Definition of Protozoa – Basic microbiology, parasitology, and immunology; nature, reproduction, growth, and transmission of common microorganisms and parasites in Bangladesh; prevention including universal precaution and immunization, control, sterilization, and disinfection; and specimen collections and examination. Students will have an understanding of common organisms and parasites caused human diseases and acquire knowledge about the prevention and control of those organisms.
Definition of Protozoa
Protozoa are unicellular, eukaryotic cells, which lack of a cell wall and motile by means of cilia, od flagella, and/or pseudopodia (with exception of apicomplexans).
Classification of Protozoa:
A. On The Basis of Habitat;
Skin – Leishmania
Eye – Acanthamoeba
Mouth – Amoebae and flagellates (usually non-pathogenic)
Gut – Giardia, Entamoeba (and invasion to liver), Cryptosporidium, Isospora, Balantidium, Cyclospora, Enterocytozoon
Genitourinary tract – Trichomonas
Blood stream – Plasmodium, Trypanosoma
Spleen – Leishmania
Liver – Leishmania, Entamoeba
Muscle – Trypanosoma cruzi
CNS – Trypanosoma, Naegleria, Toxoplasma, Plasmodium
Bone marrow – Leishmania
Lymph node – Leishmania
B. According To Organ of Locomotion;
- Rhizopoda -> Pseudoodia
- Mastigophora -> Flagella
- Ciliata -> Cilia
C. According to Speed of locomotion;
- Amoeba (Pseudopopdia) -> 0.2-3 µm/sec)
- Flagellates (Flagella) 15-30 µm/sec.
- Ciliata (Cilia) 400-2000 µm / sec.
Common protozoal infections in Bangladesh;
1. Amoebiasis (Amoebic dysentery)..
2. Giardiasis (Diarrhoea).
3. Trichomoniasis (Vaginitis).
4. Malaria.
5. Kala-azar (visceral leishmaniasis).
Diseases Caused by Flagellated Protozoa:
| Protozoal Parasites | Pathogenic Effects |
| Trichomonas vaginalis | Trichomoniasis |
| Giardia intestinalis | Giardiasis (Diarrhea) |
| Leishmania species | Kala-azar, PKDL |
| Trypanosoma cruzi | Chagas’ disease or American Trypanosomiasis |
| Trypanosoma brucei | Sleeping sickness or Human African Trypanosomiasis |
Modes of Reproduction of Protozoa:
Protozoa usually reproduce asexually by binary fission; some have sexual cycles, involving meiosis and the fusion of gametes or gametic nuclei resulting in a diploid zygote. The modes of reproduction of protozoa is given below –
| Modes of reproduction | |
Asexual | Binary fission |
| Endodyogeny | |
| Multiple fissions or schizogony | |
| Budding | |
Sexual | Fusion of gametes |
| Conjugation | |
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