Zika virus: What parents should know

With news and concern about the Zika virus growing, a CHOC Children’s infectious disease specialist explains what parents and mothers-to-be need to know about the virus.

Zika virus is a mosquito-transmitted disease that can cause rash and fever in adults and children, but seldom prompts hospitalization, says Dr. Antonio Arrieta, president of CHOC’s medical staff.

However, babies born to women who were infected with Zika virus while pregnant may be at risk for developing microcephaly, a condition marked by an unusually small head at birth, often reflecting limited brain development, he says.

Zika originated decades ago in Uganda, but has spread through Southeast Asia, the Pacific lslands and the Americas – including Brazil, where physicians in recent months noticed a substantial uptick in the number of babies born with microcephaly, Dr. Arrieta says.

To that end, the Centers for Disease Control has cautioned pregnant women or women trying to become pregnant about traveling to several countries, including Cape Verde, Mexico and Samoa, as well as places in the Caribbean, Central America and South America. See the CDC’s website for the most recent travel information.

The CDC advises pregnant women who have traveled to these locations and experienced fever, rash, joint pain or red eyes during or recently after their trip to consult their doctor.

Further, routine imaging will alert pregnant women who have traveled to affected countries if their baby is at risk for microcephaly, Dr. Arrieta says.

The virus is transmitted by a specific species of mosquito, Aedes spp, which is found in some areas of the United States. The best way to protect against bites is to wear insect repellent, particularly during spring and summer, Dr. Arrieta says.

He cautions that pregnant women should first consult with their obstetrician regarding safety of different insect repellent formulations.

More information about the Zika virus – including travel alerts – is available on the CDC’s website.

Clinical Trials in Pediatrics

“A clinical trial is a research project that involves patients,” says Dr. Antonio Arrieta, a CHOC Children’s Pediatric Infectious Disease Specialist. “All drugs, vaccines and medical devices have to go through phases of research before they are approved by the U.S. Food and Drug Administration. If researchers and physicians don’t  conduct these trials, we don’t know how good the drugs are or how we are supposed to use them. The expectation is that these new drugs will be better or improve the established standard of care. The standard of care oftentimes has a lot of room for improvement. We think we can do better. We want to make sure new drugs are safe and that we get the best results. Some trials we have done have  introduced new agents that have greatly improved mortality rates and the survival of patients.”

Physicians and researchers conducting clinical trials talk to other physicians at CHOC to identify potential patients to participate. “We make sure they meet the criteria and then talk to the parents to get informed consent,” says Dr. Arrieta. “We discuss the pros and cons of the study and why we are doing it. It’s voluntary and there are no consequences to not participating. We monitor patients closely to make sure the child is responding to treatment or gets better. No procedures are done on children that will increase their pain or discomfort and we can stop a trial with a patient any time the parent wishes.”


  • Average number of peer-reviewed research papers published annually from CHOC’s Infectious Disease Division: 6-7
  • Approximate number of clinical trials underway at CHOC at any given time: 300
  • Approximate number of newborns exposed to HIV in-untero referred to CHOC’s Pediatric HIV Clinic each year: 10

View the full feature on Kids and Clinical Trials

Dr. Antonio Arrieta
Dr. Antonio Arrieta
CHOC Pediatric Infectious
Disease Specialist


Dr. Arrieta is the Director of Pediatric Infectious Diseases and the Director of Infectious Disease Clinical Research at CHOC Children’s. He specializes in infectious diseases, including pediatric HIV. A native of Peru, Dr. Arrieta completed his fellowship at UCI Memorial/Miller Children’s Hospital in Long Beach and his residency at Southern Illinois University in Springfield. He joined the CHOC staff in 1991.

Dr. Arrieta’s philosophy of care: “My philosophy of care is one that is shared by everyone at CHOC, and that is one of service. We are here to serve the children of Orange County regardless of their backgrounds. We help people stay healthy or we help them return to health.”

