Pathogenesis of Anthrax - A Progress Report

The dynamics of the host-parasite interaction after challenge with anthrax was studied by developing a procedure for survival experimentation that cannulated the thoracic and right lymph ducts. After aerosol challenge bacilli were observed in the lymph as early as nine and usually before 16 hours post-challenge and prior to observations of bacilli in the blood. Most bacilli are retained in the reticulo-endothelial system (RES) through an incubation period until the preterminal septicemia occurs. This stage is characterized by a logarithmic increase in numbers of bacilli and an increasing concentration of toxin. The doubling rate in the septicemic stage and number of bacilli/milliliter of blood at death are constants in each host species; however, immunization reduces the terminal number. Four different experimental approaches show that the rhesus monkey infected with anthrax dies of toxin. Two unevaluated tests give early indication of anthrax infection, namely cholinesterase inhibition and a cytoplasmic effect for guinea pig tissue cell sheets. A live vaccine as a booster following antigen results in a tremendous increase in resistance to;challenge. Antibiotic treatment with mice work shows clearly that penicillin is the antibiotic of choice. Streptomycin, aureomycin, and terramycin have value; chloramphenicol is of little value. A mathematical model of pathogenesis of anthrax has been developed.