Epidemiology

• Worldwide geographical distribution
  • Outbreaks most commonly occur in tropical and subtropical regions.
  • Since 2015, epidemic outbreaks have been reported in South America (especially Brazil).
• Epidemiology in the US
  • The overwhelming majority of cases (> 25,000) are reported in US territories, most of which occurred in Puerto Rico

Etiology

• Pathogen: Zika virus
  • Genus: flavivirus, type of arbovirus
  • Positive-sense, single-stranded, enveloped RNA
• Route of transmission
  • Vector-borne transmission by the mosquito Aedes aegypti (common)
  • Transplacental transmission from the mother to the fetus
  • Sexual transmission
    • The virus persists in the testicles.

Pathophysiology

Clinical features

• Approx. 80% of cases remain asymptomatic
• In symptomatic patients, the manifestations are usually mild and last for 2–7 days
  • Low-grade fever
  • Flu-like symptoms: headache, arthralgia, myalgia, non-purulent conjunctivitis, malaise
  • Maculopapular, pruritic rash (20% of cases)

Complications

• Guillain-Barre syndrome
• During pregnancy
  • Congenital Zika syndrome: growth restriction and significant CNS complications in neonates resulting from intrauterine transmission of the Zika virus
    • Microcephaly (craniofacial disproportion)
    • Ventriculomegaly
    • Subcortical calcifications
    • Spasticity (contractures), hyperreflexia, seizures
    • Ocular abnormalities (e.g., pigmentary retinal mottling)
    • Sensorineural hearing loss
  • Miscarriage

Diagnostics

Treatment