Literature Review
The Zika virus is linked to several neurologic complications such as Guillain-Barré syndrome, according to research published online ahead of print May 16 in JAMA Neurology. Current data suggest that acute Zika virus infection in pregnant women could infect fetal and brain tissue, potentially resulting in microcephaly or disability in the infant or fetal death. According to the Centers for Disease Control and Prevention (CDC), the number of pregnant women with the Zika virus in the United States has tripled, raising concerns about travel to infected regions. Ocular involvement in the children of infected women also has emerged as a complication.
Currently there is no Zika virus vaccine, and limited data are available regarding the best approaches for diagnosis and treatment. J. David Beckham, MD, the corresponding author of the JAMA Neurology review article, and colleagues reviewed the available evidence and identified the neurologic complications of the Zika virus and its impact on global human health.
Zika Virus Timeline
The Zika virus (which was named after the Zika forest in Uganda) was first isolated in Uganda in 1947. The first natural case of infection with Zika virus was reported in 1964 in a European man working in Uganda. He developed a five-day syndrome of frontal headache; a maculopapular rash on the face, neck, trunk, and upper arms; fever; and myalgias. The patient was diagnosed with the Zika virus using acute and convalescent serum samples indicating the development of neutralizing Zika virus antibodies. In subsequent decades, the virus was reported in West Africa and Asia.
J. David Beckham, MD
During a 2007 Zika virus outbreak in the Yap State of Micronesia, symptoms such as fever, myalgias, rash, and conjunctivitis were reported, but no neurologic complications were noted. However, in 2013, a Polynesian woman developed Guillain-Barré syndrome seven days after an acute febrile illness attributed to the Zika virus. She showed symptoms of bilateral paresthesias and ascending muscle weakness. At three days after admission, she developed tetraparesis, diffuse myalgia, and bilateral facial, asymmetric peripheral facial palsy. Tests for common causes of Guillain-Barré syndrome were negative, but results for Zika virus were positive at eight and 28 days after the original acute febrile episode.
In 2015, reports emerged about a possible association between a Zika virus outbreak in Brazil and microcephaly during pregnancy. The Brazil Ministry of Health confirmed an increase in microcephaly in areas affected by the Zika outbreak. In December 2015, Zika virus RNA was detected in the amniotic fluid of two pregnant women whose fetuses were found to have microcephaly. Zika virus RNA also was detected in the brain and tissues of an infant with microcephaly who died in the neonatal period.
In 2016, a European woman who had lived in Brazil grew ill during her 13th week of pregnancy, likely because of Zika virus infection. Her fetal ultrasonography results were normal at 14 and 20 weeks of gestation, but by 32 weeks, the ultrasonography revealed severe microcephaly in the fetus.The flavivirus has spread rapidly across Latin America and the Caribbean since the outbreak in Brazil. As of May 18, 2016, 544 travel-associated cases of the virus have been reported in the US, according to the CDC. The CDC issued a travel advisory for Zika-affected areas and published guidelines for caring for women with possible Zika exposure who are or may become pregnant. If a pregnant woman has traveled to areas affected by a Zika outbreak, the CDC recommends that she undergo a Zika virus testing algorithm to evaluate her fetus for microcephaly.
Eye Abnormalities in Neonates
Eye abnormalities in neonates also have emerged as complications of Zika virus infection. In a case series of 29 infants with microcephaly that was published in JAMA Ophthalmology, 23 of the 29 mothers reported suspected Zika symptoms during pregnancy. In addition, ocular abnormalities were found in 10 of the 29 children (34.4%). Seven of the 10 affected children had bilateral disease. The most common findings were focal pigment mottling of the retina and chorioretinal atrophy in 11 of the 17 eyes with abnormalities, followed by optic nerve abnormalities in eight of the 17 eyes. These data suggest that Zika virus infection in neonates could cause significant eye disease.
Diagnosis and Prevention
Unlike infection with the West Nile virus, patients with acute Zika virus symptoms are viremic for an average of three days following initial symptoms. The virus can be detected in samples using reverse transcription-polymerase chain reaction assay. This assay is based on two one-step, real-time, reverse transcription-polymerase chain reactions that target the Zika virus premembrane and envelope genes.