SUMMARYAn account is given of some human diseases which affect one sex more than the other.An age–sex relationship has been noted among British patients with acquired toxoplasmic lymphadenopathy. This is compared with the findings of other European workers.A possible explanation is offered taking all these diseases into consideration together with some of the experimental work done in animals and some of the variations in immunological responses by man.

SUMMARYSome of the factors influencing the isolation rate of Bordetella pertussis during a whooping cough epidemic in West Glamorgan, Wales, are reported. The organism was isolated from 39 % ofpatients with clinical whooping cough, pernasal swabbing being much more successful than cough plates. Isolation rates were increased in the non-immunized, particularly in the first year of life. Erythromycin and co-trimoxazole significantly reduced the isolation rate of B. pertussis but this did not occur with penicillin. In this study 200 of patients were culture positive 6 weeks after the onset of their infection. It is suggested that the Department of Health and Social Security recommendation of a minimum period of three weeks exclusion ofchildren from school is inadequate. During the epidemic, the proportion of strains of B. pertussis containing antigen 2 more than doubled.

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SUMMARY Four strains of Corynebacterium diphtheriae were sent to UK participants in the UK National External Microbiological Quality Assessment Scheme, who were asked to examine the strains for toxin production by in vitro methods. Laboratories achieved 162/176 (92%) and 160/175 (91 %) correct results with two rapid toxin producers and 145/175 (82%) with a slow toxin producer. With a non-toxigenic strain 26/175 (15%) laboratories reported toxin production. Of the 173 laboratories reporting on all four strains, only 120 (69%) achieved the correct result for all. There was no significant association between the use of various methods and results, with the exception that laboratories using a full set of positive, weak positive, and negative controls made fewer errors than those not using controls. A number of unsatisfactory practices were revealed by the trial, however, and recommendations on preparation of inoculum, media, peptones, animal sera, and use of controls are made.The United Kingdom National External Microbiological Quality Assessment Scheme has been described previously.' As part of the bacteriology portion of this scheme simulated specimens containing various pathogens are distributed to participants. Although most of these pathogens occur commonly in the UK, rarer but important pathogens are occasionally distributed for educational purposes. C diphtheriae has been distributed on a number of occasions with an average success rate in isolation and identification of 85%. No systematic information had been sought on toxigenicity testing of these strains, and in view of the continued occurrence of this species in the UK2 the Public Health Laboratory Service thought it would be useful to investigate the ability of laboratories to demonstrate toxin production in the event of another outbreak.