IMPROVED ASSAY TECHNIQUE FOR COXIELLA BURNETII IN CHICK EMBRYO

Abstract

The egg 50% lethal doses (IiD5o) for Coxiella burnetii range from 105 to 10-6, whereas the 50% infectious doses (ID5o) determined by microscopic examination range from 10-10 to 10-11 (Weiss and Pietryk,

A human time dose response model for Q fever

“…The inhaled dose for 50% infection in humans is estimated in Brooke et al (2013) as 1.18 bacteria, Brooke et al (2015) as 0.71 bacteria, Tamrakar et al (2011) as much as 10 bacteria and Jones et al (2006) as low as 1 organism. In the Brooke papers they actually use the human Tigertt data and fit their model so it correlates well with their animal based model (guinea pigs), while we have taken the Tigertt data with additional data reported in Anno and Deverill (1998) (based on Anno and Deverill's interpretation of the dose required to cause infection in 50% of guinea pigs via intraperitoneal injection, GPIPID50 ( Riley et al, 1964 )); this is why our d 50 values differ by an order of magnitude, though the difference between 1 and 10 organisms is perhaps microbiologically negligible. In other in vitro studies, detailing the number of bacteria to cause infection, Shannon et al (2005) state below 10 organisms, Schaik et al (2013) state 1–10 organisms, and Howe et al (2010) state 1 organism.…”