November 10, 2010 (Atlanta, Georgia) — West Nile virus (WNV) might persist for years after acute infection, resulting in long-term neurological consequences in more people than previously thought, a new study suggests.

Kristy Murray, DVM, PhD, from the University of Texas School of Public Health, in Houston, presented the findings here at the American Society of Tropical Medicine and Hygiene 59th Annual Meeting.

“West Nile virus is not just an acute disease,” Dr. Murray told Medscape Medical News. “Patients who have the neuroinvasive form of disease will more than likely have long-term symptoms and sequelae,” she said. “This is a major finding, considering that more than 1.7 million Americans have been exposed since this virus first came to the United States in 1999,” she added.

WNV infection is generally asymptomatic, but a neuroinvasive variant that can result in encephalitis, meningitis, and acute flaccid paralysis occurs in approximately 1 in 150 infected individuals, according to the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.

Dr. Murray and colleagues initially observed that a larger than expected number of patients who presented with WNV infections were experiencing progressive neurological disease or kidney failure. They subsequently investigated long-term outcome in 151 patients with WNV in Houston beginning in 2002.

Of patients who presented with encephalitis, 77% had abnormal neurological findings, and 23% exhibited renal disease (including 5 deaths from renal failure).

Previously, the researchers found that 5 of 25 subjects tested positive for WNV viral particles in the urine. The current analysis indicated that 34 of 81 subjects (42%) had persistent WNV viral shedding in the urine. Of those patients, 65% had proteinuria and 13% developed renal failure.

Excerpt:

Millions of travelers visit the United States every year during
warm months when risk of vector-borne disease is highest. The
epidemiology and geographic distribution of the principal
vector-borne diseases in the United States are reviewed and
recommendations for visitors to reduce their risk of disease are
described. Travel advice should focus on preventing Lyme disease,
anaplasmosis and babesiosis in the northeast and north central
States, West Nile virus disease in western plains States, and
Rocky Mountain spotted fever and tularemia in the southeast;
other diseases and itineraries requiring particular attention are
described. All travelers to the United States should be advised
to practice personal protection against arthropod bites,
including appropriate use of insect repellents, especially when
visiting rural and suburban areas during the warm months.
Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Excerpt:

Researchers at Vanderbilt University have identified a new family of odor sensors that mosquitoes use to locate their prey. Their discovery could help explain the puzzling mechanisms behind the mosquito’s sense of smell and further the discovery of new deterrents and traps. Funded by NIAID, the study was published in the journal PLoS Biology in August 2010.

Mosquitoes’ olfactory system, or sense of smell, is crucial for their survival. Mosquitoes use it to identify mates and locate a host. While its importance is well-accepted, the exact mechanisms behind the mosquito’s olfactory system are poorly understood.

For about ten years, scientists have been examining Anopheles gambiae, the primary vector of malaria, and studying a set of odor sensors called AgORs (A. gambiae odorant receptors). Now, the Vanderbilt team, led by Laurence Zwiebel, Ph.D., has discovered a new set of receptors, AgIRs (A. gambiaevariant ionotropic receptors) by examining the larval olfactory system.

Excerpt:

Although the risk of infection with hepatitis and human
immunodeficiency viruses from blood transfusions has been reduced
to negligible levels, emerging infections continue to offer
threats. Such threats occur with any infection that has an
asymptomatic, blood-borne phase. In the past, it was thought that
any emerging transfusion-transmitted disease would have
epidemiologic properties similar to those of AIDS or viral
hepatitis. Over the past 20 years, however, greatest concern has
arisen from variant Creutzfeldt-Jakob disease, West Nile virus,
and Babesia. These and other emerging infections are discussed in
the context of blood safety. Copyright (c)  2010 Elsevier Inc.
All rights reserved.