Winter 2012 - Douglass Hanly Moir Pathology

ParapertussisBordetella parapertussis, like B. pertussis, is a recognised cause ofwhooping cough in all ages and, in some countries, causes up toone-third of whooping cough cases.Dr Michael WehrhahnMicrobiologistThe clinical presentation is similar tothat of B. pertussis but is generallymilder, with the majority of patientshaving a cough lasting less than a weekand entire illness that resolves withina month. The “whoop” is a feature inup to 60% of cases and post-tussivevomiting in up to 40% of cases.The reduced severity of parapertussisinfection is thought to be related to alack of key virulence factors, such aspertussis toxin (PT), that are found in B.pertussis. There is no cross immunitybetween pertussis and parapertussisand, as the components in the currentpertussis vaccine target toxins likePT, the vaccine has limited, if any,protection against parapertussis.In those with severe disease causedby B. parapertussis, one can expectclinical improvement from the sameantibiotics recommended for thetreatment of B. pertussis. Integrated Cycler fordetection of B. pertussis andB. parapertussis Child with whooping coughNo data is available with regard tothe value of prophylaxis for highriskcontacts of patients with B.parapertussis and it is not a notifiabledisease, in contrast to B. pertussis.While culture, in the past, has beenthe main way of differentiating thesetwo species, few laboratories inAustralia still culture for B. pertussis/parapertussis. At DHM, the recentintroduction of a real-time multiplexPCR that detects B. pertussis andB. parapertussis simultaneously hasallowed the diagnosis of an additionalproportion of whooping cough cases.This test is performed Monday to Fridaywith a result expected within 24 hours.Diagnosis of parapertussis may preventunnecessary further investigation of apatient’s cough illness and support thedecision to treat with antibiotics.For further information, or to discuss a patient please contactDr Michael Wehrhahn on 98 555 2877