Bordetella parapertussis evolved in a host population that had already developed immunity to "B. pertussis", where being able to evade "B. pertussis" immunity was an advantage. Two lineages of "B. parapertussis" have been described. The first infects humans and is responsible for a minority of cases of the disease pertussis (also known as whooping cough). The second, ovine, lineage causes chronic nonprogressive pneumonia in sheep. Both lineages are thought to have evolved from a "B. bronchiseptica"-like ancestor. This disease can be symptomatic or asymptomatic and may predispose hosts to secondary infection. Bordetella parapertussis Bordetella parapertussis is a small Gram-negative bacterium of the
Meleda disease 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 "Meleda"), thought to be because of a founder effect. It is of autosomal recessive inheritance.