South Korean health authorities have discovered cholera bacteria in waters off Geoje Island.

The Korea Centers for Disease Control and Prevention(KCDC) said on Thursday that cholera bacteria was found in seawater collected 50 centimeters off Daegye Port in the island's Jangmok Village.

The location is close to the source of seafood blamed for the infection of the second patient.

The KCDC is analyzing the genotype of the bacteria to see if it matches those found in three recent cholera patients. Test results are expected to come out on Friday afternoon. 

If the genotype is found to be identical then waters off Geoje Island will be confirmed as the source of the current cholera outbreak in the region.

The first case of the disease in 15 years was reported late last month and since then health authorities have conducted 662 seawater tests. The latest test is the first time that cholera bacteria has been discovered in local waters.