With the Zika virus now circulating in two dozen countries and territories across the Americas, the mosquito-borne pathogen seems destined to reach the United States and likely sooner rather than later.
What is far less certain, say public health and infectious disease experts, is Zika’s potential reach and impact here. The South is seen as especially vulnerable because of its warm, humid climate and pockets of poverty where more people live without air-conditioning or proper window screens. Plus, the region is already home to mosquitoes that can transmit the virus.
Some models estimate as many as 200 million people live in areas that might be conducive to the spread of Zika during summer months — including along the East and West coasts and much of the Midwest. That makes for a huge target as researchers scramble to determine exactly how the virus manifests itself in the human body, who is particularly at risk, and why.
Their urgency comes amid increasing reports from Brazil, the current epicenter of Zika, of thousands of newborns with a rare condition involving brain damage. Doctors there have also seen a surge in another rare syndrome known as Guillain-Barré, which can lead to paralysis. With both, a link to Zika is suspected.
Already, Brazil, Colombia, El Salvador and Jamaica have urged women to postpone pregnancy. The Centers for Disease Control and Prevention has an ever-expanding advisory urging U.S. women who are pregnant from traveling to those 24 countries and territories in the Caribbean and Central and South America that have local transmission.
President Obama received a briefing Tuesday about the situation from his health and national security teams, including Health and Human Services Secretary Sylvia Mathews Burwell, CDC Director Thomas Frieden and Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
[CDC adds U.S. Virgin islands and Dominican Republic to travel advisory]
A day earlier, the World Health Organization’s director-general warned that the disease’s spread is “explosive.”Margaret Chan also described the circumstantial evidence connecting Zika to cases of microcephaly, in which a baby’s head and brain are abnormally small, as “extremely worrisome.”
So far, the experts are divided about what lies ahead for the United States. More than a dozen cases of the virus have been confirmed to date, including two announced Tuesday by Arkansas and Virginia state health officials. In each, the person was believed to have been infected while out of the country.
Fauci is downplaying the potential for a significant eruption of Zika here. He notes that dengue and chikungunya, diseases transmitted by the same kinds of mosquitoes, are widespread in Latin America. But their foothold in the United States has been well controlled, with only small clusters of cases.
“It is unlikely that we will have a major outbreak of Zika in this country,” Fauci said.
Yet Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, fears the opposite is true. He recalls spending much of 2014 insisting that the Ebola outbreak would not become a significant problem in the United States. He gives no such assurance now.
“I think we’re in for real trouble in the United States,” he said, considering how swiftly Zika can spread. He focuses on conditions throughout the Gulf Coast, where stagnant water sources — in uncollected garbage, discarded tires, untended bird baths — can be ideal breeding grounds for mosquitos much of the year.
“You’ve got to assume the worst-case scenario,” Hotez said.
[As Zika fear spreads, Brazilian moms opt for mosquito-resistant baby clothing]
Aedes albopictus, the Asian tiger mosquito, which can transmit the virus, is present from Florida to Connecticut and as far west as Illinois, said Laura Harrington, chair of Cornell University’s entomology department. It bites people as well as animals. A second species, Aedes aegypti, the yellow-fever mosquito, has a more limited geographic footprint and only bites people. But it is the primary “vector” for Zika’s transmission.
Taken together, “there are many parts of the United States that are vulnerable because of where the mosquito populations are,” Harrington said.
The experts acknowledge that any projections are hampered by their lack of knowledge about the disease. It takes between 10 to 11 days for a mosquito to become fully infected to pass on the virus, according to Nikos Vasilakis, an arbovirologist at University of Texas Medical Branch in Galveston, where researchers are studying Zika in collaboration with scientists at Yale’s School of Public Health and in Brazil. They don’t yet know what the risk is for pregnant women who are bitten by an infected mosquito and contract the virus — much less what the risk is for their fetus.
The CDC has issued guidelines for both pregnant women and newborns. For example, it recommends testing for the virus when babies have microcephaly and their mothers traveled to or lived in Zika-virus regions while pregnant. On Tuesday, agency officials held a telebriefing with clinicians nationwide to go over the guidelines as part of increased vigilance and public education.
