Breast milk is different to infant formulas or cow’s milk so there is no need to stop breastfeeding in case your baby gets sick.
Breastfeeding can help protect your baby from getting sick, but it cannot completely prevent some of the common illnesses. It is important to carry on breastfeeding even if your baby vomits as otherwise he may end up dehydrated and that can cause a lot of additional problems.
There have been numerous studies to prove that antibodies found in breast milk can help shorten the duration of an illness and allow babies to recover quicker.
You can even carry on nursing if you become sick yourself as your milk will protect the baby and he may not end up being sick at all.
One of the studies where food poisoning was examined showed a strong link between breastfeeding and
a decreased risk of sporadic salmonellosis among infants. It is therefore important to continue breastfeeding even if you suffer from food poisoning to keep protecting your baby. Hand washing and safe preparation of food is another factor that can prevent babies from getting salmonella.
This study can be accessed here; http://www.ncbi.nlm.nih.gov/pubmed/15095198