II-Phylum: Apicomplexa

• Apical complex characters: • An electron-dense polar ring at the anterior end.

• Aconoid; which is cone-shaped hollow structure consisting of one or more spirally

coiled microtubules (aids in penetrating host cells).

• Rhoptries which are composed of two ore more electron dense tubular structure which runs, through the conoid to the anterior tip of the

organism and expands into a bag-like structure• A more or less great numbers or rod like,

electrondense micronemes which may be well attached to the rhoptries.

• A number of subpellicular microtubules runs backwards from the polar ring.

• In addition most of Apicomplexa have one or more micropores for ingestion.

I- Class Sporozoa

• Members of this class characterized by:• Apical complex is well developed (conoid forms complete

truncate cone). • Reproduction generally both sexual and asexual.

• Oocysts contain infective sporozoites which result from sporogony.

• Locomotion by body flexion, gliding, undulation of longitudinal rides or flagellar lashing; flagella present only in

microgametes of some groups.• Pseudopods ordinarily absent.

• They are intercellular parasites.• Life cycle usually consisting of merogony, gamogony

and sporogony. • Small gamonts are present.* This sub-class includes:• 1-Sub-order: Eimeriorina • 2-Sub- order: Haemosporina • 3-Sub-order: Adeleorina1) Sub-order: Eimeriorina• A) Family: Eimeriidae • B) Family: Cryptosporidiidae • C) Family: Sarcocystidae

A - Sub-class: Coccidia

A) Family: Eimeriidae

*General characters:• Members of this family are homoxenous with a single host.

• Merogony and gamogony take place within the host cells (intracellular parasites).

• Sporogony ordinarily occurs outside the host's body.• The oocysts and merons (schizonts) lack an attachment

organelle.• The oocysts contain 0, 1, 2, 4 or many sporocysts, each

containing one or more sporozoites. • The microgametes have 2 or 3 flagella.

• The genera are differentiated by the number of sporocysts in their oocysts and the number of sporozoites in each sporocyst.

i) Genus: Eimeria

• The species of this genus are the most important cause of the disease for domestic animals and poultry called coccidiosis. Eimeria is a genus of

Apicomplexan parasites that includes various species responsible for the poultry disease coccidiosis. The genus is named for the German zoologist

Theodor Eimer.

*Habitat:• Most of Eimeria species are intracellular parasites of the intestinal tract, but

some occur in other organs such as liver and kidney (except the oocyst it is becomes free in the intestine).

• Each species is usually found in a specific location with the intestinal tract (e.g. in the cecum, in the duodenum, in the ileum, etc.).

• They may invade different cells in these locations.• Some species are found in the epithelial cells, others in the submucosa. Their

location within the host cell also varies.* The different species of the different hosts, special morphological characters of

oocyst and their locations as well as special Pathogenicity are cleared in the following table.

*Morphology of Eimeria developmental stages: • They are spherical, sub-spherical, ovoid or ellipsoidal in shape and vary in

size according to the species.

• Immature oocyst (freshly expelled) contains the zygote appearing as a spherical granulated mass, primarily filling the cavity of the oocyst and later

contracts from the wall of the oocyst to form sporont.

• The sporont divides into four sporoblasts and a small remaining portion called oocystic residual body.

• The sporoblasts lying down from its wall to become sporocyst.

• The protoplasm inside each sporocyst further divides to form 2 sporozoites, and a small remaining portion called sporocystic residual body.

* This is mature or sporulated oocyst (infective).

• The mature or sporulated oocyst contains 4 sporocysts each one contains 2 sporozoites (it is called tetera-sporocystic dizoic oocyst) and surrounded

with the oocyst wall which is composed of two layers clear and transparent.

• 2- Morphology of sporozoites:

• They are transparent, fusiform organisms containing a central

nucleus, large refractile globule in broad end and a small one in

the narrow end.

• 3- Morphology of merozoites:

• They are elongated 5-10 x 1.5 u with granular cytoplasm and a

central placed rounded nucleus. (the number of merozoites

inside the schizonte is fired for each Eimeria)

• 4- Morphology of macrogamete:

• It is round or oval in shape.