In the Brazilian cases, most of the exposure to Zika appears to have been during the first trimester of pregnancy. But CDC officials have said there is also some evidence that a fetus can be in danger into the second trimester.
There is no drug to treat Zika or vaccine to prevent it, although Fauci said researchers are working on the latter. The most common symptoms of infection are fever, rash, joint pain and red, itchy eyes. Symptoms are usually mild and last several days to a week.
What you need to know about the Zika virus
Play Video1:10
Authorities have confirmed a dozen cases of Zika virus in the United States. Here's what you need to know. (Gillian Brockell/The Washington Post)
One of the biggest problems in researching the possible link between Zika and cases of birth defects has to do with the widespread presence of dengue disease in the countries with high Zika infection, said Lyle Petersen, director of CDC’s vector-borne disease division. Humans produce antibodies in response to both viruses, but current tests cannot really differentiate between them.
“In people with previous dengue exposure, there’s no test to be able to sort that out,” Petersen explained.
Major past outbreaks of Zika occurred in the Pacific islands among small populations, and uncommon kinds of birth defects were not noticed right away. After Brazil began reporting increased prevalence of microcephaly last October, authorities in French Polynesia went back and analyzed their 2013-2014 Zika outbreak involving more than 30,000 people. They found an increase in microcephaly cases and of Guillain-Barré syndrome.
Brazil has said it wants to expand an experiment using genetically modified mosquitoes produced by a British company called Oxitec. The company says they can be effective at controlling pest populations: Altered male mosquitoes are released into the wild to mate with females. The offspring never reach adulthood, blocking the next generation from carrying diseases like dengue, chikungunya and Zika virus.
Oxitec says that trials involving its mosquitoes in Brazil, Panama and the Cayman Islands “all resulted in a greater than 90 percent suppression” of the wild Aedes aegypti population. This month, the company announced that Piracicaba, a city in the Brazilian state of Sao Paulo, would expand its effort to eradicate disease-carrying mosquitos.
But it’s unlikely that genetically engineered mosquitoes will be buzzing around the United States anytime soon.
Beth Ranson, a spokeswoman for the Florida Keys Mosquito Control District, which has partnered with Oxitec for a proposed trial, said that before any altered bugs could be released there, the Food and Drug Administration must first complete an environment assessment of the project. Its findings must then be opened to public comment. Even once finalized, a local board would need to approve the trial — over the expected opposition of some Keys residents.
In the meantime, Ranson said, local inspectors are pushing forward with more conventional methods such as treating and eliminating breeding areas for mosquitoes.
“We’ve always been aggressive . . . [but] we’re stepping up the aggressiveness,” she said. “We don’t want dengue, chikungunya or Zika here – we don’t want any of it.”
There will be a lot of squak about any genetically modified insect being released, regardless.
Brazil is latching onto a novel, if controversial, approach to fight the spread Zika virus: genetically modified mosquitoes.
Zika virus is transmitted to humans primarily through the bite of an infected Aedes species, such as Aedes aegypti, the yellow fever mosquito.
No vaccine or treatment exists to combat the infection, which public health officials are worried may be linked to a brain defect in infants and a rare neurological syndrome that could cause paralysis in adults. The World Health Organization has expressed alarm at the explosive spread of the virus in the Americas in recent months and says as many as 3 to 4 million people could become infected.
Releasing even more of these insects into the wild seems like the last thing a Zika-stricken country needs, but Brazil’s National Biosafety Committee recently approved multiple releases of genetically modified Aedes aegypti throughout the country. Essentially, the plan is to turn their own species against them.
[WHO: Zika virus could explosively spread, level of alarm extremely high]
Created by Britain-based Oxitec, a spin-off company from Oxford University that is a subsidiary of Intrexon Corp., these mosquitoes contain a self-destruct mechanism within their DNA in the form of an inserted gene. This gene produces a protein called tetracycline repressible activator variant (tTAV), which ties up the cell's machinery and prevents the expression of other genes key to survival. As a result, the insect dies before it reaches adulthood.
