Comparison of serologic reactions in experimental canine and simian coccidioidomycosis

Three groups of monkeys and groups of dogs were each exposed by the respiratory route to graded inhaled doses of approximately 9,500, 2,500 and 325 dry arthrospores of Coccidioides immitis strain Silveira. In sera from infected dogs, the highest median agar gel precipitin titers occurred at five and nine weeks postexposure. Titers fell after these time periods in all dose groups. Agar gel precipitin titers in the medium and low dose groups of monkeys reached their highest median values at 14 weeks postexposure and then declined slightly. Agar gel precipitin titers in infected monkeys were consistently higher than thoee in infected dogs. Highest median titers for CF antibodies occurred at the five week test period in dogs of all dose groups. After this time period, the median titers in the sera of these dogs declined. In infected monkeys, maximum median titers of CF antibodies were observed at nine and 17 weeks postexposure. The median titers forming this plateau were higher than the highest median titers found in sera of infected dogs for CF antibodies. The serologic reactions in the two animal species appeared consistent with the pathologic findings, in that the animals with the higher antibody titers also had the more severe pathology.