PHYLUM APICOMPLEXA: coccidians

1

• PHYLUM APICOMPLEXA coccidians
• Morphology and General Life Cycle

apical complex
2
PHYLUM APICOMPLEXA General Life Cycle
schizogony
trophozoite
schizont
3
PHYLUM APICOMPLEXA General Life Cycle
sporozoites
sporogony (schizogony)
invade host cells
oocyst with sporont
zygote
gametogony
macrogametocytes
microgametocytes (schizogony)
4

• PHYLUM APICOMPLEXA
• Morphology and General Life Cycle
• II. Eimeria tenella
• -- parasite of poultry
• -- invades gut epithelial cells
• -- monoxenous
• A. Life Cycle

5

• Eimeria tenella life cycle
• Chicken ingests oocyst sporozoites released
  invade gut epithelial cells
• Trophozoite ? merogony ? ca. 900 merozoites ?
  rupture release infect (2-3 generations of
  merozoites)

zygote
merozoites
6

• Eimeria tenella life cycle
• Chicken ingests oocyst sporozoites released
  invade gut epithelial cells
• Trophozoite ? merogony ? ca. 900 merozoites ?
  rupture release infect (2-3 generations of
  merozoites)
• Merozoite invades cell ? gametogony ? macro-
  microgametocytes

7

• Eimeria tenella life cycle
• Chicken ingests oocyst sporozoites released
  invade gut epithelial cells
• Trophozoite ? merogony ? ca. 900 merozoites ?
  rupture release infect (2-3 generations of
  merozoites)
• Invade cell ? gametogony ? macro-
  microgametocytes
• Fertilization ? oocyst formation

Forming oocyts
schizont
zygote
8

• Eimeria tenella life cycle
• Chicken ingests oocyst sporozoites released
  invade gut epithelial cells
• Trophozoite ? merogony ? ca. 900 merozoites ?
  rupture release infect (2-3 generations of
  merozoites)
• Invade cell ? gametogony ? macro-
  microgametocytes
• Fertilization ? oocyst formation
• Oocyst with sporont ruptures from cell ? out with
  hosts feces ? sporogony ? 8 sporozoites
  (requires oxygen)

9
Eimeria tenella oocysts in chicken feces
10

• PHYLUM APICOMPLEXA
• Morphology and General Life Cycle
• II. Eimeria tenella
• -- parasite of poultry
• -- invades gut epithelial cells
• -- monoxenous
• A. Life Cycle
• B. Pathology

11
Eimeria tenella pathology
12

• PHYLUM APICOMPLEXA
• Morphology and General Life Cycle
• II. Eimeria tenella
• III. Toxoplasma gondii
• -- DH cat
• -- IH other mammals
• -- causes toxoplasmosis
• A. Life cycle
• 1. enteroepithelial cycle only in the
  cat

13

• Toxoplasma gondii enteroepithelial stage
• Cat ingests oocyst or zoitocyst ? sporozoites
  released ? invade gut epithelial cells
• Merogony ? merozoites ? rupture, release, infect
• Gametogony ? macro- microgametocytes ? oocyst
  with sporont
• Out with hosts feces ? sporogony ? sporozoites
  (requires O2 takes 3 days)

14

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• 1. enteroepithelial cycle only in the
  cat
• 2. extraintestinal cycle in cat and
  other mammals

15

• Toxoplasma gondii extraintestinal stage
• host ingests oocyst or zoitocyst ? sporozoites
  released ? penetrate gut invade tissues
  (muscles brain lymph nodes macrophages)
• Period of rapid merogony ? merozoites
  tachyzoites ? rupture, release, infect

tachyzoites
16

• Toxoplasma gondii extraintestinal stage
• host ingests oocyst or zoitocyst ? sporozoites
  released ? penetrate gut invade tissues
  (muscles brain lymph nodes macrophages)
• Period of rapid merogony ? merozoites
  tachyzoites ? rupture, release, infect
• Rate of merogony slows ? merozoites bradyzoites
  ? accumulate in zoitocysts

17

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• B. Pathology
• -- 13 of world population is infected may
  reach 50 in some areas
• -- most infections asymptomatic or mild

18

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• B. Pathology
• 1. acute phase
• -- initial site of infection is gut
• -- can kill kittens flu-like symptoms in
  humans
• -- period of tachyzoite production
• -- transplacental ? congenital
  toxoplasmosis
• Transmission rate 45
• in U.S., 3500 infants/yr. born with severe
  infections 300 million annually
• Of infected fetuses, 9 die, 30 develop
  blindness, mental retardation, hydrocephalus
  major cause of birth defects

19

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• B. Pathology
• 1. acute phase
• 2. chronic phase
• -- bradyzoite and zoitocyst formation
• -- zoitocysts can last for months or
  years, esp. in brain

20

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• B. Pathology
• C. Immunology
• -- involves both humoral and cell mediated
  immunity, but CMI most important
• -- host immune responses slow rate of merogony ?
  bradyzoites in zoitocysts
• -- results in premunition
• -- cyst wall does not elicit inflammatory
  reaction
• -- bradyzoites can reactivate in
  immunocompromised patients, leading to
• brain damage, blindness, heart damage, etc.
• -- major problem in AIDS patients

21
Toxoplasma gondii cerebral abscess
22

• PHYLUM APICOMPLEXA
• III. Toxoplasma gondii
• A. Life cycle
• B. Pathology
• C. Immunology
• D. Treatment and Control
• -- cook meat pork and lamb esp. likely to be
  contaminated
• -- freezing at -14 oC for several hours kills
  zoitocysts
• -- clean cats litter box every 1-2 days
• -- pregnant women should not handle litter box
  or cat feces

23

• PHYLUM APICOMPLEXA
• Morphology and General Life Cycle
• II. Eimeria tenella
• III. Toxoplasma gondii
• IV. Sarcocystis spp.
• -- DH carnivores
• -- IH herbivores

24
Sarcocystis
zoitocysts
oocysts
25
Sarcocystis zoitocysts
Breast muscle Mallard duck
Sheep esophagus
Estimated that 90 of all meat in supermarkets
contain zoitocyts of Sarcocystis spp.
26

• PHYLUM APICOMPLEXA
• I. Morphology and General Life Cycle
• II. Eimeria tenella
• III. Toxoplasma gondii
• IV. Sarcocystis spp.
• V. Cryptosporidium
• -- gut epithelium lungs
• -- zoonosis in humans contracted via fecal
  contamination
• -- in AIDS patients profuse, unrelenting
  diarrhea

27
Cryptosporidium spp.
28

• PHYLUM APICOMPLEXA
• Morphology and General Life Cycle
• II. Eimeria tenella
• III. Toxoplasma gondii
• IV. Sarcocystis spp.
• V. Cryptosporidium
• VI. Pneumocystis carinii
• -- extracellular parasite in lungs
• -- causes pneumocystic pneumonia (PCP)
• -- serious problem in AIDS patients

29
(No Transcript)
30
Pneumocystis carinii
31
Pneumocystis carinii