But if reared on a diet with a special antidote — the antibiotic tetracycline, which binds and inactivates tTAV — the self-destruct mechanism will never switch on.
[Zika virus FAQ: What is it, and what are the risks as it spreads?]
Oxitec feeds its genetically modified mosquitoes tetracycline so they can survive and reproduce in the lab. For pest control purposes, mature males carrying the self-destruct gene are gathered up and released into the wild to mate with females. Offspring who inherit the gene will die without the tetracycline antidote, causing the mosquito population to drop drastically — and hopefully with it, the threat of disease.
“We've trialed this technology in the Cayman Islands, in Brazil and in Panama through four different trials, and we have shown up to 99 percent control of the mosquito population,” said Derric Nimmo, Product Development Manager at Oxitec, in a company video. In April, Oxitec started releasing its so-called “self-limiting” mosquitoes in Piracicaba, a city in the Campinas region of São Paulo state, and reported an 82 percent reduction in wild larvae by the end of the calendar year.
Because Aedes aegypti is considered the primary vector for dengue, Chikungunya and Zika viruses, the company has focused extensively on this species for public health applications. For surveillance purposes, its mosquito products also contain a heritable, fluorescent marker to differentiate between altered insects and wild ones. Monitoring the ratio of genetically modified vs. wild mosquitoes in traps after a release can help gauge whether more product is needed to further suppress the pest population.
This genetic approach and others — for instance, those that render insects infertile or disease-resistant — represent a new spin on the classical Sterile Insect Technique (SIT). During the 1930s and 1940s, the idea of SIT was conceived as a method of “birth control” for unwanted insect species. Males would be rendered sterile by exposing them to massive amounts of radiation, then released to mate with females. SIT was used to eradicate the screwworm, a deadly parasite of livestock, from the United States in the 1950s, and to tame pink bollworm moth populations in California's cotton fields since 1967.
[CDC issues interim Zika guidelines for testing infants]
Oxitec's scientists have also created self-limiting versions of common agricultural pests in the hopes of minimizing crop losses. One example is the diamondback moth, an insecticide-resistant nuisance that feeds exclusively on brassicas, such as broccoli and cabbage. Oxitec and Cornell University are planning field tests to be conducted in the summer in upstate New York, which have been granted approval by the U.S. Department of Agriculture.
One big question is whether manipulating the ecosystem in this way will have unintended, negative consequences.
Oxitec has come under criticism from various environmental groups that remain concerned about the possible effects of releasing a new strain of organism into the wild. For instance, a drastic drop in mosquito population could lead to harmful insects or other animals multiplying uncontrollably.
Supporters of genetically modified insects say self-limiting species target only one species, can still be eaten safely by predators, and are more effective/safe than insecticides. Also, the altered males and their offspring die off quickly due to the tTAV gene.
“In that sense, we're only removing Aedes aegypti and nothing else from the environment,” Nimmo said. “It's pinpoint accuracy. It's going in with a scalpel and taking away Aedes aegypti, leaving everything untouched.”
What you need to know about the Zika virus
Play Video1:10
Authorities have confirmed a dozen cases of Zika virus in the United States. Here's what you need to know. (Gillian Brockell/The Washington Post)
Well, I'm unsure.
Couple interesting tidbits on Zika and Aedes Aegyptica.
Zika originated in Aedes Aegyptica in Brazil, and has spread to other Aedes mosquitos, including the arboreal ones I would normally recommend as natural competitors and even predators. While these don't spread it to humans, they do spread the virus among other mosquitoes.
It's arrival is relatively shortly after widespread release of genetically modified Aedes Aegyptica mosquitos in Brazil (which is serving as a test bed) that were engineered so that females that mated with the genetically modified males would produce non-viable offspring.
I DON'T THINK THERE'S NECCESSARILY A CORRELATION. But it's a HELL of a coincidence.
Well, I'm unsure.
Couple interesting tidbits on Zika and Aedes Aegyptica.
