Potential impact of chemical prophylaxis on the incidence of gonorrhoea.

One of the major world-wide public health problems today is the rapidly rising; incidence of venereal disease combined with the increase in unwanted and casual pregnancies. For example, in the U.S.A., an incidence of 137 cases of gonorrhoea per 100,000 in 1957 had risen to 307 5 per 100,000 in 1971. The current epidemic has made gonorrhoea the leading reportable communi-cable disease in the U.S.A. Also, it is well known that the actual number of cases of gonorrhoea is almost four times the total number reported to health authorities by all sources. For years, attempts at 'controlling ' gonorrhoea were abandoned in favour of 'treating ' it out of existence with increasingly larger doses of penicillin. A decade ago, the less sensitive strains requiring 0-1 unit of penicillin per ml. for inhibition in vitro were extremely rare in clinical practice, but strains requiring 0 5 unit of penicillin per ml. are now common. Today, many strains of gonococci are so resistant to penicillin, that a dose so large as to approach the outer limits of safety is required to effect a cure (Goldstein, 1972). Another major problem in controlling gonorrhoea is the existence of a large number of unidentified asymptomatic females (estimated as 640,000 to 1 million). A small change in the percentage of these females will produce significant changes in the prevalence of gonorrhoea. The task of eliminating gonorrhoea can therefore be simplified by making prophylactic measures as well as medical treatment available to those at risk. Parallel examples are smallpox and measles which have been brought under control by surveillance and vaccination. There are, however, fundamental obstacles to the development of an effective vaccine against gonorrhoea. Recent work has shown that some of the intra-vaginal birth control compounds used by women als