PROTOZOA

1. Subphylum: Sarcomastigophora (Honigber and

Balamuth, 1963)

1.1. Flagellates

1.2. Hemoflagellates
1.2.1. Hemoflagellates
1.2.2. Mucosoflagellates
1.3. Amoebas
1.3.1. Intestinal Amoebas

2. Subphylum: Ciliophora (Doflein, 1910)

2.1. Balantidum coli

2.2. Symbiotic ciliates

3. Subphylum: Apicomplexa (Levine, 1970)

3.1. Coccidians
3.1.1. Eimeria
3.2.1. Isospora
3.3.1. Cryptosporidium
3.4.1. Toxoplasma
3.5.1. Neospora
3.6.1. Hammondia
3.7.1. Sarcocystis

3.2. Equine Protozoal Myeloencephalitis Organism

3.2.1. Besnotia
3.2.2. Klossiella
3.2.2. Hepatozoon
 PROTOZOA
Phylum: Sarcomastigophora
Subphylum: Mastigophora
Class: Zoomastigophora
Order: Kinotoplastidea
Family: Tryponosomatidae
Family: Cryptobiidae
Order: Trichomonadida
Family: Trichomonadidae
Family: Monocercomonadidae
Family: Retortamonadidae
Family: Cochlosomatidae
Family: Hexamitidae

Subphylum: Sarcodina
Family: Endamoebidae
Family: Vahlkampfidae
Family: Hartmannellidae
Phylum: Apicomplexa

Class: Sporozoea
Subclass: Coccidia
Order: Eucoccidiidea
Family: Eimeriidae
Family: Sarcocystidae
Family: Haemogregarinidae
Suborder: Haemisporina
Family: Plasmodiidae

Subclass: Piroplasma
Order: Piroplasmida
Family: Babesiidae
Family: Thileriidae
Phylum: Microspora
Class: Microsporea

Phylum: Myxozoa
Class: Myxosporea

Phylum: Ciliophora
Class: Kinetofragminophorea

Order: Rickettsiales
INTRODUCTION
OF
PROTOZOA
1. General Characteristics

1.1. Unicellular animals

1.2. Do not have a chlorophyll - containing

chromatopores

1.3. Mode of nutrition is holozoic

1.4. Have a well-defined nucleus

1.5. Do not have a rigid cell wall

1.5.1. Marked variation in size and shape
2. Nucleus

2.1. Eukaryotic (protozoa)

2.1.1 Nucleus enclosed in a membrane

2.2. Prokaryotic (bacteria)

2.2.1. Nucleus dispersed in cytoplasm

2.3. Number of nucleus in protozoa is usually one

2.4. Others have more than one

2.5. Types of nucleus
2.5.1. Vesicular nucleus
2.5.1.1. Has nuclear membrane w/c bounds the
nucleoplasm in which, lying more or less central, is an intranuclear
body, the endosome (or kayrosome) or nucleolus
2.5.1.1.1. Endosome is devoid of DNA
2.5.1.1.2. Nucleolus has DNA
2.5.1.1.3. Seen in Mastigophora and
Sarcodina

2.5.2. Compact nucleus

2.5.1. DNA concentrated in nucelus

3. Cytoplasm

3.1. Extranuclear part of the protozoan cell

3.2. Has 2 parts: Outer ectoplasm & Inner endoplasm
4. Locomotion
4.1. Movement is by gliding
4.2. Locomotory organelles
4.2.1. Pseudopodia
4.2.1.1. Used by amoeba-like organisms
4.2.1.2. Temporary; formed when required &
retracted when not needed
4.3. Pseudopodia

4.4. Cilia

4.5. Flagella

5. Organelles of nutrition
5.1. Pseudopodia
5.1.1. Organelles for amoeba-like organisms

5.2. Food vacuole

5.3.1. Occurs in cytoplasm & contains particulate
material in various stages of digestion
 5. Organelles of nutrition

5.3. Cytosome
5.3.1. An opening through w/c food particles are
engulfed & passed to food vacuoles
5.3.2. In ciliates the cytosome may be lined with cilia
w/c further assist in ingestion of food

6. Nutrition of Protozoa
6.1. Holophytic
6.1.1. Forms which possess chlorophyll
6.1.1.2. None of this form of veterinary importance
6.2. Holozoic
6.2.1. Utilizes preformed food
6.2.2. Food ingested by pseudopodia or through a
cytosome & passes to a food vacuole for
digestion
6.3. Saprozoic
6.3.1. Absorbs nutrients through the body wall, these
being utilized directly by the organisms
7. Excretion of waste products
7.1. Occurs directly through the body wall
7.2. By means of contractile vacuoles which
periodically discharge waste material
through the body wall or, in a few
instances, through the anal pore
8. Reproduction of Protozoa
8.1. Asexual
8.1.1. Binary fission
8.1.1.1. Commonest form of asexual
reproduction
8.1.1.2. Two daughter cells result from a
“parent” cell
8.1.1.3. Division being along the longitudinal
axis
8.1.1.3.1. Ciliates divide along the
transverse axis
8.1.1.4. Nucleus divides first and cytoplasmic
division follows
8. Reproduction of Protozoa
8.1. Asexual
8.1.2. Schizogony
8.1.2.1. nucleus divides several times before the
cytoplasm does
8.1.2.2. In some forms the nucleus of parent cell divides
mitotically into a large number of nuclear bodies,
each of which becomes associated with a portion
of the cytoplasm & little or nothing of the parent
cell remains except the greatly expanded limiting
membrane
8.1.2.2.1. Dividing form is known as schizont
8.1.2.2.2. Daughter forms are merozoites
8.1.3. Budding
8.1.3.1. Two or many daughter forms are produced by
the “parent” cell.
8.1.3.2. There is usually an unequal fragmentation of
the nucleus & cytoplasm
8.1.3.3. The budded forms are separated off and then
grow to full size
8. Reproduction of Protozoa
8.1. Asexual
8.1.4. Endopolyogeny

8.1.4.1. This is an internal budding whereby new

progeny is formed within the parent cell

8.1.4.2. Endodyogeny is a simplified form of

endopolyogeny, resulting in 2 daughter
cells

8.1.4.3. Seen in forms such as Toxoplasma &

Sarcocystis
8.1.5. Sporogony
8.1.4.1. follows syngamy
8. Reproduction of Protozoa
8.2. Sexual
8.2.1. Conjugation

8.2.1.1. Occurs in ciliate

8.2.1.2. Two organisms pair and exchange nuclear

material (from the micronucleus)