Zika originated in Aedes Aegyptica in Brazil, and has spread to other Aedes mosquitos, including the arboreal ones I would normally recommend as natural competitors and even predators. While these don't spread it to humans, they do spread the virus among other mosquitoes.
It's arrival is relatively shortly after widespread release of genetically modified Aedes Aegyptica mosquitos in Brazil (which is serving as a test bed) that were engineered so that females that mated with the genetically modified males would produce non-viable offspring.
I DON'T THINK THERE'S NECCESSARILY A CORRELATION. But it's a HELL of a coincidence.
What exactly are the mosquito mechanics, here?
Infection- Is it passed from feeding on the same plant or animal host?
Are there other methods of viral transmission, such as sexual contact among mosquitos ?
Predation- Do some mosquito actually suck the blood of other species of mosquito? Can the host survive this?
We've got a decent mosquito-killing program here, one that targets the larvae and isn't as hard on the rest of the environment.
The word that comes to mind when I see "arboreal" is "trees."
Utah Zika Case Stumps Researchers
A caregiver wasn't exposed to Zika in a way that would transmit the virus, at least from what's currently known about Zika, LiveScience reports.
July 22, 2016
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In a puzzling case, a person in Utah became infected with the Zika virus, but health officials can't figure out how the person contracted it, Live Science reports.
The infected person was a caregiver for an elderly man who had Zika. But the case is mysterious: As far as health officials can tell, the caregiver wasn't exposed to Zika in a way that would transmit the virus, at least from what's currently known about Zika. So far, the only way Zika was thought to spread from person to person is through sexual contact, and the caregiver did not have sexual contact with anyone who had Zika.
Cannot donate blood, so not that big of a deal to me. Nor, do I plan on having any kids.I beleave that you can get with your local Blood Bank and/or hospitol and set up a personal bank for you own use, but for no others. You would have to replenish on a regular basis, as the blood does go bad, even refrigerated, but tha would also increase your marrow's capaciy to replenish, within the body any large blood losses, over time. Having a personalized supply would allow for you to still contribute in case of some urgent need but would also save any additional units (that you would have used) for someone else...
So, no big deal.
The more researchers learn about the Zika virus, the worse it seems.
A growing body of research has established that the virus can cause severe birth defects — most notably microcephaly, a condition characterized by an abnormally small head and often incomplete brain development. The virus also has been linked to cases of Guillain-Barre syndrome in adults, a rare autoimmune disorder that can result in paralysis and even death.
Now, in a study in mice, researchers have found evidence that suggests adult brain cells critical to learning and memory also might be susceptible to the Zika virus.
"This was kind of a surprise," Joseph Gleeson, a professor at Rockefeller University and one of the co-authors of the study published Thursday in the journal Cell Stem Cell, said in an interview. "We think of Zika health concerns being limited mostly to pregnant women."
[For Zika-infected pregnancies, microcephaly risk may be as high as 13 percent]
In a developing fetus, the brain is made primarily of "neural progenitor" cells, a type of stem cell. Researchers believe these cells are especially susceptible to infection by the Zika virus, which can hinder their development and disrupt brain growth. Most adult neurons are believed to be resistant to Zika, which could explain why adults seem less at risk from the virus's most devastating effects.
But some neural progenitor cells remain in adults, where they replenish the brain's neurons over the course of a lifetime. These pockets of stem cells are vital for learning and memory. Gleeson and his colleagues suspected that if Zika can infect fetal neural progenitor cells, the virus might have the same ability to infect adult neural progenitor cells. That's precisely what they found.
"We asked whether [these cells] were vulnerable to Zika in the same way the fetal brain is," Glesson said. "The answer is definitely yes."
Gleeson is the first to admit that the findings represent only an initial step in discovering whether Zika can endanger adult human brain cells. For starters, the study was conducted only in mice, and only at a single point in time. More research will be necessary to see whether the results of the mouse model translates to humans, and whether the damage to adult brain cells can cause long-term neurological damage or affect behavior.
