The spiralling crisis surrounding the Zika virus is due to decades of policy failures on mosquito control and poor access to family planning services, the World Health Organization said on Monday.

“The spread of Zika... (is) the price being paid for a massive policy failure that dropped the ball on mosquito control in the 1970s,” WHO chief Margaret Chan told the opening of the UN health agency’s annual assembly.

Those failures have allowed the mosquito-borne virus to spread rapidly and create “a significant threat to global health”, Chan told some 3,000 delegates gathered from WHO’s 194 member countries.

Experts agree that Zika is behind a surge in Latin America in cases of the birth defect microcephaly -- babies born with abnormally small heads and brains -- after their mothers were infected with the virus.

The virus, which also causes the rare but serious neurological disorder Guillain-Barre Syndrome, in which the immune system attacks the nervous system, is mainly spread by the Aedes aegypti mosquito but has also been shown to transmit through sexual contact.

Programmes in the 1950s and 60s targeted the aegypti in a bid to prevent the spread of dengue and yellow fever, which it also spreads, and all but eradicated the mosquito species from Central and South America.

But when the programmes were discontinued in the 1970s, the mosquito returned.

Chan also decried policy failures in the realm of reproductive rights.

Many of the hardest-hit countries in the ongoing Zika outbreak are conservative Catholic, and she warned their “failure to provide universal access to sexual and family planning services” had exacerbated the crisis.

With the virus now present in 60 countries, countless women who may want to delay pregnancy have no access to contraception, and even fewer to abortion.

Chan pointed out that Latin America and the Caribbean “have the highest proportion of unintended pregnancies anywhere in the world”.

“With no vaccines and no reliable and widely available diagnostic tests to protect women of childbearing age, all we can offer is advice,” she told the assembly.

“Avoid mosquito bites, delay pregnancy, do not travel to areas with ongoing transmission.”

In Brazil, the hardest-hit country, more than 1.5 million people have been infected with Zika, and nearly 1,400 cases of microcephaly have been registered since the outbreak began last year.

Researchers estimate that a woman infected with Zika during pregnancy has a one percent chance of giving birth to a baby with the birth defect.

‘Not prepared to cope’

Zika is not new. The African strain of the virus was discovered in Uganda’s tropical Zika forest in 1947, and an Asian strain has long circulated on that continent, without sparking concern.

On its own Zika is fairly benign, like a bad cold or a mild flu.

But when the Asian strain jumped to Latin America last year, it suddenly wreaked havoc in a population never before exposed to the virus.

Alarmingly, the WHO last week said the Asian strain was now for the first time spreading locally in an African country -- Cape Verde, raising concern over what impact the strain might have on the population on that continent.

“The rapidly evolving outbreak of Zika virus warns us that an old disease that slumbered for six decades in Africa and Asia can suddenly wake up ... on a new continent to cause a global health emergency,” Chan said.

Zika is not the only virus that has taken us by surprise.

Chan pointed especially to the recent Ebola disaster that killed more than 11,000 people in West Africa, which revealed “the absence of even the most basic infrastructure” to deal with the outbreak.

Chan offered Monday’s assembly “a stern warning”.

“What we are seeing now looks more and more like a dramatic resurgence of the threat from emerging and re-emerging infectious diseases,” cautioning: “The world is not prepared to cope.”