Of the $222 million that the CDC allocated for domestic Zika response this year, about $200 million has been committed, Frieden said during a media roundtable in Washington. "The rest will be gone by the end of September."
The timing further raises the threat for high-risk states along the Gulf Coast, particularly if Congress again fails to act on the Obama administration's emergency funding request when lawmakers return to Washington next month.
"We're in peak mosquito season" — which typically lasts through October in the United States — and if transmission starts occurring more broadly, CDC “might not have the resources” to respond and send teams to support local and state officials, Frieden said.
The CDC has already issued unprecedented travel advisories for two areas in Florida where mosquitoes are actively spreading the virus: a one-square-mile section of Miami’s Wynwood neighborhood and a 1.5-square-mile zone in Miami Beach. Pregnant women are urged to stay out of both areas because of the danger Zika poses to a fetus.
Negotiations in Congress over a $1.9 billion Zika spending package fell apart in late June. Federal health officials have shifted money from elsewhere in the Department of Health and Human Services to fund the domestic response. That includes $38 million from fighting Ebola, $44 million from general public health emergency funds and, most recently, $81 million from programs at the National Institutes of Health and the Biomedical Advanced Research and Development Authority.
The money has gone to help states track the virus, provide assistance about birth defects caused by Zika and increase mosquito-control efforts. Within CDC itself, officials also have pulled resources from programs on immunization, disease infection and HIV outreach, including prevention treatment for people at risk of getting HIV, Frieden said.
Researchers continue to detail ever-graver consequences for babies born to mothers infected with Zika. A report from Brazil, published last week in the New England Journal of Medicine, described a newborn in Sao Paolo who had Zika virus in his blood for more than two months. While the baby had no obvious illness or visible birth defects at birth or when doctors examined him at about eight weeks, by six months he had developed severe Zika-related brain damage.
The first trimester of pregnancy is thought to be when Zika infection poses the greatest risk. In this case, however, the baby’s mother was infected late in her second trimester.
At the same time, the virus continues to spread to the rest of the world. The latest outbreak is in Singapore, a Southeast Asia travel hub, which typically has 500 full-time inspectors working to eliminate standing water where mosquitoes can breed. The fact that Zika is spreading there, with at least 82 cases now confirmed, shows how "it's going to be really tough" for other places to control, Frieden said.
During the coming weeks in the United States, Frieden expects there will be more cases of infants born with Zika-related neurological problems. As of mid-August, 17 babies infected in utero had been diagnosed with microcephaly, a condition defined by an abnormally small head and often serious brain damage.
In hard-hit Puerto Rico, the CDC estimates that 6,000 to 10,000 pregnant women will become infected during this mosquito season and that at least 100 to 270 infants will be born with microcephaly.
Without additional funding, Frieden said, the CDC won’t be able to undertake key projects to better understand and control the virus, including Zika’s long-term impact on infants and diagnostics to identify if a person has been previously infected.
In Puerto Rico, the agency also won't be able to help the island establish its own vector control program. Without one, the island has not been able to conduct effective surveillance, mosquito control or public engagement, even though Puerto Rico is experiencing a Zika epidemic and has had a history of other vector-borne diseases.
Frieden said the few additional cases that have surfaced in other parts of South Florida are considered single cases that don’t represent a greater spread of the virus.
The travel advisories will be lifted after 45 days with no new cases from local transmission — the equivalent of three mosquito incubation periods. The Wynwood area is about halfway through that period, he said, but Miami Beach is still experiencing new cases.