But the initial findings suggest that the Zika virus, which has spread to the United States and more than 60 other countries over the past year, may not be as innocuous as it seems for adults, most of whom never realize they have been infected. Researchers found that infected mice had more cell death in their brains and reduced generation of new neurons, which is key to learning and memory. The possible consequences of damaged neural progenitor cells in humans would include cognitive problems and a higher likelihood for conditions such as depression and Alzheimer’s disease.
[Obama administration to shift $81 million to fight Zika]
“Zika can clearly enter the brain of adults and can wreak havoc,” Sujan Shresta, another study co-author and a professor at the La Jolla Institute of Allergy and Immunology, said in a statement. “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.”
William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, agreed Thursday that the findings are preliminary. But he also called it troubling.
"Here's the deal — the more we've learned about the Zika virus, the nastier it is," said Schaffner, who was not involved in the study. He said scientists have had concerns all along about Zika's ability to damage the brain, but until now the worries have focused mostly on the developing brain. "This mouse study will increase our anxiety. ... It's an additional potential way that this virus can cause human illness."
That's a possibility that demands further examination, he said, given the hundreds of thousands of people already infected by Zika — a number that continues to grow daily.
"Our attention, quite understandably, has been devoted to pregnant women and newborns, and preventing those infections," Schaffner said. "This mouse study will tell investigators that, in addition to pregnant women, you have to establish some studies in older children and adults as well."
Well, I'm unsure.
Couple interesting tidbits on Zika and Aedes Aegyptica.
Zika originated in Aedes Aegyptica in Brazil, and has spread to other Aedes mosquitos, including the arboreal ones I would normally recommend as natural competitors and even predators. While these don't spread it to humans, they do spread the virus among other mosquitoes.
It's arrival is relatively shortly after widespread release of genetically modified Aedes Aegyptica mosquitos in Brazil (which is serving as a test bed) that were engineered so that females that mated with the genetically modified males would produce non-viable offspring.
I DON'T THINK THERE'S NECCESSARILY A CORRELATION. But it's a HELL of a coincidence.
The presence of the Zika virus in the general population remains a point of major concern because the number of deformed babies with Intelligence disabilities could increase in a significant manner over the next few years.
It is the news that doctors and families in the heart of Zika territory had feared: Some babies not born with the unusually small heads that are the most severe hallmark of brain damage as a result of the virus have developed the condition, called microcephaly, as they have grown older.
The findings were reported in a study of 13 babies in Brazil that was published Tuesday in Morbidity and Mortality Weekly Report. At birth, none of the babies had heads small enough to receive a diagnosis of microcephaly, but months later, 11 of them did.
For most of those babies, brain scans soon after birth showed significant abnormalities, and researchers found that as the babies aged, their brains did not grow or develop enough for their age and body size. The new study echoes another published this fall, in which three babies were found to have microcephaly later in their first year.
As they closed in on their first birthdays, many of the babies also had some of the other developmental and medical problems caused by Zika infection, a range of disabilities now being called congenital Zika syndrome. The impairments resemble characteristics of cerebral palsy and include epileptic seizures, muscle and joint problems and difficulties swallowing food.
“There are some areas of great deficiency in the babies,” said Dr. Cynthia Moore, the director of the division of congenital and developmental disorders for the Centers for Disease Control and Prevention and an author of the new study. “They certainly are going to have a lot of impairment.”
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Dr. Deborah Levine, a professor of radiology at Harvard Medical School who has studied Zika but was not involved in either study, said there would most likely be other waves of children whose brains were affected by the Zika infection, but not severely enough to be noticed in their first year.
Short Answers to Hard Questions About Zika Virus
Why scientists are worried about the growing epidemic and its effects on pregnant women, and how to avoid the infection.
“A lot of the developmental abnormalities we’re not going to see until later,” she said. “There’s going to be another group seen later in childhood, I’m afraid, and another group probably when they reach school age.”
