Health officials are investigating a cluster of possible Zika cases in Miami Beach, suggesting that transmission of the virus by mosquitoes is more widespread in one of the nation’s more populous counties than originally thought, and that efforts to contain it are falling short.
At least one other area of Miami-Dade County is also under investigation for a possible cluster of mosquito-borne transmission of Zika, according to people familiar with the investigations.Transmission of the #Zikavirus by mosquitoes is more widespread in Miami than originally thought Click To Tweet
The revelations come after Florida health officials had identified one neighborhood north of downtown Miami as a transmission zone. Health officials are likely now to expand that zone, where they have warned the public that mosquito-borne transmission of Zika is occurring, but it wasn’t clear how large the new zone will be, these people said.
Deliberations are under way over whether to designate small pockets or one large one, these people said. The news, reported by the Wall Street Journal, is just what many in Florida have feared–that the outbreak would spread, hurting the state’s tourist-dependent economy, said Susan MacManus, a University of South Florida political-science professor.
“The business community is very alarmed and of course, so are health officials,” she said.
Florida health officials had been reporting for more than two weeks that they believed mosquitoes were transmitting Zika only within a small area of roughly one square mile in the Wynwood neighborhood, just north of downtown Miami.
“This remains the only area of the state where the department has confirmed there are local transmissions of Zika,” the department said in a release Thursday.
The Centers for Disease Control and Prevention has advised pregnant women to avoid that area. The virus can cause serious birth defects if a woman contracts it while pregnant, including abnormally small heads associated with severe brain damage.
“It’s very, very scary to know that more and more places are being infected with Zika,” said Fiorella Olcese, who is 38 years old and 29 weeks pregnant with her first baby.
Already Ms. Olcese, who lives in Miami’s Brickell neighborhood, was being “super careful,” dressing in jeans, long sleeves, a hat and rain boots to go outside to walk her dog. Melissa Berthier, a spokeswoman for the city of Miami Beach, said that:
“as of yet, the Department of Health hasn’t confirmed any cases in Miami Beach” to the city.
Regardless, she said the city would continue pursuing anti-mosquito measures, which began in January and ramped up in June.
Separately, U.S. researchers have found that Zika can attack special populations of brain cells in adult mice in the part of the brain involved in learning and memory, raising new questions about how the virus may be impacting millions of adults who have been infected with the virus.
The findings, published on Thursday in the journal Cell Stem Cell, are the first to look at whether Zika can attack the same kinds of cells in adult mice that they do in fetal mice. Experts cautioned that the findings are preliminary and may not have any correlation to how Zika impacts human brain function, but they suggest the need for follow-up research.
Steve’s Take: I’ve been reporting on the Zika story for well over a year in this paper and continue to be completely dumbfounded by what still seems to be a “not my problem” attitude by our federal leadership, many of whom are still on their seven-week holiday from Washington and us citizens. Maybe they’ll someday wrap their partisan heads around the fact that we have a health emergency here and now, that calls for action, not endless, meaningless wrangling.
But let’s recap:
So Zika is not only here in the U.S., but transmission of the virus by mosquitoes in the Miami area is more widespread than originally thought. How long cases will continue to occur is also unknown.
The CDC has said it expects Zika outbreaks to resemble those of similar viruses, like dengue and chikungunya, because they are carried by the same mosquito. In 2009, three dengue cases were found in Key West, the first occurrence of dengue in Florida since 1934.
Although the Florida Keys Mosquito Control District rolled out a huge campaign, employing helicopter sprayers, backpack foggers, larvicide and teams of officers, the outbreak lasted two years.
During that outbreak, 90 symptomatic cases were confirmed and blood samples showed that 5% of Key West had been infected. Key West is a small vacation island with a wealthy, highly educated population.
Miami-Dade County, on the other hand, has a population of 2.7 million. Applying that same 5% infection rate and I come up with 135,000 Zika cases in Miami-Dade. There is currently no vaccine for Zika, thanks in large part to our inept congressional bunch.
