Localisation of serotonin and dopamine in Haemonchus contortus

► The localisation of serotonin and dopamine neurotransmitters in Haemonchus contortus was mapped using immuno-staining. ► Serotonin localised in amphidial and pharyngeal neurons in both adult female and male worms, and was also found in ray sensory neurons and a few ventral cord motor neurons in males. ► Dopamine was detected only in the neuronal commissures linking the lateral and sub-lateral nerve cords in both sexes. ► This study provides new insights into the neuronal anatomy and aminergic nervous system in H. contortus.