West Nile encephalitis reported in stem cell recipients

In a new report, US researchers describe two patients who developed fatal West Nile virus (WNV) infections after undergoing stem cell transplantation.

In a new report, US researchers describe two patients who developed fatal West Nile virus (WNV) infections after undergoing stem cell transplantation. “To the best of our knowledge, these are the first reported cases of WNV infection in recipients of hematopoietic stem cell transplants,” Dr. Chitra Hosing and colleagues, from the M. D. Anderson Cancer Center in Houston, note. Two factors may place stem cell recipients at high risk for symptomatic WNV infection, the authors note. First, they typically receive multiple blood products, which raises their risk of infection. And second, the immunosuppression seen in such patients may raise the risk of central nervous system disease once infected.The current cases, reported in the October 15th issue of Clinical Infectious Diseases, involved two older men with a history of acute myeloid leukemia who underwent matched unrelated donor bone marrow transplantation at the authors’ institution. A common thread in both cases was the use of immunosuppressants and the receipt of multiple blood products.In the first case, a 58-year-old man with a history of relapsed acute myeloid leukemia developed a fever and right shoulder weakness a few days before transplantation. Although physical exam revealed upper extremity weakness, MRI of the brain and right brachial plexus were normal. Antibiotics were given, the patient defervesced, and transplantation was performed on hospital day 7.One day after the procedure, the patient’s weakness spread to other extremities and the fever returned. Initial lumbar tap and microbiologic studies failed to yield a diagnosis. By day 10, the patient had become unresponsive. Repeat lumbar tap on day 12 revealed the presence of WNV and MRI on day 15 showed encephalitis.Despite aggressive treatment with interferon, the patient’s condition did not improve and he died on day 27, the authors note.The second case involved a 71-year-old man, also with AML, who had recurring problems with graft-versus-host disease (GVHD) following transplantation. Two days after receiving high-dose IV corticosteroids for GVHD the patient developed a fever and became progressively weaker. Later he began experiencing seizures, but CT and EEG performed at the time failed to reveal any abnormalities. As in the first case, this patient became severely obtunded. Serum samples obtained on hospital day 2 revealed the presence of anti-WNV IgM antibodies. Showing no neurologic improvement, life support was withdrawn and the patient died on hospital day 7. Analysis of brain tissue obtained at autopsy showed changes consistent with viral encephalitis.Although there are tests that can detect very small amounts of WNV in biologic specimens, “the cost of screening the entire blood supply may be prohibitive,” the authors note. “An alternative option may be to screen only the blood that is being given to severely immunosuppressed patients.”(Source: Clin Infect Dis 2003;37:1044-1049: Reuters Health: October 23, 2003: Oncolink)