8.2.1.3. Individuals separate & nuclear reorganization

takes place
8.2.2. Syngamy
8.2.2.1. Two gametes fuse to form a zygote
8.2.2.2. Males gamete is a microgamete
8.2.2.2.1. Produce from microgamonts or
microgametocyte
8.2.2.3. Female gamete is a macrogamete
8.2.2.3.1. Produce from macrogamonts or
8.2.3. Gametogony macrogametocytes
8.2.3.1. Process of gamete formation
8.2.3.2. Isogamy - gametes are similar in size
8.2.3.3. Anisogmy - gametes of different sizes
Life Cycle of Trypanosoma
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Development Final Host
occurs in zation
In IH occurs in IH
Final Host
Trypanosoma Glossina Proboscis Cattle, sheep, T
vivax1 spp./MT goat, buffalo,
camels antelope6
(long forms)
Trypanosoma Glossina spp/MT Proboscis Cattle, sheep, T
uniforme1 goat, antelope
(short forms)
Trypanosoma Glossina spp/MT Proboscis & All domestic T
congolense2 midgut animals & wild
game animals:
antelope, zebra,
warthog,
elephant (short
forms)
Trypanosoma Glossina spp/MT Proboscis & Cattle, sheep, T
dimorphon2 midgut horses, pigs
(long forms)
Trypanosoma Glossina spp/MT Proboscis & Cattle, horses, T
simiae2 midgut pig
(polymorphic)
Trypanosoma Glossina spp/MT Midgut & Pigs (short T
suis3 salivary forms)
glands
 Stage in w/c
Cyclical
Intermediate Host multiplication Locali-
Parasites Development Final Host
(IH)/ Stage In IH occurs in zation
occurs in IH
Final Host
Trypanosoma Glossina spp/MT Midgut & Domestic T Intra-
brucei4 salivary animals & cellular
glands antelopes tissues
(polymorphic) fluid
Trypanosoma Glossina spp/MT Midgut & Man & antelopes T
rhodesiensi4 salivary (polymorphic)
glands
Trypanosoma Glossina spp/MT Midgut & Man T Lymph
gambiense4 salivary (polymorphic) nodes &
glands CNS
Trypanosoma Stomoxys, Mechanical Cattle, camels, T
evansi5 Liperosa, Tabanus transmission equines, dogs,
etc
Trypanosoma
equinum5
Trypanosoma Mechanical by Equines
equiperdum5 coitus (polymorphism
inconstant)
1SectionSalivaria, Subgenus Duttonella; 2Salivaria, Subgenus Nannomonas; 3Salivaria, Subgenus
Pscnomonas; 4Salivaria, Subgenus Trypanozoon (cyclically transmitted); 5Salivaria, Subgenus
Trypanozoon (mechanically transmitted; 6Reservoir host ; MT= Metacyclic Trypomatigote; T =
Trypomastigote
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Development Final Host
occurs in Final zation
In IH occurs in IH
Host
Trypanosoma Tabanus & Posterior Bovine esp Trypomastigote Lymph
theileri1 Haematopota station Cattle & epimastigote nodes &
inner
organs
Trypanosoma Melophagus Posterior sheep
melophagium1 ovinus/ station
metacyclic
trypomastigote
Trypanosoma Hippoboscid fly Posterior goats
thedori1 Lipoptena station
caprina/
metacyclic
trypomastigote
Trypanosoma Ceratophyllus Posterior rats
lewisi2 fasciatus/ station
metacyclic
trypomastigote
Trypanosoma Spilopsylla Posterior rabbit
nabiasi2 cuniculi/ station
metacyclic
trypomastigote
Trypanosoma Triatomid bugs/ Posterior Man, dog, cat,
rangeli2 metacyclic station opossum,
trypomastigote monkey, man,
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Development Final Host
occurs in Final zation
In IH occurs in IH
Host
Trypanosoma Ruduviidae/ Posterior Dogs, cats, Trypomastigote Heart
cruzi3 metacyclic station/ pigs, foxes, Amasstigote – muscles &
trypomastigote monomorphic ferrets, dividing form Visceral
squirrels, & organs
monkeys &
man
Cryptobia Leeches/metacycli Fresh water trypomastigote blood
borreli c trypomastigote fishes (rainbow
& brown trouts,
coho & king
salmon)
Cryptobia Leeches/metacycli Marine fishes trypomastigote Gill
brachialis c trypomastigote filaments
Cryptobia Leeches/metacycli Carp, golfish trypomastigote blood
cyprini c trypomastigote
1Section Stercoraria, Subgenus Megatrypanum; 2Stercoraria, Subgenus Herpetosoma; 3Stercoraria,
Subgenus Schizotrypanum
Life Cycle of
Leishmania
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Development Final Host
occurs in Final zation
In IH occurs in IH
Host
Leishmania Phlebotomus/ midgut Human, cause amastigote
donovani1 promastigote of Kala-azar.
Dog & roents
serves as
reservoir
hosts
Leishmania Phlebotomus midgut Man. Dog, fox, amastigote
infantum1 chinensis/ jackal,
promastigote porcupines as
reservoir
hosts
Leishmania Phlebotomus midgut Human & amastigoe Liver,
chagasi1 chinensis/ dogs.Dogs & spleen
promastigote crab-eating bone
fox reservoir marrow
hosts
Leishmania Phlebotomus/ midgut Man & dogs. amastigoe Macrophag
tropica2 promastigote Gerbils & es,
rodents are endothelial
reservoirs cells, skin
lymph
nodes
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Dev. occurs Final Host
occurs in Final zation
In IH in IH
Host
Leishmania Phlebotomus midgut Man. Reservoir amastigoe Skin
aethiopica2 longipes/ host is rock
promastigote hyraxes
Leishmania Phlebotomus midgut Wild mammals amastigoe Skin
majori2 papatasi/ & man. Tree rat,
promastigote pocket mouse &
cotton & vesper
rats are
reservoirs
Leishmania Lutzomyia midgut Dogs, cats, amastigoe Ear
mexicana olmeca/ pigs, foxes,
mexicana3 promastigote ferrets,
squirrels, &
monkeys & man
Leishmania Lutzomyia midgut Rodents. Rarely amastigoe
mexicana flaviscutellata/ infects man.
amazonensis promastigote Rodents
3 reservoirs
Leishmania Lutzomyia midgut Forest rodents amastigoe Skin
braziliensis paraensis, Lut. are reservoir mucous
braziliensis4 wellcomei/ hosts. Man membrane
promastigote
 Stage in w/c
Intermediate Cyclical
multiplication Locali-
Parasites Host (IH)/ Stage Development Final Host
occurs in Final zation
In IH occurs in IH
Host
Leishmania Lutzomyia midgut Dog & man amastigoe Skin
braziliensis anduzei/
guyanensis4 promastigote

Leishmania Lutzomyia midgut Sloths, amastigoe Skin

braziliensis trapidoi/ porcupines &
panamensis4 promastigote rodents are
reservoirs

