It's a virus that has led to the World Health Organisation declaring an international emergency and the UK introducing bans on travellers making blood donations but what is zika?

The virus first came to global attention earlier this year after cases were discovered in Brazil.

Holidaymakers have now been warned that the virus could spread to Europe by the summer and pregnant women have been advised to avoid travelling to the Olympics in Rio.

It has been confirmed that two people in Ireland have the virus and the NHS has now banned travellers from giving blood for a month after returning from zika hit countries.

Men have also been advised to wear condoms for a month after returning from infected countries.

Here is everything you need to know about the zika virus.

- the virus is linked to birth defects in Brazil and the Americas

- it is caused by a virus transmitted by Aedes mosquitos. The Aedes mosquitos also transmit dengue, chikungunya and yellow fever.

- countries affected so far by the virus include America, Africa and the Oceana and Pacific Islands

- signs and symptoms of the virus include headache, conjunctivitis, skin rashes, mild fever and muscle and joint pain

- the best form of prevention from the zika virus is protection against mosquito bites

- no specific treatment or vaccine is currently available for the virus

- the virus was first identified in Uganda in 1947 in rhesus monkeys. It was first identified in human in Uganda in 1952.

- researchers believe the virus may have arrived in Brazil during the 2014 World Cup.

- women in Brazil and Colombia have been warned not to get pregnant until the effect of Zika on unborn children is better understood.

- pregnant women have been advised not to travel to Brazil and 13 countries in Latin America and the Caribbean where the virus is quickly spreading.