Experimental inhibition of nitric oxide increases Plasmodium relictum (lineage SGS1) parasitaemia

► The immune effectors involved in the resistance to avian malaria are not well known. ► We suppress the production of NO in canaries infected with Plasmodium relictum. ► Birds NO-inhibited show a higher parasitaemia, but not pay a higher cost of infection. ► NO contributes to the resistance to avian malaria. ► Parasitaemia and cost of infection can be decoupled.