Pertussis (Whooping Cough)

     In the pre-vaccine era, 93% of Pertussis cases occurred in children between 1-5 years old. Since the 1980’s, the high incidence rate shifted to children over 5 years of age and older. In 2005, booster vaccines were recommended for adolescents and adults between the ages of 11-64 years old.

 

      From 1985-1987, 25% of reported cases were in children 10 years of age and over. From 1995-1998, that number increased to 42%. The largest majority of cases have been in the vaccinated populations. During the 1980’s, 1990’s and 2000’s, the number of adolescents and adults acquiring Pertussis has increased to spite high vaccination rates. (1) (2) (3) (4) (5)

              “Although pertussis incidence remains highest among young infants, rates are also on the rise in adolescents and adults and there may be significant under-reporting in these age groups, especially those with mild or atypical infection. Compared with surveillance data from 1994 to 1996, the pertussis incidence rate among adolescents and adults increased 62% and 60%, respectively, from 1997 to 2000.”

 

     There has also been an increase in babies under 1 year acquiring Pertussis. The number of cases in babies under 3 months of age from 1990-1997 did not lower. From 1999-2000, 48% of cases were in this age group. In 2001, 62% were under 3 months old. (6)

 

     According to a 2000 CDC MMWR report: “Despite record high vaccination coverage levels with 3 doses of DTaP among U.S. children aged 19–35 months, pertussis continues to cause fatal illness among vulnerable infants. During 1980–1998, the average annual incidence of reported pertussis cases and deaths among U.S. infants increased 50%. The increased morbidity and mortality occurred primarily among infants aged <4 months, who were too young to have received the recommended three DTaP vaccinations at ages 2, 4, and 6 months.” (7)

 

 

     Pertussis has always been endemic despite a vaccine.  It has a natural circulation every 2-5 years. This has not changed since the introduction of the vaccine, and thus indicates that the vaccine may prevent some disease, but has had little impact on transmission amongst the population. The efficacy of the DTaP is roughly 85% effective but waning immunity occurs after 2-5 years. In a case controlled study, it was found that infants of adolescent Mothers, aged 15-19 years, were 6 times more likely to acquire Pertussis compared to infants of older Mothers aged 20-29 years. Death from Pertussis is rare today. The majority of deaths, 90%, are in babies under 6 months of age. DTaP is also a reactive vaccine which means it does not prevent carriage or transmission of the disease. Therefore, vaccinated adolescents, adults and children can serve as reservoirs and transmitters to unprotected infants. (8) (9)

 

 

     Some epidemiologists believe B. Pertussis has mutated by changing its DNA and genetic coding.  Scientists in the Netherlands observed changes in the structure of the circulating wild-type bacteria when compared with those who were vaccinated. The differences were the outer membrane protein pertactin and the pertussis toxin itself. Similar genetic changes have been observed in Poland, Finland and the U.S. Any changes would thus render mutated bacteria immune to vaccination. As far as changing its character, many new cases lack the common ‘whoop’, yet 30% of cases were infected. Some cases were misdiagnosed as atypical asthma.(10) (11)

 

 

     In 2005, Tdap vaccines were recommended for adolescents over age 9 and adults under age 65 due to waning immunity from the DTaP vaccine given in infancy or childhood. There are no pertussis vaccines approved for children 7–9 years of age or for persons older than 64 years. The efficacy is similar and ‘inferred’ to that of DTaP. It is unknown if immunizing adolescents and adults will actually reduce the risk of transmission to infants. Nor is it known how long this vaccine may provide some people with protection. (12)

 

     

In the early 1900’s, it was questioned whether the control of Whooping Cough was even practicable. It has and remains to this day a more severe disease in infancy than in any other age group. A vaccine has not changed that fact. Generations passed have always known that the proper care in treatment of whooping cough would not lead to fatality, and most fatalities were the result of other complications mainly in the immune suppressed. (15)

 

 

Footnotes: 

 

       1.        Medscape Today. Epidemiology and Transmission of Disease. http://www.medscape.com/viewarticle/549508_2

 

2.        CDC MMWR, September 05, 1997 / 46(35);822-826. Pertussis Outbreak Vermont, 1996.  http://www.cdc.gov/mmwr/preview/mmwrhtml/00049244.htm

 

3.        The New England Journal of Medicine. Vol. 331:16-21. July 7, 1994. The 1993 Epidemic of Pertussis in Cincinnati — Resurgence of Disease in a Highly Immunized Population of Children.  http://content.nejm.org/cgi/content/full/331/1/16

 

4.        CDC MMWR, March 27, 1987 / 36(11);168-71. Epidemiologic Notes and Reports Pertussis Surveillance — United States, 1984 and 1985. http://www.cdc.gov/mmwR/preview/mmwrhtml/00000893.htm

 

5.        See #1

 

6.        CDR Weekly 21, June 2001. Enhanced surveillance of laboratory confirmed cases of Bordetella pertussis, England and Wales: 1999 to January-March quarter 2001. www.hpa.org.uk/cdr/archives/2001/cdr2501.pdf

 

7.        CDC, MMWR. July 19, 2002 / 51(28);616-618 Pertussis Deaths — United States, 2000. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5128a2.htm

 

8.        Medscape Today. Epidemiology and Transmission of Disease. http://www.medscape.com/viewarticle/549508_2

 

9.        Clinical Infectious Diseases.Epidemiological, Clinical, and Laboratory Aspects of Pertussis in Adults. 01 JUNE 1999 Supplement, Volume 28, Number S2.  James D. Cherry. http://www.journals.uchicago.edu/toc/cid/28/s2

 

8.        Medscape Today. Epidemiology and Transmission of Disease. http://www.medscape.com/viewarticle/549508_2

 

9.        Clinical Infectious Diseases.Epidemiological, Clinical, and Laboratory Aspects of Pertussis in Adults. 01 JUNE 1999 Supplement, Volume 28, Number S2.  James D. Cherry. http://www.journals.uchicago.edu/toc/cid/28/s2

 

10.     See #9.

 

11.     Emerging Infectious Diseases. Changes in Predominance and Diversity of Genomic Subtypes of Bordetella pertussis Isolated in the United States, 1935 to 1999.Terri Hawes Hardwick, et al. http://www.cdc.gov/ncidod/EID/vol8no1/01-0021.htm

 

12.     Adacel Tdap Package Insert. www.fda.gov/cber/label/adacelLB.pdf

 

13.     IS THE CONTROL OF MEASLES AND WHOOPING-COUGH PRACTICABLE? Am J Public Health (N Y). 1916 March; 6(3): 265–268. FRANCiS GEORGE CURTIS, M. D., Chairman, Board of Health, Newton, Mass. Read at a General Session of the American Public Health Association, Rochester, N. Y., September 10, 1915.

 

14.   Whooping Cough. Am J Public Health Nations Health. 1936 May; 26(5): 523–524.

 

15.     A STATISTICAL STUDY OF WHOOPING COUGH. FREDERICK S. CRUM, PH. D., Am J Public Health (N Y). 1915 October; 5(10): 994–1017.

 

 

 

 

 

 

 
 

 

 

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