The life cycles

Question 1

Answer 1

Life cycle of African trypanosoma salivaria:

1. infected tsetse fly contain metacyclic trypomastigote in salivary glands.
2. vector bites host injecting the metacyclic trypomastigote into the host.
3. the metacyclic trypomastigote transform into blood trypomastigote in the blood stream.
4. trypomastigote multiplies by binary fission extracellularly
5. tsetse fly bites infected host being infected with blood trypomastigote.
6. blood trypomastigote goes to the midgut where it becomes pro cyclic trypomastigote and multiply by binary fission.
7. pro cyclic trypomastigote leave midgut and migrate to salivary glands where it can be found as epimastigote.
8. over time the epimastigte matures to trypomastigote and will be ready for next blood meal.
9. cycle repeats

Question 2

Answer 2

Life cycle of American trypanosoma stercoraria

1. infected kissing bug triatoma bites the host while also leaving faeces containing trypomastigote.
2. trypomastigote on the surface enters through skin by scratching on wound.
3. trypomastigote goes to the cells where it becomes amastigote
4. amastigote divides by binary fission until cell is filled and ruptures.
5. amastigote differentiate into trypomastigote outside the cell
6. blood trypomastigote are ingested by vector during blood meal.
7. within the vector the trypomastigotes go to midgut becoming epimastigotes and goes to the hindgut where they transform back to metacyclic trypomastigotes

Question 3

Answer 3

Life cycle of Leishmania

1. in vector promastigote waits in proboscis.
2. sandfly bites host and expel promastigote as it sucks blood.
3. promastigote migrate to wound and to blood and become phagocytose by macrophages.
4. within macrophages promastigote loose flagella and become amastigote.
5. amastigote replicate by simple division
6. macrophages burst and release amastigote which go to other cells and cause infection
7. sandfly bites and ingest blood containing amastigote which travels to midgut and transform into promastigote.
8. promastigote replicate in midgut by binary fission and are released into the proboscis where they remain until new host bite.
9. cycle repeats

Question 4

Answer 4

Life cycle of Giardia

1. cyst is found in contaminated food and water.
2. after ingestion the cyst goes to the SI where it breaks down releasing 2 trophozoites
3. trophozoites reproduce in SI
4. trophozoites have 2 fates:
   - some will attach to wall of intestine and the intestinal villi
   - free trophozoites will move to colon
5. in colon: trophozoites undergo encystation and form a new cyst
6. cysts passed from here into environment in the form of faces and contaminates soil and water.
7. cysts are immediately infective
8. cycle repeats

Question 5

Answer 5

Life cycle of Eimeria

1. unsporulated oocyst is released in the faces and undergo sporogony in the environment.
2. faeces containing sporulate oocyst, is ingested by host and travels to small intestine
3. In SI sporocyst breakdown and sporozoites are released
4. sporozoites enter intestinal cells and undergo schizogony.
5. 3 generation of schizogony releases 3 generations of merozoites
6. 3rd generation merozoites differentiate into micro- & macrogamete
7. Gametogeny: microgamete fertilise macrogamete and they fuse and create unsporulated oocyst. this is passed in faces and in environment sporogony happen.
8. cycle repeats

Question 6

Answer 6

Life cycle of Cryptosporidium

1. sporulated oocyst is passed in faeces
2. contained faces is ingested by host
3. within the intestine of host, sporozoites are released from oocyst.
4. schizogony occurs in small intestine releasing 2 generation of merozoites from 2 schizogony cycles.
5. merozoites mature and differentiate into micro and macrogametes
6. microgamete fertilise macrogametes and create unsporulated oocyst
7. sporogony occurs resulting in formation of sporulated oocyst which can either be thin walled or thick walled:
   - thick walled passes in faces into environment
   - thin walled rupture in small intestine releasing sporozoites, migrate to intestinal cells causing infection.
8. cycle repeats

Question 7

Answer 7

Life cycle of Cystoisospora spp.

1. unsporulated oocyst in feces
2. sporulation occurs in the environment after a certain time period
3. faces are ingested
4. inside the host the cell breaks down releasing sporozoites from the sporocysts.
5. sporozoites migrate to intestinal epithelium and other cells
6. schizogony occurs in intestinal epithelium or cell releasing merozoites which divide by binary fission until cell is full and rupture
7. free merozoites have 2 fates:
   - enter and infect other cells within host
   - differentiate into micro and macrogamete
8. macrogamete and microgamete fuse together and create an unsporulated oocyst in SI.
9. unsporulated oocyst is released in faces and undergo exogenous sporogony in environment. the sporulated oocyst remain in environment for a long time until its again eaten by host of paratactic host.
10. cycle repeats

Question 8

Answer 8

Life cycle of Hepatozoon canis:

