ST. LOUIS -- Twelve more human cases of the West Nile virus have been reported in Missouri, based on preliminary tests announced Wednesday by the state health department. So far, 89 human cases have been reported in the state.

The latest cases included: a 23-year-old woman, 7-year-old boy and 61-year-old man from St. Louis County; a 41-year-old man from Kansas City; a 43-year-old woman from Laclede County; a 51-year-old man from Callaway County; a 53-year-old man from St. Charles County; a 61-year-old man from Monroe County; and in the city of St. Louis, a 27-year-old woman and a 91-year-old man, 79-year-old man and a 43-year-old man.

The health department is awaiting confirmation from the Centers for Disease Control and Prevention in Atlanta on all but four of the cases.

The mosquito-borne virus is most dangerous for children, the elderly and people with weak immune systems. One Missourian has died from West Nile.

West Nile symptoms usually occur seven to 10 days after infection. They are generally similar to the flu -- fever, chills, headache, neck pain and aching muscles.

In rare cases, the virus can cause swelling of the brain and prove fatal.

People can reduce their chances of getting the virus by using insect repellents containing DEET or by limiting the amount of time spent outside when mosquitoes are most active. Eliminating pools of water also cuts down on places for mosquitoes to breed.

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On the Net

Missouri health department: http://www.dhss.state.mo.us/WestNileVirus

CDC: http://www.cdc.gov