In a recent update, the Centers for Disease Control and Prevention now state that Zika virus is transmissible through any type of sexual activity that involves exposure to genital secretions. Previously thought to be sexually transmitted by males to their partners, a recent case in New York City showed that the infection could be passed from a female to a male.

Zika virus carries a risk of severe birth abnormalities in a fetus when infection occurs during a pregnancy. Chief among these is microcephaly, a condition where head growth is decreased as a result of damage to brain tissue. The virus is responsible for at least 1600 abnormal newborns in Brazil and 12 in the United States.

The significance of the new findings regarding sexual transmission is that the population at risk for spreading Zika has now increased considerably. In a revamp of its official recommendations, the CDC now advises against unprotected sex with any person, male or female, who has traveled to or lives in an area with Zika. This includes female-female through vaginal secretions as well as male-male through seminal fluid.

The CDC also released new data that suggests Zika may exist in a pregnant woman for longer than the week or so previously thought. Testing should be performed up to two weeks from exposure or the appearance of symptoms. The CDC stated, “”Expanding the use of the Zika-specific test could provide more women with Zika virus infection a definite diagnosis and help direct medical evaluation and care.”

The CDC also recommended testing all pregnant women in at-risk areas or with possible Zika exposure. These include Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) and IgM antibody studies. Previously only available at the National Institute of Health, CDC, and certain state labs, Zika tests are now more widely available through state and commercial labs.

Acute Zika virus infection causes mild symptoms (fever, rash, joint aches, red eyes) in 20 per cent of cases, but 80 per cent show no symptoms at all. While this fact may appear comforting to some, it means that there is the possibility that an asymptomatic pregnant woman may not learn she was infected until her fetus is found to be abnormal on obstetric ultrasound. Often, serial ultrasounds over time are needed; confirmation of an abnormal head growth pattern may not occur until late in the pregnancy.

Official CDC recommendations for those planning to get pregnant in the near future are as follows: “Women who have Zika virus disease should wait at least 8 weeks after symptom onset to attempt conception, and men with Zika virus disease should wait at least 6 months after symptom onset to attempt conception.” The longer period for men reflects that ability of the virus to remain active in seminal fluid for three months or more.

Zika virus is also thought to be transmissible through blood transfusions and even menstrual blood. A case in Utah where a family caregiver contracted the infection suggests that handling bodily fluids, such as blood, urine, or feces might be a risk factor.

Despite this, the grand majority of infections occur due to bites from infected mosquitoes. Controlling mosquito populations by draining standing water and other methods is considered the most effective way of decreasing Zika cases in an area. Individuals should wear loose, light-colored clothing and use mosquito repellent whenever outside in at-risk areas.

Expect CDC guidelines regarding Zika virus infection to change as more is known about the Zika virus.

Joe Alton, MD

Find out all about Zika virus in Joe Alton, MD’s latest, “The Zika Virus Handbook”. available at Amazon.