Assessment of Virulence and Infection Dynamics of a wild Algerian Eimeria media Strain

This study aimed to characterize the pathogenicity of a field Algerian strain of Eimeria media and to develop a mathematical framework to simulate its infection dynamics within a rabbitry. The research focuses on addressing the lack of specific data regarding the virulence and epidemiological spread of local strains in Algeria.

Forty five-week-old specific pathogen-free (SPF) rabbits were assigned to four groups: a control and three groups inoculated with increasing doses of sporulated oocysts (1 × 10⁴, 2.5 × 10⁴, and 5 × 10⁴). Growth performance and oocyst excretion were monitored daily for 21 days. Simultaneously, a Susceptible-Exposed-Infectious-Recovered (SEIR) model with environmental compartments was developed to analyze the impact of initial oocyst loads I(0) and transmission efficiency (β) on outbreak kinetics.

Experimental results showed a five-day pre-patent period with an excretion peak at day 7. The strain was moderately pathogenic, causing no mortality but leading to a significant dose-dependent growth inhibition, resulting in a 17.2% reduction in mean body weight at day 21 post-inoculation in the highest-dose group (D50) compared to the control. Mathematical simulations explored the theoretical dynamics of infection, suggesting that a high initial environmental load accelerated the outbreak, bringing the infection peak forward to days 15-20, whereas a low initial load slowed the dynamics, postponing the peak to days 30-35.

Eimeria media represents a moderate economic impact to the rabbit industry. The integration of biological data into an exploratory SEIR model suggests that initial environmental contamination and transmission rate are important control points. Effective management should prioritize proactive biosecurity to minimize oocyst loads and potentially reduce outbreak severity.