Dr. Art Leis, left, senior scientist at Methodist Rehabilitation Center,and Dr. Dobrivoje Stokic, right, administrative director of research at MRC.
West Nile Virus can cause a polio-like paralysis
JACKSON – Two physicians at Methodist’s Center for Neuroscience and Neurological Recovery (CNNR) are making major contributions to the understanding of West Nile virus (WNV), a devastating disease that is a problem in many countries around the world.
Art Leis, MD, a neurologist at Methodist’s Center for Neuroscience and Neurological Recovery (CNNR) and Dobrivoje S. Stokic, MD, director of the CNNR, were the first to discover and report that WNV can attack the motor cells of the spinal cord, causing fatigue, muscle weakness and a polio-like paralysis. The team is now working with researchers at Queens Square in London, U.K., to learn more about the severity of neurological injury associated with the virus.
Leis said what they found is that neuroinvasive WNV infection can cause a form of poliomyelitis that is pathologically identical to the polio epidemics of the 1940s and 1950s.
“These types of neurological and neuromuscular manifestations of WNV infection should be recognized by physicians and healthcare providers, particularly if these symptoms develop during the summer or early fall,” Leis said. “It continues to surprise me there are a number of physicians who are unaware of the major clinical features of WNV infection. Traditionally, most patients infected with WNV are completely without symptoms. Those who come to medical attention usually develop either a severe summer flu type presentation or what we call neuroinvasive disease. The latter can result in encephalitis, which is swelling of the brain cells, meningitis, which is swelling of the lining around the brain, or poliomyelitis.”
The discovery of poliomyelitis resulting from WNV started in 2002 when physicians at CNNR noticed some patients coming down with an acute asymmetric paralysis. Electrodiagnostic studies localized the problem to the grey matter of the spinal cord. In addition, many patients presented with WNV fever associated with very prolonged, persistent, lingering symptoms ranging from generalized weakness to disabling fatigue.
“We did some investigation into the WNV fever group and found a high proportion of these patients actually showed evidence that their brain or spinal cord had also been attacked by the virus,” Leis said. “We have now been able to confirm through spinal fluid and blood studies that a high percentage of patients with relatively benign fever conditions were also showing injuries to portions of the brain and spinal cord.
“Prior to our research, the Centers for Disease Control and Prevention and state health departments were telling the public that only one percent of patients who were infected were developing this neuroinvasive disease. We’re finding that this number is much too low. There is a much higher percentage of patients whose central nervous system is being attacked by the virus.”
Leis said the message should be even stronger about how important it is to avoid mosquito bites, and for doctors to be more aware of the clinical features of WNV infection.
“We are seeing the devastating effects of this virus,” he said. “Currently there are no treatments approved for WNV. The standard remains supportive care. However, there are some candidate therapies, drugs that can alter the events leading to the destruction of neurons or cells in brain. Drugs used include high dose steroids, interferon preparations and intravenous immune globulin (IVIG) containing WNV antibodies. IVIG is going to be very important in the future.”
IVIG is extremely costly. Right now it is primarily manufactured in the Middle East where people have been exposed to WNV for many years, and have developed an immune response to WNV much more so than in North America.
The sobering news that WNV is more invasive than previously thought adds urgency to the need to prevent mosquito bites. In addition to wearing repellents or clothing that covers the body, especially when mosquitoes are most active at sunset and dusk, Leis said it is critical to avoid stagnant water in and around your own home because several studies have shown that the mosquitoes that bite and infect victims are literally homegrown.
“Mosquitoes can go from larvae stage to flying insects in a matter of four days,” Leis said.
In addition to prevention, Leis thinks it is important that more governmental funds be dedicated to trying to control this infection.
Back in 2002 Leis used to be optimistic about the development of a vaccine. But even with several companies working on it, a vaccine still hasn’t been approved.
The incidence of WNV in Mississippi increased in 2011 with five times as many cases being reported by the end of September than were seen in all of 2010. While the 48 cases reported are still small compared to the state’s overall population, the increase is of concern, especially considering the lack of approved treatments for WNV.
“We know that WNV is here in our state and that we can expect to have cases on a yearly basis,” said Paul Byers, MD, acting state epidemiologist at the Mississippi State Department of Health (MSDH). “The number of reported cases fluctuates on a yearly basis, which means some years we may have more cases than in previous years. The important thing for people to remember is that WNV is present in our state and residents should take the proper precautions to prevent mosquito bites.”