The World Health Organization (WHO) has said there is "an urgent need to co-ordinate all international efforts" to tackle the Zika virus. The health arm of the UN declared that the situation meets the conditions for a "public health emergency of international concern", signalling the seriousness of the outbreak.

Experts are concerned at the pace and extent the virus is spreading, and it is linked to thousands of cases of microcephaly, or underdeveloped brains in newborn babies. WHO director-general Dr Margaret Chan said the connection between microcephaly and the Zika virus is "strongly suspected but not yet scientifically proven".

Dr Chan confirmed: "I am now declaring that the recent cluster of microcephaly and other neurological abnormalities reported in Latin America following a similar cluster in French Polynesia in 2014 constitutes a public health emergency of international concern."

The statement by the WHO puts Zika in the same category as the Ebola virus, which has caused over 11,000 deaths since it broke out in West Africa in 2014. The latest epidemic killed five times as many people than all the previous outbreaks combined.

The declaration by the WHO should trigger fast-tracked international research and aid to put an end to the infection. The mosquito-borne virus is prevalent in South America, with an estimated 1.5 million Brazilians estimated to have caught it, according to a Reuters report. It is thought to be behind 3,700 cases of microcephaly in Brazil since October. Brazil is set to follow the US and ban blood donations from those affected by the virus.

The virus can only be spread via mosquitoes, but it has already made its way across 24 countries. At present, there is no treatment for Zika and according to the WHO, it could take a year to successfully develop a vaccine.

The health body has warned that there is a likelihood that Zika could "spread explosively". Brazil's Health Minister Marcelo Castro told Reuters: "Eighty percent of the people infected by Zika do not develop significant symptoms. A large number of people have the virus with no symptoms, so the situation is more serious that we can imagine".

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