Universidad Peruana Cayetano Heredia in Lima, Peru

Pediatric Infectious Disease

More about Dr. Arrieta

This article was featured in the Orange County Register on May 19, 2014, and was written by Amy Bentley.

Infectious Disease Clinical Trials at CHOC

Infectious_Disease_Research_CHOCClinical trials involving real patients help doctors and researchers learn the effectiveness of a new drug or medical device, and lead to advancements with potential to improve thousands of lives.

At any time, CHOC Children’s staff doctors, nurses and others are involved in about 300 clinical trials in many specialties, says Dr. Antonio Arrieta, director of infectious diseases and the director of infectious disease clinical research at CHOC.

These trials examine the safety and effectiveness of new medications, vaccines and medical devices as CHOC research physicians and their staffs seek to answer medical questions and develop new or improved drugs that can help children worldwide.

“CHOC is one of the best hospitals in the country and in the world when it comes to providing clinical care,” says Dr. Arrieta. “We also are seeking to make CHOC equally a leader in the discovery and development of new medications and medical devices for children.”

Dr. Arrieta and his team in are assessing the impact of a new and improved vaccine that would reduce invasive Pneumococcal disease, which can cause serious illnesses like pneumonia, meningitis and others.

Dr. Arrieta recently presented data from this research to the international community at a conference in Dublin hosted by the European Society for Pediatric Infectious Diseases and attended by more than 3,000 clinicians, researchers, residents and students.

“We want to share this with the international community,” Dr. Arrieta said. “This infection is of greater severity and more common in third-world countries that don’t have this vaccine.”

Orange County has seen a decline in cases of children with invasive Pneumococcal disease since the first vaccine was released in 2010. It is given to babies at the ages of 2, 4, 6 and 18 months.

Another area of research Dr. Arrieta’s team is working on involves an effort to treat a severe form of fungal infection in infants called candida, which can be fatal for premature babies.

“The current standard of care of is quite toxic so we are involved in an international trial involving a new agent that we think is going to improve the overall outcome of these babies,” he says.

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Health Workers on Alert for Measles

New measles cases continue to be reported in Measles_alertOrange County, leaving health care providers on alert for potential cases of the contagious disease.

“Any one case is troubling,” says Dr. Antonio Arrieta, CHOC Children’s director of infectious diseases. ”We shouldn’t be seeing measles in the U.S.”

The state has seen an increase in measles cases this year: Less than four months into the year, California has seen more measles cases in 2014 than in the entire year of 2010, the most recent year of available data.

Symptoms begin with high fever, transition to rash

Highly contagious, measles is transmitted through the air, Dr. Arrieta says. The disease is also strong: Contagions can remain in the air for hours after an infected person leaves an area, he says.

Symptoms typically begin to surface eight to 10 days after initial exposure to the virus, and then develop in stages. Early symptoms include a high fever – typically between 103 and 105 degrees Fahrenheit – cough, watering eyes and runny nose. A rash becomes apparent around the third day of symptoms, worsening the next day and continuing to spread over the body as the disease progresses.

People are contagious about four days before the rash begins and four days afterward, according to the Centers for Disease Control (CDC).

Measles is not treated. Instead, physicians allow the disease to run its course, while monitoring for possible complications, which are more dangerous than the disease itself. Dr. Arrieta says that most children with measles will develop pneumonia, which the CDC reports as the complication most likely to cause death in youth. One in 10 measles cases leads to ear infections, and 8 percent of sufferers report diarrhea, the CDC says.

A child with measles. Source: Centers for Disease Control
A child with measles. Source: Centers for Disease Control

Further, one child in every 1,000 measles cases will develop a brain inflammation that can lead to convulsions, the CDC reports.

Immunity ‘critical mass’ is necessary

“This highlights the problem that if you’re not immunized, you are at risk,” Dr. Arrieta says.

Dr. Arrieta emphasizes that the vaccine is safe and readily available. Following the vaccination, some children have mild reactions, such as a short-lived, low-grade fever.

