Whooping cough (pertussis) Flashcards
what is the definition of whooping cough?
Pertussis (also known as whooping cough) is an upper respiratory tract infection (URTI) characterised by a severe cough. Bordetella pertussis is the typical aetiological agent.
what is the epidemiology of pertussis?
still high incidence despite vaccines
what is the aetiology of pertussis?
B pertussis is the typical aetiological agent. Other Bordetella species that may rarely cause pertussis or pertussis-like cough include B parapertussis, B bronchiseptica, or B holmesii; these species are not vaccine-preventable.
what are the risk factors for pertussis?
Under 6 months old Baby bone to mother infected >34 weeks No or incomplete vaccinations School teacher or care workers Close contact with infected person (sibling) Household contact with infected person
what is the pathophysiology of pertussis?
Transmission of disease occurs through direct contact with droplet discharges from respiratory mucous membranes of infected people. Pertussis is highly contagious, with up to 80% of susceptible household contacts developing clinical disease after exposure to an index case. B pertussis can enter and survive within phagocytic leukocytes and non-phagocytic cells. It is unclear how this affects pathogenesis and the host immune response. B pertussis infection can cause a primary pertussis pneumonia with subsequent respiratory failure and death. Bacteraemia does not occur.
the AB type exotoxin produced inhibits Gi leading to increases in cAMP levels
Toxins = chronic inflammation after 2 weeks of standard URTI with coughing up to 6 weeks
what are the key presentations of pertussis?
Presence of risk factors Cough Inspiratory whooping Rhinorrhoea Post-tussive vomiting
what are the first line and gold standard investigations for pertussis?
Culture of nasopharyngeal aspirate or swab from posterior nasopharynx - may be positive for B pertussis
PCR of nasopharyngeal aspirate - positive or negative
Serology - positive or negative
FBC - elevated WBC
what are the differential diagnoses for pertussis?
Upper respiratory infection
Community acquired pneumonia
Respiratory syncytial viral infection
how is pertussis managed?
Under 1 month:
Azithromycin or clarithromycin, azithromycin: 10 mg/kg orally once daily for 3 days, clarithromycin: 7.5 mg/kg orally twice daily for 7 days
Infants and children >1 month:
azithromycin: 10 mg/kg (maximum 500 mg/day) orally once daily for 3 days or clarithromycin: children <8 kg: 7.5 mg/kg orally twice daily for 7 days; children 8-11 kg: 62.5 mg orally twice daily for 7 days; children 12-19 kg: 125 mg orally twice daily for 7 days; children 20-29 kg: 187.5 mg orally twice daily for 7 days; children 30-40 kg: 250 mg orally twice daily for 7 days
Non pregnant adults:
azithromycin: 500 mg orally once daily for 3 days or clarithromycin: 500 mg orally twice daily for 7 days
Pregnant adults:
erythromycin base: 500 mg orally four times daily for 7 days
what are the complications of pertussis?
Pneumonia
Seizure
Apnoea
Rib fracture
what is the prognosis of pertussis?
Most deaths are infants under 1 month old
Very good prognosis for older children and adults
what type of vaccine is given for pertussis?
toxoid
which culture agar should be used to identify bordetella pertussis?
bordet-gengou agar
