Zika virus, already in Houston, poses global health threat

What you need to know about the Zika virus. What you need to know about the Zika virus. Image 1 of / 29 Caption Close Zika virus, already in Houston, poses global health threat 1 / 29 Back to Gallery

The mosquito-borne Zika virus that causes birth defects and reached Houston this month was identified Thursday as "spreading explosively" in the Americas during a World Health Organization briefing.

WHO Director-General Dr. Margaret Chan will convene a committee on Monday to determine whether the outbreak amounts to an international public health emergency. Cases have been reported in 23 countries.

The virus first identified in a monkey in the Zika forest of Uganda in 1947 has recently emerged with a vengeance in South and Central America, infecting millions. Zika is suspected in thousands of cases of microcephaly, a birth defect that causes newborns to have abnormally small heads and neurological complications.

FOLLOWING ZIKA: Things you need to know about the Zika virus

The U.S. Centers for Disease Control and Prevention confirmed Houston's first case this month. A traveler returning from El Salvador in November fell ill with fever, rash and joint pain. The agency determined that she brought the illness into this country following a month of investigation and testing.

Zika is part of a family of viruses that includes yellow fever, Dengue virus and West Nile virus. It is spread by two types of Aedes mosquitoes, both of which are found here.

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, said in a recent Chronicle story that he predicts that Zika will gain a foothold in our region.

"It's just a matter of time before it hits the U.S. and the Texas Gulf Coast," he said.

The WHO committee will offer advice about "the appropriate level of international concern" and about "recommended measures that should be undertaken in affected countries and elsewhere," Chan said Thursday.