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CDC: Zika Findings "Not Reassuring"

The Zika virus under a microscope
Now identified in 32 countries and islands in the Americas alone, the Zika virus
may spread faster than previously thought and potentially cause greater harm.

All of the cases of Zika virus infection suspected in Brazil last year -- as many as 1.3 million -- are believed to have originated with a single infected person who entered the country in 2013, a leading research scientist said last week.

Halting the epidemic is likely to take years, said Dr. Aimee Ferraro, and will extend across all boundaries and borders to involve medical, scientific and environmental specialists. On Wednesday, the CDC announced new evidence that the virus can cause "severe fetal brain defects."

What makes the epidemic so different is that most people who are infected won’t know it and may not even develop symptoms. But it can be hazardous to pregnant women and their developing offspring -- most prominently, through  a condition known as microcephaly -- and it is "spreading explosively," according to the World Health Organization.

The epidemic is abetted by those who become infected while travelling to places where Zika is prevalent, and then carry it back to their home countries.

“Interestingly, 80 percent of these cases will not be diagnosed,” Ferraro said. “And that’s a big problem, because these imported cases could result in local spread of the virus in the United States, Europe, Australia (and) other places where we don’t normally see Zika.”

Ferraro, an epidemiologist and CDC-contributor based in Peru, made the observations at an April 7 webinar hosted by Walden University.

At a White House briefing four days later, Dr. Anne Schuchat of the CDC noted that new findings are unfurling at a rapid pace: "We continue to be learning pretty much every day, and most of what we're learning is not reassuring.

"We have learned that the virus is linked to a broader set of complications in pregnancy, not just the microcephaly, but also prematurity, eye problems and some other conditions.  We have learned that the mosquito vector, the Aedes aegypti mosquito, is present in a broader range of states in the continental U.S." -- 30, instead of 12.

On Wednesday, more news came in a statement from CDC Director Dr. Tom Frieden, as he released the results of recent

research: “This study marks a turning point in the Zika outbreak.

"It is now clear that the virus causes microcephaly.  We are also launching further studies to determine whether children who have microcephaly born to mothers infected by the Zika virus is the tip of the iceberg of what we could see in damaging effects on the brain and other developmental problems.”

Two maps of the United States showing Aedes aegypti and Aedes albopictus mosquitoes are or have been previously found.  Aedes aegypti range is the southern half of the United States.  Aedes albopictus range is the eastern half of the United States as well as the southwest.
30 States Potentially Affected: A CDC map shows the possible range of the two species of mosquito that can transmit Zika. 
The agency stressed that neither map shows actual infestation, or reported cases of the virus -- but rather,
only where the species may appear

The current Zika outbreak began in April 2015 in Brazil – set to host the Olympics this summer -- and has spread through certain Latin American nations, the Caribbean and elsewhere.

The World Health Organization last week declared the epidemic a Public Health Emergency Of International Concern – the same designation accorded to the Ebola virus and otherwise seldom-invoked in the modern era.

Closely related to the West Nile virus and Dengue and primarily transmitted to humans by mosquito bites, the first human cases of Zika-related disease were reported in Africa as early as the 1950s. Of 176 species of mosquitos identified in the U.S., only two are known to  have the potential to spread Zika -- but females can bite many people over their 30-day lifecycle.

Some 61 nations have reported the presence of Zika, said mainly to have been spread by travelers or “locally acquired.”

While the number of Zika cases worldwide is difficult to estimate, the WHO believes that as many as 4 million people across the globe could be infected by year’s end.

Authorities have also reported that Zika infection can be sexually transmitted.

The leading complication of Zika infection among pregnant women is microcephaly, a birth defect in which a baby’s head is smaller than expected when compared to babies of the same sex and age, according to the CDC. Babies with microcephaly can have a range of problems, including seizures, developmental delays and hearing and vision loss.

A side-by-side sketch of a baby's head showing the difference between a baby with a typical head size and a baby with microcephaly.
Wide-Ranging Problems: Microcephalic infants can develop lifelong limitations, motor deficits among them.
The CDC  and WHO have issued precautions for pregnant women and urged aggressive mosquito-control measures.
Homeowners should be sure, for example, to eliminate standing water around their properties after periods of heavy rain
to prevent  mosquito breeding and be sure screens are secure. A contributing cause of the viral spread is the absence 
of screening  in older housing stock of many affected countries, Ferraro said. 

In late March, CDC updated its guidelines for women of reproductive age to provide recommendations for women and couples who want to get pregnant.

Of the 346 cases reported in the U.S. (through April 6), 32 were pregnant women, seven were sexually transmitted, and one had Guillain-Barré syndrome, a neurological disorder which can be a complication of Zika infection, the CDC reported. See the list of affected countries.

“I don’t think (Zika) is something that will be going away this year,” Ferraro said.  

Typically, one of every four people infected with Zika develop mild symptoms, usually apparent within two to seven days.  Among those symptoms are a skin rash and conjunctivitis, the researcher said.

“People usually don’t get sick enough to go to the hospital – and they very rarely die of Zika.  For this reason, many people don’t realize they’ve been infected,” Ferraro said.

Zika treatment includes supportive care, such as rest, consumption of fluids and acetaminophen.

Date Last Reviewed:  April 2017