Zika is a mosquito-borne virus that was first identified in 1952 in Uganda and the United Republic of Tanzania. The Zika virus is transmitted to people through the bite of an infected mosquito (Aedes aegypti in tropical regions). This is the same mosquito that transmits yellow fever, dengue, and chikungunya. Sexual transmission of Zika virus has also been described. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific.
Health authorities have observed an increase in Guillain-Barré syndrome (a potentially fatal neurological condition that can cause paralysis) and an increase in babies born with microcephaly (a birth defect characterized by abnormally small heads associated with severe cognitive disorders, intellectual disability, and possibly death). These coincide with Zika virus infections in the general public. Scientists believe Zika can potentially spread into the brain of a fetus through a pregnant woman’s amniotic fluid, attacking the neural cells and stunting the baby’s brain development. On Feb 1, 2016, WHO declared the cluster of microcephaly cases and other neurological disorders as a health emergency. The Zika infection is spreading rapidly globally. There is currently no vaccine available and a number of new vaccines are under development.
In order to respond to the global epidemic, the Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) consortium (with Global Healthcare Consulting as an Executive Committee and Coordination Team member and leading the case definitions development) has developed a globally standardized case definition of microcephaly (along with the definitions of other key obstetric and neonatal outcomes, guidelines and tools). The case definitions, guidelines and tools have been extensively review by peers and stakeholders to ensure their applicability, usefulness and acceptability in developed and low and medium income countries.
The use of these definitions, guidelines and tools will be useful in pre-and post-licensure safety and pharmacovigilance surveillance systems and help support enhanced surveillance and collection of safety data that can be consolidated and compared across sites, countries, and programs worldwide.