The following sentence is what doctors are commonly telling folks in high risk areas where the virus lives and breathes; it reads as follows: “For all the fear and concerns in some parts of the country, health officials say the reality is that most people who become infected will not have any symptoms, and of those who do, only a fraction will develop severe illness. ” What have you been told? Nothing worthwhile and therefore you’re no better off than before this was told to you.
Now let me try to explain what this virus can do to a healthy person. But before I get into the details, let me just say this: West Nile virus is a threat that can potentially change the quality of your life.
A 2009 study shows that people who have been infected with West Nile virus may have persistent virus in their kidneys for years after initial infection, potentially leading to kidney problems. The research appears in the January 1, 2009 issue of The Journal of Infectious Diseases.
Back when the kidney risk was first discovered, the spread by infected mosquitoes was approximately 25,000 human cases causing more than 1,000 deaths. Many more have become infected without showing symptoms the report claimed. Previous animal studies raised the possibility that patients may still be infected with the virus several years after recovering from their initial illness. Prior to this latest research, however, humans were thought to remain infected with West Nile virus only for the first few days of illness. The study, led by Kristy Murray, DVM, PhD at the University of Texas School of Public Health in Houston, demonstrates that not all individuals clear the virus from their system within the first few days—and that it can remain in the kidneys for years, potentially leading to kidney failure.
Dr. Murray and her colleagues followed more than 100 patients in Houston with severe initial West Nile virus infections for seven years. Individuals were evaluated and blood samples collected every six months. More than half continued to have infection-related symptoms years after their initial illness, although symptoms began to plateau around two years after infection. The deaths of five participants due to kidney failure led researchers to consider whether the kidney could be a preferred replication site for the virus.
To test this hypothesis, Dr. Murray and her team collected urine samples from 25 patients from their original cohort and tested them for presence of West Nile virus. In this group, five patients (20 percent) tested positive for the virus. Viral RNA could be detected in the urine for at least six years following infection. Four of the five patients who tested positive for the virus also experienced chronic symptoms. Of these five, one patient developed kidney failure. These results show that the West Nile virus is capable of long term persistence in patients, particularly when chronic symptoms are present.
In an accompanying editorial, Ernest Gould, PhD, of the Centre for Ecology and Hydrology in Oxford, England, points out that this study raises the additional concern that West Nile virus and other flaviviruses may be transmitted to mosquitoes by apparently healthy humans or animals. This possibility has the potential to start epidemics in new regions of the world.
According to Dr. Murray, patients who have been infected with West Nile virus should “have their kidneys monitored by their physician for any evidence of disease and be aware that persistent infection of the kidneys can happen.” Dr. Murray also reminds the public to take proper precautions to protect themselves from mosquito bites during transmission seasons, typically the summer and fall, to avoid infection.
More research is needed to “understand the underlying mechanisms related to the shedding of virus particles in urine, whether shedding of the virus is constant or intermittent, and whether or not this represents true infection resulting in kidney disease,” the investigators say. They continue to evaluate all study participants, particularly in regard to kidney function. In addition, they are focusing on developing treatment options for those who remain infected with the virus.
Quite frankly, more research should have been done but it hasn’t, and till now, no one has reported these hideous, little-known facts.
So what actually happens to that 1 out of 150 people infected that develops the more severe illness? The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.
Hence, West Nile virus, in all reality, is an acute threat. Not only does it cause death or brain-related disability in a tiny fraction of cases, but a new Houston study suggests it routinely can result in serious, lasting damage.
Baylor College of Medicine researchers, tracking local people for years after they were infected with the mosquito-borne infection, found four in 10 had varying stages of chronic kidney disease related to the virus. The kidney disease is potentially fatal.
“This demonstrates that everybody, not just the elderly and the immune-compromised, needs to take precautions against mosquitoes,” said Kristy Murray, a professor of tropical medicine at Baylor College of Medicine and the study’s senior author. “Healthy people appear to be quite at risk of kidney disease from bites, too.” Murray said she was very surprised by the study findings – that West Nile-related kidney disease is occurring, that it’s common and that it’s about as likely to affect infected people without symptoms as those with severe symptoms.
She focused on kidney disease after learning about a few study participants’ unexpected development of kidney problems. Because of the study, published online in the journal PLoS, the team is advising doctors to screen patients with any history of West Nile infection for kidney disease and those with unexplained kidney disease for the virus, Murray said.
She estimated that roughly 45,000 Houston-area people have been infected with the virus, many of whom don’t know it. Texas is in the midst of its most prolific West Nile season ever, although the greatest numbers by far are occurring in the northern part of the state.
Dallas County has confirmed 270 human cases of West Nile disease and 11 deaths this year. Harris County has had 19 cases and three deaths.
Still, Harris County’s deaths so far represent the most at this point of the season in recent years. Wednesday night, it conducted aerial spraying of 63,000 acres in the west and north.
U.S. health officials said Wednesday that Texas’ active season has the nation on pace for the largest outbreak ever. National numbers lag behind the local numbers, but the U.S. Centers for Disease Control and Prevention is reporting 1,118 West Nile illnesses, up from fewer than 700 cases a week ago. The CDC reports 41 deaths. Only one in 150 infected get severe symptoms from West Nile disease, which must here be repeated ,can lead to imbalance, coma, paralysis and death. But the conventional wisdom has been that people without symptoms – eight of 10 of those infected – and people who recover from mild cases are then immune from the disease.
In her study of 139 Houston-area people infected with the virus and followed for 10 years, however, Murray found that the virus commonly takes residence in the kidney and replicates there, resulting in inflammation and disease as the body tries to fight the infection.
People who survived the disease’s most severe symptoms were most likely to have suffered kidney damage – 60 percent, within seven to nine years after infection – but a significant percentage of disease occurred in all groups. In those who never had symptoms, 39 percent had kidney disease four to six years later.
Overall, 40 percent of study participants had kidney disease at four to six years and 43 percent had it at seven to nine years.
People who had experienced severe West Nile disease were the most likely to have serious kidney damage.
Chronic kidney disease is divided into five stages. The first two are milder, but stages four and five are usually irreversible and can result in dialysis or transplantation. The estimated 2 million people infected nationally could mean an additional 150,000 Americans having some stage of kidney disease.
Though there is no treatment for the West Nile virus, Murray said it is important to catch the kidney disease as early as possible so it can be monitored.
Dr. Lyle Petersen, a CDC West Nile specialist, called Murray’s study “intriguing and interesting,” but said more work is needed to confirm the findings. “If true, they are of importance,” he added.
Murray, a former CDC official who is a Texas pediatrician, said the team continues to look into the phenomenon and has confirmed the presence of persistent infections by finding the live virus in patients’ urine with an electron microscope, a more sensitive test than was used in the study.
She said the next step is to understand the relationship between infection and kidney disease.
Dr. Petersen’s response, calling Murray’s study, “intriguing and interesting” not only doesn’t go far enough, it misses the urgency necessary for warning at risk communities.
After reading much of the data, I could not help but point out the research that revealed the risk that West Nile presents to the kidney. Below, please read the following tips on how you could prevent contracting this devastating disease.
TIPS FOR PREVENTION
There are no vaccines to prevent West Nile infections and no medications to treat the disease, which is more dangerous to people older than 50. To reduce exposure, public health officials urge people to:
• use repellent.
• wear long sleeves and pants at dawn and dusk when mosquitoes are most active.
• make sure there are screens on all doors and windows to keep mosquitoes out.
• regularly drain any standing water.