Leishmania Lutzomyia midgut Dog is amastigoe Skin

peruviana4 verrucarm & Lut, reservoir host
peruensis/
promastigote

1Cause of Visceral leishmaniasis; 2Old World Cutaneous leishmaniasis; 3American Cutaneous

leishmaniasis or ‘Leishmania mexican complex; 4’Leishmania braziliensis complex’
Morphology & Life Cycle
of Protozoa
 Parasite Morphology Multiplication Localization Host
Tritrichomonas Pear-shaped, w/ 3 Longitudinal Bull – preputial Cattle. May occur
foetus anterior flagella, 1 binary fission cavity; cow – in zebu, pig, horse
post. flagellum, vagina & deer
undulating
membrane
extends posteriorly
Tritrichomonas Pyriform shaped Binary fission Stomach, nasal pig
suis w/ 3 ant. Flagella, passages,
undulating cecum & small
membrane runs intestine
entire length of
body
Tritrichomonas Pyriform-shaped Binary fission Cecum & colon horse
equi w/ 3 anterior
flagella &
undulating
membrane
Tritrichomonas Crescent-shaped Binary fission ceca Chicken, turkey &
eberthi w/ 3 anterior duck
flagella &
undulating
membrane
Tritrichomonas Do do Cecum & Ox & zebu
enteritis Colon
 Parasite Morphology Multiplication Localization Host

Tritrichomonas Do do Cecum & colon Rats, mouse,

muris hamster, wild
rodents
Tritrichomonas Do do Cecum & colon Rat, house mouse
minuta & golden
hamsters
Tritrichomonas Do do Cecum & colon Guinea pig
caviae
Trichomonas Pyriform-shaped do Upper digestive Pigeon, turkey,
gallinae w/ 4 anterior tract dove, chicken,
flagella & hawk, eagle
undulating
membrane, no
post. Flagellum
Trichomonas Do do intestine pheasant
phasioni
Trichomonas Do do Vagina, man
vaginalis prostate &
urethra
Trichomonas Do do Mouth Man & monkey
tenax
Trichomitus d0 do Colon & cecum pigs
rotunda
 Parasite Morphology Multiplication Localization Host

Trichomitus Do do Colon & cecum Rats, mice, hamster

wenyoni & rhesus monkeys
Tetratrichomonas Do do Colon & cecum pig
buttreyi
Tetratrichomonas Pear-shaped w/ 4 do Lower digestive Turkey, guinea fowl,
gallinarum ant flagella & 1 tract & liver quail & fowl
posterior flagellum
Tetratrichomonas Pyriform-shaped w/ do cecum sheep
ovis 4 ant. Flagella,
undulating
membrane & 1
trailing flagellum
Tetratrichomonas do do cecum Calves
pavlovi
Tetratrichomonas do do cecum Rat, mouse, vole
microti hamster, rodents
Pentatrichomonas Ova to pear- do intestine Man & primates
hominis shaped w/ 5 free
ant flagella,
undulating
membrane
 Parasite Morphology Infection / Localization/ Host
Multiplication Pathogenicity
Monocercomonas Pyriform-shaped w/ 3 binaryfission Rumen cattle
ruminantium anterior flagella, a post
flagella , no undulating
membrane
Monocercomonas Do binaryfission Cecum (non- Guinea pig
Pistillum & M. pathogenic)
minuta
Histomonas Pleomorphic, has 3 Ingestion of Ceca (primary) Turkey, chicken,
meleagridis flagella Embryonated & liver peafowl,
Stages: invasive stage eggs of ceca Cause of pheasant,
– cecal & worm blackhead in guinea-fowl
liver lesions Binary fission turkeys
vegetative
stage – center
of lesion
resistance
stage
Infection: ingestion of
embryonated
eggs of
cecal worm
 Parasite Morphology Infection / Localization / Host
Multiplication Pathogenicity
Parahistomonas Similar to histomonas, Ingestion of Ceca (non- Gallinaceous
wenrichi but has 4 flagella Embryonated pathogenic) birds, chiefly
eggs of ceca pheasant
worm
Binary fission
Chilomitus Elongate body, 4 Binary fission Cecum (non- Guinea pig
caviae anterior flagella pathogenic)
Hexamastix Pyriform, has 6 flagella Binary fission Cecum (non- Guinea pig
robustus & H. one of which is trailing pathogenic)
caviae
Enteromonas Pyriform or spherical, Binary fission cecum Man, primates,
hominis has 3 flagella & one hamster, rat &
trailing flagellum rabbits
Enteromonas Do do do pig
suis
Ebteromonas Do do do Guinea pig
caviae
 Parasite Morphology Infection / Localization / Host
Multiplication Pathogenicity
Costia necatrix & Ovoid to pyriform, has 4 do skin Fresh-water
C. pyriformis flagella (2 short & 2 Fish
long)
Cochlosoma Oval body which is do Posterior large Domestic & wild
anatis broad anteriorly & intestine & ducks
narrow posteriorly, has ceca (catarrhal
6 flagella enteritis)
Hexamita Pear-shaped, 2 nuclei, Longitudinal Duodenum & Turkey, quail,
meleagridis has 6 anteior & 2 binary fission & small intestine partridge,
posterior flagella invasive form, (catarrhal pheasant,
which enteritis) chicken
penetrated
epithelialcells,
schizogony
 Parasite Morphology Infection / Localization / Host
Multiplication Pathogenicity
Hexamita do do Small intestine pigeon
columbae (catarrhal
enteritis)
Hexamita muris do do Posterior Rats, mouse &
intestine & hamsters
ceca (enteritis)
Hexamita pitheci do do Large intestine Rhesus monkey
Hexamita do do intestine Goldfish,
salmonis salmonids
Hexamita pyriform do Intestine (acute Fresh water
intestinalis catarrhal fishes
enteritis
Giardia lamblia Pear-shaped which has do Duodenum & Monkeys, pigs,
been cut in half other parts of budgerigars.
longitudinally small intestine Man (colon).
 Parasite Morphology Infection / Localization / Host
Multiplication Pathogenicity
Giardia canis do do Duodenum & dog
jejunum
Giardia cati do do Small intestine cat
(non-
pathogenic)
Giardia chincillae do Small intestine chinchilla
& duodenum
(severe blood-
stained
diarrhea)
Giardia bovis do do Small intestine ox
Giardia muris do do do mouse
Entamoeba w/ quadrinucleate do Intestine Man, monkey,
histolytica cyst moved by (cystic form (amoebic dog, cat, rat &
pseudopodia occurs in dysentery of pig.
vertebrate hosts) man) Experimentally
rat, mouse,
guinea-pig &
rabbit
 Parasite Morphology Infection / Localization / Host
Multiplication Pathogenicity
Entamoeba coli do do Cecum & colon Man & monkey
(non-
pathogenic)
Entamoeba do do Mouth & Man & primates
gingivalis gingival tissue
around teeth
(harmless)
Entamoeba do do mouth Dogs & cats
canibuccalis
Entamoeba do do mouth horses
equibuccalis
Entamoeba do do mouth pig
suigingivalis
Entamoeba do do Intestine & liver Reptiles, lizards
invadens (amoebiasis) & snakes
Acanthomoeba do do Lungs (fatal bull
spp. gangrenous
pneumonia)
 ORDER: EUCOCCIDIIDAE

