Zika virus infection in humans appears to have changed in character while expanding in geographical range. Zika virus has now been clearly established as the cause of severe fetal malformations, particularly microcephaly. The risk of fetal injury appears to be greater when maternal infection occurs in the first trimester of pregnancy. Zika virus has now been established as the cause of Guillain-Barré syndrome (GBS) in adults. Although most cases of Zika virus infection are transmitted as the result of mosquito bites, patients can acquire the infection through sexual contact. Both male-to-female and female-to-male transmission have been documented. Currently, real-time reverse transcription polymerase chain reaction (rRT-PCR), immunoglobulin M (IgM), and plaque reduction neutralization (PRNT) tests are available to detect Zika infection, although each test has limitations. If a patient has had symptoms of Zika virus infection for less than 5 days, serum and urine should be obtained for rRT-PCR testing. If symptoms have been present for 5 to 14 days, urine should be tested by rRT-PCR because urine samples appear to remain positive for virus longer than serum samples do. Early-stage trials examine whether an experimental vaccine is safe and generates immune responses in vaccinated volunteers. A safe and effective, fully licensed Zika vaccine will likely not be available for several years.Read More