Human pathogens: Bordetella pertussis, Bordetella parapertussis.
Survives only briefly outside human respiratory tract
Affect children 1-5. Very young children are protected to some extent by maternal antibodies.
Serotyped on the basis of cell-surface molecules 'agglutinogens'.
Transmission: droplets by coughing
Binds to ciliated epithelium in upper respiratory tract
Major virulence factor
Cause:
Facilitate attachment to ciliated epithelial cells in respiratory tract
Adenylate cyclase, which is taken up by leukocytes
-> increase in intracellular cAMP
-> interference with leukocyte function
Causes vasoconstriction and ischaemic necrosis
Inhibits cilia movement
Prevents regeneration of damaged cells
Contribute to attachment to host cells
Whooping cough (Pertussis)
1-3 weeks
Nonspecific symptoms
Progress to dry non-productive cough
Paroxysms of coughing
-> may be associated with cyanosis/vomiting
Elevation in WBC in late catarrhal phase or early paroxysmal phase
3-4 weeks.
Complications
Infections e.g. otitis media, pneumonia
CNS dysfunction e.g. encephalopathy, seizure
Cultured on selective agar (containing blood and charcoal, and antibiotics to inhibit other growths)
Diagnosis can be made on clinical grounds on paroxysmal cough.
Serologic test for antibodies to B. pertussis
First line: erythromycin
Second line: trimethoprim/sulfamethoxazole
Supportive treatment
Prophylaxis for close contacts: erythromycin
2 forms of vaccine
Immunisation starts at 2 month old.
Things to revise/add later:
Bibliography:
About | |
Created | 20040402 |