1. Parasite Mrs. Ohoud S.alhumaidan
we will talk about an introduction of parasite , definition of parasitology ,
Classifications of parasite
mode of transmission
The clinically important protozoa and helminthes with their life cycle
Mrs. Ohoud S.alhumaidan

2. Introduction Paraitology : Parasitism : (chapter 21) Parasite :
is an organism baring food and shelter temporarily or permanent and living in or on another organism.
Kind of parasite ( according to habitat )
Ectoparasites : (chapter 21)
Endoparasites : (chapter 21)
There are many type of parasite other than human parasite like plant parasite and animal parasite
Parasitism : Two organisms living together, one is benefited ‘’called parasite’’ and the other is harmed ‘’called host’’
Endoparasite :Parasites found inside the body of the host.
Can be in blood, tissue, or gastro-intestinal tract.
Are Protozoa and Helminthes.
Ectoparasite :Live on the outside or skin of the host.
Are Arthropods: Insects (mosquitoes, lice, and fleas) and Arachnids (ticks, mites, or spiders).

3. Endoparasite
Ectoparasite

4. 1-Facultative parasite:
Parasites can be:
1-Facultative parasite:
parasites able to live both free living and parasite living e.g. Strongyloides species.
2-Obligate parasite:
parasite living permanently in a host and cannot live without a host e.g. Trichomonos species.
3-Coprozoic (spurious) parasites:
foreign organisms which have been swallowed merely pass along alimentary canal of man (without establishment) to be recovered in faeces. (without affect)
Parasites can be
Facultative parasite: parasites able to live both free living and parasite living e.g. Strongyloides species.
Obligate parasite: parasite living permanently in a host and cannot live without a host e.g. Trichomonos species.
Coprozic (spurious) parasites: foreign, pass through alimentally canal without affect. Or
Coprozoic or spurious parasite foreign organisms which have been swallowed merely pass along alimentary canal of man (without establishment) to be recovered in faeces.

5. HOST Host : Classification of Hosts (see page 358 chapter 21)
organism harboring the parasite species may be affected or not.
Classification of Hosts
1-Definitive host or final host : ( sexual development)
Eg: man.
(see page 358 chapter 21)
2-Intermediate host: ( asexual development)
Eg: Taenia>>>>>>> adult man
Larva –--- cattle
3-Reservoir host (carrier):
the carrier host is well adapted to the parasite and tolerates the infection but serve as source of the infection to other organisms
4-Vector:
an arthropod which carries the parasite from one host to another.
Types of hosts:
a-Definitive or final host : host with adult stage or sexually reproducing forms of the parasite.
b-intermediate host : host with the larval stage or asexually reproducing forms of parasite.
c-Reservoir host : animal that harbors the same species of parasite as man . such animal help to maintain the cycle of parasite in nature and act as a potential source for human infection with this parasite.

6. Classification of parasites
General classification: animal parasites are classified according to international code taxonomy – Each parasite belong to a:
Kingdom
Phylum
Class
Order
Family
Genus
Species
Some have further divisions to:
Sub – order, super family, sub – species
in classification, scientific parasitic name is of 2 parts:
Genus name and species name. Ex: Plasmodium Falciperum
Genetic name (one word): plasmodium
Species name (two words): plasmodium falciperum.
Genus: means group of close related species.
Species: means population with the same genetic characters.

7. Mode of parasitic infections
Congenital from mother to fetus.
Sexually transmission
Ingestion of contaminated food and water or undercooked meat in which the infective stage has developed.
Penetration of the skin due to contact with infected soil or water stream.
Inhalation of dust carrying the infective stage of parasite.
Vectors: through the bite or faeces of infected vector or by swallowing the vector.

8. Classification of parasites
Protozoa
Helminthes
Intestinal
Blood and tissue
Urogenital
Cestodes
Trematodes
Nematodes
arthropods

9. Protozoa

10. Protozoa See page 72 chapter 5
Protozoa life cycle consist of two stage :
Cyst
Infective stage, dormant, immotile.
Trophozoite
Vegetative stage. Can be motile.
Protozoa:
Eukaryotic unicellular organism
Classified in the second kingdome (protista)
Most of protozoa are unicellular , found in soil and water

11. Protozoa are classified (according to their method of locomotion)
See page 73 , chapter 5 , table 5-3)
Flagellates (e.g. Giardia lamblia).
Amoeboids (e.g. Entamoeba histolytica).
Sporozoans (e.g. Plasmodium).
Ciliates (e.g. Balantidium coli).

