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