Chan said that countries "dropped the ball" on mosquito control in the 1970s and called the ending of effective control practices a "massive policy failure."
She said that abandoning policies that kept mosquito numbers down set the stage for a resurgence of a disease that had "slumbered" for six decades in Africa and Asia, only to "wake up on a new continent to cause a global health emergency."
Chan also said that family planning and sex education failures illustrated an "extreme consequence" of the disease, as causal links between the mosquito-borne virus and microcephaly, a condition which results in babies being born with severe brain abnormalities, become scientific consensus.
"The possibility that a mosquito bite during pregnancy could be linked to severe brain abnormalities in newborns alarmed the public and astonished scientists," she told the Assembly, the supreme decision-making body of the WHO, in Geneva.
In April, the WHO confirmed
that the virus causes microcephaly and Guillain-Barre syndrome, a condition which attacks nerve cells in the victim's nervous system and can lead to paralysis.
Latin American and the Caribbean have the highest proportion of unintended pregnancies globally, she said.
'The world is not prepared to cope'
Lambasting failures to prepare for global outbreaks with forward-thinking policies like ongoing mosquito control, she said that all the organization could do to protect women of childbearing age is "offer advice. Avoid mosquito bites. Delay pregnancy. Do not travel to areas with ongoing transmission."
She said that increased cases of dengue, chikungunya and Zika were evidence of a "dramatic resurgence" from emerging and re-emerging infectious diseases, exacerbated by urbanization and the excellent conditions for outbreaks that this population movement presents.
"For infectious diseases, you cannot trust the past when planning for the future... The world is not prepared to cope."
She added that "in an interconnected world... few threats to health are local anymore."
Recent efforts in affected countries, such as Brazil, have led to innovative mosquito control techniques, such as genetic modification
and mosquito-killing billboards
However, Zika's ongoing spread is threatening to have far-reaching consequences, with leading Canadian public health professor Amir Attaran, writing in the Harvard Health Review that the summer Olympic Games in Rio de Janeiro should be postponed or moved to prevent "a foreseeable global catastrophe."
IOC President Thomas Bach, meanwhile, said that the Games, which open in early August, will go ahead.
"We are working closely with the World Health Organization," he told CNN. "They are the ultimate authority... and we trust the (WHO) 100%."