12. Protozoa infection Intestinal Blood and tissue Entamoeba histolytica
Giardia lamblia
Cryptosporidium
Malaria
Toxoplasma
Trypanosoma
Leishmaina
Urogenital tract
Trichononas Vaginalis

13. Entamoeba histolytica
Name of Disease:
Amoebiasis (Amebic dysentery)
Parasite:
It possess both trophozoite and cyst forms.
It moves by Pseudopodia (false feet)
Dysentery Stool with blood and mucus.
Entamoeba histolytica :
is an ameba that feeds on cells in the human colon. It is the cause of amebic dysentery (bloody diarrhea) as well as colonic ulcerations. The infection is also referred to as amebiasis. If the organisms spread throughout the body via the bloodstream they may cause abscesses in the liver or, less frequently, other organs.
The organism has two forms. The cyst is round and micrometers in diameter, and contains four nuclei when mature. It is resistant to desiccation and stomach acid, and can survive long enough in the environment to be spread to other humans. When the cyst reaches the large intestine, it excysts and the four nuclei present in the cyst become four separate amebae, each of which undergoes binary fission immediately; thus the ingestion of a single cyst leads to 8 trophozoites. The trophozoite, micrometers in diameter, is the active form of the organism and it is in this form that the damage is done to the body.

14. Entamoeba histolytica
Geographical distribution:
Word wide, but more common in tropical and subtropical countries and in countries with poor sanitation
Habitat:
The lumen of the large intestine.
Reservoir:
Mainly: humans
Rarely: dogs, pigs, monkeys
E. histolytica is spread by the fecal-oral route.

15. Amoebiasis Mode of transmission :
See page 362 , chapter 21 , table 21-3)
Infection is associated with poor hygiene:
Fecal oral rout
By flies transporting cyst from feces to food
Fecally soiled hands of infected food handlers
Anal sexuall contact

16. Life cycle: Cyst: infective stage
Inters mouth through contaminated food, drink, fly, or through using human stool as fertilizer
To L.I. lumen and change into trophozoite (pathogenic stage)
Can do erosion through B.V. to liver and other organs
Produce lytic enzymes (capable of doing lysis and produce ulcer)
Flask shape ulcer

17. Cyst wall disintegrates and release trophozoites. Cyst Ingested
Cyst passes to small bowel
Trophozoites colonize colon.
Cause ulceration of colon,
Can further spread to other organ and cause abscesses (mainly liver)
Trophozoites form cysts that passes in feces.

18. Morphology: Entamoeba histolytica
Trophozoite
Pathogenic stag
Cyst:
Infective stage
Nuclei

19. Dysentery: blood+mucous diarrhea (as a result of flask shape
Clinical picture:
Dysentery: blood+mucous diarrhea (as a result of flask shape
ulcer wall invasion)
Sever abdominal pain
Tenesmus: sense of incomplete evacuation
(the patient at this point should be seeking medical advice)
Complication:
intestinal: peritonitis, appendicitis, Hemorrhage
Extra intestinal:
Most commonly: liver hepatitis (sever right abdominal pain)
Fever
amoebic liver abscess (sever pathology in the
liver because the inflammation spots came together)
shoulder pain and Toxemic manifestations
Also in lung, skin, and brain

20. Plasmodium sp. (Malaria)
Name of Disease:
Malaria 
systemic infection with malaise, fever, chills, sweating, headache, and nausea.
The frequency with which the cycle of chills, fever and sweating is repeated is referred to as periodicity and depends on the particular species of plasmodium.
Parasite: four species are known to infect human
Plasmodium falciparum
(the most deadly and dangerous ,)
Plasmodium vivax.
(the most common species, )
Plasmodium ovale.
Plasmodium malaria.
RBC
Plasmodium sp.

21. Plasmodium sp. (Malaria)
Approximately 300 million people worldwide are affected by malaria and between 1 and 1.5 million people die from it every year
Geographical distribution:
Previously extremely widespread, the malaria is now mainly confined to Africa, Asia and Latin America
The problems of controlling malaria in these countries are aggravated by inadequate health structures and poor socioeconomic conditions. The situation has become even more complex over the last few years with the increase in resistance to the drugs normally used to combat the parasite that causes the disease.

22. Plasmodium sp. Mode of transmission :
See page 366 , chapter 21 , table 21-4)
By female anopheles mosquito
Blood transfusion
Contaminated needls

23. Life Cycle: Plasmodium sp.( chapter 21, page 367, figure 21-7)
Infected mosqiti inject the sporozoit
Sporozoit migrate to liver and form merozoit
Merozoit invade to RBC
The merozoit becom trophpzoit
Trophozoit multiplies and produce merozoit and cause RBC rubtured
Merozoit becom gametocyte
Mosqiti pick up the gametocyte from infected humen

24. Plasmodium sp. (Malaria)
Pathology and clinical significance:
When merozoits invade the blood cells, using hemoglobin as a nutrient, eventually, the infected red cells rupture, releasing merozoits that can invade other erythrocytes. If a large numbers of red cells rupture at roughly the same time, a paroxysm (sudden onset) of fever can result from the massive release of toxic substance.
Plasmodium falciparum is the most dangerous species. P. malriae, P. vivax, and P. ovale cause milder form of the disease, probably because they invade either young or old red cells, but not both. This is in contrast to P. falciparum, which invades cells of all ages.
Plasmodium falciparum is characterized by persistent high fever and orthostatic hypertension. Infection can lead to capillary obstruction and death if treatment is not introduced.

