The diagnosis and treatment of malaria infection requires detectingthe presence of malaria parasite in the patient as well as identification of the parasite species. We present an image processing-basedapproach to detect parasites in microscope images of blood smear andan ontology-based classification of the stage of the parasite for identifying the species of infection. This approach is patterned after the diagnosis approach adopted by a pathologist for visual examination and hence is expected to deliver similar results. We formulateseveral rules based on the morphology of the basic components of a parasite namely chromatin dot(s) and cytoplasm to identify parasite stage and species. Numerical results are presented for data taken from various patients. Sensitivity of 88% and specificity of 95% is reported by evaluation of the scheme on 55 images.