the Beverley strain were obtained in increased yield from the peritoneal fluid of Mastomys treated with hydrocortisone. Cysts were obtained in increased yield by passage of the brain of Sigmodon into laboratory mice.3. Four species of mosquitoes were fed through a membrane or on sucrose solution on media containing either cysts or trophozoites of Toxoplasma gondii. In some experiments blood was added to ensure passage of the feed to the mosquito stomach, in others it was excluded so that at least part would pass to the crop.4. A spurious ‘cyst’ resembling but distinguishable from Toxoplasma was noted in the homogenate of mouse brain.5. In no instance did mosquitoes retain infectivity as demonstrated by injection into mice, beyond the third day, but since experiments were not carried on beyond the fourteenth day the existence of an occult form cannot be excluded.

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Excessive Perinatal Mortality in a Small Town Associated with Evidence of Toxoplasmosis

Cited by 17 publications

References 11 publications

Clinical Pitfalls in Retrospective and Prospective Drug Teratogenicity Studies

Clinical Pitfalls in Retrospective and Prospective Drug Teratogenicity Studies

Toxoplasma skin- and dye-test surveys of severely subnormal patients in Lincolnshire

The survival ofToxoplasmain infected mosquitoes

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