Snapshot A 26-year-old man presents to his primary care physician for weakness in his legs. He had recently spent spring break in the Caribbean exploring jungles and caves and had multiple bug bites from this trip. He recalls a febrile illness with an itchy rash and conjunctivitis that occured shortly after this trip. A few days ago he experienced bilateral weakness in his extremities with occasional foot drop and difficulty walking. He reports no difficulty breathing. On physical exam, he has no fever and no rash. His lower extremities have depressed bilateral deep tendon reflexes and 3/5 in strength. His sensation is intact. He is admitted for monitoring and treatment for this complication of a viral illness. Introduction Classification Zika virus an enveloped positive-sense, single-stranded RNA flavivirus transmission Aedes mosquitoes can be vertically and sexually transmitted Associated conditions microcephaly Guillain-Barré syndrome Epidemiology Incidence more common in tropical and subtropical climates Central and South America the Caribbean Risk factors mosquito exposure travel to endemic areas sexual exposure to others who have traveled to endemic areas ETIOLOGY Pathogenesis the Zika virus replicates in skin cells (e.g., keratinocytes and fibroblasts), which undergo cell death the virus spreads via blood and induces an innate immune response may potentially penetrate through the placental barrier, leading to teratogenicity Presentation Symptoms Zika virus infection may have a pruritic rash miscarriage arthralgia headache hematospermia (males) Physical exam Zika virus infection conjunctival injection low-grade fever macular or papular rash vertically transmitted to fetus congenital microcephaly intracranial calcifications ocular lesions Studies Labs serum or urine Zika virus immunoglobulin M (IgM) often the initial test screen in pregnant women with risk factors during the first and second trimester serum or urine reverse-transcriptase polymerase chain reaction (RT-PCR) confirmatory testing if IgM is positive Making the diagnosis based on clinical presentation and laboratory studies Differential Dengue fever distinguishing factor often presents with signs of hemorrhage and without conjunctivitis Treatment Conservative supportive care indication all patients modalities hydration pain control anti-pyretic medications Complications Permanent neurologic damage Guillain-Barré syndrome Prognosis Most infections are asymptomatic If symptomatic, the disease will occur 3-12 days after exposure typically, the disease is self-limited If vertically transmitted, fetuses often have microcephaly, intracranial calcifications, and cerebral malformation