West Nile virus has killed its first Maryland resident this year, the state confirmed Thursday.

The case was one of 13 reported in the state since July 1, according to the state Department of Health and Mental Hygiene. Of those, at least seven have resulted in severe illnesses affecting the nervous system, such as encephalitis or meningitis, according to the Centers for Disease Control and Prevention.

Montgomery, Prince George's, Washington, Anne Arundel, Baltimore, Harford and Wicomico counties and Baltimore have all had at least one resident infected with the mosquito-borne disease, while Cecil and Dorchester counties each have had at least two, according to the CDC. The CDC's data did not have the location of the 13th case, and Maryland health officials refused to release it.

Department spokeswoman Dori Henry also refused to say where or when the resident died, citing confidentiality concerns. In the past, more specific information has been released at the end of the year, she said.

However, officials in Prince George's, Montgomery and Harford counties and Baltimore City said they have had no fatalities. Officials in other jurisdictions could not be reached.

Just over the Potomac River, Virginia has had four reported cases of West Nile, one of which was in Northern Virginia, according to Virginia Department of Health spokeswoman Marian Hunter. The District reported its first case last week. Neither Virginia nor D.C. has reported any deaths.

Nationwide there have been nearly 1,600 human cases in 43 states, according to the CDC, including 65 people who have died. With 733 people infected, Texas has seen the most cases.

While some parts of the country are experiencing abnormally high rates of West Nile infection, Maryland's level of infection is normal, said Kim Mitchell, chief of rabies and vector-borne diseases at the state Department of Health and Mental Hygiene. "It's going to show up every year just like the flu."

Most people who are infected get West Nile fever, which could mean symptoms like fever, headache and body aches. People over the age of 50 are at a greater risk of developing a severe illness, but even then it's rare. About 0.7 percent of the people infected every year develop something worse, like meningitis or encephalitis.

According to Mitchell, the best way to avoid infection is to avoid being bitten.