Tag Archives: Zika virus

Zika infections

One in ten pregnant women infected with Zika in the US had babies with birth defects

According to a report issued by the Centers for Disease Control and Prevention, one in 10 pregnant women from continental United States who had been infected with Zika had babies with birth defects. The report, which is the most comprehensive analysis of Zika-infected American pregnancies, answers many worrisome questions the public posed during the height of the crisis but leaves many issues open.

Zika infections

Pregnant women infected with Zika risk giving birth to babies with an abnormally small head and brain. Credit: Flickr, bra_j

Zika is spread mostly by the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). There is no vaccine for Zika virus disease yet, which causes symptoms like mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise, or headache. The symptoms subside after 3-7 days but the biggest threat Zika possess is to pregnant women. It’s well established now that pregnant women infected with Zika risk giving birth to babies with microcephaly, a condition that causes babies to be born with abnormally small heads and brains,  and Guillain-Barré syndrome.

“Zika virus can be scary and potentially devastating to families. Zika continues to be a threat to pregnant women across the U.S.,” said CDC Acting Director Anne Schuchat, M.D. “With warm weather and a new mosquito season approaching, prevention is crucial to protect the health of mothers and babies. Healthcare providers can play a key role in prevention efforts.”

The CDC report confirms previous studies which found women infected in the first trimester of their pregnancy are the most vulnerable. Some 15% of American women known to be infected with Zika during their first trimester had babies with birth defects. Overall, 10% of infected pregnant American women gave birth to babies with brain damage or other birth defects, so getting infected later in pregnancy can also be risky.

In total, the report covered 1,297 pregnancies which were tracked from Jan. 15 through Dec. 27, 2017. Of these pregnancies, 972 were confirmed to be Zika infected by lab evidence, which resulted in 895 live births and 77 losses (abortions, miscarriages, stillbirths).  Every 50 state and Washington, D.C, had at least once case of Zika-infected pregnancy.

Overall, 51 babies were born with birth defects. For the 250 cases or so where the presence of the Zika virus was confirmed, 24 pregnancies or 10 percent resulted in birth defects, most of which involved microcephaly. In eight cases, the damage included other brain malformations and dysfunctions in the central nervous system.

The report comes with a couple of caveats. Only 25 percent of the babies included in the study had their brains scanned, despite the CDC’s recommendation that all babies born to women with potential Zika infections should have their brains scanned. This limitation means we’re likely underestimating the birth defects that follow Zika in pregnancy. For instance, some babies that look fine at birth, i.e. with a normally sized head, might later be diagnosed with some congenital Zika syndrome.

“CDC recommends that pregnant women avoid travel to areas with risk of Zika and unprotected sex with a partner who has traveled to an area with Zika to prevent Zika-related birth defects in their babies,” said Peggy Honein, Ph.D., the Zika Response’s Pregnancy and Birth Defects Task Force co-lead. “CDC continues to work closely with health departments on the U.S. Zika Pregnancy Registry to follow up infants with possible congenital Zika virus infection and better understand the full range of disabilities that can result from this infection.”

[panel style=”panel-danger” title=”Key findings from the CDC’s report” footer=””]

  • Forty-four states reported pregnant women with evidence of Zika in 2016.
    • Most of these women acquired Zika virus infection during travel to an area with Zika.
  • Nearly 1,300 pregnant women with evidence of possible Zika infection were reported to the U.S. Zika Pregnancy Registry.
    • Of the 1,000 pregnancies that were completed by the end of the year, more than 50 had Zika-related birth defects.
  • Among pregnant women with confirmed Zika infection, about 1 in 10 had a fetus or baby with birth defects.
    • Confirmed infections in the first trimester posed the highest risk – with about 15% having Zika-related birth defects.
  • About 1 in 3 babies with possible congenital Zika infection had no report of Zika testing at birth.
  • Only 1 in 4 babies with possible congenital Zika infection were reported to have received brain imaging after birth.




Zika virus solution might lie in oil of common flower

As the Zika virus outbreak threatens to spread from South America to the rest of the world, scientists are scrambling to find a cure for the mosquito-borne disease. Although Brazil is currently using synthetic pesticides and transgenic mosquitos in an attempt to control the Aedes aegypti mosquitos that carry the virus, a team of New York University (NYU) scientists is now suggesting that the answer might be as simple as a common flower and a pot of boiling water.

