Minerva

For most of this century doctors have argued that reappearance of tuberculosis in a “cured” patient is due to reactivation of old, dormant disease. DNA fingerprints of Mycobacterium tuberculosis isolated from 16 patients in South Africa suggests, however, that recurrences are usually due to new primary infections (New England Journal of Medicine 1999;341:1174-9). Three quarters of the sample had been infected by two different strains of the pathogen at different times; the best evidence yet that reinfection is common in endemic areas.

A paper in Gut (1999;45:741-3) challenges another received wisdom, that the common hepatic duct dilates after cholecystectomy to replace the reservoir function of the gall bladder. The duct stayed resolutely undilated in 59 patients who had open cholecystectomy followed by ultrasound measurements of the hepatic duct at intervals for five years. This means, say the authors, that patients with a dilated duct after gall bladder surgery should be investigated, particularly if they have symptoms.

If low income causes ill health, money becomes a treatment that can be tested in randomised trials. Sadly, a careful search of various electronic databases yielded only 10 trials of extra income, none of which included reliable analyses of the money's impact on health …