Like other infectious diseases whoop ing-cough generally occurs in epidemics, which are more frequently met with dur ing the spring and autumn months, and in a peculiar way are frequently ciated with epidemics of measles. The majority of cases occur in children under the age of four years; it is seldom met with in children over twelve years; in early infancy it is peculiarly severe and fatal.
Observations in epidemics including 1163 cases of whooping-cough showed that strong children seemed more dis posed than weak ones. Five children had second attacks, and 37 who were exposed to the disease at one time with out taking it contracted it at a subse quent exposure. In the sputa of 147 patients examined Ritter's diplococcus tussis convulsivm was found in every instance. Ritter (Arch. f. Kinderh., 13. 20, H. 3 and 4, '96).
Pathology.—In simple uncomplicated cases, beyond a catarrhal inflammation of the larynx and trachea little is to be noted. In severe cases the inflammation may extend to the smaller bronchi. In fatal cases the tracheal and bronchial glands are found enlarged; more or less extensive catarrhal pneumonia is gener ally present; frequently we find collapse of lung with associated emphysema.
Complications and Segue every ease of whooping-cough more or less tracheitis is present, which, under imper fect hygienic conditions_ or undue ex posure, readily becomes converted into a bronchitis, adding to the violence of the symptoms. It becomes still more serious if a bronchopneumonia develops: a con dition indicated by sudden rise of tem perature and increased clyspnoea. This complication adds greatly to the fatality of the disease. Some emphysema of the lung is probably developed in every seri ous case; a few instances have been noted where emphysema of the cellular tissue of the mediastinum has occurred: a con dition which may go on to general sub cutaneous emphysema and death. The digestive system is in every case apt to be more or less deranged; vomiting in some cases is a troublesome complication, and may interfere with necessary nutrition. A catarrhal condition of the intestines producing diarrhoea is liable to occur in infants during the summer months.
In all children an attack of pertussis appears to induce an increased irritability of the spinal and cerebral centres. Con vulsions are liable to occur, due in some instances to merely temporary causes; in others to serious cerebral lesions such as intracranial haemorrhage or thrombosis, and followed by more or less extensive paralysis, and sometimes by disturbances of sight and hearing. haemorrhage due to mechanical causes is not infrequent; epistaxis occurs frequently; subconjunc tival hemorrhage is more rare; intra cranial hemorrhage is generally menin geal, intracerebral being distinctly less frequent.
Among the more important sequelw of the disease are various chronic pulmonary affections: emphysema, chronic bronchi tis, asthma, atelectasis, and chronic in terstitial pneumonia. It is to be remem bered also that after an attack of whoop ing-cough has run its course latent tuber culosis and syphilis may suddenly show indications of activity, the heart may show signs of overstrain, and a condition of undue nervous irritability may persist for many months.
During recent epidemic of whooping cough occurrence of albuminuria noted in from 10 to 12 per cent. of the cases, and a mortality of 5 to 6 per cent. from acute nephritis. The urine should be frequently examined during this disease.
Stefano Mireo (Archivio per le Sci. Med., vol. xiv, No. 1, '90).
There is danger of dilatation of the right heart in severe cases of pertussis, a venous stasis first occurring from in flammation of the finer tubes and broncho-pneumonic foci, with overload ing of the right heart and the general venous system. Silbermann (Archly f. Kinderh., B. IS, S. 24, '95).
Prognosis.—Pertussis is more to be dreaded during the winter and early spring months than during summer. The mortality is very high when an at tack develops during early infancy, espe cially in rachitic children, in tubercular children, or in children suffering from adenoid growths in the naso-pharynx. The disease assumes a specially fatal character in foundling-asylums and hos pitals where broncho-pneumonia of a se vere type is liable to develop. In children over six years of age, serious complica tions are rare.