DISEASE: A viral infection,

  1. 1 in 5 infected w/ virus become ill; 80% asymptomatic
  2. Symptoms: fever, rash, joint pain, conjunctivitis (red eyes); muscle aches, headache.
  3. Incubation time from exposure to symptoms unknown: likely a few days to 2 weeks.
  4. Illness usually mild: several days to a week duration.
  5. Virus is actively in the blood while the person is ill or asymptomatically infected, and then for 10 weeks or more after (latest knowledge); virus in semen up to 9 weeks post onset of infection.Zika virus persists in the placenta for an unknown number of months after maternal infection; it may persist in the brain of even grossly normal-appearing fetuses, even after birth, for an unclear amount of time.
  6. Hospitalization uncommon and death rare.
  7. Microcephaly (head cirucumference > 2 standard deviations below the mean) and fetal neurological damage (including blindness, retardation, and motor dysfunction) occur with increased frequency and severity in ZD-infected pregnant women; microcephaly estimated currently at 1%.
  8. Association with Guillaine-Barre’ Syndrome.


1. Same mosquitoes (daytime feeders, white-striped legs) that cause dengue and chikungunya: illness similar.

  • Aedes aegypti: Mainly S. California, South Texas, Florida (but, at least 30 U.S. states)
  • Aedes albopictus:As far north as New York

2. Body fluids: exposure by intimate sexual contact (vaginally or rectally) with or transfused blood from Zika virus (ZV) infected person.

The virus is detectable in breast milk, but transmission has not been reported by that route.

3. Virus has been detected in sperm, urine, and saliva, but it is unknown if the latter two can transmit infectious virus.

NOTE: 1. To be at risk for current ZD, you would have had to have been mosquito-exposed in a geographic area with active ZD within the past 2 weeks or have had intimate contact with body fluids of someone who had been in an area with active ZD.

2. If you travel through a Zika-active country, you should maintain mosquito repellents on your skin and clothes (see below, under “Prevention”) while there and for 2 weeks after leaving the Zika zone to prevent passing the virus to the home country mosquito population (since there is an high percentage of Zika infections without symptoms).


  1. American Samoa, Cape Verde, Africa; SE Asia (before current explosive outbreaks*)
  2. Barbados, Bolivia, Brazil, Colombia, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Nicaragua, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, U.S. Virgin Islands, Venezuela (check the cdc.gov website for updated information on ZD activity areas)

*May be because this is a novel virus in these “new” areas; in old ZD areas, much of population may be immune from virus prevalence established long ago.

Zika Next Door: Mexico

ZD is present throughout Mexico, except for areas above 6,500 feet (2,000 meters) elevation which is essentially a strip of mountains starting just below New Mexico and curving eastward down the very center of the country ending near the southern border. So, all coastal areas, including Cabo San Lucas Peninsula and the Yucatan Peninsula (Cancun, Cozumel) are risk areas. The ZD mosquitoes do not live about 6,500 feet. In those elevated areas, ZD can still be contracted through sex.


  1. Antibody testing (see item 5 under “Pregnancy”):blood
  2. RT-PCR test for viral genetic material (done at CDC):blood, urine, saliva
  • Saliva testing increases sensitivity of ZD detection
  • Urine testing increases the time-window of detectable virus

TREATMENT (no specific anti-viral medication)

  1. Rest, fluids
  2. Tylenol (acetaminophen or paracetamol) for discomfort, fever; NO aspirin or other ant-inflammatories until rule out dengue or bleeding tendencies.

PREVENTION (no vaccine)

  1. Wear long-sleeved shirts, pants
  2. Use air conditioning, window/ door screens, mosquito bed nets
  3. Empty standing water containers
  4. Repellants*: DEET (> 30%; 20%, if long-acting formulation), picardin (> 20%), IR3535, para-methane-diol products, or oil of lemon eucalyptus extract (> 30%) *If pregnant or breastfeeding, use an EPA-registered agent; DEET and picardin are safe with pregnancy.
  5. Permethrin applied to clothing (or buy pre-treated clothes)
  6. If have had ZD after credible exposure, continue mosquito barriers (Permethrin-treated clothes and insect repellents on exposed skin) for 1 week post-departure from the ZD areas to diminish potential virus spread from you to mosquitoes in your home locale, then to others; 60-80% of Zika Disease can be without symptoms, so you can have the virus in your blood up to a week after last exposure and have no idea of that.
  7. After exposure in a ZD-zone
    • Men should practice safe-sex for at least 6 months; duration of Zika virus in semen unknown.
    • Women should avoid becoming pregnant for at least 8 weeks.
    • Zika virus has been isolated from semen at least 2 weeks after infection onset.
    • Blood may be ZV negative while semen is positive.
    • Current pattern and duration of ZV shedding from genital-urinary tract of men is unknown.
  8. With sexual intercourse, practice barrier and other contraceptive measures while in ZD zones and for 8 weeks (women) or 6 months (men) after departure from them (or abstain).
  9. World Health Organization (WHO) currently strongly recommends pregnant or possibly pregnant women NOT TRAVEL to ZD countries.

