West Nile Virus Infection Health Article

Diagnosis

Diagnosis requires clinical observation by an experienced physician as well as positive results from specific laboratory tests. Factors that assist in the diagnosis are recent travel experiences, the season that the symptoms developed, the age of the patient, and whether there are reports of other cases in the same geographical location that the patient was present during the time of exposure. Patients who have encephalitis, meningitis, or symptoms involving the central nervous system, which could lead a physician to suspect the West Nile virus, can be referred to health departments nationwide or the Centers for Disease Control (CDC) for testing. The CDC has confirmed all human cases.

The diagnostic test involves an assay that detects a virus-specific antibody (IgM) in the cerebral spinal fluid from patients. Blood can also be tested. If this test is negative, it is very unlikely that the infection is due to the West Nile virus; the other clinical explanations such as St. Louis encephalitis (SLE) should be considered. There is also a test that measures SLE virus-specific antibodies. Currently, there is a vaccination for horses, but not for humans.

Laboratory findings include normal to elevated white blood cell numbers with anemia (low red cell numbers). A deficiency of sodium in the blood (hyponatremia), which is usually associated with encephalitis, as well as normal glucose and a general increase in proteins can all be observed. A magnetic resonance imaging (MRI) scan can also be helpful, if specific areas of the brain show an abnormality, including the leptomeninges and/or the periventricular areas.

Treatment team

The treatment team might consist of the physician who initially sees the patient, usually a general practitioner, an infectious disease specialist, and neurologist. In severe cases, a complete medical team consisting of emergency room physicians and staff, nurses, and officers from the CDC might be necessary. Due to the risk of an epidemic, it is important for physicians to report these types of infections to the local health department.

Treatment

There is no cure for West Nile virus infection once the infection occurs. Treatment, therefore, is supportive and palliative. In the more severe cases, recurrent hospitalizations may necessitate life support services. The primary treatment is focused on lessening the symptoms and preventing secondary infections, which could include urinary tract infections and pneumonia in patients that develop severe illness. Intravenous fluids can be helpful during hospitalizations, along with airway management and good nursing care.

Recovery and rehabilitation

Most patients who develop symptoms recover from West Nile virus infections. The symptoms can be no worse than getting the flu. However, older patients and patients with health-related problems (particularly those that affect the immune system) have more difficulty recovering.

Clinical trials

The Warren G. Magnuson Clinical Center is currently recruiting participants for a clinical trial on the West Nile virus. The Patient Recruitment and Public Liaison Office's e-mail address is prpl@mail.cc.nih.gov.

The National Institutes of Health is conducting phase II clinical trials to investigate whether an experimental drug, Omr-IgG-am™IV, is a safe and effective treatment for West Nile virus-induced infections. This drug contains antibodies that help fight infection and is designed to target the West Nile virus. Another study by the same center has also been initiated to investigate the natural history of infection in patients with, or at risk of developing, West Nile virus-specific encephalitis or myelitis.

A third clinical trial sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) in phase I and II is to test the tolerability of Omr-IgG-am, its efficacy as a vaccine, and its effectiveness in reducing morbidity and mortality (disability and death) in patients with a confirmed diagnosis of the West Nile virus disease. The contact is Walla Dempsey; the e-mail is wdempsey@niaid.nih.gov.

Finally, a clinical trial is ongoing to identify healthy individuals who might be eligible for a phase I vaccine clinical trial sponsored by the Vaccine Research Center at the National Institutes of Health. The Patient Recruitment and Public Liaison Office's e-mail address is prpl@mail.cc.nih.gov.

High doses of a drug called Ribavirin and another called interferon alpha-2b were found to be effective in research studies, but currently no controlled clinical trials in humans have been initiated for these or other types of medications in the therapeutic management of West Nile virus infections and encephalitis.

Prognosis

The prognosis for persons with West Nile virus infection is quite favorable in patients that are young and in otherwise good health. Older persons and patients with health complications can have a poorer prognosis. In rare cases, death is possible.