Answer:
Cells infected with human papillomavirus.
Explanation:
Koilocyte is a type of squamous epithelial cell that has a number of structural changes, which leads the cell infected by human papillomavirus. Koilocyte have many cellular changes like:
Human papillomavirus (HPV) is the most common sexually (active) transmitted infection. Sometimes it can be transmitted during birth (from mother to the child).