West Nile Virus: An Emerging Virus in North America (original) (raw)

West Nile virus and its emergence in the United States of America

Veterinary Research, 2010

Zoonotic West Nile virus (WNV) circulates in natural transmission cycles involving certain mosquitoes and birds, horses, humans, and a range of other vertebrates are incidental hosts. Clinical infections in humans can range in severity from uncomplicated WNV fever to fatal meningoencephalitis. Since its introduction to the Western Hemisphere in

West Nile Virus in the United States: Guidelines for Surveillance, Prevention, and Control

2013

Promote health and quality of life by preventing and controlling vector-borne diseases The following CDC, Division of Vector-Borne Diseases staff members formed the technical development group that prepared this report: We are grateful to representatives from the following organizations for their thoughtful review and contributions to this document: 5 Foreword As West Nile virus (WNV) spread and became established across the United States following its first identification in New York City in 1999, the responses of all levels of the public health system have resulted in a detailed understanding of WNV transmission ecology and epidemiology as well as development of systems and procedures to reduce human risk. This includes an expanded capacity to diagnose and monitor WNV infections in humans, measure WNV transmission activity in vector mosquitoes, and implement effective WNV control programs. These guidelines, which update the third revision released in 2003, incorporate this new kno...

Estimated cumulative incidence of West Nile virus infection in US adults, 1999–2010

Epidemiology and Infection, 2013

West Nile virus (WNV) was first recognized in the USA in 1999. We estimated the cumulative incidence of WNV infection in the USA from 1999 to 2010 using recently derived age-and sexstratified ratios of infections to WNV neuroinvasive disease (WNND) and the number of WNND cases reported to national surveillance. We estimate that over 3 million persons have been infected with WNV in the USA, with the highest incidence rates in the central plains states. These 3 million infections would have resulted in about 780 000 illnesses. A substantial number of WNV infections and illnesses have occurred during the virus' first decade in the USA.

Epidemiology and Transmission Dynamics of West Nile Virus Disease

Emerging Infectious Diseases, 2005

From 1937 until 1999, West Nile virus (WNV) garnered scant medical attention as the cause of febrile illness and sporadic encephalitis in parts of Africa, Asia, and Europe. After the surprising detection of WNV in New York City in 1999, the virus has spread dramatically westward across the United States, southward into Central America and the Caribbean, and northward into Canada, resulting in the largest epidemics of neuroinvasive WNV disease ever reported. From 1999 to 2004, >7,000 neuroinvasive WNV disease cases were reported in the United States. In 2002, WNV transmission through blood transfusion and organ transplantation was described for the first time, intrauterine transmission was first documented, and possible transmission through breastfeeding was reported. This review highlights new information regarding the epidemiology and dynamics of WNV transmission, providing a new platform for further research into preventing and controlling WNV disease.

West Nile Virus in the United States: Guidelines for Detection, Prevention, and Control

Viral Immunology, 2000

The epidemic/epizootic of West Nile (WN) encephalitis in the northeastern United States in the summer and fall of 1999 was an unprecedented event, underscoring the ease with which emerging infectious pathogens can be introduced into new geographic areas in today's era of rapid transportation and increased movement of people, animals, and commodities. This epidemic/epizootic and the increased frequency of other exotic pathogens being imported into the United States raises the issue of whether local, state, and national public health agencies are prepared to deal with epidemics/epizootics of vector-borne infectious diseases. The overwintering of WN virus and the epizootic transmission in the summer of 2000 reinforces the need to rebuild the public health infrastructure to deal with vector-borne diseases in this country. This article summarizes guidelines for surveillance, prevention, and control of WN virus that were drafted in December 1999 to help prepare state and local health departments for monitoring WN virus activity in the spring and summer of 2000 and also summarizes the data collected from those surveillance systems through September 2000.

West Nile virus: lessons from the 21st century

Journal of Veterinary Emergency and Critical Care, 2004

Introduction: West Nile virus (WNV) first appeared in the United States in 1999, causing illness and death in birds, horses, and humans. While the initial outbreak of this sometimes deadly viral disease was limited to the northeastern United States, the virus had an inexorable migration across the continental United States over the next 3 years, causing huge losses among the affected species. The purpose of this review is to present currently available information regarding the epidemiology, diagnosis, treatment, and prevention of WNV infection. Veterinarians, particularly those in an emergency practice, serve as an important source of reliable information regarding this disease for animal owners and the public in general. Data sources: Data sources used for the preparation of this review include computer-based searches of PubMed and Commonwealth Agricultural Bureaux (CAB) abstracts. A search in PubMed using 'West Nile' retrieved 1468 'hits' or references, while a similar search in CAB abstracts produced 815 references. Additional information was obtained from various meeting proceedings, particularly data presented in abstract form, and from the Centers for Disease Control (CDC) website dedicated to WNV. Human data synthesis: Prior to the mid-1990s, reported large-scale epidemics of WNV infection in humans predominantly presented as acute, mild, febrile disease, sometimes associated with lymphadenopathy and skin rash. The recent large epidemic in the United States, in contrast, has prominently featured encephalitis, particularly among the elderly. Additionally, polioencephalomyelitis-like complications resulting in long-term neurologic sequelae have been reported. There are many WNV-permissive native avian and mosquito hosts in the Unites States and there appear to be few limitations to the spread of the disease in the United States. It is expected that the virus will be identified in all 48 continental states, Mexico, and Canada by the end of 2003. Veterinary data synthesis: The horse is the animal species most affected by the recent WNV epidemic in the United States, and losses to the equine industry have been large and unprecedented. A United States Department of Agriculture (USDA)-approved vaccine against WNV has been in use in horses since 2001 and appears to be effective in limiting the incidence of disease in well-vaccinated populations. WNV infection has been documented in other species of mammals, including camelids (alpaca/llamas) and dogs, and veterinarians should include WNV as a differential diagnosis for animals presenting with clinical signs consistent with central nervous system infection. A large concern exists for endangered bird populations, particularly birds of prey, whether in zoos or in the wild.

West Nile Virus: an Update on Recent Developments

Clinical Microbiology Newsletter, 2012

West Nile Virus arrived in North America just over 12 years ago, and since that time, much has been learned about its pathology and transmission of infection and the factors affecting prevalence. Key developments uncovered critical risk factors for severe neurologic disease and revealed successful host defense strategies. At present, only equine vaccines are available; human vaccines remain in various stages of clinical trials. This review discusses the advances in and limitations of the current research related to the emergence and continued dissemination of West Nile virus throughout the Americas.

THE EMERGENCE OF WEST NILE VIRUS DURING A LARGE OUTBREAK IN ILLINOIS IN 2002

2005

In 2002, the world's largest outbreak of neuroinvasive West Nile virus (WNV) disease occurred. Illinois reported 21% of the total cases in the United States, the most among all states. The epidemiology of WNV in Illinois in 2002 was examined to determine factors associated with severe disease and death. A total of 884 cases were identified and there were 66 deaths. The overall attack rate of WNV infection was 7.1 per 100,000 population and this increased with age. The median ages of patients and patients who died were 56 and 78 years, respectively. Among patients who died, 91% were diagnosed with encephalitis and the case-fatality rate for patients with encephalitis was 18.6%. Patients more than 50 years old had a significantly higher risk of being reported with encephalitis (relative risk [RR] ‫ס‬ 3.3, 95% confidence interval [CI] ‫ס‬ 2.6−4.3%) and death (RR ‫ס‬ 22.3, 95% CI ‫ס‬ 5.5−90.4%). Clinicians evaluating elderly patients with WNV infection should assess patients closely for progression of disease.