Pertussis vaccine and new mutations in the pathogen that existing vaccines are unable to effectively control. Some studies have suggested that while acellular pertussis vaccines are effective at preventing the disease, they have a limited impact on infection and transmission, meaning that vaccinated people could spread the disease even though they may have only mild symptoms or none at all. For children, immunizations are commonly given in combination with immunizations against tetanus, diphtheria, polio, and haemophilus influenzae type B at two, four, six, and 15–18 months of age. A single later booster is given at four to six years of age (US
Riggs' disease Riggs himself. Riggs' disease Riggs' disease, also known as pyorrhea of a toothsocket or gingivitis expulsiva, is a historical term for periodontitis (gum disease), The condition was described as a purulent inflammation of the dental periosteum. It was named after American dentist John Mankey Riggs (1811–1885). Riggs' disease was said to produce the progressive necrosis of the alveoli and looseness of the teeth. The teeth may become very loose and fall out of the sockets. Mark Twain wrote briefly about Riggs' disease in his short essay, "Happy Memories of the Dental Chair", in which he claims to have been examined