In the new study, doctors at two clinics in the northeastern Brazilian states of Pernambuco and Ceará described the cases of 13 infants who had tested positive for the Zika virus. In 11 of the babies, brain scans taken days or weeks after birth showed significant neurological damage, including improperly formed brain areas, excess fluid in some places and abnormal calcium deposits, or calcification, which probably resulted from brain cell death. But the size of their heads, though small, was not small enough to be considered microcephaly. So doctors monitored their progress as they grew.
Dr. Vanessa van der Linden, another author of the study and a neuropediatrician at the Association for Assistance of Disabled Children in Recife, Brazil, where most of the babies in the study are patients, said the type of brain damage in the babies who later developed microcephaly “presented the same pattern, but less severe” than those with it at birth.
The babies in the study published this fall also appeared to have a pattern of similar, but less severe, brain damage, said Dr. Antonio Augusto Moura da Silva, of the Federal University of Maranhão and an author of that study, which was published in Emerging Infectious Diseases. He and his colleagues studied 48 babies with brain abnormalities in the northeastern state of Maranhão, identified six babies who did not have microcephaly at birth, and found that three of them later developed it.
“We were worried, but now that we’ve started following those cases, we are very sad,” Dr. Silva said. “The picture is really terrible. At the least, if they have microcephaly, we expect them to have a very poor quality of life.”
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Experts and the authors of the studies said it was unclear why these infants’ brains did not develop enough to match their age and body size. Dr. Ernesto T. A. Marques Jr., an infectious disease specialist at the University of Pittsburgh and the Oswaldo Cruz Foundation in Recife, who was not involved in either study, said it could be that because of the initial fetal brain damage, “the necessary pathways and hormones that organize growth of the neonatal brain are not there anymore and the brain doesn’t grow.”
It could also be the result of the immune system responding to the original Zika virus infection. Dr. Moore said that another possibility might be that there was still some infection that continued to damage the brain. But she said that seemed less likely, given that follow-up tests for Zika virus conducted on seven of the babies did not find evidence of active infection.
Zika Virus Rumors and Theories That You Should Doubt
The oldest babies in these studies are only just over a year old, too young for researchers to identify cognitive problems or delays in skills like speech. But some deficits are clear: Many of the babies had serious physical deficits tied to neurological damage, including overly tense muscles, muscle weakness and the inability to voluntarily move their hands.
Still, unlike many babies born with microcephaly, most of the 13 in the new study had social interaction skills like smiling and making eye contact. And eight of them had good head control, an important skill for developing the ability to sit or walk.
While cautioning that the study involved too few cases to make generalizations, Dr. van der Linden said that it appeared that most of these babies had good eye contact because the damage was less severe in brain areas involving vision than it was in areas involving motor skills.
Dr. Marques said that head control, the ability to lift and support the head without help, in babies with microcephaly was “quite rare.” Having a social smile and eye contact is less rare, he said, depending on the type of visual damage and on whether they receive enough visual stimulation to strengthen their ability to use their eyes.
“At this age, 80 percent of brain stimulus comes from the eyes,” he said. “If you don’t have that working and you lose this window of opportunity, these babies cannot recover it.”
One baby, a boy, had no anomalies at birth. His limbs looked normal and his head size was proportional to his body, Dr. Moore said. But brain scans soon after birth showed excess fluid and abnormalities in his cortex and corpus callosum, which separates the two hemispheres. At 11 months old, he had microcephaly, and also epilepsy, difficulty swallowing, involuntary muscle contractions, and muscles that were too stiff and restricted his movement, she said.
Another baby had a sloping forehead and slight depressions in the front of his head at birth, as well as similar types of brain damage, apparent on scans, Dr. Moore said. By the time he was 1, he had developed microcephaly that was among the most severe of the babies in the study, and had muscular and swallowing problems. But he also had good eye contact, researchers reported.
In six of the cases, the mothers reported having a symptom of Zika infection, a rash, between the second and fifth months of pregnancy. That supports other evidence suggesting that babies born to mothers who were infected late in the first trimester suffer the most serious effects. But since there are no symptoms in 80 percent of cases of Zika infection, it was unclear when most of the women were infected, and researchers are still unable to say whether the virus is more damaging to babies if their mothers experience symptoms