UNITED NATIONS (CMC) — The head of the United Nations health agency has issued a new warning on the mosquito-borne Zika virus, saying that “the more we know the worse things look”.

World Health Organization (WHO) Director-General, Dr Margaret Chan, said that in less than a year, the status of Zika has changed from “a mild medical curiosity” to a disease with severe public health implications.

She, however, said the knowledge base is building very rapidly, thanking all countries and their scientists who have worked to help build up the evidence base.

“The virus is currently circulating in 38 countries and territories. On present knowledge, no one can predict whether the virus will spread to other parts of the world and cause a similar pattern of fetal malformations and neurological disorders.

“If this pattern is confirmed beyond Latin America and the Caribbean, the world will face a severe public health crisis,” Chan warned.

According to WHO, the world was alerted to the first appearance of Zika in the Western Hemisphere on May 7, 2015, when Brazil confirmed that a “mysterious outbreak” of thousands of cases of mild disease with rash was caused by the Zika virus.

In July last year, the country then reported an increase in cases of Guillain-Barré syndrome (GBS), followed by an unusual increase in microcephaly among newborns in late October.

“The possibility that a mosquito bite could be linked to severe fetal malformations alarmed the public and astonished scientists,” Dr Chan said.

“The association with Guillain-Barré syndrome and other severe disorders of the central nervous system has expanded the risk group well beyond women of child-bearing age. We now know that sexual transmission of the virus occurs.”

She detailed how a pattern has emerged in which initial detection of virus circulation is followed, within about three weeks, by an unusual increase in cases of GBS.

Detection of microcephaly and other fetal malformations comes later, as pregnancies of infected women come to term, Chan said.

To date, she said 12 countries and territories have now reported an increased incidence of GBS or laboratory confirmation of Zika infection among GBS cases.

Chan said additional effects on the central nervous system have been documented, notably inflammation of the spinal cord and inflammation of the brain and its membranes.

Since February 1, she said WHO has convened seven international meetings and published 15 documents that translate the latest research into interim practical guidance to support Latin American and Caribbean, as well as other, countries as they respond to the Zika outbreak and its neurological complications.

Several Caribbean countries have reported cases of the Zika virus including Barbados, Dominica, Grenada, Guyana, Jamaica, Suriname, and Trinidad and Tobago.

WHO said more than 30 companies are working on, or have developed, potential new diagnostic tests and  23 projects are being worked on by 14 vaccine developers in the United States, France, Brazil, India, and Austria.

WHO estimated that at least some of the projects will move into clinical trials before the end of this year, but several years may be needed before a fully tested and licensed vaccine is ready for use.