A vaccine effective against Zika virus is theoretically possible but may not be delivered anytime soon

Taylor-Robinson, Andrew W

Similar to the etiological agents of yellow fever, Japanese encephalitis and dengue, Zika is a member of the Flavivirus genus of enveloped, positive sense, single-stranded RNA viruses. 8 Compared to each of these close relatives, infection with which can be severely incapacitating for a person of any age, it is thought that approximately 80% of adults infected with Zika show no clinical manifestations. 9 Hence, for several days after being bitten by an infectious mosquito, they may serve as asymptomatic carriers of infection. If a person is ill, the main symptoms may last for up to 1 week and are similar to but less severe than other related febrile illnesses -a mild headache, fever, myalgia, arthralgia, conjunctivitis, and maculopapular rash. 10 The principal possible consequence of Zika infection, for which there is now claimed to be a causal link, 11 occurs via congenital transmission from a pregnant female to her fetus in utero or newborn baby, 10, 12 the effects of which can be severe. 13 In Brazil alone, the virus has been associated with over 4,000 cases of microcephaly, 2 a previously uncommon condition that as a result of aberrant brain development produces babies with abnormally small heads and, in most cases, neurological impairment. In March 2016, Panama registered a baby born with microcephaly linked to the Zika virus, in what is thought to be the first such case outside Brazil during the current outbreak. The baby died within 4 hours and at postmortem examination the virus envelope protein was detected by enzyme-linked immunosorbent assay in the baby's umbilical cord. 14 Rarely, Zika is also associated with, but still not proven to be causally linked to, Guillain-Baré syndrome, a neural demyelination syndrome that is considered to be an autoimmune sequela of infectious disease. 12, 15