An estimated 80% of people infected with the Zika virus have no symptoms, making it difficult for pregnant women to know whether they have been infected. The mosquito-borne virus has been linked to brain damage in thousands of babies in Brazil. There is no vaccine or treatment for Zika, which causes mild fever and rash.

US President Barack Obama called for rapid development of tests, vaccines and treatments to fight the virus that could spread to the United States in warmer months. US health officials are stepping up efforts to study the link between Zika virus infections and birth defects.

“The president emphasized the need to accelerate research efforts to make available better diagnostic tests, to develop vaccines and therapeutics and to ensure that all Americans have information about the Zika virus and steps they can take to better protect themselves from infection,” the White House said in a statement.

National Institutes of Health director Dr. Francis Collins cited a Lancet study published on 14th January, in which researchers predicted the Zika virus could be spread in areas along the East and West Coasts of the United States and much of the Midwest during warmer months, where about 200 million people live.

National Institutes of Health director Dr. Francis Collins said, “it is now critically important to confirm, through careful epidemiological and animal studies, whether or not a causal link exists between Zika virus infections in pregnant women and microcephaly in their newborn babies.”

The US Centers for Disease Control and Prevention also announced the new instructions for pediatricians treating infants, whose mothers may have been exposed to the virus during pregnancy. In the guidelines, the CDC made it clear that it considers the Zika virus as a nationally notifiable condition and instructs doctors to contact their state or territorial health departments to facilitate testing of potentially infected infants.

Dr. Kathryn Edwards of Vanderbilt University, who serves on the American Academy of Pediatrics’ committee on infectious disease, said that the guidelines are intended to help establish whether Zika causes microcephaly and to help pregnant women who may have been infected with the virus. Microcephaly is a lifelong condition with no known cure, the CDC website said.

By Premji