Although splenic cell apoptosis and high levels of IFN-γ, IL-12, TNF-α, and other cytokines might contribute to host lethality, the direct causes of severe disease and host death are likely due to multiple factors, including excessive inflammatory responses, a compromised immune system, organ failure, and metabolic disturbances such as hypoglycemia and lactic acidosis that we did not study here24. The gene discussed is TNF; the disease is lactic acidosis.