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Human H5N1 influenza

Q：What is the present global condition of H5N1 influenza in humans?
A：There have been massive H5N1 avian influenza outbreaks in some countries, which led to several human cases. From year 2003 to 9 December 2010, fifteen countries had reported confirmed human cases of A/H5N1, including: Azerbaijan, Bangladesh, Cambodia, China, Djibouti, Egypt, Indonesia, Iraq, Lao People's Democratic Republic, Myanmar, Nigeria, Pakistan, Thailand, Turkey and Viet Nam. 303 out of 510 infected humans have died, with an average mortality rate close to 60 percent.
Q：How do humans become infected with H5N1 influenza viruses?
A：According to the investigation report of human H5N1 cases, people become infected through direct contact with infected poultry, their secretions, or surfaces contaminated with excretions. Majority cases occur in rural or periurban areas where households breed small quantities of poultry flocks, which often roam freely, sometimes entering homes or sharing outdoor areas where children play. As infected birds shed large quantities of virus in their faeces, opportunities for exposure to infected droppings or to environments contaminated by the virus are abundant under such conditions. Moreover, because many households in Asia depend on poultry for income and food, many families sell or slaughter and consume birds when signs of illness appear in a flock, and this practice has proved difficult to change. Exposure is considered most likely during slaughter, defeathering, butchering, and preparation of poultry for cooking.
Q：What are the symptoms of H5N1 influenza in humans?
A：The incubation period of seasonal influenza is about 2 to 3 days, while the incubation period of H5N1 influenza has longer span (from 2 to 8 days and can reach up to 17 days).
The primary symptoms of H5N1 influenza include high fever (usually higher than 38˚C) and flu-like symptoms. During the early stage of the disease, the patient may experience diarrhea, nausea, abdominal pain, chest pain, bleeding nose and gums and other symptoms. Respiratory symptoms are not always evident in all confirmed human cases. Clinical cases showed that watery diarrhea without blood appears to be more common in H5N1 influenza patients than those infected with normal seasonal influenza.
Many human cases presented low respiratory tract symptoms when they first seek medical treatment. Recent evidence shows that patients experience respiratory distress 5 days after the first sign of symptoms occur. In patients infected with the H5N1 virus, clinical deterioration is rapid. In Thailand, the time between onsets of illness to the development of acute respiratory distress was around six days (time period may range from 4 to 13 days). Kidney, heart and other organ dysfunctions are also one of the likely effects of avian influenza in humans.

最後更新日期 2012/11/6