• The nucleus is clearly seen and a karyosome is visible.

• There is a large granules being found on the periphery of the cell (They are able to form the wall of the oocyst after fertilization of macrogamete).

• 5- Morphology of microgamete:

• The nucleus of microgametocyte is divided to produce a large number of nuclei.

• Each nucleolus surrounded by a part of cytoplasm to form microgamete.

• These microgametes are slender, slightly bent and the anterior end is pointed with two flagella for locomotion. They measure about 5 g in length.

*Life cycle of Eimeria species:

*Pathogenicity of Eimeria species:

* The Pathogenicity of Eimeria species depends on a number of factors, some of which are probably still unknown. Among those that might be mentioned are:

• The number of oocyst (infective dose).• The number of cells destroyed per infecting oocyst.

• The number of merozoite generations.• The number of merozoites in each generation. • The location of the parasite in the host tissue.

• The degree and time of reinfection.• The degree of acquired or natural immunity of the host.

** Coccidial infections are self-limiting and the asexual reproduction does not continue indefinitely in the absence of reinfection.

• When the parasites penetrate the epithelial cells in large numbers, destroying them mechanically with the result of inflammatory changes.

• The affected intestinal wall does not take a part in the digestive process producing an allergic reaction which may lead to haemorrhages, increase of water of the intestinal

contents leading to Increase of peristaltic movement and diarrhoea.• In very heavy infection with some spp. Which found deeply in mucosa or sub mucosa

like E. tenella destruction is severe that hemorrhage occures.

*Diagnosis of Eimeria species: -

• Clinical symptoms.• History of the disease. • Post-mortum lesions, the best method to know the site

and type of the lesions.• Detection of the immature oocysts in faeces. • Sporulation of the oocyst to detect the species.

*Treatment & control:

1- Application of anticoccidial drugs as: Sulphonamide derivatives (sulphamethazine, sulphamethazine, sulphaquinoxalline and sulphademidine).

• Diphenylmethane derivatives.

• Diphenylsulphide.

• Nitrofurazone.

• Furazolidone.

• Amprolium

2- Sanitation and hygienic measures are effective in preventing the disease.

3- Treatment of infected birds

4- Prophylactic use of anticoccidial drugs either in food or water

5- Good ventilation, cleaning of the farm

6- Disinfection of farm, farm utensils to kill the oocyst

Eimeria spp. Location Pathogenicity

E. tenella EimeriaHighly pathogenic, lesions in

Caeca.

E. neecatrix Intestine Highly pathogenic.

E. brunetti IntestineMarkedly pathogenic in intestine

(Posterior).

E. acervulina IntestineSlightly to highly pathogenic

Intestine (anterior).

E. maximaSmall and large intestine

.Slightly, moderate pathogenic

E.praecox Small and large intestine Slightly, moderate pathogenic

Eimeria species of turkeys

E. meleagridisNon pathogenic (small & large

Intestine).

E. melegrimitis Small and large intestineModeratly to markedly pathogenic

(Small intestine).

E. adenoeides Highly pathogenic (Caecum)

Eimeria Species of Geese

E. truncata Kideny Highly pathogenic (in kidneys)

E. anseris Intestine Mild

Eimeria Species of Ducks

E. anatis Intestine Unknown.

Eimeria species of pigeons

E. labbeana Intestine

Eimeria Species of Rabbits

Eimeria spp. Location Pathogenicity

E. stiedae liver (bile duct) Pathogenic causing lesions in liver

E. magna Small and large intestine Pathogenic in intestine

E. perforans Small and large intestine Pathogenic in intestine

E. media Small and large intestine Pathogenic mild pathogenic.

E. irresidua Small and large intestine Highly Pathogenic

E.piriformis Unknown.

E.elongata Unknown

E. intestinalis Highly pathogenic

Eimeria Spp. of Mammals:

• E.brasiliensis, Eimeria alabamensis, Eimeria bovis, E.cyllndrlca, E.ellipsoidalls, E.Zurnii, and E.auburnensis) cattle.