The Mexican Marigold flower that could be the key to fighting the Zika virus. Credit: New York University

The Mexican Marigold flower that could be the key to fighting the Zika virus. Credit: New York University

Some plants have evolved chemical defenses in the form of potent insecticides to protect themselves from insect damage. For example, pyrethrins are commonly used as an insecticide and insect repellant and originate from a type of Chrysanthemum flower.

Back in 1991, a study published in the Journal of the American Mosquito Control Association found that the essential oil of the Tagetes minuta plant – also known as the Mexican Marigold – can kill A. aegypti larvae for at least nine days at just 40 parts per million, which is considered to be a very small amount.

Using this research as a foundation, NYU chemical and biomolecular engineering professor Mark Green and his team discovered that this essential oil is a potent larvicide when added to standing water, which is where the A. aegypti mosquitos lay their eggs. Green claims that since these particular mosquitos spread the Zika virus – along with the dengue, yellow fever and chikungunya viruses – at a local level, this kind of treatment is very effective.

“This mosquito bites where it’s born, so by treating standing water in an area, you can effectively eliminate that population,” he said, adding that these natural pesticides are much safer than synthetic alternatives. “You could make this yourself and use it around the yard, just by boiling the plant and treating any standing water.”

Although pesticide demand is increasing due to the recent fears of a Zika spread, Green suggests that scientists invest more effort into natures chemical defenses such as the oil of the Mexican Marigold.

“These plant chemicals are the product of hundreds of millions of years of evolution, as plants learned to defend themselves against similar insects,” he said. “Why shouldn’t we take advantage of that intelligence to protect ourselves?”

Adult Aedes aegypti mosquito, a vector or carrier of the Zika virus. Credit: Wikimedia Commons

Will Zika Become the Next Ebola?

Reminiscent of the 2014-2015 Ebola panic, news of the Zika epidemic has spread like wildfire. The virus, which was once a serious risk for expectant mothers in Brazil, may be well an “explosive pandemic” deserving of international attention from the World Health Organization (WHO).

What is Zika?

Adult Aedes aegypti mosquito, a vector or carrier of the Zika virus. Credit: Wikimedia Commons

Adult Aedes aegypti mosquito, a vector or carrier of the Zika virus. Credit: Wikimedia Commons

A virus transmitted primarily by mosquitoes, Zika may cause the infected person to develop symptoms such as fever, headache, joint pain, rash or conjunctivitis. However, only roughly 20% of those with the Zika virus are symptomatic.

This low percentage of symptomatic carriers is linked to much of the threat from the virus, as it makes it especially hard to follow and detect.

“In many ways the Zika outbreak is worse than the Ebola epidemic of 2014-15…[because] most virus carriers are symptomless. It is a silent infection in a group of highly vulnerable individuals — pregnant women — that is associated with a horrible outcome for their babies,” said Wellcome Trust head Jeremy Farrar about the virus.

zika symptoms

Credit: Wikimedia Commons

The primary concern of the Zika virus is that correlates to birth defects in babies born to affected mothers. While the link has not yet been proven, infected unborn babies are at high risk to develop microcephaly. Microcephaly is a sometimes fatal disease, in which the affected baby’s brain is smaller than average, with underdeveloped functioning.

In 2014, the Brazilian Ministry of Health reported that Brazil suffered fewer than 150 cases of microcephaly in infants. From October 2015 through January 2016, however, more than 4,700 cases in Brazil are suspected. In the past year, reports of Zika infections have occurred in 21 different countries.


Credit: Wikimedia Commons

University of Texas Medical Branch scientists pilot the search for a cure to the virus, but no treatment has yet been discovered. A cure is of utmost necessity for those living in areas populated by the Aedes Aegypti mosquito. Developing a vaccine could take years, and testing it on pregnant women would make it an even higher-risk endeavor.

How does Zika spread?

Mosquitoes primarily transmit the Zika virus, and it’s mostly commonly been found in Brazil and equatorial climates.

A few cases have also documented sexual transmission of the virus. Experts recommend waiting to try to get pregnant for several weeks after returning from South or Central America. The delay is an extra precaution against having a baby with microcephaly.

