Health officials in Guelph have uncovered a “cluster” of the sexually transmitted disease chlamydia in the area where University of Guelph students live. The health unit identified 520 cases of chlamydia last year in Guelph and the two surrounding counties that it serves. They recently plotted the cases on a map and found the numbers were much higher in and around campus. Rosalyn LaRochelle, clinical manager of Wellington-Dufferin-Guelph Public Health, told the Guelph Mercury that 91 per cent of those with chlamydia infections report that they hadn’t used condom when having sex. “The message is: ‘Wear a condom. You can’t go wrong,’ ” said LaRochelle.