In 2015, Zika went from a footnote in virology to the forefront of international media with reports of microcephaly in newborns from Brazil. Causality was firmly established in May between Zika infection during pregnancy and fetal neurological defects by the Centers for Disease Control (CDC).
Symptoms and Treatment
Zika was first identified in Uganda in the 1940s but was thought to cause only mild illness that included fever, rash, arthralgia and conjunctivitis, with limited reports of more serious complications such as Guillain-Barré syndrome. Once infected, symptoms typically appear within three to 12 days. Approximately 50 percent or more of infected individuals display no symptoms, confounding the identification of Zika-infected individuals. Currently, no approved therapies are available and treatment is limited to supportive care.
Multiple Modes of Transmission
Classified as a Flavivirus like West Nile and yellow fever, the primary vector is Aedes aegypti, a small mosquito active during the day and found in and around houses. Other species of Aedes, and more recently Culex mosquitoes, have also been identified as potential carriers, implying that Zika could spread further than initially anticipated.
Zika is also transmitted through sex with an infected partner. The virus can remain in human fluids for an extended time and it stays in semen longer than other fluids. A woman clears the virus in eight weeks, though men can take as long as six months.
Prevention of Zika infection is limited to prevention of transmission, as no vaccine is available.
The most effective mosquito repellant is n,n-diethyl-m-toluamide (DEET). DEET concentration can vary by product, though the following is considered safe:
- 10-40 percent for average exposure in adults.
- 50-100 percent for higher risk exposure in adults.
- 30 percent or less in children older than two years of age.
- DEET is not recommended in children under two.
- DEET is safe for pregnant and breast-feeding women.
Repellents should be reapplied every four to eight hours, based on manufacturer’s directions.
Alternate products containing citronella, lemon eucalyptus oil, tea tree oil, or garlic are available, though they are less effective and require frequent reapplication.
For prolonged exposures, permethrin can be used on clothing and outdoor equipment, but is not recommended for skin.
To prevent sexual transmission, the CDC recommends the use of condoms if one partner has lived in or traveled to an area where Zika has been identified.
The CDC has provided recommendations to prevent further transmission by exposed individuals. Use insect repellant for three weeks, use condoms or abstain from sex, monitor for symptoms and talk with a doctor. Though there is no commercially available diagnostic test for Zika, a doctor can order a laboratory RNA-based test.
In teaching my daughter about the natural dangers of her world, I often find myself saying, “Don’t be scared, be aware.” A similar approach can be useful when talking with patients, especially with the unfolding Zika epidemic.
-Bethany Ensor Crotts, is a PharmD candidate at Sullivan University, College of Pharmacy and Chair of the APhA Operation Immunization.