Every few years, a “new” (not really) funny-sounding infectious disease is in the news and causing anxiety: first it was SARS (severe acute respiratory syndrome), then avian flu, swine flu, dengue, MERS (Middle East respiratory syndrome), chikungunya, Ebola, and now in 2016 it’s Zika virus.
Zika virus was first identified in 1947 at the East African Virus Research Institute (now the Uganda Virus Research Institute) in Entebbe, Uganda, as a cause of febrile illness in rhesus macaques. (1) Until 2007, Zika virus caused only rare cases of human disease in Africa and Southeast Asia. However, in April 2007, an outbreak was reported on Yap Island that subsequently spread to other Polynesian islands. This was followed in 2015 by an explosive and widespread outbreak in South and Central America that is ongoing. Brazil seems to be particularly severely affected.
Although no autochthonous cases of Zika virus have been identified in the United States, recently imported cases have been reported. (2) A total of 32 states potentially have the mosquito species Aedes aegypti that serves as the vector for spreading Zika virus infection. This same mosquito vector spreads dengue and chikungunya viruses. Some are concerned that the virus may adapt, possibly allowing spread of the infection through Aedes albopictus, another mosquito present in the United States. (3)
The incubation period for Zika virus infection is 2 to 14 days. The disease has a wide spectrum and only 1 in 5 infected patients becomes symptomatic. Hospitalizations are uncommon and death is rare. Clinically, Zika virus infection presents similarly to many other viral infections, with fever (often low-grade), vomiting, maculopapular rash, arthralgias, myalgias, retro-orbital pain, and conjunctivitis.
Serologic diagnosis is not dependable because of potential cross-reactivity with dengue and chikungunya viruses. Polymerase chain reaction that can detect the RNA of Zika virus is available from the Centers for Disease Control and Prevention (CDC) and some state health departments.
There is no commercially available test for Zika virus and no specific antiviral treatment; management is primarily supportive. There is also no vaccine to protect against Zika virus infection. Prevention is largely dependent on avoidance of areas where there is active Zika virus transmission as well as mosquito control and measures to prevent mosquito bites.
Compared to previous “new” emerging infections, Zika virus infection has particular interest for pediatricians because of the major concern that such infection may be responsible for microcephaly in infants born to infected women. Although no causal relationship has been determined between Zika virus infection during pregnancy and microcephaly in the newborn, the many-fold increase in cases of microcephaly in the midst of a Zika virus epidemic offers compelling epidemiologic suggestion of a link. (4) A total of 2,401 suspected cases of microcephaly have been reported in Brazil during the period of outbreak. Of these, 134 were confirmed as being related to Zika virus infection, 102 were considered not related, and 2,165 are still under investigation. (5) Further careful research is needed to determine if this temporal association is causative.
Because of this concern, the CDC recommends that pregnant women avoid travel to areas of ongoing Zika virus transmission. If travel is necessary, measures should be taken to prevent mosquito bites. Pregnant women returning from areas of Zika virus activity should consider testing to determine if they have become infected. (6)This “new” viral infection is another reminder that world is becoming smaller, and infections once exotic and far off can reach our shores quickly and sometimes stealthily. We need to be vigilant in identifying potential emerging infection threats quickly. Building public health infrastructure in under-resourced parts of the world benefits not just local populations but those of us in the resource-rich parts of the world.
1.Dick GWA, Kitchen SF, Haddow AJ. Zika virus. I. Isolation and serological specificity. Trans R Soc Trop Med Hyg. 1952;46(5):509–520
2.McCarthy M. First US case of Zika virus infection is identified in Texas. BMJ. 2016;;352:i212
3.Fauci AS, Morens DM. Zika virus in the Americas – yet another arbovirus threat. N Engl J Med. 2016 Jan 13. Epub ahead of print
4.Oliveira Melo AS, Malinger G, Ximenes R, Szejnfeld PO, Alves Sampaio S, Bispo de Filippis AM. Zika virus intrauterine infection causes fetal brain abnormality and microcephaly: tip of the iceberg? Ultrasound Obstet Gynecol. 2016;47(1):6–7
5.European Centre for Disease Prevention and Control. Epidemiological Update: Outbreaks of Zika Virus and Complications Potentially Linked to the Zika virus infection. 2015. Available at: Epidemiological update: Outbreaks of Zika virus and complications potentially linked to the Zika virus infection Accessed January 25, 2016
6.Petersen EE, Staples JE, Meaney-Delman D, et al. Interim guidelines for pregnant women during a Zika virus outbreak – United States, 2016. MMWR Morb Mortal Wkly Rep. 2016;65(2):30-33