AIDS activist, father of 5, is second out gay man to run
Hook-up apps cited as main cause for spike
None in research group contracted HIV over two-year period
Highly infectious strain troublesome, doctors say
Hook-up apps, condomless sex likely factors
STD is difficult to detect early, spreads fast
Other STIs down but gay, bi men at risk
Disease seeing highest rates since 1995
Reported cases nearly doubled
Epidemic of infection in U.K. men
