RT Book, Section
A1 Cherry, Cara
A1 Kersh, Gilbert J.
A2 Boulton, Matthew L.
A2 Wallace, Robert B.
SR Print(0)
ID 1182667428
T1 Q Fever
T2 Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e
YR 2022
FD 2022
PB McGraw Hill
PP New York, NY
SN 9781259644511
LK accessmedicine.mhmedical.com/content.aspx?aid=1182667428
RD 2024/04/19
AB Q  fever  in  humans  is  caused  by  infection  with  the  gram-negative  bacterium  Coxiella  burnetii.  The  organism  grows  intracellularly  in  a  parasitophorous  vacuole  at  acidic  pH  (4.75).1C.  burnetii  is  a  member  of  the  gammaproteobacteria  and  is  classified  in  the  order  Legionellales,  family  Coxiellaceae.  This  bacterium  infects  a  broad  range  of  animal  species,  and  is  thought  to  be  transmitted  primarily  by  inhalation,  but  tick  transmission  could  play  a  role  in  maintaining  the  bacteria  in  wildlife.  Q  fever  is  a  zoonosis,  and  humans  usually  acquire  the  disease  via  inhalation  of  contaminated  dust  or  dried  material  from  animal  waste,  with  a  small  number  of  organisms  (<10)  thought  to  be  able  to  initiate  an  infection.2  Infected  livestock,  such  as  cattle,  sheep,  and  goats  are  the  primary  reservoirs  for  human  exposure.  The  organism  can  grow  to  very  high  densities  in  the  placenta  of  infected  livestock.  Therefore,  these  animals  shed  the  largest  amounts  of  C.  burnetii  during  parturition.  The  replicative  form  of  C.  burnetii  has  been  described  as  the  “large  cell  variant”  (LCV),  whereas  nonreplicating  C.  burnetii  will  form  a  spore-like  “small  cell  variant”  (SCV).3  The  SCV  is  resistant  to  heat  and  desiccation  resulting  in  impressive  stability  in  the  environment.4  The  environmental  stability,  transmission  by  inhalation,  and  low  infectious  dose  have  led  to  classification  of  C.  burnetii  as  a  potential  bioweapon  and  inclusion  on  the  list  of  select  agents  maintained  by  the  U.S.  Department  of  Health  and  Human  Services.