an update on zika virus
TRANSCRIPT
An Update on Zika Virus
Sonja A. Rasmussen, MD, MS
Centers for Disease Control and Prevention (CDC), Atlanta, GA
National Library of Medicine webinarMarch 10, 2016
Center for Surveillance, Epidemiology, and Laboratory ServicesDivision 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
http://www.cdc.gov/zika/geo/index.html - 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-Barré 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 2016. DOI: 10.1056/NEJMoa1602412
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 2014-2015 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. 2016 Feb 10. [Epub ahead of print]
NEJM (2)
Brasil P, et al., N Engl J Med. 2016 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 2013-2014
• 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 www.cdc.gov/zika and www.cdc.gov/mmwr/zika_reports.html