Thousands of migrants marched from Central America to the U.S. border over the last six weeks, but many of them are suffering from respiratory infections, tuberculosis, chickenpox and other serious health issues — including HIV.

Of the 6,000 migrants gathered in Tijuana just south of the U.S. border near San Diego, more than a third of them (2,267) are being treated for health-related issues, a spokesman for Tijuana's Health Department told Fox News.