Possible Significance of PPLO in Human Genital Infection

The organism causing pleuropneumonia in cattle, still a devastating disease in South Africa and parts of Australia, was discovered in 1898 by a group of French workers.In 1923 a very similar organism was found to be the cause of another animal disease, agalactia of sheep and goats.Since then a con- siderable number of organisms of the same group, some pathogenic, others saprophytic, have been dis- covered by various workers.It has thus emerged that a whole family of microbes exists, differing from both bacteria and viruses.Some of these play an important part in the aetiology of disease in animals and probably also in humans.The organisms possess very small filterable elements, not larger than the elementary bodies of the pox viruses.In addition, they possess larger forms of varying sizes and shapes, which have no rigid cell walls.Unlike the viruses they can be grown on artificial media of special constitution.On solid media their colonies are very small (10 to 500 ,uin diameter) and have a characteristic appearance with a dense centre, embedded in the medium, and a lighter, superficially spreading, peripheral zone.PPLO also have a peculiar mode of producing infection, which follows a similar pattern in the various diseases caused by organisms of the group.A few instances may suffice to demonstrate this.Agalactia is a seasonal disease which affects the ewes only after lambing.Lactation stops and the animals produce a purulent secretion instead of milk.They probably become infected while grazing in fields contaminated by other herds, but symptoms only develop at lambing time.Bronchopneumonia occurs widely in laboratory rats as well as in wild rats.It can be acute, but very often takes a slow and chronic course.Very old rats invariably show severe lung lesions which are usually * Paper read to the Medical Society for the Study of Venereal Diseases at Cambridge,