No evidence of avian influenza A (H5N1) among returning US travelers

Avian influenza A (H5N1) infection with respiratory failure and meningoencephalitis in a Canadian traveller

Since 1997, more than 600 individuals worldwide have been infected with the poultry-originating influenza, H5N1. This report describes the first case of avian influenza A (H5N1) in the Western hemisphere in a 28-year-old woman who had just returned from a trip to Beijing, China. The typical manifestations of H5N1 are described, and signs and symptoms are discussed.

In an urban centre in Alberta, an otherwise healthy 28-year-old woman presented to hospital with pleuritic chest and abdominal pain after returning from Beijing, China. After several days, this was followed by headache, confusion and, ultimately, respiratory failure, coma and death. Microbiology yielded influenza A subtype H5N1 from various body sites and neuroimaging was consistent with meningoencephalitis. While H5N1 infections in humans have been reported in Asia since 1997, this is the first documented case of H5N1 influenza in the Western Hemisphere. The present case demonstrated the typical manifestation of H5N1 influenza but, for the first time, also confirmed previous suggestions from human and animal studies that H5N1 is neurotropic and can manifest with neurological symptoms and meningoencephalitis.

Seroevidence for H5N1 influenza infections in humans: meta-analysis

The prevalence of avian H5N1 influenza A infections in humans has not been definitively determined. Cases of H5N1 infection in humans confirmed by the World Health Organization (WHO) are fewer than 600 in number, with an overall case fatality rate of >50%. We hypothesize that the stringent criteria for confirmation of a human case of H5N1 by WHO do not account for a majority of infections but rather the select few hospitalized cases that are more likely to be severe and result in poor clinical outcome. Meta-analysis shows that 1 to 2% of more than 12,500 study participants from 20 studies had seroevidence for prior H5N1 infection.

Knowledge, attitudes, and practices of US travelers to Asia regarding seasonal influenza and H5N1 avian influenza prevention measures

BACKGROUND

International travel is a potential risk factor for the spread of influenza. In the United States, approximately 5%-20% of the population develops an influenza-like illness annually. The purpose of this study was to describe the knowledge, attitude, and practices of US travelers to Asia regarding seasonal influenza and H5N1 avian influenza (AI) prevention measures.

METHODS

We surveyed travelers to Asia waiting at the departure lounges of 38 selected flights at four international airports in New York, Chicago, Los Angeles, and San Francisco. Of the 1,301 travelers who completed the pre-travel survey, 337 also completed a post-travel survey. Univariate and multivariate logistic regression were used to calculate prevalence odds ratios (with 95% CI) to compare foreign-born (FB) to US-born travelers for various levels of knowledge and behaviors.

RESULTS

Although the majority of participants were aware of influenza prevention measures, only 41% reported receiving the influenza vaccine during the previous season. Forty-three percent of participants reported seeking at least one type of pre-travel health advice, which was significantly higher among US-born, Caucasians, traveling for purposes other than visiting friends and relatives, travelers who received the influenza vaccine during the previous season, and those traveling with a companion. Our study also showed that Asians, FB travelers, and those working in occupations other than health care/animal care were less likely to recognize H5N1 AI transmission risk factors.

CONCLUSION

The basic public health messages for preventing influenza appear to be well understood, but the uptake of influenza vaccine was low. Clinicians should ensure that all patients receive influenza vaccine prior to travel. Tailored communication messages should be developed to motivate Asians, FB travelers, those visiting friends and relatives, and those traveling alone to seek pre-travel health advice as well as to orient them with H5N1 AI risk factors.

Avian influenza--a review for doctors in travel medicine

First identified in humans in Hong Kong, influenza A/H5N1, known commonly as avian influenza, has caused human disease in 15 countries around the world. Although the current number of confirmed patients is tiny compared to seasonal and the recently emerged H1N1 'swine' influenza, H5N1 remains a candidate for the next highly pathogenic influenza pandemic. Currently, H5N1 has very limited ability to spread from person-to-person but this may change because of mutation or reassortment with other influenza viruses leading to an influenza pandemic with high mortality. If this occurs travellers are likely to be affected and travel medicine doctors will need to consider avian influenza in returning febrile travellers. The early clinical features may be dismissed easily as 'the flu' resulting in delayed treatment. Treatment options are limited. Oral oseltamivir alone has been the most commonly used drug but mortality remains substantial, up to 80% in Indonesia. Intravenous peramivir has been filed for registration and IV zanamivir is being developed. This review will focus on the epidemiological and clinical features of influenza A/H5N1 avian influenza and will highlight aspects relevant to travel medicine doctors.

Seasonal influenza in adults and children--diagnosis, treatment, chemoprophylaxis, and institutional outbreak management: clinical practice guidelines of the Infectious Diseases Society of America

Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients.