Final answer:
The emergence of Zika virus is attributed to the spread of its mosquito vector aided by global travel, urbanization, climate change, and other human activities that have created suitable environments for mosquito breeding.
Step-by-step explanation:
The reasons for the emergence of Zika virus are thought to be primarily due to the expansion of the geographical range of its mosquito vector, the Aedes species, and changes in human activities that have facilitated the spread of vector-borne diseases. The Zika virus, discovered in 1947, remained largely obscure until major outbreaks in the 21st century highlighted its potential for widespread human illness. The virus garners particular concern due to its association with severe fetal abnormalities, like microcephaly, when pregnant women are infected.
During the last decade, factors such as global travel, urbanization, and anthropogenic alteration of ecosystems have all contributed to the Aedes mosquitoes spreading beyond their initial habitats. Climate change has also played a role in expanding the suitable environments for these mosquitoes to breed. Additionally, the possibility of sexual transmission, transfer from mother to child during pregnancy, and through blood transfusions have added complexity to controlling the spread of Zika virus.