Protozoa Medical Parasitology PDF

PROTOZOA MEDICAL PARASITOLOGY GENERAL FEATURES Single-celled eukaryotic microorganisms The single protozoal cell performs all functions. Most of the protozoa are completely nonpathogenic Few may cause major diseases such as malaria, leishmaniasis, and sleeping sickness. CYTOPLASM Ectoplas...

PROTOZOA MEDICAL PARASITOLOGY GENERAL FEATURES Single-celled eukaryotic microorganisms The single protozoal cell performs all functions. Most of the protozoa are completely nonpathogenic Few may cause major diseases such as malaria, leishmaniasis, and sleeping sickness. CYTOPLASM Ectoplasm: Outer homogeneous part that serves as the organ for locomotion and for engulfment of food by producing pseudopodia is called as the ectoplasm. It also helps in respiration, discharging waste material, and in providing a protective covering of cell. Endoplasm: The inner granular portion of cytoplasm that contains nucleus. The endoplasm shows number of structures the golgi bodies, endoplasmic reticulum, food vacuoles, and contractile vacuoles. NUCLEUS The nucleus is usually single but may be double or multiple. The nucleus contains one or more nucleoli or a central karyosome. The chromatin may be distributed along periphery (peripheral chromatin) or as condensed mass around the karyosome. REPRODUCTION Asexual reproduction Sexual reproduction Reproduction usually occurs asexually in protozoans; however, sexual reproduction occurs in cillates and sporozoas. ASEXUAL REPRODUCTION Binary fission: a single parasite divides either longitudinally or transversally into two or more equal number of parasites. Multiple fission or schizogony: Plasmodium exhibits schizogony, in which nucleus undergoes several successive divisions within the schizont to produce large number of merozoites Endodyogeny: Some protozoa like Toxoplasma, multiply by internal budding, resulting in the formation of two daughter cells. SEXUAL REPRODUCTION Conjugation: In ciliates, the sexual process is conjugation, in which two organisms join together and reciprocally exchange nuclear material (e.g. Balantidium coli). Gametogony or syngamy: In sporozoa, male and female gameto cytes are produced, which after fertilization form the zygote, which gives rise to numerous sporozoites by sporogony (e.g. Plasmodium). LIFE CYCLE Single Host: Protozoa like intestinal flagellates and cillates require only 1 host, within which they multiply asexually in trophic stage and transfer from one host to another by the cystic form. Second host: In some protozoa like Plasmodium, asexual method of reproduction occurs in one host (man) and sexual method of reproduction in another host (mosquito).