A 75-year-old woman who was stricken last month with the year’s first documented local case of West Nile virus has died, and four other Southern Nevadans have come down with the disease, the Southern Nevada Health District reported Tuesday.
Two of the four new cases, a 68-year-old woman and a 64-year-old man, remain hospitalized with the same potentially fatal form of the disease. A horse that contracted the disease was euthanized.
The name of the woman who died – she is the fourth to die of West Nile in Clark County since 2003 – and details of her death were not released by the health district because of privacy laws. The Clark County coroner’s office did not handle the case.
"She had the more serious neuroinvasive form of the disease and was not able to recover from it," said Devin Barrett, a senior disease investigator with the health district. "At 75, it’s so difficult for a person to recover from any sort of illness, and we have to remember with West Nile, there is no treatment. That’s why it’s so important we take precautions against mosquito bites, wear mosquito repellent … long pants and shirts …. remove standing water."
The neuroinvasive form of the virus affects nervous systems and can cause encephalitis, an inflammation of the brain, and meningitis, which causes inflammation to the membrane around the brain and spinal cord. Someone who survives this form of the disease can be left paralyzed.
A 25-year-old woman was diagnosed with the serious form of the disease but quickly recovered after she was hospitalized, Barrett said.
"It’s easier for younger people to bounce back and recover," Barrett said. "It is much more difficult for those over 50."
With no specific treatment for the disease, victims are hospitalized and given supportive treatment, including intravenous fluids, help with breathing and continuous nursing care.
A 52-year-old man with the less serious form of the disease – the symptoms are much like the cold or flu – was not hospitalized.
"People with either form of the disease complain about how weak and tired they are, that they lose their energy," Barrett said. "Sometimes they find it hard to go from the bed to the restroom. Those with the more serious form progress to an altered mental state and confusion. They start feeling so weak that they can’t walk or function and are hospitalized."
Barrett said people ask her how long it takes to overcome the disease, and she tells them she can’t answer the question with specifics. "It’s so dependent on someone’s immune system and their personal strength and drive," she said. "It can be how hard you work in rehabilitation that determines how quickly you come back from effects of the disease."
Though vector control experts found a second West Nile-positive mosquito pool in the 89145 ZIP code – the early pool was found in 89107 – Barrett said "we believe mosquitoes infected with the virus are now throughout the Las Vegas Valley."
Barrett said the five-member vector control unit of the health district continues to set traps for mosquitoes through the valley.
Mosquitoes pick up the virus from infected birds and transmit it to humans, birds and other animals they bite.
Eighty percent of the people who contract the virus never have symptoms.
As of Sept. 25 this year, the Centers for Disease Control and Prevention reports that there have been 3,545 cases of West Nile virus disease in people across the country, including 147 deaths. Of these, 1,816 were classified as neuroinvasive disease, and 1,729 had the less serious form of the disease.
The number of cases reported in 2012 is the highest number of West Nile virus disease cases reported to the CDC since 2003. Seventy percent of the cases have been reported from eight states: Texas, Mississippi, South Dakota, Michigan, California, Louisiana, Oklahoma and Illinois.
Thirty-eight percent of all cases have been reported from Texas.
Since the disease first appeared in the United States in 1999, it has sickened 30,000 people and killed more than 1,200.
Barrett said the number of cases in Clark County this year is typical. Though it is becoming cooler, she said it is still possible that more cases will be seen in Southern Nevadans.
"There is about a four-week incubation period," she said.
As she did last month, Barrett told Clark County residents to remove standing water that can be a dangerous breeding ground for mosquitoes.
If people see water in places that include pots, wheelbarrows and tires, she said they should be turned over and emptied.
She said residents who see standing water near washes or creeks or on public land should call health district vector control at 759-1220. Reports of dirty, "green" swimming pools should be made to city of Las Vegas enforcement authorities at 229-6615 and to Clark County officials at 455-4191.
Contact reporter Paul Harasim at email@example.com or 702-387-2908.Symptoms
The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.
Up to 20 percent of the people infected have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back.
SOURCE: Centers for Disease Control