SUBORDER: EIMERIINA

Family: Eimeriidae

1. Members are, with a few exceptions, intracellular parasites of the

epithelial cells of the intestine

2. They have a single host in which they undergo asexual (schizogony,

merogony) and sexual (gametogony) multiplication

3. The macrogamonts (male) and microgamonts (female) develop

independently, the latter producing many gametes

4. A zygote is formed from the union of the male and female gametes,
and by a process of sporogony, a variable number of spores
(spococysts) containing one or more sporozoites are formed
 SUBORDER: EIMERIINA

Family: Eimeriidae

6. Genera members of family Eimeriidae:

6.1. Tyzzeria - no sporocysts, 8 sporozoites in the oocyst

6.2. Isospora - 2 sporocysts each containing 4 sporozoites

6.3. Eimeria - 4 sporocysts each containing 2 sporozoites

6.4. Wenyonella - 4 sporocysts each containing 4 sporozoites

7. Life Cycle & morphological stages of coccidia

7.1. Oocyst
7.1. 1. resistant stage of the life cycle

7.1. 2. contains a zygote, is extruded from the host tissues and

passed to the exterior in the feces
7.1. 3. under appropriate conditions oocyst forms the infective
oocyst
37
 SUBORDER: EIMERIINA

Family: Eimeriidae
8.1. Oocyst

8.1. 1. common shapes for oocysts are spherical, sub-spherical,

ovoid or ellipsoidal, and they vary in size according to
species

8.1. 2. wall of oocyst is composed of 2 layers and is generally clear

and transparent with a well-defined double outline; in some
species, however, it may be yellowish or even green in color
8.1.3. other species possess striations or punctuations

8.1. 4. several species of coccidia possess a micropyle at one

extremity, this usually being the pointed end
8.1. 5. the micropyle may be covered by a micropyle cap, and
occasionally there may be a dome-shaped projection of the
cyst wall to the exterior in the form of a polar cap

38
 SUBORDER: EIMERIINA

Family: Eimeriidae

8.2. Sporulated Oocyst

8.2. 1. this contains 4 (Eimeria) or 2 (Isospora) sporocysts

8.2. 2. the sporocysts in Eimeria are more or less elongate ovoid

forms with one end more pointed than the other

8.2. 3. at the more pointed end is the stieda body, and in some
forms a micropyle may occur at the same place

8.2. 4. an oocystic residual body and a polar granule may also be

present in the oocyst

8.2. 5. typically, the sporozoites are bent and comma-shaped and

contain a round homogenous vacuole at one end

39
 SUBORDER: EIMERIINA

Family: Eimeriidae

8.3. Life Cycle

8.3. 1. the parasitic life cycle of coccdia is initiated when the
infective oocyst is ingested by the appropriate host
8.3. 2. excystation, which occurs in the intestine, releases the
contained sporozoites
8.3. 3. two separate stimuli are necessary for excystation:

8.3. 3. 1. the first is provided by CO2

8.3. 3. 2. the second, which is pH-dependent and effects the
release of sporozoites, is provided by trypsin and
bile
8.3. 4. bile facilitates the entry of trypsin through the altered
micropyle, which then digests the sporocystic plug
permitting escape of the motile sporozoites
8.3. 5. liberated sporozoites measures 10µm by 1.5 µm and are
transparent, fusiform organisms which show contraction and
elongation and rapid gliding movements 40
 SUBORDER: EIMERIINA

Family: Eimeriidae

8.3. Life Cycle

8.3. 6. the conoid serves as an organ of penetration into host cells

8.3. 7. penetration process is quick and completed within a few

seconds
8.3. 8. in the case of Eimeria, initially, the sporozoites invade the
intestinal epithelium at the tips of the villi and are engulfed
there by macrophages and carried by them through the
lamina propia of the villi to reach the epithelium in the
depths of the glands of Leiberkuhn.
8.3. 9. in the gland of Leiberkuhn, the sporozoites leave the
macrophages and enter the epithelial cells to undergo
further development

41
 SUBORDER: EIMERIINA

Family: Eimeriidae

1. Asexual reproduction or schizogony

1.1. this process is initiated when the sporozoite enters the epithelial
cell and become round up
1.2. in many forms development occurs above the nucleus of the
epithelial cell, in a few below it, and in one bovine species, within
the nucleus
1.3. the rounded – up sporozoite is , at this stage, known as a
trophozoite, and within a few days the nucleus of the trophozoite
divides by schizogony to become schizont (1st generation
schizont)

1.4. the 1st generation schizont divides asexually by schizogony to

produce fusiform organisms called merozoites (1st generation
merozoites)

42
 SUBORDER: EIMERIINA

Family: Eimeriidae

1. Asexual reproduction or schizogony

1.5. when the schizont is mature the 1st generation merozoites are
released, and they then enter other epithelial cells in the area
and continue the cycle of asexual development
1.6. the 1st generation schizont divides asexually by schizogony to
produce fusiform organisms called merozoites (1st generation
merozoites)
1.7. in the new host cell the merozoite first rounds up to become a
trophozoite and then undergoes multiple fission as before

1.8. the 2nd generation schizont in some species is much larger than
the first, whereas in others it is much smaller

1.9. the number of 2nd generation merozoites produced varies

according to species
1.10. the 2nd generation merozoites may proceed to a 3rd or more
generations of asexual reproduction, or they may differentiate
into sexual or gametogonous forms 43
 SUBORDER: EIMERIINA

Family: Eimeriidae

2. Sexual reproduction or gametogony

2.1. microgamonts rupture and liberates the microgametes which
fertilize the macrogametes
3. Sporogony

3.1. with few exceptions, sporulation does not occur until the oocyst
is shed to the exterior of the body.