Zika is spreading in the U.S., which is an irrefutable fact. At least we mostly know what we’re facing as far as the likely damage may be to our country’s health, right?
Concerns over the Zika virus have focused on pregnant women due to mounting evidence that it causes brain abnormalities in developing fetuses. However, new research in mice from scientists at The Rockefeller University (New York City) and La Jolla Institute for Allergy and Immunology suggests that certain adult brain cells may be vulnerable to infection as well.
Among these are populations of cells that serve to replace lost or damaged neurons throughout adulthood, and are also thought to be critical to learning and memory. “
This is the first study looking at the effect of Zika infection on the adult brain,” says Joseph Gleeson, adjunct professor at Rockefeller, head of the Laboratory of Pediatric Brain Disease, and Howard Hughes Medical Institute (Chevy Chase MD) investigator. “Based on our findings, getting infected with Zika as an adult may not be as innocuous as people think.”
Although more research is needed to determine if this damage has long-term biological implications or the potential to affect behavior, the findings suggest the possibility that the Zika virus, which has become widespread in Central and South America over the past eight months, may be more harmful than previously believed.
The new findings were published in Cell Stem Cell on August 18.
“Zika can clearly enter the brain of adults and can wreak havoc,” says Sujan Shresta in a press release. Shresta, a professor at the La Jolla Institute of Allergy and Immunology added, “But it’s a complex disease–it’s catastrophic for early brain development, yet the majority of adults who are infected with Zika rarely show detectable symptoms. Its effect on the adult brain may be more subtle, and now we know what to look for.”
The researchers say a healthy brain could fight off potential effects of Zika that are yet to be fully understood, but people with weakened immune systems may be vulnerable.
“In more subtle cases, the virus could theoretically impact long-term memory or risk of depression, but tools do not exist to test the long-term effects of Zika on adult stem cell populations,” said Gleeson.
Gleeson and his colleagues suspected that if Zika can infect fetal neural progenitor cells, it wouldn’t be a far stretch for them to also be able to infect these cells in adults.
In a mouse model engineered by Shresta and her team to mimic Zika infection in humans, fluorescent biomarkers lit up to reveal that adult neural progenitor cells could indeed be hijacked by the virus.
“Our results are pretty dramatic–in the parts of the brain that lit up, it was like a Christmas tree,” says Gleeson. “It was very clear that the virus wasn’t affecting the whole brain evenly, like people are seeing in the fetus. In the adult, it’s only these two populations that are very specific to the stem cells that are affected by virus. These cells are special, and somehow very susceptible to the infection.”
The researchers found that infection correlated with evidence of cell death and reduced generation of new neurons in these regions. Integration of new neurons into learning and memory circuits is crucial for neuroplasticity, which allows the brain to change over time. Deficits in this process are associated with cognitive decline and neuropathological conditions, such as depression and Alzheimer’s disease.
Two quotes from researchers in the Cell Stem Cell study are dispositive of my latest, personal concern for all of us:
- “Our data therefore suggest that adult as well as fetal neural stem cells are vulnerable to Zika virus neuropathology;” and
- “…there may in fact be consequences of exposure in the adult brain.”
So a scientifically reasoned scenario could be (not will be, quite yet) we adults get infected with Zika, we have at most a mild case of it, recover and think that’s the end of our brush with it. Only later do we fall prey to Zika-induced early dementia, Alzheimer’s, epilepsy, personality changes and depression.Steve's Take: Contact your representatives and ask them to fund a #Zikavirus vaccine Click To Tweet
For months I’ve been urging you to contact your representatives and plead with them to provide sufficient funding to help make a Zika vaccine. We’re the United States, after all. We can do this. What is it about this “health emergency” (World Health Organization‘s words) don’t they get there in those hallowed, Capitol Hill suites? Hypocritical; irresponsible. (My words.)
Note: This article included material provided by Rockefeller University. Note: material may have been edited for length and content. For further information, please contact the cited source.