Zika virus (ZIKV) swept through the Americas and led to recognition of its neurotropism. Zika circulation elsewhere in the world, nonvector transmission including maternal–fetal/sexual/transfusion routes, and additional reports on congenital Zika syndrome (CZS) and Guillain–Barré syndrome (GBS) have been published.
In 2018–2019, ZIKV transmission occurred in Cuba, India, and is suspected to appear sporadically in other countries. Maternal–fetal ZIKV transmission appears to occur in about 26% of ZIKV-infected pregnant women. The US ZIKV Pregnancy and Infant Registry identified 6% of live births to have at least one ZIKV-associated birth defect; 9% had at least one neurodevelopmental abnormality; 1% had both. Infectious virus was rarely isolated from semen of ZIKV-infected male patients beyond day 38 after symptom onset. Brazilian blood donations had low ZIKV prevalence in 2015–2016; in the United States, screening donations was cost-effective only in the high mosquito season in Puerto Rico.
ZIKV transmission continues; many countries with competent mosquitoes are at risk. Transmission can occur without detection where surveillance is poor and laboratory capacity limited. Travelers are important sentinels. Variations exist among ZIKV strains and Aedes mosquitoes that influence competence for transmission. Maternal–fetal transmission results in significant rates of abnormality. Identification of infectious virus in semen clarifies sexual transmission risk, with updated recommendations for preconception planning. ZIKV neurotropism requires further research and long-term follow-up.
aDivision of Infectious Diseases and Travel Medicine, Mount Auburn Hospital, Cambridge
bHarvard Medical School
cDepartment of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
dDepartment of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, USA
Correspondence to Lin H. Chen, MD, Division of Infectious Diseases and Travel Medicine, Mount Auburn Hospital, 330 Mount Auburn Street, Cambridge, MA 02138, USA,. Tel: +1 617 499 5026; fax: +1 617 499 5453; e-mail: firstname.lastname@example.org