Last winter, an obscure virus was making headlines for causing microcephaly and other birth defects in newborns in Brazil and other South American and Central American countries. We reviewed some Zika facts on The PediaBlog in January:

  • It is spread by the same two species of mosquitos that also carry dengue virus, yellow fever virus, and Chikungunya.
  • The incubation period ranges from 3-12 days after the bite of an infected mosquito.
  • Infection with Zika virus usually results in no symptoms. (60-80% of infected people remain asymptomatic.)
  • Those who do get sick have mild symptoms — fever, rash, joint pain, headache, conjunctivitis — that quickly resolve with no treatment within a few days.
  • Complications, hospitalizations, and deaths have been extremely rare as a result of infection with Zika virus.
  • There is no specific treatment for Zika virus and no vaccine to prevent it.


Last week, the CDC reported 1,658 cases of Zika in the United States. All patients except for one (who got infected in a laboratory mishap) acquired the infection while traveling outside the U.S. None of the U.S. cases involved mosquito bites that occurred within U.S. borders. But by Monday of this week, 15 locally-acquired cases of Zika were reported in a small area of south Florida, prompting the Centers for Disease Control and Prevention (CDC) to issue the first domestic travel warning of the Zika outbreak. The warning is aimed at pregnant women and their partners to avoid traveling to an area comprising 10 square miles north of downtown Miami. Residents have been asked to take mosquito control measures such as draining standing water, covering up exposed skin with clothing, and using insect repellent as officials begin spraying the area with insecticides. Federal health experts are concerned that Zika will spread by way of mosquito bites to other southern states and even points northward, where the transmitting mosquitoes also live. Unfortunately (but not unsurprisingly), Congress has been unable to agree on providing adequate federal funds to fight the outbreak in an organized and effective manner, so health departments around the country are hamstrung in their responses to the spreading disease. On her terrific Travel-Ready M.D. blog, Dr. Sarah Kohl is advising pediatricians and others who work in primary care to help their patients manage Zika’s risks:

One of the most surprising facts about Zika is its ability to harm a baby, even if the mother doesn’t have symptoms. The virus is able to cross the placenta and attack the infant’s nervous system at any time during pregnancy, particularly in the first trimester.

You need to convey the seriousness of this to your patients. Additionally, you need to help them prevent an unintended pregnancy if traveling to an area of Zika infection.

  • Zika can cause brain, eye, and developmental problems, even for babies with a normal head size.
  • If the baby is infected, Zika RNA is detectible in the mother’s blood stream throughout the entire pregnancy. This means the viral infection is ongoing throughout the pregnancy.
  • Over half of all pregnancies in the USA are unplanned.


Now you have the potential for a hot mess.


We now know that Zika can be sexually transmitted, so men have an added responsibility to their partners:

For men the story is quite complex. Zika can hide in semen for a very long time. {Unfortunately we don’t actually know how long}

Current recommendations are based upon case reports of known spread from human to human. You should advise your male travelers to:

  • Use condoms for 8 weeks upon return from a Zika-prone area if they don’t have any symptoms of Zika
  • Use condoms for 6 months if returning with symptoms of Zika
  • Use condoms if their partner is pregnant for the remainder of the pregnancy, regardless of symptoms.


Dr. Kohl recommends the use of long-acting insect repellents containing either 20% picaridin or 30% DEET in liposomal formulation.

If you or a family member are planning to travel to the Caribbean, Central America, or South America, let your pediatrician, internist, and obstetrician know. On the eve of the Games of the XXXI Olympiad in Rio de Janeiro, Brazil, we will certainly hear more about Zika virus over the next two weeks. We can only hope everyone stays safe as they compete for the gold!


More PediaBlog on Zika virus here and here.


(Image: CDC.gov/Laboratory-confirmed Zika virus disease cases reported to ArboNET by state or territory — United States, 2015–2016 (as of July 27, 2016)