The spread of the virus is limited by climate, by mode of transmission, by expiration of the virus in the blood of an affected person and by preventative measures the rest of the world can take in the meantime.

How does Zika compare to Ebola?

Unlike Ebola, Zika has not been reported as deadly to infected persons. Neither does it remain in a person indefinitely. So far, those infected with Zika appear to retain the virus in their blood for a week, and in semen for up to two weeks.

Reports of Zika outbreaks have increased at a staggering rate of 2500% from 2014 to 2016, however, leading the WHO to declare it a global public health emergency. The 4,700 reported cases of Zika in 2015-2016 still pale in comparison to the 11,000 deaths from Ebola in 2014-2015. The rate of increase may not bode well regarding the spread of Zika in the coming years, but fortunately the virus is not transmitted as easily person-to-person as Ebola.

How can you take precaution?

Pregnant women or those who may become pregnant are advised to steer clear of tropical countries. Couples are advised to wait one month before having unprotected sex after the man has been potentially exposed to the virus. Additional precautions include wearing bug repellant, emptying pools of standing water and covering up to prevent bites.

After a week of having the virus, infected persons should be fully recovered. However, many unknowns surround the disease — which is why exercising caution for a month following any travel to countries with reported Zika outbreaks is strongly recommended.

While the virus is spreading at an alarming rate, IFL Science writer Justine Alford also points out that infections will not always lead to an epidemic within a country or across the globe. Countries without carrier mosquitoes do not need to panic. However, prevention measures and additional studies are needed so that countries and organizations will be ready to react if the need arises.




The golf ball-shaped Zika virus. Credit: Purdue University

What the Zika virus looks like in 3-D

Researchers have been racing to image the structure of the Zika virus whose outbreak in the Americas is causing malformations in newborns and autoimmune diseases. A team at Purdue University in West Lafayette finally cracked the code, revealing a virus very much akin to the dengue and West Nile viruses.

The golf ball-shaped Zika virus. Credit: Purdue University

The golf ball-shaped Zika virus. Credit: Purdue University

The golf-shaped structure was determined using  cryoelectron microscopy. This technique allowed Michael Rossmann of Purdue and colleagues to create a sharp 3-D image of the virus. You can even see the sugars protruding  from proteins in Zika’s shell like little-red doorknobs.

[ALSO SEE] Why Zika causes birth defects

It’s these knobs that may help the Zika virus attach and infect human cells. So, this latest effort couldn’t be more welcomed. “This certainly gives us great hope that we will be able to find a vaccine or antiviral compounds,” Rossmann said.

A couple weeks back, many publishers accounting for thousands of journals released all Zika-related articles for free. This coupled with the painstacking efforts scientists all over the world are pitching in gives hope that a vaccine might be developed soon.


Study estimates Zika Virus risk across 50 biggest cities in US

With the Zika virus running rampant through South America, outbreaks could pop up in several US cities. A study from the National Center for Atmospheric Research (NCAR) estimated this hazard in the largest cities in the US, finding that the south and especially the southeast is quite vulnerable to the threat posed by Zika.

Many US cities face potential risk in summer of low, moderate, or high populations of the mosquito species that transmits Zika virus (colored circles). The mosquito has been observed in parts of the United States (shaded portion of map) and can establish populations in additional cities because of favorable summertime meteorological conditions. In addiiton, Zika risk may be elevated in cities with more air travelers arriving from Latin America and the Caribbean (larger circles). This image is freely available for media & nonprofit use.
Credit: Image based on data mapped by Olga Wilhelmi, NCAR GIS program.

Key factors can combine to produce a devastating Zika outbreak, and those unfortunate conditions may very well allign in some American cities. The Aedes aegypti mosquito, which is spreading the virus in much of Latin America and the Caribbean, will start moving more and more to the north as the weather warms up. The east coast is in a similar situation, with higher temperatures than most of the ocuntry. Summertime weather conditions are highly favorable for mosquito populations as far north as New York City and across the southern tier of the country as far west as Phoenix and Los Angeles, NCAR models showed. Wintertime conditions are too cold across all the country, bar southern Florida and Texas. However, it’s especially these (often impoverished) areas that especially vulnerable in the case of an outbreak.

