Parastiology

Question 1

Parasitology Exercise 2: Phylum Sarcomastigaphora

What is the classification?
what is the morphology?
What is the life cycle?
What’s the diagnosis, symptoms and medical significance?

Answer 1

Classification
Kingdom: Protista
Phylum: Sarcomastigaphora
Subphylum: Sarcodina
Order: Amoebida
Genus: Entamoeba
Species: Entamoeba Histolytica, Entamoeba Coli

Question 2

Parasitology Exercise 2: Phylum Sarcomastigaphora

what is the morphology?

a) Phylum Sarcomastigaphora
b) Subphylum Sarcodina
c) Entamoeba Histolytica (Trophozoite + Cystic form)

Answer 2

Morphology of Phylum Sarcomastigaphora:

• Term for protozoans that move by either one or more flagella or pseudopods
• Phylum includes both free-living and parasitic protozoans
• Cell size is usually 10-30µm
• Protozoans replicate by binary fission or sexually by fusion of two gametes (syngamy)
• Unicellular

Morphology of Subphylum Sarcodina:

Amoeboid protozoans which move and feed by temporary cytoplasmic extensions called pseudopods (pseudopodia).

Morphology of Entamoeba Histolytica:
Has two forms: Trophozoite and Cyst
1) Forma Minuta (commensal Trophozoite ): Organisms which live in organisms. They use food resource but do not harm. Live in upper digestive tract., 10-20µm and up to 4 nuclei.
2) Forma Magna (pathogenic Trophozoite ): Real parasite; Ingest blood cells and invade intestinal wall causing ulcers. 20-30µm and feed on erythrocytes.
3) Forma cystica (invasive): Cysts (which are swallowed), survival of organism when conditions in large intestine are hard. E. Histolytica has 4 nuclei and E. Coli has 8 nuclei

All three formas can transform from one into the other.
F. Magna never transforms to F. Cystica
F. Minuta changes to F. Magna back to F. Minuta then to F. Cystica.

Question 3

Parasitology Exercise 2: Phylum Sarcomastigaphora

What is the life cycle?

Answer 3

Lifecycle:

• Cysts and trophozoites are passed in faeces.
• Cysts are found in formed stool, trophozoites are found in diarrheal stool.
• Infection by Entamoeba histolytica occurs by ingestion of mature cysts in fecally contaminated food, water, or hands.
• Excystation occurs in the small intestine and trophozoites are released and migrate to the large intestine.
• Trophozoites multiply by binary fission and produce cysts, and both stages are passed in the faeces.
• Because of the protection of their walls, the cysts can survive days to weeks in the external environment and are responsible for transmission.
• Trophozoites passed in the stool are rapidly destroyed once outside the body, and if ingested would not survive exposure to the gastric environment.
• In many cases, the trophozoites remain in intestinal lumen (noninvasive infection) of individuals, passing cysts in their stool.
• In some patients the trophozoites invade the intestinal mucosa (intestinal disease),
• May pass through the bloodstream, to sites outside the intestine such as the liver, brain, and lungs (extraintestinal disease).

Question 4

Parasitology Exercise 2: Phylum Sarcomastigaphora

What’s the diagnosis, symptoms and medical significance?

Answer 4

Definitive host: Human
Intermediate Host: NONE
Invasive stage: Ingestion of mature cysts

Medical significance:
Amoebic dysentery and amoebiasis
Parasite lives in the intestine and causes inflammation, liver abscess and lung damage if abscess ruptures.

Symptoms:
Severe diarrhoea, abdominal pain, tenderness, swollen abdomen, and coughing if there is lung damage.

Diagnosis:
Look at cysts/trophozoites in stool sample under microscope:
Diarrhoea: F. Magna
Hard Stool: F. Cystica
Blood sample to see if E. Histolytica antibodies are present in blood.
Liver/CT scan for liver abscesses.

Question 5

EXERCISE 3 Phylum Sarcomastigaphoria, Subphylum Mastigaphora

What is the classification?

Answer 5

Kingdom: Protista
Phylum: Sacromastigophora
Subphylum: Mastigophora
Order: Amoebida
1-	Genus Trypanosoma (Sleeping sickness)
•	Trypanosoma Gambiense
•	Trypanosoma Rhodesiense
•	Trypanosoma Equiperdum
2-	Genus Leishmania
•	Leishmania Donovani
•	Leishmania Tropica
•	Leishmania Braziliensis
3-	Genus Trichomonas
•	Trichonomas Tenax
•	Trichomonas Hominis
•	Trichomonas Vaginalis
4-	Genus Lamblia – Lambila Intestinalis

Question 6

EXERCISE 3 Phylum Sarcomastigaphoria, Subphylum Mastigaphora

what is the morphology?

Answer 6

Morphology of Subphylum Mastigophora:
• Protozoan which possess one or more flagella at some time in the life cycle allowing self-propelled movement and sensation
• Axostyle for body support
Genus Trypanasoma:
Morphology
• A protozoan with flagella
• Extracellular parasite
• Flagella consisting of 5-9 parallel fibrils
• Large, oval nucleus in middle of body
• Tapered anterior, blunt posterior
• Kinetoplast (mitochondria) near posterior

Question 7

EXERCISE 3 Phylum Sarcomastigaphoria, Subphylum Mastigaphora

What is the life cycle?

Answer 7

Life Cycle: (Trypanosoma Gambiense. Trypanosoma Rhodesiense, Trypanosoma Equiperdum)
Human stage:
1- Infected Tsetse fly takes a blood meal and injects metacyclic trypomastigotes into skin (infective stage)
2- Parasites enter lymphatic system and pass into bloodstream
3- Inside the host they transform into blood stream trypomastigotes, which are carried to other sites around the body
4- They reach various body fluids (e.g. blood lymph and spinal fluid) and continue to replicate by binary fission.
5- Trypomastigotes in blood - diagnostic stage.
Tsetse Fly stage:
6- Tsetse fly takes a blood meal from a host (bloodstream trypomastigotes are ingested)
7- In fly’s midgut bloodstream trypomastigotes transform into procyclic trypomastigotes
8- Procyclic trypomastigotes multiply by binary fission, leave the midgut and transform into epimastigotes.
9- Epimastigotes reach salivary glands and continue multiplying by binary fission.
10- They transform into metacyclic trypomastigotes.
Cycle in the fly takes approx. 3 weeks.

Question 8

EXERCISE 3 Phylum Sarcomastigaphoria, Subphylum Mastigaphora

What’s the diagnosis, symptoms and medical significance?

Answer 8

a) Trypanosoma Gambiense:
Morphology: 15-30µm
Disease: Gambian Trypanosomiasis (sleeping sickness)
Carrier: Tsetse flies (glossina genus)
Definitive Hosts: Human
Symptoms: Inflammation at biting site, headache, fever, joint and muscle pain.

b) Trypanosoma Rhodesiense:
Morphology: Looks same as T. Gambiense
Disease: Rhodesian Trypanosomiasis 
Carrier: Tsetse flies (Glossina)
Definitive Host: Human
Symptoms: More fatal than Gambian disease. Causes neuro-inflammation and can lead to death.

c) Trypanosoma Equiperdum:
Disease: Causes Syphilis in horses (not harmful to humans)

Diagnosis: Presence of parasite in body fluid or tissue by microscopy, analyse blood samples, look for antibodies specific to Trypanosoma.