Your periods are dependent upon the hormones in the body. The hormones can get imbalanced during the stress of an infection and there is reported cases of delay in such cases. But if it is delayed by more than 10 days, you should visit your gynecologist so that you can be examined and undergo investigations such as ultrasound, thyroid profile, etc. to find the underlying cause and have it treated accordingly. Keep yourself well hydrated, have a good and balanced nutrition and rest well to heal.