Tami H. Skoff, Cynthia G. Thomas

Infectious Agent

Pertussis is caused by fastidious gram-negative coccobacillus, Bordetella pertussis.

Mode of Transmission

It is spread by person-to-person transmission via aerosolized respiratory droplets or by direct contact with respiratory secretions.

Occurrence

• B. pertussis circulates worldwide, but disease rates are highest among young children in countries where vaccination coverage is low, which is primarily in the developing world.
• In developed countries, the incidence of pertussis is highest among unvaccinated infants and increases again among adolescents.
• Immunity from childhood vaccination and natural disease wanes with time; therefore, adolescents and adults who have not received a Tdap booster vaccination can become infected or re-infected.

Risk for Travelers

• Pertussis remains endemic worldwide, even in areas with high vaccination rates.
• Travelers who come in close contact with infected persons are at risk for disease. Infants too young to be protected by a complete vaccination series are at greatest risk for severe pertussis requiring hospitalization.

Clinical Presentation

• In classic disease, mild upper respiratory tract symptoms begin 7–10 days (range 6–21 days) after exposure, followed by a cough that becomes paroxysmal. Coughing paroxysms may be frequent or relatively infrequent and are often followed by vomiting. Fever is absent or minimal. The CDC/Council of State and Territorial Epidemiologists’ clinical case definition for pertussis includes cough for ≥2 weeks with paroxysms, whoop, and/or post-tussive vomiting.
• Disease in infants <6 months of age can be atypical with a short catarrhal stage, gagging, gasping, or apnea as early manifestations; among infants <2 months of age, the case–fatality rate is approximately 1%.
• Recently immunized children may have mild cough illness; older children and adults may have prolonged cough with or without paroxysms. The cough gradually wanes over several weeks to months.

Diagnosis

• Factors such as prior vaccination status, stage of disease, antibiotic use, specimen collection and transport conditions, and nonstandardized tests may affect the sensitivity, specificity, and interpretation of available diagnostic tests for B. pertussis.
• Current CDC guidelines for the laboratory confirmation of pertussis cases include culture and PCR (when the above clinical case definition is met); serology and direct fluorescent antibody (DFA) tests are not confirmatory tests included in the case definition.

Treatment

• Macrolide antibiotics (azithromycin, clarithromycin, and erythromycin) are recommended for the treatment of pertussis in persons ≥1 month of age; for infants <1 month of age, azithromycin is the preferred antibiotic.
• Antimicrobial therapy with a macrolide antibiotic administered <3 weeks after cough onset can limit transmission to others.
• Postexposure prophylaxis is recommended for close contacts of cases and for individuals at high risk of developing severe disease. The recommended agents and dosing regimens for prophylaxis are the same as those indicated for the treatment of pertussis.

Preventive Measures for Travelers

Vaccine

• Travelers should be up to date with pertussis vaccinations prior to departure.
• Complete vaccination of children <7 years of age with five doses of acellular pertussis vaccine in combination with diphtheria and tetanus toxoids (DTaP) is recommended; an accelerated schedule of doses may be used to complete the DTaP series.
• There is no pertussis-containing vaccine licensed for children 7–9 years of age. If a child turns 10 years old during the vaccination series with Td (tetanus and diphtheria toxoids vaccine), a single dose of Tdap may be substituted for one of the Td doses.
• Adolescents aged 11–18 years should receive a single dose of Tdap instead of Td for booster immunization against tetanus, diphtheria, and pertussis if they have completed the recommended childhood DTwP/DTaP vaccination series. Adolescents who received their last Td (tetanus and diphtheria toxoids vaccine) 5 years or more previously should also receive a single dose of Tdap.
• Adults 19–64 years of age should receive a single dose of Tdap to replace a single dose of Td for booster immunization against tetanus, diphtheria, and pertussis if their last tetanus toxoid-containing vaccine (e.g., Td) was administered 10 years or more prior. Tdap is not licensed for adults 65 years of age or older.
• Tdap can be given in intervals <10 years from the last Td to provide pertussis protection prior to travel, except in those individuals with a contraindication to vaccination.
• Adolescents and adults who have never been immunized against pertussis, tetanus, or diphtheria, have incomplete immunization, or whose immunity is uncertain should follow the catch-up schedule established for Td/Tdap. Tdap can be substituted for any one of the Td doses in the series.

References

1. Edwards KM, Decker MD. Pertussis vaccines. In: Plotkin SA, Orenstein WA, editors. Vaccines. 4th ed. Philadelphia: W.B. Saunders; 2004: p. 471–528.
2. CDC. Preventing tetanus, diphtheria, and pertussis among adolescents: Use of tetanus toxoid, reduced diptheria toxoid and acellular pertussis vaccines. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2006;55(RR-17):1–37.
3. American Academy of Pediatrics. Pertussis. In: Pickering LK, Baker CJ, Long SS, McMillan JA, editors. Red book: 2006 report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006. p. 498–520.
4. Tiwari T, Murphy TV, Moran J. Recommended antimicrobial agents for the treatment and postexposure prophylaxis of pertussis: 2005 CDC guidelines. MMWR Recomm Rep. 2005;54(RR-14):1–16.
5. CDC. Pertussis vaccination: Use of acellular pertussis vaccines among infants and young children. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 1997;46(RR-7):1–25.