Nejm 2005;352:1215

Cause:Bordetella pertussis(similar to hemophilus); occasionally sporadically by adenovirus (Nejm 1970;283:390). From respiratory tract of infected persons esp, during catarrhal stage; 90% attack rate

Pathophys:

Rapid bacterial multiplication causes decreased tracheal and bronchial ciliary action, which in turn causes infection by strep, staph, etc. Endotoxin produced and released when bacteria die causing cell irritation and occasional death; perhaps neurotoxic effects on CNS

Coughing causes anoxia, which somehow causes hemorrhages

Worldwide, worst in developing countries. Highest incidence in children <5 yr. Female morbidity > male. In US, increased to >11 000 cases/yr in 2003, 5× that in 1980, w many infections in adults

Sx:

Catarrhal stage (mild cough) × 2 wk; then paroxysmal coughing lasting weeks to months

in adults (Ann IM 1998;128:64), nonproductive intermittent chronic cough (>2 wk), 12-21% of those w that sx?! (Jama 1996;275:1672, 1995;273:1044); diaphoresis (50%)

Si:Spasmodic coughing, long drawn-out with rapid sharp inhalations (whoops); small petechial hemorrhages throughout body; no fever

Paroxysmal stage lasts >2 wk, 27% still have cough at 90 d ("cough of 100 days")

Seizures; secondary pulmonary infection and atelectasis; meningitis; in infants, apnea and death 75% are <1 yr, 40% <3 mo (Ann IM 1972;76:289)

r/o croup (Croup (Acute Laryngotracheobronchitis))

Lab:

Bact:Culture, if sx 4 wk, of sputum or nasal/pharyngeal swab during catarrhal stage, and/or PCR tests of same

Hem:Wbc's increased with high % (usually >50%) lymphocytes, looks like CLL in a child

Serol:ELISA IgG antibody titers increased after 3 wk, though cutoffs for dx on single titer controversial

Rx:

Preventive

• Immunize with antigens 1, 2, and 3 in children between age 6 wk and <6 yr; use acellular pertussis as DTaP for immunizations beginning at 2 mo, 70-90% effective compared to placebo while whole cell vaccine is only 40-60% effective and has encephalitic/neurologic cmplc's (Nejm 1996;334:341, 349, 391; 1995;333:1045; Jama 1996;275:37). No cross-placental transfer.
• In adults and adolescents, use acellular pertussis, DTaP, instead of tetanus boosters (Jama 2005;293:3003; Nejm 2005;353:1555, 1615)
• Hyperimmune globulin
• Antibiotics prophylactically or to sick pts to decrease infectivity, do shorten course: erythromycin 40 mg/kg in children, 1 gm/d in adults; or azithromycin; or Tm/S × 10 d, 8 mg/40 mg/kg in children, 320/1600 in adults