An Update on Zika Virus Sonja A. Rasmussen, MD, MS Centers for Disease Control and Prevention (CDC), Atlanta, GA National Library of Medicine webinar March 10, 2016 Center for Surveillance, Epidemiology, and Laboratory Services Division of Public Health Information Dissemination

What is Zika virus? Flavivirus Closely related to dengue, yellow fever, Japanese encephalitis and West Nile viruses Transmitted to humans primarily by Aedes species mosquitoes

Transmission Aedes species mosquito – Aggressive daytime biters, prefer to bite people, live indoors and outdoors, also bite at night – Also transmit dengue and chikungunya viruses – Lay eggs in domestic water-holding containers – Live in and around households Other modes of transmission – Maternal fetal (intrauterine and perinatal), sexual, laboratory exposure – Theoretical – blood transfusion, organ or tissue transplantation, breast milk

Where has Zika virus been found? Prior to 2015, Zika outbreaks occurred in Africa, Southeast Asia, and the Pacific Islands Currently outbreaks are occurring in many countries and territories - Last updated February 29, 2016

Zika Virus in the Continental U.S. Local mosquito-borne transmission of Zika virus has not been reported in the continental United States With current outbreaks in the Americas, cases among U.S. travelers will most likely increase Imported cases may result in virus introduction and local spread in some areas of U.S. Aedes aegypti Aedes albopictus

Clinical Findings Clinical illness usually mild – severe disease requiring hospitalization uncommon, deaths rare Symptoms last several days to a week Most common findings of Zika are: – Fever – Rash – Joint pain – Conjunctivitis (red eyes) Guillain-Barr é syndrome reported in patients following suspected Zika virus infection – Relationship to Zika virus infection is not known

Clinical Features Brasil P et al. N Engl J Med DOI: /NEJMoa

Zika Virus and Congenital Microcephaly Reports of a substantial increase in number of babies born with microcephaly in Brazil first noted in 2015; true baseline unknown – Zika virus infection identified in several infants and pregnancy terminations with microcephaly and in early fetal losses – Some infants with microcephaly have tested negative for Zika virus Increase in central nervous system malformations in fetuses and infants following Zika virus outbreak in French Polynesia

What is Congenital Microcephaly? Clinical finding of a small head at birth, compared to infants of same sex and gestational age Determined by measurement of head circumference Reliable assessment of intracranial brain volume Often leads to cognitive and/or neurologic issues

Maternal-Fetal Transmission of Zika Virus Evidence of maternal-fetal transmission – Zika virus detected prenatally in amniotic fluid in pregnancy with fetal microcephaly and intracranial calcification detected on ultrasound – Zika virus infection confirmed in infants with microcephaly in Brazil and in infants whose mothers have traveled to Brazil but delivered in the US – Zika virus RNA identified in specimens of fetal losses Oliveira Melo A, et al., Ultrasound Obstetr Gynecol 47(1): 6-7, 2016

MMRW Martines RB., et al., MMWR Morb Mortal Wkly Rep Early Release February 10, 1016

NEJM Mlakar J, et al., N Engl J Med Feb 10. [Epub ahead of print]

NEJM (2) Brasil P, et al., N Engl J Med March 4. [Epub ahead of print]

MMWR (2) Meaney-Delman D et al., MMWR Morb Mortal Wkly Rep. 2016; 65(8):211-4.

Microcephaly and Zika What we know Small number of positive test results for Zika virus infection in infants with microcephaly Microcephaly pattern consistent with Fetal Brain Disruption Sequence Based on photos/scans of a small number of affected infants from Brazil Retrospective investigation in French Polynesia outbreak in Infants with other intrauterine infections such as cytomegalovirus (CMV) What we don’t know Causal relation between Zika virus and microcephaly or other adverse outcomes Full spectrum of phenotypes in affected infants Impact of timing of infection during pregnancy Impact of severity of maternal infection Magnitude of the possible risk of adverse outcomes

Treatment No specific medication available to treat Zika Treat symptoms with:  Rest  Fluids to prevent dehydration  Medicine such as acetaminophen (Tylenol®) to reduce fever and pain Zika virus can stay in blood for about a week – important to prevent others from getting sick by preventing mosquito bites during first week of illness

Prevention No vaccines available to prevent Zika Best way to prevent Zika is to prevent mosquito bites  Long sleeves, long pants  EPA-registered mosquito repellents  Permethrin treated clothing  Stay in places with air conditioning or with window/door screens  Sleep under a mosquito bed net if overseas or outside

Travel: Pregnancy Pregnant women should consider delaying travel to areas with Zika or talk to a healthcare provider before traveling Women trying to get pregnant should talk to a healthcare provider before traveling If traveling, pregnant women should strictly follow steps to prevent mosquito bites.

CDC Zika Response

Summary - 1 Zika virus continues to circulate and cause locally-transmitted disease in the Americas Consider the possibility of Zika virus infection in travelers with acute fever, rash, arthralgia, or conjunctivitis within 2 weeks after return Studies are underway to characterize the relationship between Zika and congenital microcephaly and between Zika and Guillain- Barre syndrome

Summary - 2 Pregnant women in any trimester should consider postponing travel to areas of Zika virus transmission Guidelines for evaluation and management of pregnant women and infant have been developed Latest information is available at and