3.2. initially, the zygote almost fills the oocyst cavity, but within a
few hours outside the host the protoplasm contracts from the
wall of the oocyst to form a sporont and leaves a clear space
between it and the wall
3.3. the sporont divides into 4 sporoblasts, any remaining cytoplasm
being left as an oocyst residual body
3.4. the sporoblast are, initially, more or less spherical, but later they
elongate into ovoid or elliptical bodies which then become
sporocysts by the laying down of a wall of refractile material
around each sporoblast
 SUBORDER: EIMERIINA

Family: Eimeriidae

3. Sporogony

3.5. the protoplasm inside each sporocyst further divides to form two
sporozoites; protoplasm remaining from the division is left as a
sporocystic residual body

Coccidia of Domestic Fowl

1. Eimeria acervulina
2. Eimeria brunetti

3. Eimeria hagani

4. Eimeria maxima

5. Eimeria mitis

6. Eimeria mivati

7. Eimeria necatrix
8. Eimeria praecox
9. Eimeria tenella 45
 FAMILY: EIMERIIDAE

Genus: Eimeria
Species of coccidia that are of economic importance to poultry
Species Hosts Occurrence of Developmental
Stages
E. acervulina Birds & chickens Anterior part of the small
intestine
E. brunetti Chickens (4-9 weeks Small intestine, ceca & cloaca
old)
E. hagani Domestic poultry Small intestine
E. maxima Domestic poultry Small intestine
E. mitis Domestic poultry Ant. small intestine, occasionally
in post. Small intestine
E. mivati Domestic fowl Small intestine, extend to rectum
E.necatrix Domestic fowl Asexual – small intestine; sexual
- ceca
E. praecox Domestic poultry Upper part of small intestine
E. tenella Domestic poultry ceca 46
 FAMILY: EIMERIIDAE
Characteristic of oocysts of coccidia species that are of economic importance to
poultry

Species Shape of Wall of Micropyle Sporulation time (hours)

oocyst Oocyst
29oC 26-28oC 20-24oC Room
Temp.
E. Acervulina Ovoid smooth Present - 72 - 25

E. brunetti Ovoid smooth Absent - - 18 1-2

days
E. Hagani Broadly - Absent - - - 1-2
ovoid days
E. Maxima Large Slight Absent 2 days
ovoidal yellow
E. Mitis Sub- - - 18 - - 2 days
spherical,
tapering
E. Mivati Ellipsoidal Smooth, absent 11-12 - - -
to broadly Colorless
ovoidal
E. Necatrix Ovoidal Smooth, Absent 18 - - 2 days
colorless
E. Praecox Ovoid Smooth Absent 2 days

E. Tenella Broadly smooth Absent 18 21 24 24-48

ovoidal 47
 SUBORDER: EIMERIINA

Family: Sarcocystidae

Genus: Toxoplasma

1. Characteristics of Genus: Toxoplasma

1.1. oocysts with 2 sporocysts, each with 4 sporozoites

1.2. facultatively or obligatorily heteroxenous

1.3. definitive host is felid

1.4. merogony in both intermediate and definitive hosts and can cause
infection in intermediate and definitive hosts

1.5. schizonts (meronts) and gametocytes (gametes) in enteric cells of

felidae

1.6. sporogony occurs outside host

1.7. single species is recognized: Toxoplasma gondi

48
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Definitive Hosts:
1.1. domestic cat (Felis catus)

1.2. jaguarundi (Felis yagouaroundi)

1.3. ocelot (Felis paradalis)

1.4. mountain lion (Felis concolor)

1.5. leopard cat (Felis bengalensis)

1.6. bobcat (Lynx rufus)

2. Intermediate Hosts:

2.1. there is little host-specificity, and almost every warm-blooded

animal, including man, can be infected
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Life cycle:
1.1. two cycles of development occurs, an ‘enteroepithelial’ and an
‘extraintestinal’ cycles, involving 5 developmental stages
1.2. the enteroepithelial cycle occurs in cats and is similar to that of
other coccidia consisting of enteroepithelial multiplicative stage
and gamonts resulting in oocyst production, with sporogony
1.3. the extraintestinal stages occur in the extraintestinal tissues of
cats and other mammalian and avian hosts and designated these
as tachyzoites (rapdily multiplying stages) and bradyzoites
(slowly multiplying stages)

1.4. Enteroepithelial cycle:

1.4. 1. occurs in the intestine
1.4. 2. bradyzoites enter epithelial cells and a number of
morphological types of multiplicative stages occurs
1.4. 3. consists of multiplicative, gamonts, and oocyst stages
50
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Enteroepithelial Cycle:

1.1. Mutiplicative stages: these are designated as types A,B,C,D & E

1.1. 1. type A
1.1. 1.1. this appears 12-18 hours after infection
1.1. 1.2. it is the smallest of the multiplicative types and
this is evident as collections of 2 or 3 organism in
the jejunum
1.51 1.3. division is by endodyogeny (formation of daughter
cells by internal budding)
1.1. 2. type B

1.1. 2.1. occurs 12-54 hours after infection

1.1. 2.2. it has a prominent nucleolus
1.1. 2.3. it divides by endodyogeny and endopolygeny
(internal budding resulting in many daughter forms)
51
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Enteroepithelial Cycle:

1.1. Mutiplicative stages: these are designated as types A,B,C,D & E

1.1. 3. type C

1.1. 3.1. occurs 24-54 hours after infection

1.1. 3.2. divides by scizogony (merogony)
1.1. 3.3. it is elongate and have a subterminal nucleus
1.1. 4. type D
1.1. 4.1. occurs from 32 hours to 15 days after infection

1.1. 3.2. accounts for over 90% of all Toxoplasma found in

the small intestine at this time
1.1. 3.3. smaller than Type C forms and divide by
endodyogeny, schizogony and by separation of
single merozoites from the nuclear mass (3 modes
of division occur simultaneously)
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Enteroepithelial Ccle:

1.1. Mutiplicative stages: these are designated as types A,B,C,D & E

1.1. 5. type E
1.1. 5.1. occurs 3-15 days after infection
1.1. 5.2. divides by schizogony
1.1. 5.3. resembles Type D
1.2. Gamonts
1.2. 1. occurs 3-15 days after infection
1.2. 2. occurs throughout the small intestine and are common in
the ileum
1.3. Oocyst stage
1.3.1. oocyst formation occurs in the epithelial cells of the small
intestine
1.3.2. initially, its development is identified by the occurrence of
plastic granules in the cytoplasm of macrogametes 53
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

1. Enteroepithelial Cycle:
1.3. Oocyst stage
1.3.3. later, it is surrounded by argyrophilic membranes
1.3.4. oocysts are discharged from the epithelial cells and shed in
the feces
2. Extraintestinal cycle

2.1. the only form in the life cycle which occurs in non-felines but may
occur in cats
2.2. the cycle starts almost simultaneously with the enteroepithelial

2.3. stages of development:

2.3.1. tachyzoites (endozoites)– rapidly multiplying forms

(trophozoites) of acute infection

2.3.2. bradyzoites (cystozoites) – slowly multiplying encysted

form seen in chronic infection
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii
2. Extraintestinal cycle
2.4. Tachyzoite formation
2.4. 1. seen in acute visceral infections
2.4. 2. in cats this development occurs in the lamina propia,
mesenteric lymph nodes and distant organs, coexistingly
with the enteroepithelial cycle
2.4. 3. in other animals tachyzoites are the first stage found
following ingestion of sporulated oocysts
2.4. 4. tachyzoites develop in a vacuole in a variety of cell types,
including fibroblasts, hepatocytes, reticular cells and
myocardial cells
2.4. 5. the organism multiply by endodyogeny

