parasitology INTRODUCTION OF MEDICAL PARASITOLOGY

THIS TOPIC INTRODUCTION OF PARASITOLOGY

1. Unit 1: Introduction  Host: definitive host, intermediate host  Parasite; ectoparasite , endoparasite , temporary parasite, permanent parasite, obligatory parasite, facultative parasite.  Host parasite relationship; commensalism, mutualism, pathogenic. Infection and infestation  Classify medically important parasites and explain intestinal, urine, blood and tissue parasites.

2. Host: A host is a larger organism that provides shelter and nourishment to a smaller organism, called a parasite.  Parasites live on or in the host's body, harming it and possibly causing death . The harmed or infected organisms are called the host.

3. Definitive host: It is that host that harbors the sexually active phases of the parasite. Also called the “primary” host. Site of sexual reproduction for the parasite.  Parasite spends a longer duration of its life cycle in this host. Parasites ’ gamete fusion and zygote formation happen in this host. Examples: a)  Plasmodium  is a malarial parasite causing malaria. Definitive Host = Female  Anopheles  mosquito

4. Intermediate host: It is that host that harbors the non-sexual (reproductively/sexually immature) phases of the parasite. Also called the “secondary” host. Site of asexual reproduction for the parasite. Parasite spends a shorter/transient duration of its life cycle in this host . Parasites’ sexual differentiation happens in this host. a)  Intermediate Host = Humans b)  Intermediate Host = Mosquito c)  Intermediate Host = Mosquito

5. Parasite: An  organism  that lives in or on an organism of another species (its host) and benefits by  deriving   nutrients  at the other's expense . Ectoparasite : An   ectoparasite  is a parasite that lives or feeds on the  surface  of that host. The word ‘ ecto ’ means ‘outer’. The parasites that live on the external surface of the host organism are termed as ectoparasites . Examples include ticks on dogs, lice in human hair, Cuscuta growing on green plants etc.

6. Endoparasite : The word ‘ endo ’ means ‘inner’. The parasites that live inside the body of their host such as in the kidney, liver, lungs, red blood cells etc. are termed as endoparasites . They have specialised body parts such as hooks and suckers that help them to attach to the host body and derive nutrition. Examples include Plasmodium (malarial parasite), liver flukes that parasitise the liver in human beings.

7. Temporary parasite: Temporary parasites live in contact with the host for only a part of their cycle or occasionally at the time of feeding, for example, bedbugs and leeches. In contrast, permanent parasites live in contact with the host throughout their life, for example,  Ascaris lumbricoides , Entamoeba , etc.

8. Permanent parasite: A permanent parasite is associated with a host for long periods, whereas a temporary parasite is found in or on a host only for short periods: examples of the former are human helminths and blood protozoans , and examples of the latter are mosquitoes and leeches that visit hosts for blood-sucking only for short periods.

9. Obligatory parasite: An organism that can not complete its life cycle without its host is called obligate parasite . They cannot live without host. A  facultative parasite is an organism that may resort to parasitic activity, but does not absolutely rely on any host for completion of its life cycle.

10. Facultative parasite : A  facultative parasite is an organism that may resort to parasitic activity, but does not absolutely rely on any host for completion of its life cycle. examples of facultative parasites include: Candida Acanthamoeba

11. Host parasite relationship: Commensalism: Commensalism is a relationship between individuals of two species in which one species obtains food or other benefits from the other without either harming or benefiting the latter. Mutualism: Association between organisms of two different species in which each benefits. Mutualistic arrangements are most likely to develop between organisms with widely different living requirements. Several well-known examples of mutualistic arrangements exist .

12. Pathogenic : Pathogenic is a medical term that describes viruses, bacteria, and other types of germs that can cause some kind of disease. The flu, various parasites, and athlete's foot fungus are all considered to be pathogenic. 

13. Infection The invasion and growth of germs in the body. The germs may be bacteria, viruses, yeast, fungi, or other microorganisms. Infections can begin anywhere in the body and may spread all through it . An infection can cause fever and other health problems, depending on where it occurs in the body.

14. Infestation: Infestation  is the state of being invaded or overrun by  pests  or  parasites .  It can also refer to the actual organisms living on or within a  host .

15.  Classify medically important parasites and explain intestinal, urine, blood and tissue parasites. Parasites of medical importance come under the kingdom called protista and animalia . Protista includes the microscopic single-celled eukaroytes known as protozoa . In contrast, helminthes are macroscopic, multicellular worms possessing well differentiated tissues and complex organs belonging to the kingdom animalia .

16. Medical Parasitology is generally classified into: • Medical Protozoology - Deals with the study of medically important protozoa. • Medical Helminthology - Deals with the study of helminthes (worms) that affect man. • Medical Entomology - Deals with the study of arthropods which cause or transmit disease to man.

17. Classify medically important parasites PROTOZOA: E.g. Entameba histolytica HELIMINTHS: E.g. Fasciola hepatica Flagellates: E.g. Giardia lamblia , Trichomonas vaginalis , Leishmania donovani Cestoda : Taenia saginata , Echinococcus granulosus , Hymenolepsis nana Sporozoa : Plasmodium falciparum , Toxoplasma gondi Nemathelminthes : (Nematodes )A. lumbricoides , W. bancrofti Ciliates: Balantidium coli

18. explain intestinal parasite :  roundworms, pinworms, hookworms, tapeworms and liver flukes explain urine: Trichomonas , Schistosoma hematobium and micofilaria explain blood: Haemoproteus spp., Leucocytozoon spp., Trypanosoma spp., Plasmodium spp. (malaria) and microfilaria.   explain tissue: Sarcoptes scabei , Demodex species, Tunga penetrans , and myiasis -causing fly larvae.