1. dog ingest tick, In gut sporozoites are released and enters the hosts tissues. merogony merozoits are released and form mature merits. asexual reproduction.
2. merozoites invade leukocytes
3. tick ingest leukocytes with merozoites. gametogony inside tick
4. sporogony inside tick, mature oocyst in mouthpart of the tick

Question 9

Answer 9

Life cycle of Sarcocystis

1. sporocyst in faces is ingested by intermediate host
2. sporocyst migrates to SI. sporocyst breaks down releasing sporozoites
3. sporozoites move to intestinal mucosa and blood vessels
4. three generation of schizogony occurs here and release 3 generations of merozoites
5. third generation of merozoites migrates via cysts to become slowly dividing bradyzoites of IH
6. merozoites undergo asexual reproduction within cysts to become slowly dividing bradyzoites:
   - sarcocyst can be micro or macro
   - these sarcocysts remain in muscle
7. meat/muscle containg bradyzoites is consumed by carnivores
8. in the intestine of car the sarcocyst ruptures and release active bradyzoites which infect mucosa and differentiate into micro and macrogametes
9. microgamete fertilise macrogamete forming unsporulated oocyst with thin wall
10. the thin wall rupture on or before excretion from the body via faces

Question 10

Answer 10

Life cycle of Toxoplasma gondii

1. unsporulated oocyst is passed in faces of cats, and undergo sporulation in environment
2. sporulated oocyst is ingested by IH where it invades cells forming vacuoles containing bradyzoites
3. vacuoles form tissue cysts in muscle and brain
4. within vacuoles T.gondii replicate by binary fission until infected cell burst and trachyzoites are released
5. cat ingest cells with the cyst where it undergo sexual reproduction in SI

Question 11

Answer 11

Life cycle of Babesia

1. Tick bites vertebrate and sporozoites are released, Sporozoites enter the Ec and develop into a ring form
2. schizogony occurs in IH. Asexual reproduction continues until cell ruptures and merozoites are released and enter new RBC.
3. merozoites can be in Ec individually, in pairs or in spheroid form
4. tick bites infected host and ingest infected Ec, some are destroyed in GIT of tick, but spheroid form continue to form micro and macrogametes
5. fusion of micro and macrogamete result in ray bodies, which form ookinete

• ookinete can penetrate female egg meaning new generation of larva after hatching will have parasite in salivary glands
• ookinete can penetrate salivary gland of tick and continue with sporogony. this can be passed from one stage to the next
  6. cycle repeats

Question 12

Answer 12

Life cycle of Theileria

1. Sporozoitesare injected during blood meal by Ixodid tick
2. Schizont (Koch´s body) inside the cytoplasm of newly dividing lymphocyte, eventually forming merozoites
3. Free motile merozoites enter RBC
4. Binary fission inside RBC (at low rate)
5. A few free merozoites enter other Ery
6. Formation of oval or spherical gamonts
7. -8. Gamonts free in blood masses inside tick gut
8. (8.1-8.4) Formation of microgamonts, which give rise by fission to microgametes. Microgametes fuse with the macrogamete
9. Macrogamete
10. Zygote
11. -13. Formation of motile kinete from ovoid immobile zygote inside intestinal cells of the tick. Note that the division of nucleus may start before leaving the intestinal cells
12. After moult of Ixodid tick and attachment to a new host, kinetes enter cytoplasm of cells of salivary gland and give rise to young sporonts, which grow and initiate repeated nuclear division
13. Parasitism leads to considerable enargement of the host cell and its nucleus. Inside the giant host cell, the sporont forms thousands of sporozoites which is trasmitted during the next blood meal

Question 13

Answer 13

Life cycle of Plasmodium

1. female mosquito sucks blood of host and release sporozoites in blood of IH
2. sporozoites in host firstly go to the liver to complete extraerythrocytic stage. this stage involves schizogony
3. binary fission occurs within hepatic cell of liver. hepatic schizont become full and rupture releasing merozoites
4. merozoites leave the liver and penetrate RBC where another generation of schizogony occurs, forming early trophozoite stage with two fates:
   - early trophozoite transform into late trophozoite blood stage schizogony will rupture over time and cycle continue
   - early trophozoite differentiate into micro and macrogamete
5. mosquito sucks blood of infected host and zygote develops by gametogony
6. zygote is motile and travels through GI epithelium creating oocyst
7. sporogony occurs in oocyst, forming sporozoites
8. sporozoites move to salivary gland and the cycle repeats

Question 14

Answer 14

Life cycle of Histomonas meleagridis:

1. FH ingest earthworm with heterakis egg containing histomonas
2. in cecum heterakis hatch – histomonas released
3. histomonas attach to mucosa —> ulcers and necrosis
4. amoeboid form penetrates the wall —>migrates to the liver
5. in cecum histomonas is ingested by heterakis – infected eggs out of faeces of FH

Question 15

Life cycle of Sarcocystis bovicanis

Answer 15