2.4. 6. eventually, 8-16 or more organisms accumulate in a host

cell, which then disintegrates and new cells are infected
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii
2. Extraintestinal cycle
2.5. Bradyzoite formation
2.5.1. occurs mainly in the brain, heart and skeletal muscles
2.5.2. bradyzoites multiply slowly, mainly by intracellular
endodyogeny
2.5.3. cysts containing thousands of these forms may persist for
months or years after infection
2.5.4. bradyzoites in the cysts are closely packed together,
somewhat lancet-shaped and possess a terminal nucleolus
2.5.4. cyst formation coincides with the development of immunity
2.5.4. 1. if immunity wanes, bradyzoites are capable of
initiating renewed tachyzoite proliferation and
additional cysts containing bradyzoites may be
formed from these tachyzoites if immunity returns
2.5.4. 2. however, bradyzoite formation may occur in the
absence of immunity
56
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

Comparative infectivity:

1. When given by the oral route, oocysts are more infective than
tachyzoites and bradyzoites in cysts
2. Oocysts are more infective than tachyzoites and bradyzoites in cysts
when given subcutaneously or intraperitoneally

General Characteristics of the Toxoplasmosis

1. Most infections with T. gondii are probably asymptomatic

2. Asymptomatic acute toxoplasmosis plays an important role in congenital
infection in man and sheep, and asymptomatic chronic human infection
may be important where immunosuppressive therapy is used for other
medical disorders
3. In most acute infections the route of infection is the intestinal tract;
organisms are disseminated by the lymphatics and portal blood with
invasion of various organisms and tissues
57
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

General Characteristics of the Toxoplasmosis

4. The parasites multiply in the tachyzoite form, producing areas of

necrosis; parasitism reaches high levels, and animals may succumb
during this period
5. During the height of parasitism, organisms may appear in secretions
and excretions such as urine, feces, milk, conjunctival fluid and even
in the saliva (rare)
6. There is little or no spread of toxoplasmosis form one animal to
another in the acute phase, even when the animals are confined in a
close space (e.g. mice in the same jar)
7. Persistence of the bradyzoites incysts is characteristic of the chronic
infection:

7.1. this phase can live for some considerable time; in dogs for up to
10 months, and in rats, mice and pigeons they have been found
for as long as 3 years after infection
 FAMILY: SARCOCYSTIDAE

Toxoplasma gondii

Diagnosis of Toxoplasmosis

1. Serological test
1.1. dye test - Depends on the principle that antibody and an
accessory factor (compliment-like serum factor,
Probably properdin) modify living Toxoplasma so that
these fail to stain with methylene blue at pH 11.
- Proliferative forms of Toxoplasma which had not been
modified by antibody stain readily , and the test is
quantitated by finding the higher dilution of serum
which will modify 50% of the toxoplasms in a
standard suspension
- the test may be dangerous to use since it requires
live parasites
1.2. complement fixation test
1.2.1. antibodies usually appear later & disappear sooner than
those detected by the other tests, & in most cases
antibodies disappear following the disappearance of
clinical signs
 SUBORDER: HAEMOSPORINA

Family: Plasmodiidae

1. General Characteristics

1.1. macro- and microgamonts develop independently , the zygote is

motile

1.2. schizogony occurs in vertebrates and sporogony in invertebrates

1.3. pigment is usually formed in the host cell

1.4. three genera are of importance:

1.4. 1. Plasmodiium

1.4.2. Haemoproteus

1.4. 3. Leukocytozoon
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

General Characteristics

1. The genus contains the malarial organisms of man, other mammals and
vertebrates

2. Schizogony occurs in the red blood cells and also in endothelial cells of inner
organs

3. Sexual phase of the cycle occurs in blood-sucking insects; for mammalian forms
these are Anopheline mosquitoes and for avian forms, Culicine mosquitoes

4. Common species of avian malarial organisms:

4.1. species with round or irregular gamonts w/c displace host cell nucleus

4.1. 1. Plasmodium cathemerium

4.1. 2. Plasmodium gallinaceum
4.1. 3. Plasmodium juxtanucleare
4.1.4. Plasmodium relictum
4.1. 5. Plasmodium griffithsi
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

General Characteristics

4. Common species of avian malarial organisms:

4.2. species with elongate gamonts which do not usually displace
the cell nucleus
4.2. 1. Plasmodium circumflexum
4.2. 2. Plasmodium durae
4.2. 3. Plasmodium elongatum
4.2. 4. Plasmodium fallax
4.2. 5. Plasmodium hexamerium
4.2. 6. Plasmodium lophurae
4.2. 7. Plasmodium polare
4.2. 8. Plasmodium rouxi
4.2. 9. Plasmodium vaughani
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

Life Cycle:

1. Sporozoites do not enter erythrocytes directly, but rather developed as

exoerythrocytic forms in cells of the reticuloendothelial system prior to invasion
of the erythrocytes
2. Following introduction of the sporozoites from infected Culicine mosquitoes,
numerous preerythrocytic schizonts are found in the macrophages and
fibroblasts of the skin near the point of entry

3. Sporozoites do not enter erythrocytes directly, but rather developed as

exoerythrocytic forms (cryptozoites) in cells of the reticuloendothelial system
prior to invasion of the erythrocytes

4. Merozoites from this first generation of pre-erythrocytic schizonts from a second

generation of pre-erythrocytic schizonts: the metacryptozoites

5. Merozoites from the metacryptozoites enter erythrocytes and other cells of the
body and in the latter form exoerythrocytic schizonts

6. In the case of P. gallinaceum, P. relictum and P. cathemerium, these other cells

are endothelial cells, but in the case of P. elongatum and P. vaughani they are
cells of the haemopoietic system
63
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

Life Cycle:
7. In some species of avian plasmodium (e.g. P. gallinaceum & P. elongatum), the
exoerythrocytic developmental stages may be added to by forms which are
derived from erythrocytic cycle – these are known as phanerozoites, being
derived from the merozoites of the schizonts in the erythrocytic cycle

8. The erythrocytic cycle is initiated 7 to 10 days after infection by merozoites from

metacryptozoites and at other times by merozoites from exoerythrocytic
schizonts located, according to species, in the endothelial or haemopoietic cells

9. On entering the RBC, the merozoite rounds up to form a trophozoite.

9.1. trophozoite is a small rounded form containing a large vacuole which

displaces the cytoplasm of the parasite to the periphery of the cell

9.2. the nucleus is situated at one of the poles, giving the young form a ‘signet
ring’ appearance when stained by the Romanowsky stians

10. The early trophozoites undergo schizogony to produce merozoites, the number
depending on the species of parasites
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

Life Cycle:

