NEW ORLEANS — Louisiana and Mississippi are leading the nation in the number of people who have become the most seriously ill from West Nile virus this year. State health departments are warning residents to take precautions against mosquitoes, which spread the virus.
“Not in my house, not on my skin, not in my yard,” said Dr. Raoult Ratard, Louisiana’s state epidemiologist, as he repeated the state slogan for fighting the disease Wednesday. Precautions 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 — even a bottle cap.
As of Aug. 21, Louisiana had 18 cases of West Nile encephalitis or meningitis out of a national total of 133, the Centers for Disease Control and Prevention reported Wednesday on its website. Mississippi had 15 such “neuroinvasive” cases, Texas 14 and California 12.
South Dakota had nine, Iowa seven, Nebraska six and Alabama and Pennsylvania five each.
Dr. Paul Byers, Mississippi’s state epidemiologist, said Mississippi is “always” among the states with the highest rates for West Nile virus.
“Regardless of whether we report the disease in your county … we want everybody to take those appropriate precautions,” Byers said.
Reports of infections of the brain and nervous system are more reliable indicators of West Nile’s seriousness than statistics for flu-like West Nile fever or symptomless infections found most often when people donate blood, he and Ratard both said.
That’s because most patients will be hospitalized, Ratard said. “And it’s the major problem with West Nile,” he added. “One out of 10 (with neuroinvasive West Nile virus) will die; one out of 10 will have permanent disabilities.”
The CDC reported eight deaths so far this year: two in South Dakota and one each in Louisiana, Iowa, Ohio, Georgia, Tennessee and North Carolina.
Overall, the CDC said, 45 states and the District of Columbia have reported the virus in people, birds or mosquitoes this year.
About one in five infected people becomes ill, and the virus spreads to the nervous system in about one in 150, according to the CDC.
West Nile fever diagnoses depend on whether a patient even goes to the doctor, and then on whether the doctor tests for it. And most people bitten by an infected mosquito never show any symptoms. They’re diagnosed only if their blood is tested.
The CDC reported 98 cases of fever and 89 positive blood tests.
Six states — Florida, Indiana, Missouri, New York, Oregon and Utah — have diagnosed only one or two fever cases and none in the nervous system. The only reports in New Mexico and Montana were from a single blood test in each.
Ratard said 1,054 people in Louisiana have come down with the most serious form of the disease over the past 16 years. “So we probably have 100,000 to 200,000 people that were infected in Louisiana, and that are immune,” Ratard said.
CDC figures often lag behind state reports. Louisiana reports there have been 31 residents with dangerous nervous system infections, including two deaths, and 13 cases of West Nile fever. Mississippi has reported 10 fever cases in addition to the 15 nervous system infections, Byers said.
Variations from state to state and year to year depend on various local factors, Ratard said.
He noted that although Louisiana is seeing more cases this year than last, numbers are still down considerably from the worst years, such as 2002 and 2012. Louisiana had 142 nervous system infections by this week in 2002, out of a total of 204 for the year. There were 95 such cases by now in 2012, out of 160 for the year.
There were nearly 3,000 cases of encephalitis and meningitis caused by the virus in both 2002 and 2012.