Bird Flu Symptoms

Bird flu symptoms in birds

Bird flu infections in birds fall into one of two types – mild or severe. The mild form of bird flu produces symptoms so minor that the outbreak may go entirely unnoticed, while the severe form may kill almost 100% of infected birds within 48 hours.

Mild bird flu symptoms

• Ruffled feathers
• Reduced egg production
• Minor respiratory disease

Severe bird flu symptoms

• Serious respiratory disease
• Attacks multiple organs and tissues
• Massive internal haemorrhaging

Bird flu symptoms in humans

For the moment, humans are most likely to catch bird flu by coming into contact with infected birds. Of all the known strains of avian influenza A viruses, only H5N1, H7N3, H7N7 and H9N2 have ever been known to infect humans. By and large, these human infections have produced only mild symptoms and very little serious illness, except for those caused by the deadly H5N1 strain of bird flu. This strain has been responsible for several human deaths, and several more cases of serious illness.

Even so, with less than 200 (so far) confirmed human cases of bird flu, there is a great deal still to learn about how the virus behaves in humans. From the limited data available, it appears that H5N1’s incubation period may be longer than the two to three days usually observed in seasonal influenza, and may range from two to seventeen days. The virus is unusually aggressive, causing patients to deteriorate rapidly with a high probability of death.

Common initial symptoms include:

• High fever with a temperature usually higher than 38 degrees Celsius
• Influenza-like symptoms

Other early symptoms in some patients include:

• Diarrhoea
• Vomiting
• Abdominal pain
• Chest pain
• Bleeding from the nose and gums

Although some patients may present without any respiratory symptoms at first, manifestations in the lower respiratory tract are a common early feature of the disease. Many patients develop primary viral pneumonia, which does not appear to respond to antibiotics. The time between the patient becoming ill and developing signs of acute respiratory distress is often around six days, with a range of between four and thirteen days. Multiorgan dysfunction is also often observed in patients infected with the H5N1 strain of bird flu.

Who is most at risk?

For the moment, people who work of live in close proximity to infected birds are most likely to become infected with bird flu. Those who slaughter, defeather, butcher or prepare infected birds for consumption are particularly at risk, although there is evidence to suggest that people using untreated faeces from infected birds as fertilizer have also succumbed to the disease, as have children who play in areas where free-range poultry forage for food.

Bird Flu Treatment

For the moment, the primary treatment for bird flu is oseltamivir, commercially called Tamiflu. This prevents the virus from escaping from the cells where it is hosted, although it is unclear how effective Tamiflu will be against the H5N1 strain of bird flu. There is evidence to suggest that bird flu is already developing a resistance to Tamiflu, so use of Relenza as an alternative antiviral treatment may be necessary.

Unfortunately, for best results, both drugs must be administered within 48 hours of symptoms developing. This is likely to prove very difficult to achieve in the event of a bird flu pandemic, as both drugs are in extremely short supply.