11. Schizogony may continue indefinitely, the length of each cycle of schizogony
depending on the species of parasites
12. The release of merozoites from the schizonts occur synchronously in the host,
and in human malaria this is associated with a paroxysm of fever

13. Fever does not appear to be a significant part of the syndrome in avian hosts

14. After a number of asexual generations has occurred, some merozoites undergo
sexual development with the formation of microgamonts (male) and
macrogamonts (female)
15. Development in mosquito is rapid:
15.1. within 10-15 minutes the nucleus of the microgamonts divides, and
through process of exflagellation,6 -8 long, thin, flagella-like
microgametes are extruded from the parent cell

15.2. these microgametes remain attached to the parent cell for a few minutes,
lashing actively; they become detached and swim away to find and
fertilize, the macrogamete
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

Life Cycle:

15. Development in mosquito is rapid:

15.3. the zygote resulting from fertilization is motile and is called an ookinete

15.4. the ookinete penetrates the mid-gut mucosa and comes to lie on the outer
surface of stomach, forming an early oocystabout 50-60 µm in diameter
15.5. the nucleus of the oocyst divides repeatedly to produce a very large
number of sporozoites
15.6. maturation of the oocyst takes a variable period time depending on the
species of parasites, temperature and species of mosquito; but in general,
it is 10-20 days

15.5. when mature, the oocyst ruptures, liberating the sporozoites into the body
cavity of the mosquito, and these then migrate all over the body of the
mosquito but eventually reach the salivary glands
15.6. they are now infective to a new host, infection occurring when the
mosquito takes a blood meal
15.7. a mosquito remains infected for its life-span, transmitting malarial
parasites every time a blood meal
 SUBORDER: HAEMOSPORINA

Genus: Plasmodium

Differences Between Male and Female Gamonts

Criteria Microgametes Macrogametes

Number Less numerous More numerous

Romanowsky Stains Less intense intense

Nucleus More diffuse less diffuse

Chromosomes haploid haploid

Species of Plasmodium

Species Hosts Gamonts Schizogony Merozoite Transmitter

s
Produced
P. Passerine Rounded, with rod- 24-hr cycle w/ 6-8 Culex &
cathemerium birds shaped rather a peak of Aides
course pigment segmentation
granules & dis- about 6-10
place nucleus of P.M.
cell
P. gallinaceum Domestic fowl Round & 36-hour cycle, 8-30 Aedes,
(India), possessing peak of Armigeres
pheasants, pigment granules segmentation
goose, of relatively large noon &
partridge & size and few in midnight,
peacock number; schizonts, alternately
round to irregular.
Both stages cause
displacement of
host cell nucleus
P. Domestic Round to irregular, 24-hour cycle 3-7, unknown
juxtanuleare chicken, & relative small, usually 4
turkeys parasites tend to
be in contact with
host cell nucleus
 Species of Plasmodium
Species Hosts Gamonts Schizogony Merozoites Transmitter
Produced
P. relictum Pigeon, Round to 12-hour to 36- 8-32 Culex,
mourning dove, irregular, hour cycle Anopheles
a number of displace the & Aides
antidae & host cell
various nucleus;
passerine birds pigment fine &
pinpoint
P. griffithsi Turkeys - - - -
Rangoon,
Burma
P. circumflexum Passerine Both schizonts 48-hour cycle 12-30 -
birds, ruffed & gamonts are
grouse & elongate & tend
Canada goose to encircle the
RBC nucleus,
although they
are not in
contact with it,
nor do they
displace the
nucleus
P. elongatum English Elongate - - -
sparrow,
canaries &
69
ducks
 Species of Plasmodium

Species Hosts Gamonts Schizogony Merozoites Transmitter

Produced
P. durae Turkey (Africa) Elongate, 24-hour 6-14 -
transmissible nucleus of host cycle
to ducks cell frequently
displaced;
pigment
granules
usually large &
stain intensely
P. fallax Owl, African Large, - - -
guinea-fowl, resembling
chickens & those of
pigeons Haemoproteus,
tending to
surround the
nucleus of host
cell without
displacing it
P. lophurae Fire-back Large, 24-hour 8-18 -
pheasant elongate, host cycle
(Lophura cell nucleus
igniti), not displaced
chickens & 70
 SUBORDER: HAEMOSPORINA

Species of Plasmodium
Species Hosts Gamonts Schizogony Merozoites Transmitter
Produced
P. hexamerium Passerine Gametocytes - 4-8 -
birds & schizonts,
elongate
P. Rouxi Sparrow, Gamonts 24-hour 4 -
finches elongate, host cycle
cell nucleus
not displaced

P. Vaughani American Gamont 24-hour 4 -

robin, elongate, host cycle
starling, & cell nucleus
other not displaced
birds

71
 SUBORDER: HAEMOSPORINA

Genus: Haemoproteus

General Characteristics:

1. The parasite is transmitted by blood-sucking insects in which

developmental stages, comparable to those of the genus
Plasmodium, occur
2. Gametocytes occur in erythrocytes and possess a halter-shaped
appearance encircling the nucleus (synonym Halteridium)
3. Pigment granules also occur
4. Schizogony occurs in the endothelial cells of the blood vessels
of inner organs, especially in the lungs

5. The parasite is transmitted by hippoboscid flies and in some

cases by genus Culicoides

5. The genus is widespread in birds and also in reptiles

 SUBORDER: HAEMOSPORINA

Species of Haemoproteus
Species Characteristics FH IH

H. columbae The only forms that occur in RBC Domestic & Hippoboscid fly
are gamonts. These may range wild pigeons
from tiny forms to elongate,
crescent-shaped gamonts,
which partially enclose the host
cell in the form of a halter.
Gamonts displace the nucleus
but not to the edge of the cell
H. canachites same Spruce Culicoides
grouse spagnumensis
(Canachites
canadensis)
H. danilewskii Parasite occupies the entire host Hooded unknown
cell cytoplasm; it completely crow
surrounds the host nucleus;
gamonts displace the nucleus
H. lophortyx Mature gamonts are halter- California Vector: Lynchia
shaped & contain numerous Valley quail hirsuta;
pigment granules, & the transmitter: H.
schizonts are found in the live, lophortyx 73
 SUBORDER: HAEMOSPORINA

Species of Haemoproteus
Species Characteristics FH DH

H. meleagridis Gamonts elongate and sausage- Domestic & unknown

shaped, partially encircling the wild turkeys
host cell nucleus, and frequently
in close contact with it
H. nettionis Gamonts elongate & sausage- Domestic duck Culicoides
shaped, partially, and in some & goose, &
cases almost completely, other wild
encircling the host cell nucleus. ducks, geese &
Cell nucleus may also be swans
displaced; pigment granules are
usually coarse & tend to be
grouped at the poles of the
parasite
H. sacharovi Gamonts are distinctive in that Domestic Pseudolynchi
they completely fill the host cell pigeon, a canarensis
when they are mature; they mourning dove & Culicoides
distort it & push the host cell & turtle dove
nucleus to one side; gamonts
possess little pigment compared
with other species of 74
Haemoproteus
 SUBORDER: HAEMOSPORINA