25. Toxoplama gondii Name of the disease: Toxoplasmosis.
Geographical distribution:
World wide. Approximately 50% of human
Population of USA has been infected.
Reproduction:
Sexually reproduction (Definitive host) 
In Cats, where Oocysts are
released in feces of cat.
Asexual reproduction (intermediate host)
In worm blooded animals
(cats, mice, humans, and birds).

26. Mod of Transmission
1.eating row, undercooked meat of sheep and cow containing viable trophozoits (bradyzoits)
2. swallowing food and water contaminated with infected cat feces
3.Congenital transmission, through placenta (fatal) especially when infection occurs during pregnancy
4. person to person: ex. By blood transfusion or organ transmission

27. Toxoplama gondii See page 361 , chapter 21 , table 21-2)
Mod of Transmission :
See page 361 , chapter 21 , table 21-2)

28. Clinical symptoms
Infection of normal human hosts are common and usually asymptomatic.
Infection in immunocompromised individuals is very sever and they my suffer relapse of the infection.
Congenital infections can also be sever, it can result in still births, brain lesions, and they are a major cause of blindness in newborns.

29. Helminthes ( worms)

30. Helminthes ( worms) Eukaryotic and multicellular parasites
ranging from barely visible roundworms (0.3 mm) to huge tapeworms 25 meters long .
helminthes grouped them into three categories:
Nematodes (roundworms),
Trematodes (flukes)
Cestodes (tape- worms)
helminthes grouped them into three categories:
1-nematodes (roundworms),
2-trematodes (flukes), and
3-cestodes (tape- worms) and discussed basic characteristics of each group.

31. Helminthes
live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient absorption, causing weakness and disease
Sources for human infection are contaminated food, soil, and water or infected animals,
routes of infection are by oral intake or penetration of unbroken skin

32. Helminthes Cystods (flat worms) Trematodes (fluks)
Nematodes
(round worms)
Ascaris lumbricoides
(Roundworm)
Cystods
(flat worms)
Taenia saginata
Trematodes
(fluks)
(Schistosomiasis)
Bilharzia

33. Nematodes (Roundworms)
elongate, cylindrical shape.
Nonsegmented and tapered at both ends .
Sexes are separate.
the vast majority are free- living soil and freshwater worms, but around 200 are parasitic, including 50 species that affect humans.
Nematodes divided into:
intestinal nematodes ( e,g, Ascaris lumbricoides
Tissue nematodes
General features:
Elongated worm, cylindrical, unsegmented and tapering at both ends.
Variable in size, measure less than 5mm~as long as 100cm.
Sex separate and male is smaller than female
typically less than 2.5 millimeters long. The smallest nematodes are microscopic, while free-living species can reach as much as 5 centimeters and some parasitic species are larger still.
Male work is typically smaller than the female .

34. Ascaris lumbricoides (Roundworm)
Ascaris lumbricoides is the largest nematode (roundworm) parasitizing
the human intestine
1/3 the world population is infected with this worm
Geographical distribution:
world wide, common among people with low standard of living and among children
Morphology:
Adult: in small intestine adult egg: infective stage
Ascariasis is prevalent worldwide, especially in tropical and subtropical countries.

35. Life cycle: 2 phases: lung and intestinal
Egg ingested, hatches in duodenum; larvae penetrate intestine wall, enter blood vessels and embolize through liver to lungs.
They then migrate into airspaces, up trachea and are swallowed, taking up permanent adult residence in the small intestine; ~ 2 months from egg to mature adult
Each female produce 200,000 eggs per day
Adult worms can live 1 to 2 years.
The eggs have a lipid layer,,,The eggs thrive in warm, moist soils and resist cold and chemical disinfectants; they are also sensi- tive to sunlight, high temperatures, and drying.
after ingested eggs hatch in the human intestine, the larvae embark upon an odyssey in the tissues. First they penetrate the intestinal wall and enter its lym- phatic and circulatory drainage. From there, they are swept into the right ventricle of the heart, and eventually arrive at the capillaries of the lungs. From this point, the larvae migrate up the respiratory tree to the glottis. Worms entering the throat are swallowed and re- turned to the small intestine, where they reach adulthood and re- produce, producing up to 200,000 fertilized eggs a day.
Ascaris lumbricoides, a roundworm, infects humans when an ingested fertilised egg becomes a larval worm that penetrates the wall of the duodenum and enters the blood stream. From there, it is carried to the liver and heart, and enters pulmonary circulation to break free in the alveoli, where it grows and molts. In three weeks, the larvae pass from the respiratory system to be coughed up, swallowed, and thus returned to the small intestine, where they mature to adult male and female worms. Fertilization can now occur and the female produces as many as 200,000 eggs per day for a year