“This research can help us anticipate the timing and location of possible Zika virus outbreaks in certain U.S. cities,” said NCAR scientist Andrew Monaghan, the lead author of the study.

“While there is much we still don’t know about the dynamics of Zika virus transmission, understanding where the Aedes aegypti mosquito can survive in the U.S. and how its abundance fluctuates seasonally may help guide mosquito control efforts and public health preparedness.”

“Even if the virus is transmitted here in the continental U.S., a quick response can reduce its impact,” added NCAR scientist Mary Hayden, a medical anthropologist and co-author of the study.

The study doesn’t propose a fixed chance for this year, but even in the case of an outbreak, it wouldn’t be as dramatic as it was in South America. A higher percentage
of Americans live in air-conditioned conditions or in sealed offices, and green areas and parks are often sprayed with insecticide. But this doesn’t mean that there is
no risk.

Aside for meteorological conditions, poverty and lack of access to proper sanitation also favorize the spread of the virus. Add to this the higher mobility of people
from the US, and you could end up with a recipe for disaster. All in all, this is a complex issue, and a disease we don’t properly understand yet. If we want to avoid
a global outbreak, basic precautions have to be set.

“The results of this study are a step toward providing information to the broader scientific and public health communities on the highest risk areas for Zika emergence in the United States,” said Kacey Ernst, an epidemiologist at the University of Arizona and co-author of the study. “We hope that others will build on this work as more information becomes available. All areas with an environment suitable to the establishment of Aedes aegypti should be working to enhance surveillance strategies to monitor the Aedes aegypti populations and human populations for disease emergence.”

“This research highlights the complex set of human and environmental factors that determine whether a mosquito-borne disease is carried from one area to another, and how severely it affects different human populations,” said Sarah Ruth, program director in NSF’s Division of Atmospheric and Geospace Sciences. “By integrating information on weather, travel patterns, mosquito biology, and human behavior, the project team has improved our ability to forecast, deal with, and possibly even prevent future outbreaks of Zika and other serious diseases.”

Journal Reference:

Andrew Monaghan, Cory Morin, Daniel Steinhoff, Olga Wilhelmi, Mary Hayden, Dale Quattrochi, Michael Reiskind, Alun Lloyd, Kirk Smith, Christopher Schmidt, Paige Scalf and Kacey Ernst. On the seasonal occurrence and abundance of the Zika virus vector mosquito Aedes aegypti in the contiguous United States. PLOS Currents Outbreaks,

Transplant Organizations issue a guidance statement regarding Zika virus

The Zika virus has been in the headlines lately for its apparent association of microcephaly in the children of mothers infected when they were pregnant. While there is a strong correlation, a true causation has not been completely verified, and is still being investigated.  In most people the virus causes only very mild illness that resolves on its own (such as fever, rash, muscle aches, and headache), and in many individuals is completely asymptomatic. Occasionally, its effects can be more severe, such as leading to reported cases of Guillain-Barre syndrome (a severe neuromuscular illness causing paralysis). It is still not known exactly why some people may develop severe complications while the majority do not. Zika virus has been covered previously on the ZME website.

It is also known that while the Zika virus typically spreads by an insect vector (the mosquito Aedes aegypti in most cases), it is now thought to also spread by sexual contact. It is uncertain if transmission could occur thorough organ donation, but if virus is present in the blood or other body fluids, then this mode of transmission would be possible in principle. Due to concern that this unusual mode of transmission could affect a vulnerable population, the Organ Procurement and Transplantation Network (OPTN) and United Network for Organ Sharing (UNOS) has set up an Ad Hoc Disease Transmission Advisory Committee (DTAC) to provide information and recommendations to transplant physicians, and this month came out with the first guidelines. As a transplant physician myself ( I’m a pediatric nephrologist, caring for children with End-Stage Kidney Disease who will need or have received a kidney transplant), I recognize the need to be certain that our supply of donor organs are safe for our patients, and to be able to advise our current transplant patients about travel to areas where Zika is known to be endemic.

Organ transplant recipients (such as heart, liver, kidney, lung, etc) represent a vulnerable population. In order to prevent rejection of the donor organ, the patient must be immunosuppressed with medications, making it difficult to fight off infections that most of us wouldn’t be very bothered by. It is completely unknown, at the present time, how Zika virus would affect an immunosuppressed individual. It’s affects could remain mild, as it is in most people with a normal immune system, or it could have serious unforeseen consequences.