Species of Haemoproteus
Species Microgamonts Macrogamonts Pathogenesis
H. columbae Stains pale blue to Stains dark with Low, adult birds
pinkish with Romanosky, Romanosky stain, usually show no
the nucleus is pale pink nucleus is evidence of
and diffuse, and pigment compact, staining disease. However,
granules are collected dark purple to an acute form of
into a spherical mass red, & the the infection has
cytoplasm been reported in
pigeon nestlings,
in which heavy
mortality has
been recorded
H. canachites same same Unknown
H. danilewskii same same unknown
H. lophortyx same same Enlarged spleen &
pigmentation of
the lungs & liver.
Clinical signs
include
droopiness,
anorexia & death
may follow 1075
 SUBORDER: HAEMOSPORINA

Genus: Haemoproteus

Life Cycle:

1. The endogenous developmental cycle is initiated when sporozoites are injected

by an infected hippoboscid fly
2. Sporozoites enter the blood stream, penetrate endothelial cells of blood vessels
and here develop into early schizonts
3. The early stages are minute cytoplasmic bodies with a single nucleus, but by
growth & nuclear division 15 or more small, unpigmented masses, or cytomeres,
each with a single nucleus, are produced.
4. Each cytomere continues to grow, and its nucleus undergoes repeated division
until the now greatly enlarged endothelial cell is filled with a large number of
multinucleated bodies, or cytomeres, surrounded by a fine cyst wall
5. Each cytomere produces an enormous number of minute merozoites

6. subsequently, the endothelial cell breaks down and the cytomeres are liberated;
these accumulate in the capillaries which they may block, but soon after
liberation, the cytomeres rupture & the merozoites escape into the blood stream
 SUBORDER: HAEMOSPORINA

Genus: Haemoproteus

Life Cycle:
7. The development to cytomere stage takes about 4 weeks
8. The merozoites enter the blood cells and become gamonts, although it is
probable that the others enter further endothelial cells and repeat the asexual
cycle, this being carried on for several generations
9. The young gamonts first appear in the blood about 30 days after infection
10. Although multiple infections of RBCs with trophozoites may occur, it is rare for
more than one mature gamont to exist in a cell
11. Subsequent development occurs in hippoboscid flies
12. Development in the hippoboscid fly is comparable to that of the genus
Plasmodium in the mosquito
12.1. exflagellation of the male gamonts occurs in the midgut of the fly, and the
motile zygote (ookinete) migrates to the outer surface of the mid-gut
12.2. in the outer surface of mid-gut sporogony takes place with the production
of sporozoites
12.3. sporozoites are liberated in the body cavity of the insect & pass to the
salivary glands to await injection into the host
77
 SUBORDER: HAEMOSPORINA

Genus: Leucocytozoon

General Characteristics:

1. Parasite undergoes schizogony in the endothelial and parenchymatous cells of

the liver, heart, kidney and other organs of avian hosts
2. Large schizonts are produced

3. The gametogonous stages occur in the circulating blood, and the infected host
cells become grossly distorted and assume a spindle shape
4. No pigment is produced
5. The vectors are black flies of the genus Simulium
6. Common species:
6.1. Leucocytozoon simondi – FH: domestic & wild ducks & geese
6.2. Leucocytozoon smithi – FH: domestic & wild turkeys
6.3. Leucocytozoon caulleryi – FH: domestic chicken
6.4. Leucocytozoon bonasae - FH: ruffed grouse & ptarmigan
6.5. Leucocytozoon mansoni – FH: capercaillie, black grouse, hazel grouse
6.6. Leucocytozoon marchouxi - FH: doves & pigeons
6.7. Leucocytozoon sakharoffi - FH: crow, blue jay, raven, rook, jackdaw 78
 SUBORDER: HAEMOSPORINA

Leucocytozoon Species:

Species Mature Gamonts Macrogametes Microgametes

L. Simondi Elongate, oval bodies; nucleus Stain dark blue with Slightly smaller than
of the host cell is elongate & Romanosky stains, macrogametes, the
forms a long, thin, dark nucleus is compact, cytoplasm stains less
crescent along one side of the & several vacuoles deeply, usually a
parasitized cell; occasionally, occur in darkly pale blue color, & the
round forms of the parasite stained cytoplasm nucleus is diffuse &
occur in undistorted host cell. stains pale pink
L. Smithi Elongate, host cell is greatly - -
distorted& elongated; the
nucleus of the host cell is
elongated, forming a dark
band on one side of the
parasite, & this is frequently
split to form dark band on
each side of the parasite
L. Caulleryi round; the host cell is not Natural vector:
distorted as in the other Culicoides arakawae
species but is enlarged. Host
nucleus is compressed on one
side of the cell, forming a band
extending about 1/3 of the
way around the parasite
79
 SUBORDER: HAEMOSPORINA

Genus: Leucocytozoon

Life Cycle:

1. The endogenous developmental cycle is initiated when sporozoites injected by

the Simulium fly are carried by the blood stream to various cells of the body,
producing 2 types of schizonts: hepatic schizonts & megaloschizonts
2. The first asexual generation takes place in the kupffer cells of the liver

3. the schizonts are small, and they produced merozoites, some of which may
enter blood cells to become gamonts, while others initiate, hepatic
schizonts and megaschizonts

4. The hepatic schizonts occur in the parenchyma liver cells, and they produce a
number of cytomeres, which by multiple fission, form a large number of small
merozoites

5. the megaloschizonts are more numerous than the hepatic forms and apparently
develop in lymphoid cells or macrophages & are found in the brain, liver, lungs,
kidney, intestinal tissue and lymphoid tissues 4-6 days after infecton

6. the schizonts contain a large number of cytomeres which in turn produce a

much larger number of merozoites
 SUBORDER: HAEMOSPORINA

Genus: Leucocytozoon

Life Cycle:

7. With rupture of hepatic schizonts and the megaloschizonts, merozoites are

released into the blood and these appear as gamonts in the peripheral
circulation 6-7 days after infection & enter lymphocytes.

8. The majority of the merozoites probably develop into gamonts, but it is

presumed that some may initiate further asexual reproduction

9. Development in the insect vector is essentially the same as Plasmodium in the

mosquito

Pathogenesis:

1. L. simondi is markedly pathogenic for young ducks & geese

2. The clinical signs of leucocytozoonosis are sudden in onset, and death may occur
within a day or so

3. Ducklings are listless, anorexic, show rapid breathing (due to large number of
megaloschizonts in capillaries of lungs) and may show nervous derangements
prior to death
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