D.C.
Yes, keep nursing. Here's what I found on www.kellymom.com:
http://www.kellymom.com/health/illness/mom-illness.html
Just make sure you keep drinking plenty of fluids so you stay hydrated.
If mom has food poisoning, breastfeeding should continue. As long as the symptoms are confined to the gastrointestinal tract (vomiting, diarrhea, stomach cramps), breastfeeding should continue without interruption as there is no risk to the baby. This is the case with most occurences of food poisoning. If the food poisoning progresses to septicemia, meaning the bacteria has passed into mom's bloodstream (mom would most likely be hospitalized), see this guidance from Dr. Ruth Lawrence:
"Maternal infections of the genitourinary or gastrointestinal tract do not pose a risk to infants except in the rare circumstances when septicemia occurs and bacteria might reach the milk. Even in this event, continued breastfeeding while the mother receives appropriate antibiotic therapy that is compatible with breastfeeding is the safest course for the infant. If the infecting organism is especially virulent or contagious (e.g., an invasive group A streptococcal infection causing severe disease in the mother), breastfeeding should continue after a temporary suspension during the first 24 hours of maternal therapy. Prophylactic or empiric therapy for the infant, against the same organism, may be indicated." [source: Lawrence RM & Lawrence RA. Given the Benefits of Breastfeeding, what Contraindications Exist?
Pediatric Clinics of North America 2001 (February);48(1): 235-51.]
The best thing you can do for your baby when you're sick is to continue to breastfeed. When you have a contagious illness such as a cold, flu, or other mild virus, your baby was exposed to the illness before you even knew you were sick. Your milk will not transmit your illness to baby, but it does have antibodies in it that are specific to your illness (plus anything else you or baby have been exposed to) - they'll help prevent baby from getting sick, or if he does get sick, he'll probably not be as sick as you.