The Rise of the Zika Virus

February 11, 2016

The Zika virus, once viewed as a short-lived, mild illness, has gained notoriety in recent months due to an increased association with birth defects, specifically microcephaly, in pregnant women infected with the virus across the globe.¹ Brazil, the epidemic epicenter, estimates over one million Brazilians are infected with the virus.² News on the spread of this infection across the world has been exponentially rising over the last several weeks, including local Texas cases reported in Harris, Bexar, Dallas, and Travis Counties within the last month. Most recent news details viral transmission through sexual contact, a previously questionable mode of transmission. This instance, reported in Dallas County on February 2, 2016, is the first known account of local transmission of the virus within the United States.³ All other known cases of Zika virus within the continental United States have been contracted outside of the country, typically from recent travel to cautionary areas where Zika virus is well known.⁴

Zika virus, first named in 1947 for a mosquito collection discovered in the Zika Forrest of Uganda, is a part of the flavivirus family, also including dengue, West Nile, and yellow fever viruses. As an arbovirus, Zika is usually spread by insect-to-human contact.⁴ Mosquitos are the primary vector with infected Aedes species mosquitoes, specifically Aedes aegypti and Aedes albopictus, being the main carriers of the virus.⁵ Viral transmission occurs through sexual intercourse, blood transfusions, and potentially from mother to fetus around the time of childbirth.⁴ The Centers for Disease Control and Prevention (CDC) published an official health advisory warning on January 15, 2016 urging travelers to avoid travel to Cape Verde, Mexico, Samoa, and many countries in the Caribbean, Central and South America. This alert specifically urged women of childbearing age to avoid travel to these areas if at all possible.⁵

Zika virus has not been seen to commonly cause devastating effects to those infected, with up to 80% of people who contract the virus being asymptomatic. If symptoms do arise, they typically begin 2-3 days after initial contact and last 7 days. Symptoms are commonly mild and include rash, headache, bone and joint pain, and fever. Rare reports of Guillain-Barre syndrome have also been noted after infection. Much of the apprehension with Zika virus has been linked to potential birth defects. Microcephaly, a birth defect associated with a small head and incomplete brain development, has been noted as a major concern, particularly for women who contract the virus in their first trimester.⁵ Brazil reported 1,248 infants born with microcephaly in 2015, which correlates to a 20-fold increase in incidence. Most recently, vision-threatening eye abnormalities have been linked to infants born with microcephaly, including ocular lesions and optic nerve changes.² Currently, there is no treatment or vaccine available for Zika virus, with supportive care being the only current recommendation.^{4, 5}

Due to the lack of resources available to treat or prevent Zika virus, the best protection presently is education. Prevention relies on reducing mosquitoes through source control (e.g., removal and modification of breeding sites) and reducing contact between mosquitoes and people.⁶ Recently, the American Red Cross has developed a statement addressing blood product donations, in order to decrease transmission risks. The Red Cross has implemented a self-deferral for blood donors who have traveled to Mexico, the Caribbean, or Central or South American within 28 days of blood donation. In addition, if symptoms arise in a donor within 14 days of donation, the Red Cross should immediately be notified.⁷

Daily Zika virus updates providing education on prevention, travel, and viral spread can be found on the CDC website.⁸

References

1. Zika virus: what happened when. Available at: http://www.npr.org/sections/health-shots/2016/02/10/466127813/zika-viru…. Accessed February 11, 2016.
2. de Paula Freitas B, de Oliveira Dias J, Prazeres J, et al. Ocular findings in infants with microcephaly associated with presumed Zika virus congenital infection in Salvador, Brazil.JAMA Ophthalmol. doi:10.1001/jamaophthalmol.2016.0267. Published online February 9, 2016.
3. Cable News Network. Zika has been sexually transmitted in Texas, CDC confirms. (Updated February 4, 2016). Available at: http://www.cnn.com/2016/02/02/health/zika-virus-sexual-contact-texas. Accessed February 4, 2016.
4. Vox Science and Health. Zika virus, explained in 6 charts and maps. (Updated January 28, 2016.) Available at: http://www.vox.com/2016/1/20/10795562/zika-virus-cdc-mosquitoes-birth-d…. Accessed February 3, 2016.
5. Centers for Disease Control and Prevention. Recognizing, managing, and reporting Zika virus infections in travelers returning from Central America, South America, the Caribbean, and Mexico. (Updated January 15, 2016). Available at: http://emergency.cdc.gov/han/han00385.asp. Accessed February 4, 2016.
6. World Health Organization. Emergency preparedness, response. Available at: http://www.who.int/csr/disease/zika/en. Accessed February 4, 2016
7. American Red Cross. Red Cross statement on the Zika virus. (Updated February 3, 2016.) Available at: http://www.redcross.org/news/press-release/Red-Cross-to-Implement-Blood…. Accessed February 4, 2016.
8. Centers for Disease Control and Prevention. Zika virus. (Updated February 10, 2016). Available at: http://www.cdc.gov/zika. Accessed February 11, 2016.