Several patients in Northern Ireland have been diagnosed with the Zika virus as the battle to stop the global spread of the mosquito-borne disease continues.

A spokesperson for the Public Health Agency (PHA) told The Independent fewer than five cases had been confirmed since 2015, with some being historic.

“All have a history of travel to Zika-affected areas,” she added. “There is no specific treatment for Zika virus disease other than supportive measures, such as analgesics and hydration, for those who have symptoms and patients affected are advised to rest and drink plenty of fluids.”

Several English and Scottish people have also been diagnosed with the virus, which causes mild symptoms including a rash, fever and headache in most cases.

Zika virus could spread to Europe say WHO

Zika does not occur naturally in the UK but can be “imported” by people who have travelled abroad to countries where transmission is active.

The disease has been declared a global public health emergency by the World Health Organisation after it was linked to birth defects.

Previously regarded as localised and relatively harmless, a massive outbreak that started last year in Brazil (see the chart below) brought the illness sharply into focus because of emerging links to microcephaly – a congenital disorder that can shrink unborn babies’ brains and heads and reduce life expectancy.

There is no known cure or vaccine for the virus, which the was believed to be exclusively spread by mosquitos until tests confirmed it can also be transmitted through sexual contact.

Zika has spread quickly since April, with millions of cases forecast this year in South America alone and patients reported in dozens of countries including th US, Philippines and Malaysia.

The Zika virus - in pictures Show all 5 1 /5 The Zika virus - in pictures The Zika virus - in pictures A three-month-old, who has microcephaly, in Recife, Brazil. A rise in microcephaly cases is thought to have been caused by the spread of the Zika virus in affected countries Getty Images The Zika virus - in pictures A mother holds her baby who has microcephaly Getty Images The Zika virus - in pictures A five-month-old baby, who has microcephaly, in Recife, Brazil Getty Images The Zika virus - in pictures A pediatric infectologist examines a two-month-old baby, who has microcephaly, in Recife, Brazil Getty Images The Zika virus - in pictures A baby affected with microcephaly

The outbreak has prompted a series of travel alerts for pregnant women visiting areas of transmission, with expectant mothers urged to protect themselves from mosquito bites or avoid affected zones.

As well as microcephaly, Zika has been associated with other neurological disorders including serious brain and spinal cord infections, and the long-term health consequences of are unclear.

Active outbreaks have been reported in at least 58 countries or territories, most of them in the Americas, with Brazil the worst-affected according to the US Centres for Disease Control and Prevention.