A Suffolk County woman is being treated in a local hospital after being diagnosed with the 13th human case of West Nile virus in the state this year.Health officials identified the patient only as a woman in her 60s. "This is the 13th case of West Nile virus acquired in Massachusetts by a resident," said Public Health Commissioner Dr. Monica Bharel. "It is not surprising that we are seeing more cases than usual this year given the intense mosquito activity that has been detected during the season."On Monday, health officials announced that a Suffolk County man in his 50s was diagnosed with the state's 12th case of West Nile Virus. That man is also in the hospital for treatment after becoming ill on Sept. 11. In 2017, there were six human cases of the disease identified in Massachusetts. Humans usually become infected through the bite of a mosquito carrying the virus. "With shorter day lengths we are starting to see the numbers of mosquitoes go down," said DPH State Epidemiologist Dr. Catherine Brown. "However, it is definitely too early in the season to become complacent. Risk of additional transmission to people continues to be elevated."