ZD AND PREGNANCY: ZD infected pregnant women with increased frequency may birth newborns with microcephaly (disproportionately small heads), significant nervous system damage, or have other adverse outcomes of their pregnancies.

  1. In any trimester of pregnancy, postpone travel to ZD areas (the younger the fetus, the worse).
  2. Sexually active women of childbearing age who are heading to ZD areas should,
    • Get a pregnancy test prior (and possibly after) travel.
    • Practice birth control 2 weeks pre-travel, during, and for 8 weeks after travel exposure (and have a pregnancy test upon return if usual menses are missed).
    • Strictly prevent mosquito bites (see “Prevention”).
    • Consult with your gynecologist or an Infectious Diseases specialist.
  3. Once the ZD virus is cleared from the blood, a fetus will not be infected (nor is there future risk with pregnancy).
  4. ZD testing should be done on any pregnant woman who has been in a Zika virus zone, between 2-12 weeks post-exposure; within 2 weeks of ZD-like illness.
  5. There may be false-positive Zika antibody tests (cross-reactions with dengue, West Nile, and yellow fever viruses or yellow fever and Japanese encephalitis vaccines).
  6. When Zika virus arrives in the U.S. and resides in our mosquitoes, childbearing age, sexually active women will need to,
    • Practice strict mosquito bite avoidance and arrange their homes for this.
    • Time pregnancy to maximally avoid mosquito season.
  7. While pregnant, if your sexual consort has been in a ZD zone country you should either abstain from sexual intercourse or practice “safe sex” measures for the entire pregnancy.
  8. Post-ZD Pregnancy Monitoring,
    • Ultrasound monitoring for fetal abnormalities; at least one after 28 wks’ gestation (microcephaly best assessed in 3rd trimester)
    • Amniocentesis: after 6 wks from exposure, but no sooner than 21 weeks’ gestation.
    • Newborn babies who are asymptomatic from ZD- confirmed mothers should be monitored for neurological, eye/vision, and hearing problems.


    Based upon the following known facts, we can speculate on the likely implication for Zv in the near future in Texas,

    1. Zv is endemic in Brownsville, TX as of 12/15/16 (and has been along the northern border of Mexico since Dec.,2015).
    2. 80% of Zv infected people have no symptoms.
    3. Zv is transmitted by mosquitoes that are endemic throughout Texas and across the bottom 1/3 – 1/2 of the U.S.
    4. Zv persists in and is transmissible by semen for at least 6 months.
    5. Zv persists in maternal placentas for weeks-months.
    6. Zv can actively infect and persist in the brains of grossly normal-appearing fetuses, even after childbirth.


    Taking the above into account,

    1. Zv should spread throughout Texas in the upcoming mosquito season, starting around April; this will likely occur much more rapidly than last season when the virus first showed up as a locally orginated (not travel-related) infection in Miami, FL.
    2. Childbearing age, sexually active women will probably be advised,
      • To always require condom usage with sexual intercourse, unless intending pregnancy.
      • To routinely use effective mosquito repellents on exposed skin and possibly treat outdoors clothing with permethrin throughout mosquito season.
      • To undergo testing (along with their sexual partner) for Zv prior to attempting pregnancy and regularly (possibly monthly) throughout pregnancy.
      • Abstain from sexual intercourse or use condoms throughout any pregnancy.
      • Monitor a fetus repeatedly over the course of a pregnancy for development of microcephaly.
      • Confer with their gynecologist and other appropriate specialists, such as in Neonatology and Infectious Diseases, if a Zv test is positive.

    This may all change if effective vaccine becomes available, but unlikely for the 2017 warm season.


For more information on Zika Virus testing see our testing page.