West Nile virus' spread through nerve cells linked to serious co...( Oct. 18 2007 -- Scientists believe t...)

Oct. 18, 2007 -- Scientists believe they have found an explanation for a puzzling and serious complication of West Nile virus infection.

Researchers at Washington University School of Medicine in St. Louis and Utah State University showed that West Nile virus can enter a nerve cell, replicate and move on to infect other nearby nerve cells. Viruses traveling this infectious pathway can break into the central nervous system, triggering a condition known as acute flaccid paralysis that leaves one or more limbs limp and unresponsive. No treatment is currently available for this complication. Patients must undergo rehabilitation to relearn to use the affected limb.

Injection of a West Nile virus antibody, created by Washington University and a private biotechnology firm, blocked the complication in laboratory animals. The results appear online in the Proceedings of the National Academy of Sciences.

Preliminary data suggests there will be approximately 4,000 to 5,000 severe West Nile virus infections in the United States in 2007. First isolated in Africa in 1937, West Nile spread to the Middle East, Europe, and Asia before arriving in the United States in 1999. Most infections with the virus are mild or symptom-free, but infections in people with weakened immune systems and those over 50 sometimes lead to serious complications or death.

Senior author Michael Diamond, M.D., Ph.D., associate professor of molecular microbiology, of pathology and immunology and of medicine, began the new study because of a puzzling contrast in the ways West Nile virus infection affects the central nervous system.

One form of infection, encephalitis, causes inflammation of the brain and leads to fever, headaches, weakness and seizures. It is much more likely to occur in patients who are elderly or have weakened or suppressed immune systems. The other form of infection, acute flaccid paralysis, strikes patients with weakened immune systems but also affects a signif
'/>"/>