In findings today that raise more concerns about Zika sexual transmission, experiments on pregnant mice showed that the virus replicates in vaginal tissue for several days after infection and can spread to fetal brains and that replication in the genital tract might be more robust than in other sites in the body.

In other developments, Florida Gov. Rick Scott announced that he would be in Washington, D.C., the day Congress returns to work to press for immediate Zika action, while the World Health Organization (WHO) said so far no Olympic-related Zika cases have been reported, and US officials announced support for developing two point-of-case tests for Zika virus.

Vaginal persistence, spread to fetal mice

The team that conducted today's study, based at Yale University, said though the Zika immune response in mice is different than in people, the findings raise key questions about the impact of sexual transmission.

Health officials have been warning women and their partners about the risk of sexual spread as a cause of systemic infections. However, the new findings hint that the spread to fetuses through the genital route might be more direct. The group reported their findings in Cell.

To learn more about vaginal Zika replication, the researchers looked at Zika replication in vaginal tissue in wild-type mice and ones genetically modified to be susceptible to the virus. Mice generally aren't vulnerable, but researchers have developed and used modified ones to study the virus.

After experimentally infecting the mice, some of which were pregnant, the researchers saw significant replication in vaginal tissue that persisted up to 4 to 5 days, longer than other sites of infection. Also, in the pregnant mice, they detected Zika virus in the brains of the fetuses as well as weight loss.

Surprisingly, vaginal virus replication and persistence, along with virus spread to fetal brains, was seen even in the wild-type mice.

So far it's not clear if sexual Zika transmission poses a different risk of birth defects than mosquito-borne transmission, the team wrote. However, the mice findings hint at negative consequences from vaginal Zika exposure early in pregnancy.

Florida developments

In a statement today, Scott said in the time since Congress broke for its 7-week summer vacation, Florida recorded 43 local Zika cases in four of its counties. "The Zika virus demands immediate federal action, and I will impress upon our congressional members the urgency to protect our residents and visitors," he said.

Over the summer, Scott authorized $26 million in emergency state funds to battle the virus, of which $23 million has already been allocated for mosquito control and preparedness efforts.

Scott urged lawmakers to not let partisan politics overshadow the health and safety of Florida families.

The Florida Department of Health (Florida Health) still believes active transmission is occurring in two small areas in Miami-Dade County, the Wynwood neighborhood and a portion of Miami Beach. Officials, however, are investigation the possibility of local spread in Pinellas and Palm Beach counties.

Florida Health did not report any new local cases today.

WHO: Olympic-related cases still possible

The WHO today said so far health authorities haven't reported any lab-confirmed Zika infections in athletes or others associated with the Olympics in Brazil, according to its weekly Zika update. The agency added, however, that a few cases may still occur, given that the Olympics ended on Aug 21 and most people are still in their 1-week incubation period. The WHO said it is closely monitoring the situation.

No new countries or territories have reported local mosquito-born Zika infections since the WHO's report last week, which is a first. However, three more countries reported their first Zika-related birth defects: Costa Rica, the Dominican Republic, and Haiti.

Regarding a spate of Zika cases reported this summer from Guinea-Bissau, the WHO said genetic sequencing results from four cases are still pending. Global health officials are eager to know whether the virus is the strain circulating in the Americas, which, if confirmed, would signal further extension of the outbreak into Africa. The other possibility is that it is the African strain that has been endemic in the region for several decades.

Health officials are still investigating five microcephaly cases reported by Guinea-Bissau.

CDC on affected pregnancies, other infections

In its weekly update on Zika case numbers today, the US Centers for Disease Control and Prevention (CDC) said that, according to two pregnancy registries, 55 more pregnant women in US states have been infected by Zika virus, as well as 121 more in US territories. The totals are now at 584 and 812, respectively.

No new Zika-related pregnancy outcomes were reported for the states or territories. The numbers stayed at 16 babies born with Zika-related birth defects in the states, along with 5 pregnancy losses. For the territories, the total remained at 1 baby born with birth defects and 1 Zika-linked pregnancy loss.

Also, the CDC reported 227 more travel-related Zika cases in US states, lifting the overall total to 2,487. In the US territories, the number of local Zika cases climbed to 8,968, most of them from Puerto Rico, which over the past several weeks has been experiencing a surge in infections.

HHS supports 2 point-of-care tests

The US Department of Health and Human Services (HHS), meanwhile, recently announced funding to develop two point-of-care diagnostic tests for Zika virus infection, both of which could provide a result in the doctor's office within 30 minutes. They are lateral-flow serologic tests to identify Zika antibodies.

Similar to home pregnancy tests, the tests use a drop of blood instead of a drop of urine. They don't need to be sent to a lab for results, which can speed diagnosis.

On Aug 23 HHS announced a $7 million contract with OraSure Technologies, based in Bethlehem, Pa., through the agency's Assistant Secretary for Preparedness and Response (ASPR). The funding is intended to support development over the next 3 years, covering all steps needed to apply for Food and Drug Administration (FDA) approval.

The contract includes an option for up to $16.6 million in funding through 2022 and for the company to request that the FDA issue an emergency use authorization (EUA).

Richard Hatchett, MD, acting director of ASPR's Biomedical Advanced Research and Development Authority (BARDA), said in the statement that federal officials are working aggressively with the private sector to bring Zika diagnostics, vaccines, and blood screening tools to protect the public. "Pregnant women and others at risk who are recommended for Zika testing need accurate diagnostic tests that provide results quickly to guide decisions about their treatment."

Today HHS in a separate statement announced funding for a second company—Chembio Diagnostic Systems, based in Medford, N.Y. —to develop a similar test. That award would provide $5.9 million over the next year, covering continued development, manufacturing preparations, and a clinical trial to assess sensitivity and specificity. All are steps needed to apply for FDA clearance.

HHS's contract with Chembio could be extended for a total of 3 years and up to $13.2 million.

See also:

Aug 25 Cell abstract

Aug 25 Yale University news release on the study

Aug 25 Gov Rick Scott statement

Aug 25 Florida Health update

Aug 25 WHO Zika situation report

Aug 25 CDC update from Zika pregnancy registries

Aug 25 CDC update on Zika-affected pregnancies and births

Aug 25 CDC state and territory Zika case counts

Aug 23 HHS press release on OraSure Zika test development

Aug 25 HHS press release on Chembio diagnostic test support