Whooping cough eight weeks, or sometimes longer. A gradual transition then occurs to the convalescent stage, which usually lasts one to four weeks. This stage is marked by a decrease in paroxysms of coughing, although paroxysms may occur with subsequent respiratory infection for many months after the onset of pertussis. The time between exposure and the development of symptoms is on average 7–14 days (range 6–20 days), rarely as long as 42 days. Pertussis is caused by the bacterium "Bordetella pertussis". It is an airborne disease (through droplets) that spreads easily through the coughs and sneezes of an infected person. Uncertainties have
Meleda disease It may be caused by a mutation on the "SLURP1" gene, located on chromosome 8. Meleda disease Meleda disease (MDM) or "mal de Meleda", also called Mljet disease, keratosis palmoplantaris and transgradiens of Siemens, (also known as "acral keratoderma", "mutilating palmoplantar keratoderma of the Gamborg-Nielsen type", "palmoplantar ectodermal dysplasia type VIII", and "palmoplantar keratoderma of the Norrbotten type") is an extremely rare autosomal recessive congenital skin disorder in which dry, thick patches of skin develop on the soles of the hands and feet, a condition known as palmoplantar hyperkeratosis. MDM is most common on the Dalmatian island of Mljet (or