Bordetella pertussis is a gram negative pleomorphic rod that grows slowly.  It grows best on special media (Bordet-Gengou)  It is the principle cause of the whooping cough syndrome that may also be caused Bordetella parapertussis, Mycoplasma pneumoniae, Chlamydia trachomatis, Chlamydia pneumoniae, and certain adenoviruses

Epidemiology
1.  Humans are the only known host
2. It is spread by aerosolized droplets
3. The organism is most contagious during the catarrhal phase but may remain contagious for weeks after symptoms develop
4. The attack rate in unvaccinated household members is approximately 90%
5. The incubation period is 6-20 days
6. Treatment with Erythromycin will decrease infectivity and cultures will be negative within 5 days.

Clinical Course
1. Catarrhal phase- runny nose, sneezing, and cough.  Will last about 1-7 days. The most infectious period.
2. Paroxysmal cough phase- Intense cough with bouts lasting several minutes.  May become cyanotic and gasp in-between cough produces the characteristic whoop.
3. Convalescent phase- Chronic cough that may persist for weeks.
4. Infants less than 6 months of age may have associated apnea and the whoop is uncommon. May present as an ALTE
5. Older children and adults may manifest pertussis as a chronic cough.
6. Complications
     a. Cyanosis
     b. Seizures -3%
     c. Pneumonia, pneumothorax, aspiration
     d. Encephalopathy
     e. Mortality- 0.3%

Diagnosis
1. Culture of nasopharyngeal aspirate with Dacron swab that is placed onto a special media immediately.  Pertussis will grow in 10-14 days and greatest chance of culturing are in the early phases.
2. DFA- low specificity and variable sensitivity.
3. Enzyme immuno assays for immunoglobulins is not readily available.
4. Lymphocytosis in non specific.  Lymphocytes may have characteristic "baby bottom"  nuclei.
5. Clinical diagnosis

Treatment
1. Hospitalize for symptomatic care.  May require oxygen, IV fluids, feeding assistance, and monitoring for apnea
2. Antibiotic treatment (Macrolide) early in the disease may ameliorate symptoms and progression. Most of the time, diagnosis isn't considered until paroxysmal phase has begun and antibiotics will have little effect on the clinical course of the disease.  It may decrease
3. Erythromycin for 14 days is currently recommended for treatment and contact prophylaxis, is of uncertain benefit.

Control Measures
1. Droplet isolation in the hospital for 5 days after starting antibiotics or 3 weeks after start of paroxysmal cough when no antibiotics have been given.
2. Chemoprophylaxis to all household and close contacts irrespective of age and immunization status. According to Cochrane review article, there is insufficient evidence to determine the benefit of prophylactic treatament of pertussis contacts.
3. Immunization- Acellular vaccine in combination with Diphtheria and Tetanus. Given at 2,4,6,12-18 months, >4 years
4. Patients itn B. Ppertussis infection should avoid contact with young children or infants until they have completed at least 5 days of antibiotic treatment.
5. Encourage Pertussis boosters for adolescents and adults.

References
1. Wortis Naomi, Strebel Peter, et. al. Pertussis Deaths: Report of 23 Cases in the United States 1992 and 1993  Pediatrics Volume 97 Number 5 May 1996
2. 2009 Redbook
3. Waggoner-Fountain Linda, and Hayden Gregory.  Pertussis in Primary Care Practice.  Primary Care Clinics in Office Practice.  Vol 23 Number 4 December 1996
4. Heininger Ulrich, Klich Kerstin, Stehr Klemens, and Cherry James Clinical Findings in Bordetella pertussis Infections: Results of a Prospective Multicenter Surveillance Study  Pediatrics Vol 100 No. 6 December 1997 p. e 10
5. Cherry J.The Science and Fiction of the "Resurgence" of Pertussis.  Pediatrics August 2003
6. Grenberg D. Pertussis in Adolescents.  The Pediatric Infectious Disease Journal August 2005
7. Halperin SA. Pertussis-A Disease and Vaccine for All Ages.  NEJM Oct 13, 2005
8. Halperin S.A. The Control of Pertussis-2007 and Beyond.  NEJM Jan 11, 2007
9. Edelman K et al. Immunity to Pertussis 5 years after Booster in Adolescence.  Clinical Infectious Disease. 2007
10, Altunaiji SM et al. Cochrane Reviews.  Treatment and Prevention of Bordatella pertussis infection in adolescents and adults.       Cochrane Database of Systemic Reviews 2009 Issue 3