Overview 1, 2, 3, 4, 5 Pertussis is a highly communicable, vaccine-preventable disease that affects the respiratory tract. The illness is caused by Bordetella pertussis (B. pertussis) bacteria, for which humans are the only known natural reservoir.verview 1, 2, 3, 4, 5 Pertussis is a highly communicable, vaccine-preventable disease that affects the respiratory tract. The illness is caused by Bordetella pertussis (B. pertussis) bacteria, for which humans are the only known natural reservoir.
Often, cramps. 1  a sudden, involuntary, spasmodic contraction of a muscle or group of muscles, especially of the extremities, sometimes with severe pain. 2  a piercing pain in the abdomen.
Medical Definition of croup. : inflammation, edema, and subsequent obstruction of the larynx, trachea, and bronchi especially of infants and young children that is typically caused by a parainfluenza virus and is marked by episodes of difficult breathing and low-pitched cough resembling the bark of a seal.