The Morbidity and Mortality Weekly Report appeared on the same day of the week, every week; and had for as long as anyone cared to remember.

When on this particular Friday July 4 in 1981 it carried a report on the unexpectedly frequent appearance of an otherwise rare cancer and the increasingly fatal effects of a fairly benign flu few would have been expected to pay much attention. It was the fact that these outbreaks were occurring among gay men and only in the past 30 months or so that got the story into the New York Times the next day.

It was the first sign of an epidemic that was to grip and transform the gay community. And it has proved irresistible to creative artists, who have turned their minds to this moment and use it to divide the world into Before and After.

The date of the report was a coincidence – but too great a temptation for some. The film Longtime Companion could not resist he combination of the glorious height-of-summer holiday weekend and the tiny Times item.

Journalist Randy Shilts in his monumental history of the first five years, And the Band Played On, went further still, romantically tracing the outbreak to – precisely – July 4 1976, the US bicentennial year, when ships from all over the world converged on New York harbour, planting the seeds of destruction. Patient Zero, the Golden Summer, Before and After – all these are the work of artists grappling with history.