Mississippi and Louisiana  are leading the nation in the number of people who have become seriously ill from West Nile virus this year.  As of Aug. 21, Mississippi had 15 out the 133 national total cases of West Nile meningitis, the Center for Disease Control and Prevention reported on its website.  Louisiana had 18 cases, Texas had 14 cases, California had 12 cases, South Dakota had 9 cases, Iowa had 7 cases, Nebraska had 6 cases and Alabama and Pennsylvania had 5 cases each.  Precautions for preventing this disease include making sure door and window screens don’t have holes; wearing long clothes and using mosquito repellent; and making sure the yard doesn’t hold any standing water where mosquitoes might breed.