37. Clinical Symptoms: Ascaris lumbricoides
Lung phase
It causes hemorrhage, inflammation, bacterial infection.
Symptoms:
Bloody sputum, cough , wheezing, and fever.
Intestinal phase
Symptoms: Related to number of worms;
Small numbers: asymptomatic.
Large numbers: Passing of worm in stool, vomit, nausea, malabsorption and abdominal pain.
Complications:
If untreated, can cause intestinal obstruction (blockage) and
malnutrition.
Deaths form ascariasis range from 8000 to 100,000 annually worldwide.

38. Cestodes (tapeworms) Long, ribbon-like, segmented worms.
Primarily intestinal parasites.
Can reach 15 m in length.
human species are :
Taenia saginata ( the beef tapeworm )
T. solium, ( the swine tape- worm )
Diphyllobothrium latum ( the fish tapeworm )
Name of the disease:
Teniasis.

39. Taenia saginata or Beef Tape-Worms
Habitat:
is the small intestine (the ileum )
Transmission:
acquired in humans through the ingestion of raw or poorly cooked meat of infected cows. These cows have been infected via the ingestion of human feces containing the eggs of the parasite

40. Taenia saginata Morphology: Adult is divided into three parts,
1- a head: round and small. It has four suction disks
2- neck: A small, slender neck, about an inch long
3- number of segments.
Adult tapeworms and can grow up to 25 meters in the lumen of the intestine, but are usually closer to 5 meters in length
Egg present in feces

41. Taenia saginata: life cycle

42. Taenia saginata Habitat:
- adult in small intestine of man only ( devenitive host )
- Egg in feces
- larva stage in muscle of thigh, shoulder, neck and heart of
cattle only (intermediate host)
Clinical symptoms:
High infection: diarrhea and consitipation
Vomiting
Loss of appetite
Anemia

43. Trematodes (fluke) Small (about 1 cm) flat , leaf-like worms.
Infest various organs of the human host (e.g. intestinal veins, urinary bladder, liver, or lung)
All parasitic trematodes use freshwater snails as an intermediate host.
The fluke (ME floke, flat) is named for the characteristic ovoid or flattened body

44. Currently more than 200 million
Schistosoma spp.
Name of the disease:
Schistosomiasis (Bilharzia)– it is a disease of the venous system.
Transmission:
By direct skin penetration, when people come in contact with contaminated water.
Currently more than 200 million
People are infected.
Schistosoma is NOT acquired by ingestion of contaminated food, it directly penetrates the skin of swimmers in contaminated rivers and lakes.

45. Bilharzia (Schistosomiasis)
Disease of the venous system, acquired by people when they come in contact with contaminated water
Adult Schistosomes take up residence in various abdominal veins, depending on the species; they are, therefore called (Blood Flukes)
Very common among children
Transmission: Direct skin penetration
Fresh water becomes contaminated by Schistosoma eggs when infected people urinate or defecate in the water. The eggs hatch and the parasites grow and develop inside snails.
types of Schistosomiasis:
intestinal Schistosomiasis
Urinary tract Schistosomiasis

46. Schistosoma spp. Life Cycle
The cycle begins when infected humans re- lease eggs into irrigated fields or ponds either by deliberate fertil- ization with excreta or by defecating or urinating directly into the water. The egg hatches in the water and gives off an actively swim- ming ciliated larva called a miracidium* (figure 23.23a), which in- stinctively swims to a snail and burrows into a vulnerable site, shedding its ciliated covering in the process. In the body of the snail, the miracidium multiplies and transforms into a larger, fork- tailed swimming larva called a cercaria* (figure 23.23b). Cercariae are given off by the thousands into the water by infected snails.
Upon contact with a human wading or bathing in water, cer- cariae attach themselves to the skin by ventral suckers and pene- trate hair follicles. They pass into small blood and lymphatic vessels and are carried to the liver. Here, the schistosomes achieve sexual maturity, and the male and female worms remain perma- nently entwined to facilitate mating

47. Bilharzia (Schistosomiasis)
Clinical symptoms:
Most people have no symptoms when they are first infected. After few days, rash or itchy skin due to hypersensitivity reaction to the parasite.
within 1-2 months, other symptoms may develop including: fever, couph , urticaria, splenomegaly, diarrhea and abdominal pain.
Chronic Schistosomiasis:
Without treatment, schistosomiasis can persist for years.
Symptoms:
- Intestinal: GI bleeding, diarrhea, pain, and enlarged liver.
- Urinary Tract: Heamaturia (blood in urine) and dysuria (painful urination).