One of the most common ailments among pre-school children, and its symptoms and treatment, are examined by doctors at London's Great Ormond Street Hospital What is tonsillitis? Tonsillitis is a viral or bacterial infection in the throat that causes inflammation of the tonsils, which are small glands on either side of the throat. In the first six months of life they provide a useful defence against infections. Tonsillitis is one of the most common ailments in...