• Eimeria ahsata, caprina, caprovina, hirci, intricata,, pallida, & E. punctata, goat,.

• Eimeria crandallis, caprovina & ovinoidalis in sheep• Eimeria cameli, ahsata camels • Eimeria saudiensis, Arabian oryx

ii) Genus: Isospora

• In this genus the oocyst contains 2 sporocysts, each of which contains 4 sporozoites (hence, it called disporocystic teterazoic oocyst).

• The Isospora species are present in small intestine mainly of cats and dogs and other animals as well as humans.

• The life cycle, diagnosis & control is similar to that of Eimeria species.

• Sporulation occurs similar to that in Eimeria species unless in Isospora the mature oocyst contains 2 sporocysts, each of which contains 4 sporozoites (disporocystic teterazoic oocyst).

*Common species:

• Isospora felis: - It inhabits the small intestine of cats & dogs.

• I. bigemina: It inhabits the small intestine of cats & dogs.

• I. camis: It inhabits the small intestine of dogs.

• I. hominis: It inhabits the small intestine of man.

• I. gallinae: It inhabits the small intestine of chicken.

*Pathogenicity:

• Their effects occur in the intestine and are similar to those occurred in Eimeria species but less in Pathogenicity.

iii) Genus: Tyzzeria

• The oocysts of this genus when sporulated contain 8 naked sporozoites (No sporocyst)

• They inhabit the small intestine of the hosts.• The life cycle resembles to that of Eimeria species

unless the sporulated oocysts contain 8 naked sporozoites, not contain sporocysts

*Common species: • Tyzzeria perniciosa: It inhabits the small intestine of ducks.• T. anseris: It inhabits the small intestine of geese.

*Pathogenicity:• They are highly pathogenic for young.• The affect ducklings stop eating, loose weight. Become weak

and cry continually.• At necrospy, inflammation and hemorrhagic areas are seen

throughout the small intestine, especially in its upper half. The intestinal wall is thickened, round; white spots are visible through its serosal surface. In severe cases the lumen is filled with blood and often contains a cheesy exudate.

*General characteristics:

• The development just under surface membrane of the host cell or within its brush border and not in cell proper.

• Meronts with knoblike attachment organelle. Microgametes without flagella.

C) Family: Cryptosporidiidae

*General characteristics:• They are parasites of the microvillar layer (brush border) of the epithelial

cells of the intestine, gall bladder, respiratory tract, and kidneys of a very wide range of hosts.

• Cross infections are common, at least in the case of C. parvum, and man may acquire infection through contact with the faeces of infected persons, cattle, sheep, swine, horses, wild mammals, cats & dogs.

• Different species of cryptosporidium can infect birds & fishes.

• Also cryptosporidium is auto infective, where the thick-walled oocysts excyst within the intestine and release their sporozoites to reinvade the original host.

• The oocysts of cryptosporidium are 4.5x5 it, transparent and contain 4 sporozoites. The oocyst walls are smooth and colorless when viewed through a highly corrected bright field lens.

i) Genus: Cryptosporidium

• A number of Cryptosporidium infect mammals. In humans, the main causes of disease are C. parvum and C. hominis. C. canis, C. felis, C. meleagridis, and C. muris can also cause disease in humans.

• Cryptosporidiosis is typically an acute short-term infection but can become severe and non-resolving in children and immunocompromised individuals. In humans, it remains in the lower intestine and may remain for up to five weeks.

• The parasite is transmitted by environmentally hardy cysts (oocysts) that, once ingested, excyst in the small intestine and result in an infection of intestinal epithelial tissue.

Illustration showing the water borne parasite Cryptosporidium parvum in the gut. This parasite causes diarrhoea (diarrhea) which can be extremely severe in people with AIDS where it is considered to be a major opportunistic infection. Infestation with Cryptosporidium is called Cryptosporidiosis.

