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.