1. Introduction to parasitology leacture(1)
Mrs. Dalia kamal eldien
Msc in microbiology

2. parasitology
Parasitology 
is the study of parasites, their hosts, and the relationship between them.
Medical parasitology  
is the subject which deals with the parasites that infect humans, the diseases caused by them, clinical picture and the response generated by humans against them.
Human parasitology
is the study of those organisms which parasitise humans
According to the very broad definition of parasitology, parasites should include the viruses, bacteria, fungi, protozoa and metazoa (multi-celled organisms) which infect their host species
Parasite: organism living in or on, another organism known as a host, to obtain nourishment and shelter from the host as well as does harms to the host
Host : organism harboring a parasite, it supplies the parasite with nourishment and shelter, it is the injured partner.

3. parasitic infections
A parasitic disease is an infectious disease caused or transmitted by a parasite.
Many parasites do not cause diseases.
Parasitic diseases can affect practically all living organisms, including plants and mammals. 
Although parasitic infections occur globally, the majority occur in tropical regions, where there is poverty, poor sanitation and low personal hygiene

4. Sings& symptoms
Symptoms of parasitic disease may not always be obvious.
However, such symptoms may mimic anemia or a hormone deficiency.
Some of the symptoms caused by several worm infestation can include itching affecting the anus or the vaginal area, abdominal pain, weight loss, increased appetite, bowel obstructions, diarrhea, and vomiting eventually leading to dehydration, sleeping problems, worms present in the vomit or stools, anemia, aching muscles or joints, general malaise, allergies, fatigue, nervousness.
Symptoms may also be confused with pneumonia or food poisoning.

5. Mode of transmission
Parasites usually enter the body through the mouth or skin.
Parasites that enter through the mouth are swallowed and can remain in the intestine or burrow through the intestinal wall and invade other organs.
Parasites that enter through the skin bore directly through the skin or are introduced through the bites of infected insects (called vectors because they convey or transmit organisms that cause disease).
Some parasites enter through the soles of the feet when a person walks barefoot or through the skin when a person swims or bathes in contaminated water.
Rarely, parasites are spread through blood transfusion, through injections with a needle previously used by an infected person, or from a pregnant woman to her fetus.

6. Key definitions
Eukaryote: a cell with a well-defined chromosome in a membrane-bound nucleus; all parasitic organisms are eukaryotes
Protozoa: unicellular organisms, e.g. Plasmodium (malaria)
Metazoa: multicellular organisms, e.g. helminths (worms) and arthropods (ticks, lice)
Parasitisum- a relationship in which one of the participants, the parasite, either harms its host or in some sense lives at the expense of the host
Zoonosis animal’s diseases which can be transmitted to man, animal can be wild and/or domestic (these animals infected with parasites are called reservoir hosts)

7. Obligate (permanent) parasites – organisms that for all or most of their life cycle are parasitic; they have at least one host during their life-history
Temporary (intermittent) parasites – agents that are parasitic for limited periods for either feeding or reproduction
Facultative parasites – organisms that are not normally parasitic but can survive for a limited period when they accidentally find themselves within another organism
Adaptive parasites – those organisms that have capacity to live both as free-living or parasitic organisms

8. Parasite, can be:- Microparasites / Macroparasites
Endoparasites / Ectoparasites
Intracellular parasites (mostly microscopic) Extracellular parasites (they range in size from micro- to macroscopic)

9. Life cycle
Life cycle is the process of a parasite’s growth, development and reproduction.
-Direct life cycle one host .
-Indirect life cycle more than one host
Infective stage is a stage when a parasite can invade human body and live in it
Infective route is the specific entrance through which the parasite invades the human body
Infective mode means how the parasite invades human body, such as:
1. the cercariae of the blood fluke actively penetrate the skin of a swimming man
2. the infective Ascaris eggs are swallowed by man

10. Host
Host - in parasitism, it supplies the parasite with nourishment and shelter, it is the injured partner
Carrier - a person who harbours parasite, has no clinical symptoms, is an important source of infection in epidemiology
Definitive host - in which the parasite reaches sexual maturity and the adult form
Intermediate host - in which the immature or larval form , or in which the parasite undergoes asexual reproduction
Transport host - one in which the parasite does not undergo any development but it remains alive and infective to another host
Reservoir host - any animal that harbors an infection and can transmitted to humans, even if the animal is a normal host of the parasite.

11. Host parasite relation ship
Host parasite relation ship is a type of symbiotic relationship between organisms of different species, the parasite benefits at the expense of the host, we have different type include:
1-Commensalism: the association of two different species or organism in which one is benefited and the other is neither benefited nor harmed. (e.g. non pathogenic intestinal protozoa)
2-Mutilisim : the relation is benefit to both associates
3-Pathogensim : the relation in which parasite is benefit and host is harm

12. linnaeus system classification

13. Classification
The animal kingdom has been divided into two subkingdoms;
Protoza
Metazoa