The Irish Blood Transfusion Service is asking anyone who has visited the United States or Canada since the end of June not to give blood for at least 28 days after returning home. This is due to concerns about the West Nile Virus.
The disease, which first appeared in North America in 1999, can be caught by humans if they are bitten by an infected mosquito. The West Nile Virus is carried from infected birds to humans by mosquitoes. It cannot, however, be transmitted directly between humans. An infected person normally shows few signs of illness. Most suffer little more than mild flu-like symptoms, but the virus is present in their blood.
Infections in Europe are very rare, and no case has ever been reported in either Ireland or Britain. However, the National Disease Surveillance Centre (NDSC) says it is still important that people travelling to North America are aware of the infection potential.
Dr Paul McKeown, a specialist in public-health medicine at the NDSC, said earlier this summer that four out of five people bitten by a mosquito would have no symptoms at all, while about 20 per cent would develop a mild flu-like illness.
Fewer than 1 per cent develop more severe disease "which produces headache, high fever, stiff neck and sore eyes", he said.
In the rare event of the brain tissue itself becoming inflamed (encephalitis), symptoms include muscle weakness, disorientation, convulsions and coma.
In the US this year, cases have been reported in 26 states, including Florida, Pennsylvania and Vermont. No cases have been recorded in New York, California or Massachusetts.