Ninety percent of the population must be immune to measles to stop or prevent the spread of the disease – and that rate must factor people who cannot have the vaccine for health reasons or age, or those who don’t develop immunity from the vaccine, says Dr. Arrieta.

“If you account for many people who are not immune because they are too young, or have a condition that prevented them from getting the vaccines, then you are in a constant state of being close to that critical 90 percent,” he says. “If you account for all of those who can’t have the vaccine, and those who don’t want to, you’re getting even closer to going below 90 percent. In that case, at any given time, it will spread.”

The MMR vaccination – which covers measles, mumps and rubella – is administered in two doses. The first is given between 12 and 15 months of age, and yields a 90 percent chance of developing immunity against measles. The second dose can be given four weeks later, but is typically administered at age 4 or 5, and pushes the likelihood of measles immunity to 95 percent.

Measles widespread in foreign countries

Most measles cases in the United States – including two of Orange County’s reported cases in 2014 – are contracted by international travel, according to the CDC.

The CDC reports that measles is widespread throughout the world, including parts of Europe, Asia, the Pacific and Africa. Dr. Arrieta cautions parents that even developed countries report measles cases.

“Oftentimes, people don’t recognize that the countries they are traveling to have frequent measles cases,” he says. “Cases come from Europe, where people don’t think they’re at risk. It is a very small world these days.”

Learn more about the infectious diseases division at CHOC.

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Kids and the Flu

How do you distinguish a common cold from the flu (influenza)?When late fall rolls around, the flu usually rolls in with it.

“The first few days  with a cough, fever and sore throat are early signs of influenza,” says Dr. Antonio Arrieta, an infectious disease specialist at CHOC. “Fever is very common. Probably 90 percent of children  who have influenza will have a high fever.”

What else should you look out for to identify this seasonal respiratory infection?

  • Body aches
  • Chills
  • Headache
  • Runny or stuffy nose

It’s possible for your child to be on the winning team this flu season.

“The best way to fight influenza is not to get it. All children older than 6 months and adults should receive the flu vaccine. It is safe and highly effective,” Dr. Arrieta says.

What else can you do? Suggestions from Dr. Arrieta include washing one’s hands very carefully before and after taking care of young children, and avoiding close contact for long periods of time with people who have influenza or a respiratory illness.

The flu shot is safe and up to 70 percent protective. Also safe and effective is the intranasal form of the vaccine, which shouldn’t be given to children less than two years of age and with asthma or a history of wheezing, says Dr. Arrieta.

“The only effective treatment that will shorten the course of the illness is anti-viral agents,” Dr. Arrieta says.

The most familiar one is Tamiflu. It’s safe for children ages 1 and older, if necessary.

Alternatively, parents can administer over-the-counter remedies like acetaminophen for fever or discomfort, Dr. Arrieta says.

Dr. Arrieta does not recommend decongestants for flu treatment.

“They can make children drowsy and limit the parent’s ability to evaluate them if they’re not feeling well,” he says.


  • Number of days severe flu symptoms may last: 7 days
  • Number of colds Americans suffer yearly: 1 billion
  • Age recommended to begin getting yearly flu shots: 6 months

View the full feature on Kids and the Flu

Dr. Antonio Arrieta
Dr. Antonio Arrieta
CHOC Infectious Disease Specialist


Dr. Arrieta has served patients at CHOC Children’s since 1991. He is the director of pediatric infectious diseases and director of infectious disease clinical research, and specializes in the treatment of serious community acquired and nosocomial infections. Dr. Arrieta completed his fellowship at UCI Memorial/Miller Children’s Hospital in Long Beach and his pediatrics residency at Southern Illinois University.

Dr. Arrieta’s philosophy of care: “My most important message for the community is prevention mainly through timely immunization, and also by observing healthy habits and handwashing.”

Universidad Peruana Cayetano Heredia in Lima, Peru

Pediatric Infectious Diseases

More about Dr. Arrieta

This article was featured in the Orange County Register on December 3, 2013 and was written by Shaleek Wilson.