The Zika Virus: What to Know

Originally published 03/2016. Updated 12/2018.

There has been significant media attention lately regarding the Zika virus (Zika), and with mosquitoes becoming more prevalent in warmer weather, we expect an increased concern as we move into the summer months. Much has yet to be discovered regarding Zika and its ability to adhere to an oocyte.

What is known about Zika?

Although we have much to learn about the effects of the virus, we do know that it is not new --- it was first identified in 1947 in the Zika Forest of Uganda, in Rhesus monkeys. Since then, epidemiologists have tracked the virus and found evidence that it has affected the human population in both Africa and Asia as early as 1952.¹

Research has shown that the virus is transmitted to humans primarily from a mosquito called Aedes aegypti. The virus reached the Americas in 2015, with the earliest report coming from Brazil. As of July 2018, the Food and Drug Administration (FDA) has reported 91 countries and territories worldwide with active transmission of the virus.²

What are Zika virus disease symptoms?

The Centers for Disease Control believe only 20% of the population, or 1 in 5 individuals, will exhibit symptoms.  The most common symptoms include fever, rash, joint pain, or conjunctivitis (red eye).  Some individuals may also experience muscle pain and headache.  The incubation period is not fully known, but is believed to be up to a week.

Who is at risk?

Women who plan to become pregnant or men who will father a child need to take precaution.

Zika has been linked to local outbreaks of microcephaly -- a condition in which a child is born with an abnormally small head and a higher susceptibility to issues with neurological development. It is suspected that if a female is infected with Zika before or during her pregnancy, the virus may transfer to the fetus. Given this pregnancy risk, reproductive endocrinologists and other medical practitioners have become increasingly aware of potential risks to expectant mothers, as more details are being discovered.

Presently, from the perspective of reproductive donation, Zika is not known to impact the female oocyte (egg), however the FDA has reported evidence that the virus can persist in semen and other tissue such as the placenta. There are currently two confirmed cases and four probable cases involving the transmission of the virus through sexual contact.  Cases of sexual transmission of infected women to their sexual partners are limited and suggest that is less frequent than transmission from men.

Oocytes and semen are different in their biological composition. Spermatozoa, or sperm, live in seminal fluid and together they make up semen. Semen is a leukocyte-rich material, which is more susceptible to becoming infected with a virus. It is believed that Zika is likely to survive both the freeze and thaw processing of semen, thereby resulting in frozen sperm having the ability to transmit the virus at a later point in time. Since oocytes are not leukocyte-rich, it is unknown if they will be susceptible to Zika, and there have been no known cases of Zika transmission via an oocyte, to date.

What should I do to protect myself?

The Centers for Disease Control and Prevention (CDC) recommends that women postpone travel to areas where Zika is more likely to spread. If she must travel, she should discuss her plans with her physician and take preventative measures to protect herself from mosquito transmission.

Men who plan to become intended parents, and men who are intimate with women who seek to donate their eggs should also be cautious due to evidence that Zika can be transmitted via semen. It is not clear how long semen may remain infected, though findings suggest anywhere between 4–10 weeks, so if traveling abroad, men should consult with their physician about their risk of contact with this vector-borne virus.

What is California Cryobank Donor Egg Bank doing about Zika?

According to the CDC, no instances of Zika transmission during fertility treatment have been documented³; however the FDA has issued guidance to reduce the potential for transmission of Zika virus in donors.

Based on FDA guidlines⁴ and CDC recommendations, California Cryobank Donor Egg Bank has recommended to its network of fertility practices who cycle egg donors, that egg donors with a known and/or suspected Zika virus infection are not to move forward with stimulation and retrieval until the resolution of symptoms and a deferral of six months. Egg donors who have traveled to an area with active Zika transmission or had sex with an individual with Zika risk factors will also be deferred from an egg retrieval cycle for six months. These are conservative precautions as presently, there is no known case of oocyte transmission.

Additionally, California Cryobank Donor Egg Bank has recommended to its network of fertility practices that donors be educated and advised to avoid travel to areas experiencing Zika virus outbreaks. Egg donors who have traveled to an affected area or have partners who have traveled to an affected area should delay cycling for six months. In areas in which mosquitoes are prevalent, donors should utilize repellent and other precautionary tactics to avoid infection by mosquito transmission.

California Cryobank Donor Egg Bank anticipates that this course of action is conservative, given there is no known transmission of the virus from oocytes. This recommendation will remain fluid in accordance with each collection center’s regional climate and infection prevalence. As more information becomes available, California Cryobank Donor Egg Bank will revise its recommendation to ensure the safety of the men and women who utilize egg donors from the network.

Sources 

1. Centers for Disease Control: About Zika Virus Disease
   
2. Food and Drug Administration: Revised Recommendations for Reducing the Risk of Zika Virus Transmission by Blood and Blood Components
   
3. Centers for Disease Control: Exposure, Testing, & Risks
   
4. Donor Screening Recommendations to Reduce the Risk of Transmission of Zika Virus by Human Cells, Tissues, and Cellular and Tissue-Based Products (May 2018)