Eastern Health is warning doctors about an increasing number of gonorrhea infections in the region.

Communicable Disease Control in the Eastern Health region has reported 21 cases so far in 2013, compared to just five in 2012 and four in 2011.

The agency said cases of the sexually transmitted disease are increasing across Canada as it becomes more resistant to antibiotic treatment.

The painful infection can make people more vulnerable to contracting HIV and can also lead to sterility.

Eastern Health has sent out information to doctors with recommendations for treatment.