Lymph glands or nodes are normally present all over the body but in great concentration in the neck, under the arms and in the groin. They can become swollen for many reasons - for example, bacterial infection such as sore throat, viral infection such as German measles or mononucleosis, or in more serious conditions. All children will have glands that can be felt in the neck at any time. They will enlarge with infection. White blood cells are in the glands and when an infection threatens, these glands enlarge to produce more white blood cells to fight the infections. The glands themselves are not harmful but actually beneficial. They also signal more serious threats, however, such as strept. Throat. Glands will enlarge quite fast, in a matter of hours and take weeks to return to normal size. They should not be regarded with fear but regarded as a nonspecific sign of infection. A gland swollen for more than 10 days should be seen by a physician.