Zika virus

Dominic Dwyer Medical Virologist Director, ICPMR and Pathology West Westmead Hospital

Zika virus

Flavivirus • first isolated in 1947 in a rhesus monkey in the

Zika forest, Uganda • enveloped RNA virus ~11 kb • closely related to dengue, yellow fever, Japanese

encephalitis viruses • transmitted by Aedes spp. mosquitoes

Clinical presentation similar to other flaviviruses • fever, rash, myalgia, arthralgia • headache, conjunctivitis • (only) 20% symptomatic

Predicted distribution of Aedes aegypti

Kramer eLife 2015

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Knope et al. 2013; CDI 37: 55-59

Australian travellers and dengue

Zika virus - Australia (24/2/16)

Zika virus - Australia (24/2/16)

Faria NR et al. Science 10.1126/science.aaf5036 (2016)

Travelers to Brazil from countries with recorded ZIKV outbreaks between 2012 and 2015

9.9 million visitors depart Brazilian airports annually 65% to Americas, 27% to Europe and 5% to Asia

Bogoch Lancet 2016

Time series and cartography of reported ZIKV infections and microcephaly cases in Brazil

Faria NR et al. Science 10.1126/science.aaf5036 (2016)

Weekly ZIKV notifications in 5596 municipalities in Brazil (n=2791 cases)

ZIKV cases/100,000 people in each state

Suspected microcephaly cases/100,000 people in each state

Driggers RW et al. N Engl J Med 2016. DOI: 10.1056/NEJMoa1601824

Timeline: Symptoms, Radiographic and Laboratory Studies

Driggers RW et al. N Engl J Med 2016. DOI: 10.1056/NEJMoa1601824

Foetal ultrasound at 19 weeks gestation

Panel A: ZIKV-exposed foetus Thin cerebral cortex with increased extra-axial space (E), dilated third ventricle (T), enlarged frontal horns (F), apparent absence of the cavum septum pellucidum Panel B: Normal foetus at same gestational age Visible cavum septum pellucidum (C)

Serology • Acute and convalescent sera at least 14 days apart • ZIKV IgM and IgG by immunofluorescence (IFA) • EIAs available, but uncertain reliability • Main problem is cross reactivity with other flaviviruses

(and YF vaccine) • Neutralisation is the ‘gold-standard’

Test for dengue, chikungunya (co-circulating) Also consider other viral diseases, malaria, leptospirosis, rickettsial infections etc

Laboratory Testing for Zika virus

Gourinat Emerg Infect Dis 2015, Musso J Clin Virol 2015

RT-PCR • short-lived viraemia (<5 days) • Viruria (<30 days) • saliva, amniotic fluid, semen, breast milk

Test for dengue, chikungunya (co-circulating) Virus isolation

Laboratory Testing for Zika virus

Gourinat Emerg Infect Dis 2015, Musso J Clin Virol 2015

Issues for ED

• Clinical suspicion • Travel history in anyone with a fever or

suspected infection • Pregnancy history and management • Seek advice from ID/microbiology

– differential diagnosis – appropriate specimens and tests – need for testing others (partners, family etc)

• Review NSW and Commonwealth Health Department advice