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Zika Virus

Last updated: September 9, 2016

Information about the Zika virus for the Stanford community.

For the latest information on Zika virus, please refer to the CDC Zika Info website.

Stanford personnel who are planning any international travel are strongly encouraged to check in and  register international travel plans with the Office of International Affairs. Registration of travel plans will help facilitate access to emergency assistance and follow up, if needed, while on university-related international travel.

General Zika guidance

Zika virus is transmitted to people primarily through the bite of an infected mosquito from the Aedes genus, the same mosquito species that transmits denguechikungunya and yellow fever.  Zika is NOT transmitted from casual human to human contact; however Zika virus can be passed through sex from a person who has Zika virus to his or her sex partners or from a mother to her child during pregnancy. The CDC has issued a level 2 travel alert – Practice Enhanced Precautions – regarding the Zika virus due to its potential to cause birth defects. Although knowledge about Zika virus continues to evolve, the current understanding is that infection during pregnancy can cause microcephaly (small head and brain in newborns) and other poor pregnancy outcomes.

  • The major concern involves infection and illness during pregnancy, and the CDC has issued interim guidance for pregnant women, or those who are planning to become pregnant, who have visited or plan to visit Zika-impacted areas.
  • Also concerning is that Zika virus can be spread during sex by a person infected with Zika virus to his/her partners.
  • Zika virus also appears to be associated with an increased incidence of Guillain-Barré syndrome, a rare auto-immune condition associated with progressive muscle weakness and paralysis.

Outside of pregnancy, Zika virus disease is usually relatively mild and requires no specific treatment. Symptoms appear in approximately 1 out of 5 infected people and can include fever, rash, joint pain, conjunctivitis (red eyes), muscle pain and headache.  Testing for Zika virus is not normally advised unless an individual is experiencing symptoms and has recently been in areas of Zika transmission.

  • The CDC advises that women who are pregnant should not travel to areas with Zika.
  • Pregnant women, and women who are considering becoming pregnant, who must travel to one of these areas should consult with their healthcare provider before traveling and strictly follow steps to prevent mosquito bites and to prevent sexual transmission.
  • Travelers who are pregnant, or are planning pregnancy and returning from a country reporting Zika, should contact their physician for counseling.

Zika and Sexual Transmission

CDC has recently published updated guidance on the prevention of sexual transmission of Zika virus.  This is very important information for pregnant couples, couples planning pregnancy and others concerned about the sexual transmission of Zika.

Stanford-affiliated travel

Stanford personnel who are planning any international travel are strongly encouraged to check in with the Office of International Affairs to register international travel plans. Registration of travel plans will help facilitate access to emergency assistance and follow-up, if needed, while on university-related international travel. Those on Stanford-affiliated travel with health concerns should contact the following Health Centers:

Stanford students – Notify Vaden Health Center:
Robyn Tepper, MD, Medical Director
Clinic phone: (650) 498-2336; press 1 or use the VadenPatient portal to send a secure message
After-hours contact information: (650) 498-2336; press 1

Stanford faculty and staff – Notify Stanford University Occupational Health Center:
Rich Wittman, MD, Medical Director
Clinic phone: (650) 725-5308
After-hours contact information: (650) 723-6227


Currently, there is no vaccine or cure for Zika.  Although locally transmitted Zika cases in the continental United States have been reported in two localized areas of Miami, Florida, most cases have been reported in travelers returning from outside the continental US.

Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites – these mosquitoes can breed in just a teaspoon of water) and reducing contact between mosquitoes and people. The mosquitoes that carry the Zika virus (as well as dengue and chikungunya) bite both indoors and outdoors and are active during the daytime, so using mosquito precautions throughout the day during travel to areas with Zika is strongly advised. Follow steps to prevent mosquito bites:

  • Wear long-sleeved shirts and long pants.
  • Use EPA-registered insect repellents as directed.
  • Insect repellents containing DEET, picaridin and IR3535 are safe for pregnant and nursing women and children older than 2 months when used according to label.
  • Use permethrin-treated clothing and gear (boots, pants, socks, tents).
  • Stay and sleep in screened-in or air-conditioned rooms, using mosquito nets as indicated.

According to a representative of the Santa Clara County Vector Control District, to date there have not been any Aedes mosquitoes (needed for transmission) detected in Santa Clara County.  Also, over the past three years San Mateo County has had an intensive eradication program for the invasive mosquitoes, according to a department representative, no Aedes aegypti mosquitoes have been detected in their vector control program since May, 2015.

NOTE: Due to the ongoing and dynamic nature of the Zika outbreak in impacted areas, this advisory may be updated as new information becomes available. Please check back periodically.