A mosquito-borne virus linked to a rare birth defect in Brazilian newborns has the Americas in its grips and Californians worried about its possible progression to the Golden State.
The implications of the Zika virus — which also has reportedly led to paralysis in some cases — have caused widespread panic in the Southern Hemisphere since last fall, when cases of microcephaly, abnormal smallness of the head in babies, ballooned in Brazil from 150 in 2014 to 3,900 in the past four months. This week, the World Health Organization predicted the virus would spread to all countries across the Americas except Canada and Chile.
Brook Meakins, a 33-year-old East Bay woman expecting her first child, is anxiously waiting for test results to determine if she has the virus.
After Meakins and her husband returned from a holiday vacation in Bora Bora in French Polynesia, she developed a rash and achy joints and went to the hospital last week to get tested.
“We’re all keeping our fingers crossed very, very tight, of course,” she said Wednesday in a brief interview with this newspaper.
Although the U.S. Centers for Disease Control and Prevention had issued warnings for pregnant women traveling to countries where Zika is prevalent, she said she checked and didn’t find French Polynesia on the list. Still, Meakins’ doctor said there is cause for concern.
Perhaps the scariest prospect is what scientists and experts say they don’t know about this disease.
How a virus that was first identified in Uganda in 1947 — and known mostly to cause minor fever, rash and achy joints — may be linked to such tragedies is a puzzle that experts and scientists say will take time to unlock.
“We’d actually been worried about this family of viruses,” said Dr. Charles Chiu, director of the UC San Francisco Abbott Viral Diagnostics and Discovery Center.
That’s because the genus of viruses — including Zika, the West Nile virus and dengue virus — is transmitted by the same two mosquito species found everywhere in the Americas, including California.
“I don’t think it was unexpected that Zika has emerged in the Western Hemisphere,” said Chiu. “We’d already had a pre-warning of it in the increase in dengue fever … .”
The difference among the three, experts say, is that West Nile virus can be transmitted to humans through infected birds or mammals, while Zika and the other two viruses are not known to have animal hosts.
Zika is an infectious disease caused by the Zika virus, named after the Zika Forest near Entebbe, Uganda. It affects the nervous tissue, meaning the brain and spine, and some experts believe it may have mutated in such a way that it has led to widespread birth defects. Still others say that it could be related to an environmental factor — or due to something no one could have fathomed.
“We have never seen this before with Zika,” said Dr. Yvonne Maldonado, professor of pediatric infectious diseases at Stanford University. “We have to keep an open mind about what the cause might be and why it happened now and not 70 years ago.”
Zika is transmitted to people by Aedes mosquitoes, which are aggressive day-biters that typically breed and develop in small, water-filled containers.
These mosquitoes — Aedes aegypti and Aedes albopictus — have both been detected in California, according to public health officials. The aegypti, also known as the yellow fever mosquito, has been found in 12 counties, including Alameda County and San Mateo County. The albopictus, also known as the Asian tiger mosquito, has been found in five counties.
However, to date, California public health officials say there has been no transmission of the Zika virus here. As of Jan. 15, the state has reported five cases of the disease since 2011, all in travelers returning from other countries with outbreaks. Others like Meakins are being tested by the Centers for Disease Control.
Until the Brazil outbreak, according to the Journal of Emerging Infectious Diseases, the largest Zika outbreak occurred in French Polynesia during 2013-14, where Meakins just traveled.
While the origin of the introduction there is unknown, the journal said, studies showed the closest strain to the one that surfaced in Brazil was isolated from samples from patients in French Polynesia.
Even though Brazil has been experiencing a drought, the water that residents are hoarding around their homes may have become a breeding ground for the pests, said Chris Barker, assistant adjunct professor in pathology, microbiology and immunology at UC Davis.
Zika, others say, may have been introduced to Brazil during the World Cup in 2014, but an international canoe race held in Rio de Janeiro in August 2014 that included participants from four Pacific countries including French Polynesia may be more likely, the journal said.
The virus manifests itself after an infected mosquito bites a person, or an uninfected mosquito bites an infected person. In 80 percent of the cases, most infected people have no symptoms. If they develop any, symptoms are usually fever, rash, joint pain and/or red eye.
Chiu said more widespread diagnostic surveillance is needed to test pregnant women who have the virus. Chiu said when more test results are available, drugmakers could work on a vaccine, although even on an accelerated schedule it would be three to five years before it could be put into wide use.
However, a vaccine for yellow fever already is available, he said, and because it is the same genus of virus, “we do have a head start.”
Barker and Chiu both say California’s strong mosquito abatement programs should help prevent an outbreak here. Widespread air conditioning and less crowded living conditions than in other parts of the world also help.
And because the weather here is more temperate, at least during the winter months, the mosquitoes that carry Zika virus aren’t likely to make inroads.
But Barker is wary of the warmer summer months ahead.
“The biggest risk to Californians,” he said, “would be if Zika becomes transmitted and it reaches high incidence in places like Mexico, where there is frequent travel to California.”
Contact Tracy Seipel at 408-920-5343. Follow her at Twitter.com/taseipel.
