Whooping Cough Cases Continue to Rise

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April 21, 2011

Whooping cough, a respiratory infection caused by the bacteria Bordetella pertussis, has been on the rise since the 1980s and last year saw a continuation of the trend, according to the Centers for Disease Control and Prevention (CDC). Concern over the increase of this vaccine-preventable infection has prompted an update to the guidelines on vaccination for the disease. In the Morbidity and Mortality Weekly Report released January 14, 2011, the Advisory Committee on Immunization Practices (ACIP) urges booster shots for those who may require them, including teens, all adults under 65 years of age, and some older adults.

In 2009, the number of reported whooping cough infections in the United States totaled almost 17,000. The number reported in 2010 rose to over 21,000, the highest since 2005 and one of the worst years in the last 50, according to a report from The Washington Post. California was particularly hard hit by a statewide epidemic last year. Health officials there estimated that there were almost 9500 infections—the most reported in 65 years—with 10 infant deaths. Some areas of the Midwest also experienced a large increase. In Michigan, there were over 1500 cases in 2010, an increase over the roughly 900 cases reported in 2009, while Ohio saw close to 1000 cases in 2010, the most reported in that state in 25 years.

Canada has also seen increases in whooping cough since the 1990s. In that country, it is the second most frequently reported vaccine-preventable disease. In addition, there are one to three deaths each year attributed to the disease, usually occurring in infants.

Whooping cough, also termed pertussis, is very contagious and easily spread from person to person through coughing, sneezing and close contact. The infection can be serious in those with weakened immune systems and the very young and the elderly. In a child, the infection can cause prolonged spells of coughing, with the characteristic whoop as the child tries to catch his breath. In adults, the characteristic whoop is usually not observed since the adult airway is larger than an infant's. Therefore, pertussis may go unrecognized as the cause of the infection. A person with relatively mild symptoms can unknowingly spread the infection to someone who is at risk; infants who are too young to be vaccinated are particularly vulnerable.

Doctors diagnose whooping cough by signs and symptoms, physical examination, and laboratory testing. If the infection is caught early, treatment with an antibiotic may lessen the severity and prevent transmission to others. For laboratory testing, one of several methods may be performed. The bacteria can be detected using culture, which can take two or more days for results, or by using molecular techniques that detect bacterial genetic material. This latter method provides results much more quickly than culture but is not as specific and may give some false-positive results. If an outbreak is suspected, the CDC recommends that at least one positive molecular test be confirmed by culture.

To protect them from whooping cough, children younger than 6 years old usually receive a series of five shots (usually starting when they are 2 months old). The pertussis vaccine was in widespread use in the U.S. by the mid-1940s, so many people were immunized as children. While health officials are not certain of the cause of the current rise in infections, they believe it is in part a consequence of decreasing protection provided by these initial vaccinations in older populations. If these people become infected, they may then transmit it to infants and children who have not received the full series of shots. Though a booster vaccination was approved for use in 1995, vaccination rates in older children and adults have thus far been disappointing. In an effort to slow infection rates, health officials are advocating additional immunizations. Some of the main points from the ACIP include:

  • For children and teens ages 11 through 18 years old, a single booster shot is advised for those who have completed the recommended childhood diphtheria, tetanus and pertussis (DTP/DTaP) series of vaccinations.
  • For adults aged 19 through 64 years, a one-time vaccination is recommended.
  • Adults 65 years and older who are or expect to be in close contact with infants, such as grandparents and child- and health-care providers, should also receive a dose to boost their immunity if they had not previously done so.

These immunizations should serve to protect against pertussis and help prevent spread of the disease. (For a complete listing, see the CDC's web page on the ACIP's recommendations.)

If you think you may fall into one of the categories that should get a pertussis booster, consult your health care provider to determine what vaccine(s) you should receive. If you or someone in your care has symptoms of whooping cough, seek medical attention for diagnosis and treatment.

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

(January 14, 2011) Centers for Disease Control and Prevention. Updated Recommendations for Use of Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis (Tdap) Vaccine from the Advisory Committee on Immunization Practices, 2010. MMWR, 60(01);13-15. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6001a4.htm?s_cid=mm6001a4_w through http://www.cdc.gov. Accessed April 2011.

(January 7, 2011) CDC. Notifiable Diseases and Mortality Tables. MMWR, 59(52);1704-1717. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5952md.htm?s_cid=mm5952md_w#tab2 through http://www.cdc.gov. Accessed April 2011.

(August 26, 2010) CDC. Pertussis (Whooping Cough): Outbreaks. Available online at http://www.cdc.gov/pertussis/outbreaks.html through http://www.cdc.gov. Accessed April 2011.

(August 26, 2010) CDC. About Pertussis. Available online at http://www.cdc.gov/pertussis/about/index.html through http://www.cdc.gov. Accessed April 2011.

(February 17, 2010) Public Health Agency of Canada. Pertussis (Whooping Cough) Factsheet. Available online at http://www.phac-aspc.gc.ca/id-mi/pertussis-coqueluche-eng.php#tphp through http://www.phac-aspc.gc.ca. Accessed April 2011.

(November 2010) Immunization Action Coalition. Pertussis Vaccine, Questions and Answers. Available online at http://www.vaccineinformation.org/pertuss/qandavax.asp through http://www.vaccineinformation.org. Accessed April 2011. 

(February 23, 2011) Stobbe, Mike. 21,000 had whooping cough last year, says CDC. The Washington Post, Associated Press.