The DTAC advises caution for people who have already received a transplant, or those who are on the transplant list, if they will be traveling to a Zika endemic area. Those areas would include Mexico, Central America, and South America. They also recommend that when a donor is being considered (and that could include either a living donor or deceased donor), that the transplant center should take into account the donor’s recent travel history, and if they had recent symptoms of viral infection. Again, many people (around 20%) will not have any symptoms at all, making symptomatology an unreliable marker of infection. The committee does not feel that even these factors should result in absolute exclusion of that organ being used, but should be decided on an individual basis for each patient. Some patients may be in more urgent need of an organ, and may not survive if they have to wait too much longer for the next matching organ to come up. In other cases, a person may have already been on the transplant list for a very long time due to having built up a lot of antibodies to other potential donors, and may not get another matching offer for years.  It may be a decision that the patient, their family, and their transplant physicians need to make together if the organ in question is felt to be at a higher than average risk for Zika virus.

Unfortunately, routine screening methods are not yet available for use by clinical laboratories. Screening can be achieved by the CDC in suspected cases of Zika related illness, and therefore it is not yet recommended or possible for organ donor’s to be screened for Zika virus as part of a donor evaluation. With time we will likely have a better understanding of the risk that Zika poses to individuals immunosuppressed for organ transplant. We will also likely have better screening methods that will be more readily available. For now, I think it is prudent to take precautions until more is known, but feel that there is no reason to panic, since there is no evidence at this time that donor organs have been compromised in any way.


References and further reading:

“Guidances for organ donation and transplantation professionals regarding the Zika virus”.  Feb. 4 2016.  UNOS Newsroom.


Interim Guidelines for Pregnant Women During a Zika virus outbreak – United States 2016.  CDC Morbidity and Mortality Weekly Report.  Jan. 22. 2016.


Possible Association Between Zika virus infection and Microcephaly – Brazil 2015.  CDC Morbidity and Mortality Weekly Report.  Jan. 29, 2016.

Zika Virus sexually transmitted in the US

The Zika virus that created an international state of emergency just got more scarier: apparently, it can be sexually transmitted. Such a case was reported in the US.

Global Aedes aegypti predicted distribution. The map depicts the probability of occurrence (blue=none, red=highest occurrence).

The disease has been associated with thousands of babies being born with underdeveloped brains and has recently been spreading like wildfire through South America. Zika is generally transmitted through mosquito bites, like the related Dengue. However, a person contacted it without traveling to one of the infected areas, after their partner traveled to one of those areas.

“We certainly understand the concern. This needs to be further investigated to understand the conditions and how often or likely sexual transmission is, and whether or not other body fluids are implicated,” WHO spokesman Gregory Hartl told Reuters.

“This is the only the second mooted case of sexual transmission,” he said, referring to media reports about a case of an American man who returned from Senegal and is suspected of infecting his wife.

Anne Schuchat, principal deputy director for CDC, said this was the first case it had dealt with involving a “non-traveller”.

“We don’t believe this was spread through mosquito bites, but we do believe it was spread through a sexual contact.”

Fighting Zika is certainly not easy. The virus is helped by the same conditions as Ebola – warm temperatures, high humidity and poverty. The lack of hygiene is crucial for the spread of the disease, as well as for mosquitoes, which generally transmit it. For this reason, an outbreak in the US seems very unlikely, as mosquito control programs are already heavily in place. However, it’s not completely out of the question.

There are still many things we don’t know about the Zika – not even why the virus causes birth defects. Dr. Yoel Sadovsky, a Professor of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh said:

“We know very little about how Zika virus infection occurs during pregnancy and how it causes birth defects. However, what we do know from other viral infections during pregnancy is that there are several steps that are needed for viruses to affect the fetus. The first is to get into the mother’s body and then to infect or cross the placenta. At that point, the virus can enter a specific fetal compartment such as neurons which could potentially lead to a defect such as microcephaly. Alternatively the virus can remain in the placenta and may affect development of the fetus by disrupting placental function.”

It will take quite a while to figure these things out but in the meantime, the CDC advises pregnant women to avoid traveling to the infected countries (same for blood donors).