156 Whooping Cough
Whooping cough, otherwise known as pertussis, after the causative bacillus Bordetella pertussis, is an acute infectious disease of childhood. Affecting the respiratory tract, it is characterized by paroxysms of coughing, culminating in the prolonged inspiration which gives the disease its name.
Before the present century, the popular name was generally spelled without the initial “w,” and did not come into general use until the end of the eighteenth century. Until the early nineteenth century, the commonest appellation was chincough. The term pertussis was first used by Thomas Sydenham in the latter part of the seventeenth century.Distribution and Incidence
The distribution of whooping cough is now worldwide. It is generally an endemic disease that erupts in sporadic epidemics, but in most developed countries it has been controlled by immunization programs. Of clinical cases, 80 percent occur in the under-10 age group, and unlike most other communicable diseases, whooping cough develops more often in females than in males.
Etiology and Epidemiology
Although included among the more important diseases of childhood, whooping cough has been relatively neglected, and various aspects of its epidemiology are not yet fully understood. Transmission seems to be mainly airborne, apparently by droplet infection. Human beings are the only reservoir of the disease; B. pertussis cannot survive long outside the host, and quickly succumbs to drying, ultraviolet light, and temperatures above 120o to 130oF. It spreads primarily through household and schoolroom contact, although mild Subclinical cases, perhaps in adolescents and adults, may play a further (undemonstrated) role in transmission. One attack confers immunity, and rare second attacks are probably explained by infection with the much milder, and less common, Bordetella parapertussis.
Clinical Manifestations
An incubation period of 7 to 10 days is followed by an initial catarrhal stage, lasting 1 to 2 weeks. During this phase the disease is highly communicable, but the symptoms are nonspecific and resemble those of many other infectious diseases, and of minor respiratory ailments. An increasingly persistent cough develops, which in the third stage becomes more severe and spasmodic, terminating in the characteristic whoop. In acute cases, paroxysms may occur 40 or 50 times in 24 hours. The whoop is frequently followed by vomiting. In young infants, who are unable to produce the whoop and resume effective breathing quickly, episodes of cyanosis follow the paroxysm. The acute stage lasts up to 4 weeks, but paroxysms may continue for 3 months or longer. The patient is considered convalescent when vomiting ceases, and the severity of the paroxysms diminishes. Complications include collapsed lungs, anoxic convulsions, and exhaustion; secondary bacterial infections may cause otitis media or pneumonia. Bronchiectasis has become rare since the introduction of antimicrobial agents.
History and Geography
The history of whooping cough before the twentieth century is obscure. It cannot with certainty be traced back further than the mid-sixteenth century and it was almost certainly unknown to the ancient world. Although the term “chincough” was current in the early sixteenth century, the first medical description of the disease dates from 1578, when Guillaume Baillou observed a severe epidemic in Paris. He wrote of it as a familiar affliction, for which there seemed to be several names already. Moreover, it was apparently the subject of medical discussions.
Nonetheless, the prevalence of the disease remains largely obscure until the mid-eighteenth century. August Hirsch in 1886 suggested that the native habitat of the disease was originally northern Europe. But the existence of a widespread folklore with regard to its treatment may indicate a more ancient existence in such places as southern India and Malabar.
Thomas Willis in 1675 described the chincough as an epidemic disease of infants and children, usually occurring during the summer and autumn. In his view, the cough, although difficult to cure, was rarely fatal or very dangerous.
By contrast, his contemporary, Sydenham, thought it so formidable as to require the most rigorous treatment. The earliest statistics regarded as in any way reliable come from mid-eighteenth-century Sweden, where Nils Rdsen von Rosenstein described it as a familiar epidemic disease of variable fatality. The terms “whooping cough” and “chincough” first appear as causes of death in the London Bills of Mortality in 1701, and an increasing number of deaths were attributed to them. Indeed, the toll rose from 119, in the 15-year period 1702-17, to 4,252 in the period 1762-77. With the introduction of the civil registration of deaths in 1838, English mortality figures became more reliable. Deaths from whooping cough reached a peak of some 1,500 per million population under age 15 per annum in England and Wales in about 1870, after which the death rate from the disease began to decline. This fall was first manifest in agricultural areas, whereas in urban and industrial countries the death rates were slower to fall. During the 1880s, case fatality, so far as can be ascertained, stood at 10 percent, compared to 1.1 percent during World War II, and 0.1 percent in recent years. In underdeveloped countries today, hospital case-fatality rates are about 15 percent.
Although the infectious character of whooping cough was appreciated from at least the early eighteenth century, the nature of the clinical disease was simultaneously a matter of debate. Both Willis and Sydenham, for example, thought the disease seated chiefly in the chest, whereas William Harvey and his followers held it to be in the stomach and the alimentary canal. Not until Robert Watt of Glasgow, stimulated by the deaths of two of his children from the disease, undertook a series of dissections in 1812-13 did the involvement of the respiratory tract become clear.
Medical interest in the disease during the nineteenth century was minimal, until discussion began about the possibilities of prevention in the 1880s.In London, during the nineteenth century, the highest whooping cough mortality was experienced by the children of the working classes, and death was generally due to complications involving the respiratory organs. Whooping cough cases were not received into the Metropolitan Asylums’ Board’s hospitals (London) before 1910. The disease was made notifiable in the United States in 1922, but not until somewhat later in Great Britain.
Mortality and morbidity from whooping cough have declined greatly in developed countries during the twentieth century. The causative organism was first isolated by Jules Bordet and Octave Gengou in 1900, but was not grown in vitro until 1906, when its morphology and cultural characteristics were established. Vaccines against the disease were first introduced in the 1930s, and were in widespread use by the later 1940s.
But recently, there has been increasing public awareness of possible complications from whooping cough vaccine, which has been stimulated by the publicity surrounding the relatively small number of cases in which the vaccine is supposed to have caused brain damage to children. The result was that during the 1970s rates of vaccination fell off in both Britain and Japan, where immunization is voluntary. In both countries the disease subsequently began to increase in prevalence, and epidemic outbreaks in 1978 and 1982 were similar in scale to those of the 1950s, when the immunization program was new. Another large outbreak was anticipated in 1986, but was aborted by intensive publicity concerning the benefits of vaccination, which caused immunization rates to rise.
Anne Hardy
Bibliography
Brooks, G. F., and T. M. Buchanan. 1970. Pertussis in the United States. Journal of Infectious Disease 122: 123-5. '
Radbill, Samuel X. 1943. Whooping cough in fact and fantasy. Bulletin OftheHistory OfMedicine 13: 33—55.
Smith, Francis B. 1979. The people’s health, 1830-1910. London.
Watt, Robert. 1813. A treatise on the history, nature, and treatment of chincough. Glasgow.