Climate, crowding, and hygiene profoundly influence the epidemiology of the nonvenereal treponematoses of childhood (yaws, pinta, and endemic syphilis). Crowding, primitive conditions, and poor hygiene have characterized settings permitting spread of endemic syphilis, typically within family units, and yaws persists in some developing tropical countries. At one time, endemic syphilis was a problem even in Northern Europe and North America, disappearing as living conditions improved. The WHO/UNICEF-coordinated global program for eradication of the endemic treponematosis in the 1950s and 1960s greatly reduced yaws prevalence throughout the developing world. Endemic syphilis was eradicated in Bosnia, and pinta disappeared in Latin America. The next generations were rendered fully susceptible to adult syphilis, as immunity from the childhood treponematoses no longer occurred and sexual behaviors became more liberal. Many tremonematologists believe all clinical and epidemiological differences between venereal syphilis of adults and endemic syphilis in children, and perhaps even between syphilis and yaws, reflect ecologic factors and sexual behaviors, rather than essential differences in pathogenicity of Treponema pertenue (the cause of yaws) and the variants of Treponema pallidum associated with endemic syphilis of children or venereal syphilis of adults.

Similarly, poor hygiene, flies, and crowding characterize the epidemiologic niche for ocular trachoma strains of C. trachomatis (serovars A, B, Ba, and C) while sexually transmitted LGV strains of C. trachomatis now require tropical developing country settings, whereas genital serovars D-K of C. trachomatis cause urethral and cervical infections throughout the world.

Modern studies have not sufficiently addressed the effectiveness of hygiene or use of antiseptics in preventing transmission or acquisition of chancroid or syphilis in high-risk populations.

The influence of geography, crowding, and hygiene on transmission of the endemic treponematoses, chlamydia, and chancroid somewhat presages current concepts of the social and spatial concentrations of STD, and the spread of these infections along social networks and spatial contiguity or transportation links (41-44). Rothenberg (41) and others (45) documented geographic clustering of high gonorrhea incidence in a few urban census tracts. An impact on AIDS and STD of shortsighted policies for public services—not only public health services