Pertussis (Whooping Cough)
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Pertussis is a respiratory infection caused by bacteria. It is also known as “whooping cough” because the major symptom is severe spells of coughing followed by a whoop sound before the next breath. The illness lasts for several weeks. About 20-30% of infants less than 12 months old with pertussis are so sick they are admitted to hospital; brain damage occurs in approximately 1 out of 400 of these hospitalized infants. Studies in Britain show that children who had pertussis in infancy have a much higher rate of learning and behaviour problems than children who did not have the infection.
Routine vaccination of infants and young children has resulted in a marked decline of pertussis in every country with a vaccination program. A booster is now recommended for adolescents and adults, combined with the tetanus and diphtheria vaccines.
Public Health Agency of Canada. Canadian Immunization Guide. Evergreen edition. http://www.phac-aspc.gc.ca/publicat/cig-gci/index-eng.php (external link)
Canadian Paediatric Society. http://www.caringforkids.cps.ca/handouts/immunization-index (external link)
- Early 1900s – Pertussis killed 5 out of every 1000 children born in the United States before their fifth birthday. Most deaths involved infants less than 12 months of age.
- 1900–1940 – Infant deaths from pertussis decreased by over 70% due to better nutrition, less overcrowding and smaller families. However, while deaths decreased, the number of reported cases stayed the same.
- 1930s – The first “whole-cell” vaccine is developed. However, it causes more adverse reactions in children than any other vaccine: fever, irritability, crying, drowsiness and vomiting. On rare occasions, children have trouble breathing or have an allergic reaction such as anaphylaxis (which can lead to shock or obstruction of the respiratory tract).
- 1940s to 1990s – A new whole-cell vaccine is developed which eliminates the risk of anaphylaxis. Acetaminophen (like Tylenol) reduces the other symptoms such as fever and crying.
- 1995–1996 – Pertussis decreased across Canada, but the incidence varied from province to province. Between 1995 and 1996, pertussis incidence decreased between 30% to 75% in Newfoundland, Nova Scotia, New Brunswick, Quebec and Ontario. During the same period, it increased between twofold and tenfold in Prince Edward Island, Saskatchewan, British Columbia and Northwest Territories.
- 1997 – “Acellular vaccine” (a vaccine composed of purified proteins) was introduced into Canadian vaccination programs. It causes fewer reactions and is just as effective as whole cell vaccine.
Case Study #1 — Japan
- Before 1950 – 100,000 cases of pertussis per year
- 1974 – 200–400 cases of pertussis per year; 2-3 deaths
- 1975 – Use of pertussis vaccine halted following the death of two infants after receiving the vaccine. Two months later, the ban was lifted when the deaths were found to be unrelated to the vaccine. However, due to unfavourable publicity, many parents chose not to have their children vaccinated.
- 1976–79 – The vaccination rate fell, resulting in an epidemic of pertussis; 13,000 reported cases and more than 100 deaths.
Case Study # 2 — England and Wales
- 1975 – Following news reports of the alleged dangers of pertussis vaccine, vaccination rates declined from 75% to 25%.
- 1977–79 – Lower vaccination rates led to an epidemic affecting more than 100,000 people, including 100 deaths.