There are 17 words that start with 'infect'.
| infect | infects | 
| infected | infecter | 
| infector | infectant | 
| infecters | infecting | 
| infection | infective | 
| infectors | infections | 
| infectious | infectivity | 
| infectiously | infectivities | 
| infectiousness | |
Note: These 17 words that start with 'infect' are found from the USA & Canada version of the tournament Scrabble word list.