*Diagnosis:

• Demonstration of the oocyst in feces, using Ziehl-Neelsen stained smears

• Serological diagnosis

• Molecular diagnosis, real-time PCR

* Treatment:

• Spiramycin and sulpha compounds

* Control:

• The cyst is highly resistant to disinfectant especially chlorine

• UV disinfection of water give good results

2) Sub-order: Haemosporina

• Macrogamete and microgamete develop independently. • They are without conoid.• The zygote is motile (ookinete).• Microgamont produces about 8 flagellated microgametes. • The sporozoites are naked.• They are heteroxenous, with merogony in vertebrate host

and sporogony in invertebrate one. • They are transmitted by blood sucking insects.• If the erythrocytes are invaded, pigment (haemozoin) may

be formed from the host cell hemoglobin. It is a haemecontaining protein different from hemoglobin and hematin.

A) Family: Plasmodiidaei- Genus: plasmodium

*General characteristics:• The gamonts occur in the erythrocytes.• Merogony takes place in the erythrocytes and also in various

other tissues, depending on the species.• The exoerythrocytic meronts are solid or, at the most,

vacuolated bodies. • Members of this genus are parasites of mammals, birds and

reptiles.• They are normally transmitted by mosquitoes; Anopheles

transmits the mammalian species and culicines or sometimes Anopheles transmits the avian and reptilian ones.

• Members of this genus cause malaria in human & birds.

Morphology of the different stages:

* The sporozoites; are more slender, spindle-shaped, about 15 u. long with a nucleus in the center.

*The cryptozoites: (Exoerythrocytic or pre-erythrocytic merons) each cryptozoites consists of a small chromatin dot surrounded by an area of cytoplasm. The nucleus of the liver cell is pushed to one side and shows degenerative changes.

* The schizont stage: It contains about 24 merozoites, each consisting of a chromatin dot surrounded by a piece of cytoplasm. The pigment granules (haemozoin) are usually collected into a single dark mass between the merozoites.

* The trophozoites: • Ring stage it is round with large vacuole in the center.• Amoeboid form.

* The macrogamete: It is spherical or ovoid in shape, shows dark blue cytoplasm and small compact nucleus.

* The microgametes; They are flagellum like and composed essentially of a nucleus, a single flagellum, and an outer all membrane.

* The ookinete, Is banana-shaped, and may has a round end and a narrow other.

* The oocyst; It is a ball -like about 40-55 g in diameter on the outer surface of the midgut of mosquito.

*Common malaria species

A) - Avain malaria species *Plasmodium gallinaceum.• It affects fowls and may be other birds.• Exoerythrocytic stage occurs in the endothelial cells and

reticuloendothelial cells of spleen, liver and brain.

*P. canthemerium:- It is common in passerine birds, sparrow.

*P. circumflexum:- It is common in passerine birds.

*P. relictum:- It is infect pigeon & dove and highly pathogenic to pigeon.

B) Human malaria species:• Plasmodium vivax. (Benign malaria)

• P. malariae.

• P. oval.• P. falciperum (malignant malaria or black water fever).

*Pathogenicity:• They produce malaria disease in man & birds.

• In man, the disease is characterized by sever chill, and it is followed by burring fever, headache and sweating. This gradually subsides, the temperature falls and after 6-10 hours the patient feels much better until the next paroxysm.

• The destruction of erythrocytes causes anemia.

• A highly fatal, cerebral form of malaria may occur in falciparum infections. It is due to clogging of the capillaries of the brain by agglutinated (sludged), infected erythrocytes.

• Also in falciparum malaria, there is a black water fever (The colour of urine is black due to hematine).

• Jaundice and hamoglobinuria.

* Diagnosis:• Microscopic examination of thin blood film for detection

the parasite. • Some serological tests.• PCR and Molecular protocols.*Treatment and control:• Treatment of infected persons with suitable drugs as:

Chloroquine at rate of 5 mg/kg. b.w.• Paludrine at rate of 7 mg/kg. b.w.• Quinacrine (prophylactic against falciparum malaria.

Primaquine. Pyrimethamine.• Control the vector (Mosquito species).