Guatemala is facing a growing HIV epidemic.
And towns bordering Mexico are transmission hot spots for the virus.
Human trafficking, sexual abuse, prostitution and drug use in these towns create the kind of high-risk behaviour that leads to HIV transmission.
Northern-bound migrants, desperate to escape poverty, have nothing to lose, and are often preyed on by gangs, corrupt police and others.
Al Jazeera’s Dave Mercer reports from Tecun Uman.