Part is related to Belong. Belong is etymologically related to Long. Long is derived from Vehicle. Vehicle is related to Transportation. 
Infection is a type of Illness. Illness is related to Heal. Heal is related to Repair. 
Part <--RelatedTo--> Belong --EtymologicallyRelatedTo--> Long --DerivedFrom--> Vehicle <--RelatedTo--> Transportation 
Infection --IsA--> Illness <--RelatedTo--> Heal <--RelatedTo--> Repair 