Stanford University advisory on Zika virus

The mosquito-borne Zika virus has been featured in media reports recently, with ongoing monitoring and health advisements from the U.S. Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO) and the governments of affected countries. The situation is still developing, which is why there are frequent updates and changes to these advisements and to the lists of impacted areas.

General travel guidance

Zika virus is transmitted to people through the bite of an infected mosquito from the Aedes genus, the same mosquito that transmits dengue, chikungunya and yellow fever. The CDC has issued a level 2 travel alert – Practice Enhanced Precautions – regarding the Zika virus due to its potential association with birth defects. Although knowledge about Zika virus is evolving, at this time the virus appears to be associated with microcephaly (small head and brain in newborns) and other poor pregnancy outcomes in women infected during pregnancy.

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 Zika-impacted areas.

Outside of pregnancy, Zika virus disease otherwise 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.

  • The CDC advises pregnant travelers to areas with known Zika virus transmission to postpone their travel, if at all possible.
  • 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.
  • Travelers who are pregnant, or are planning pregnancy and returning from a country reporting Zika, should contact their physician for counseling.

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 with concerns about Stanford-affiliated travel 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


To date no locally transmitted Zika cases have been reported in the continental United States, but cases have been reported in returning travelers. According to Dr. Noor Tietze, the director of the Santa Clara County Vector Control District, there have not been any Aedes mosquitoes (needed for transmission) detected in Santa Clara County, and none have been found in in Menlo Park (San Mateo County) since May 2015. Santa Clara County Vector Control has an active program for the detection of Aedes mosquitos termed "Cobra," which stands for Container Breeding Mosquito Assessment, and they will be releasing additional information in the near future.

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.