Primary pneumonic plague in the African Green monkey as a model for treatment efficacy evaluation

Background Primary pneumonic plague is rare among humans, but treatment efficacy may be tested in appropriate animal models under the FDA 'Animal Rule'.Methods Ten African Green monkeys (AGMs) inhaled 44-255 LD₅₀ doses of aerosolized Yersinia pestis strain CO92. Continuous telemetry, arterial blood gases, chest radiography, blood culture, and clinical pathology monitored disease progression.Results Onset of fever, >39°C detected by continuous telemetry, 52-80 hours post-exposure was the first sign of systemic disease and provides a distinct signal for treatment initiation. Secondary endpoints of disease severity include tachypnea measured by telemetry, bacteremia, extent of pneumonia imaged by chest x-ray, and serum lactate dehydrogenase enzyme levels.Conclusions Inhaled Y. pestis in the AGM results in a rapidly progressive and uniformly fatal disease with fever and multifocal pneumonia, serving as a rigorous test model for antibiotic efficacy studies.