One of them develops conjunctivitis or pink-eye. As a precaution the child is sent home, where he recovers with rest.

Pink-eye is common among elementary school children. The doctor’s main concern is isolating the child so he does not infect other children. Because she knows the patient’s family and knows nobody in the family has traveled outside the country, she does not think the conjunctivitis could be due to Zika.

The other children who show no symptoms are bitten by mosquitoes in their own yards in the following days, and those mosquitoes become carriers of Zika.

After the virus penetrates the salivary glands of one of those mosquitoes, it lands on the arm of a friend of the child’s mother and bites her. The woman kills the mosquito with a sharp slap, seemingly before it draws any blood. But the mosquito has already sawed its proboscis under the skin of the woman, injecting its infected saliva.

The woman jokes to her friend as she leaves that her reflexes aren’t as quick as they used to be now that she’s pregnant.

This is how it starts.