Dallas County health officials said a 14th person with West Nile virus had died.
Dallas County Health and Human Services said the patient was diagnosed with the neuroinvasive form of the virus.
The patient lived in zip code 75062, which is in Irving.
The county health department did not provide any other details about the patient for privacy reasons.
Dallas County has 325 human cases of West Nile virus. North Texas as a whole has more than 800 human cases and 24 fatalities.
West Nile Virus Facts
Most people bitten by a West Nile virus-infected mosquito will not show any symptoms. Symptoms, if they appear, are fever, headache, nausea, body aches, swollen lymph nodes and skin rashes.
Fewer than 1 percent of those infected with West Nile virus experience the serious form of the illness. Serious symptoms include high fever, severe headache, neck stiffness, disorientation, tremors or convulsions, vision loss, muscle weakness and numbness or paralysis.
Both Dallas and Richardson are urging residents to: