Whooping cough old may have little or no cough and instead have periods where they do not breathe. The time between infection and the onset of symptoms is usually seven to ten days. Disease may occur in those who have been vaccinated, but symptoms are typically milder. Pertussis is caused by the bacterium "Bordetella pertussis". It is an airborne disease which spreads easily through the coughs and sneezes of an infected person. People are infectious from the start of symptoms until about three weeks into the coughing fits. Those treated with antibiotics are no longer infectious after five days. Diagnosis is by
Tay–Sachs disease Researchers are looking at gene therapy or enzyme replacement therapy as possible treatments. Tay–Sachs disease is typically first noticed in infants around 6 months old displaying an abnormally strong response to sudden noises or other stimuli, known as the "startle response". There may also be listlessness or muscle stiffness (hypertonia). The disease is classified into several forms, which are differentiated based on the onset age of neurological symptoms. Until the 1970s and 1980s, when the disease's molecular genetics became known, the juvenile and adult forms of the disease were not always recognized as variants of Tay–Sachs disease. Post-infantile Tay–Sachs was