Possible Active Zika Transmission in US Under Investigation as CDC Updates Guidelines

*Updated on 7/28/2016 at 3:21 PM EST

The Centers for Disease Control and Prevention (CDC) has been working alongside the Florida Department of Health (DOH) to investigate two possible non—travel-related cases of Zika virus infection in two separate counties. Now, health officials are confirming two new non–travel-related Zika cases identified in Florida, bringing the total to four cases.

The first case had been confirmed in Miami-Dade County, Florida, on July 19, 2016. The individual had no recent history of travel to Zika-endemic countries. Just two days later, a second, unrelated case was reported in Broward County, Florida. These cases were reported shortly after an elderly patient in Salt Lake City, Utah, died with an unusually high viral load of Zika. The patient had recently returned from a trip to a country with active Zika transmission. What has baffled health officials in Utah is that one of the decedent's family members, who had no travel-history to a Zika-endemic country, had contracted the virus while caring for the patient. The Florida DOH has confirmed that the third and fourth newly diagnosed non—travel-related Zika cases are in pregnant women.

A rise in the number of Zika infections in individuals who have no history of travel to Zika-endemic areas gives way to the question: is Florida experiencing active Zika transmission? The answer to this question remains to be seen; meanwhile, the Florida DOH and the CDC are currently investigating other possible modes of infection transmission through which these individuals may have contracted the virus. In the meantime, the US Food and Drug Administration is urging that blood establishments stop blood collection in the infected counties "until the blood establishments implement testing of each individual unit of blood collected in the two counties with an available investigational donor screening test for Zika virus RNA or until the blood establishments implement the use of an approved or investigational pathogen inactivation technology." Furthermore, the FDA also recommends that Florida counties in close proximity to those with possible active Zika transmission implement similar precautions.

This news comes on the heels of the end of Zika epidemic in a country which had previously been reported to have the second highest prevalence of the virus: Colombia. The virus had been actively circulating the South American country since September 2015, during which time 8,826 Zika cases were confirmed through lab testing. The Ministry of Health decided to declare the end of the epidemic after they observed a steady drop in new cases. As with the Ebola epidemic, although the Zika epidemic is declared over, the Ministry of Health expects to see sporadic cases throughout the country.

CDC Updates Zika Guidance

News of the first potentially locally-acquired Zika cases has come with additional precautions from the CDC, regarding virus transmission. As a result of newly available data, which indicate that pregnant women infected with the Zika virus may exhibit longer periods of viremia, the CDC has increased the recommended Zika testing period from 7 days to 14 days after viral exposure. The CDC advises that all pregnant women exposed to the virus be tested, regardless of whether or not they experience Zika-like symptoms. Previously, the virus was thought to only be present in an individual’s blood for seven days after symptom onset.

Additionally, the CDC has also updated its guidance in regards to Zika infection prevention. In light of the recent confirmation of the first case in which a female sexually transmitted the Zika virus to a partner, the amendment "expands CDC's definition of sexual exposure to Zika to include sex without a barrier method (including male or female condoms, among other methods) with any person-- male or female-- who has traveled to or lives in an area with Zika." In a statement, the CDC confirms that Zika transmission from a female to a sex partner is "uncommon and... unlikely to result in serious side effects;" however, the CDC advises precautionary methods among pregnant women who have female sex partners with recent history of travel to or residence in a Zika-endemic region. As such, consistent use of adequate barrier methods during all sexual encounters is advised.

In an exclusive interview with Contagion, Stephen Redd, MD (RADM, USPHS), director of the Office of Public Health Preparedness and Response (OPHPR) at the CDC, expressed his concerns regarding protecting Americans from Zika. He stated, “the US government response to Zika right now is really operating on a shoestring.” Likewise, in an interview with TIME magazine, CDC Director Tom Frieden, MD, warned, “Without additional resources, this is like fighting a fight with one hand tied behind our backs.”

With the confirmation of non—travel-related cases of Zika infection and the lack of adequate funding, it seems that Zika efforts may become more stagnant in the near future.