Our experiments with esculetin, a specific inhibitor of LOX, suggest that an unidentified enzyme(s) analogous to lipoxygenases could be present in An. gambiae. Esculetin treatment prior to P. berghei infection resulted in a significant increase in oocyst numbers, suggesting that the inhibition of leukotriene and/or lipoxin synthesis makes mosquitoes more susceptible to infection. The gene discussed is LOX; the disease is infection.