Tamiflu's role in helping keep bird flu at bay

For how long is Tamiflu effective?

Tamiflu can be used as a treatment for influenza or to prevent it.

As a treatment, one capsule is taken twice a day.

For prevention, one is taken per day. Tamiflu is not a vaccine; its protection lasts for 24 hours.

The Government has stockpiled enough of the drug to give one 10-capsule course each to 21 per cent of the population. Details of its use will not be finalised until a pandemic occurs, but it seems unlikely that it will be used preventively - other than to protect some people immediately following exposure to someone with flu symptoms.

Health Minister Pete Hodgson has said that except in that way, all public health advice is against using Tamiflu preventively in a pandemic.

Will it be safe to drink from rainwater tanks, given that birds can carry the flu?

Untreated water from rainwater tanks is expected to be free of bird droppings containing bird flu - but it may still be contaminated with other nasty bugs.

It is considered far more likely that pandemic influenza would be introduced to New Zealand by humans than birds.

Bird flu virus can survive in water for up to four days at 22C and more than 30 days at 0C.

Migratory waterfowl such as ducks and geese have been infected with the bird flu virus of greatest current concern, H5N1, but these kinds of birds do not migrate to New Zealand from Asia and Eastern Europe, the regions affected by the virus.

Migratory shorebirds do fly to New Zealand from Siberia and Alaska and some stop off in Asia on the way. They pose a much lower risk than waterfowl of transmitting bird flu.

This is because they shed less flu virus and mix less with poultry.

Tests on migratory shorebirds and nearby mallard ducks in New Zealand have not yielded any bird flu virus.

However, if the risk of bird flu from tank water remains a worry, consider treating the water. Then other potential pathogens from the droppings of birds, possums and rats on the roof will be killed or removed as well.

Sources: Ministry of Health, Biosecurity New Zealand, World Health Organisation.