The epidemic is concentrated in groups like men who have sex with men, transgenders, and people who inject drugs or sell sex.

According to a 2006 study as many as one in every 125 men and women between the ages of 15 and 49 may be infected with HIV.

And this doesn't include the children who are diagnosed with the virus because of their parents.

The problem has transformed some parts of the city and has sparked a rise in facilities being opened to treat the patients.

Photographer Malcolm Linton and writer Jon Cohen have captured haunting images and stories from Tijuana to show the distance that separates aspiration from reality, alongside the grip AIDS has taken on some residents.

In their book, Tomorrow Is a Long Time, they follow two dozen people over two years who were living with HIV or at high risk of infection.

Selling sex further increases risk, as does smoking crystal meth, a drug used by many Tijuana sex workers including Fernanda.

She works in the city's Red Light District and, even though she knows how to protect herself during sex, she says some men demand they do it without.

Oscar Villareal, 28, makes himself up as a women in a hotel room in downtown Tijuana before going out to look for clients. Oscar called himself Beto by day and would cruise a local park as a gay man, but at night he became Alessandra, Alé for short, who worked the clubs and the streets of the red light district