Kirn - Protozoa Ebook

Question 1

Are Protozoa eukaryotes?

Answer 1

Yes

Question 2

What is the best way to diagnose a protozoan infection?

Answer 2

Microscopically - they large

Question 3

What are the two pathogenic flagellates?

Answer 3

Giradia lamblia

Trichomonas vaginalis

Question 4

Giardia lamblia

• how is it spread?
• morphology?
• disease?
• prevention

Answer 4

Otherwise known as backpackers diarrhea because infections are acquired by consuming contaminated water. It multiplies in the lumen of the intestine.

Cells have two nuclei and a large ventral sucker disk

Gives acute diarrhea (chronic in AIDS patients)

Prevent by boiling water, iodine treatment, filtering water etc.

Question 5

Trichomonas vaginalis

• epidemiology
• morphology
• disease

Answer 5

Sexually transmitted and multiplies in the GU mucosal membranes

Cells have a flagella at one end and an undulating membrane which extends part way down the cell

In women the disease is limited to the external genitlaia, vagina, cervix. The symptoms are itching, burning, and a pale yellow watery discharge. In men the urethral infection may remain localized or ascend to the prostate or seminal vesicle.

Question 6

What are the hemoflagellates?

Answer 6

Trypanosomas and Leishmanias

Question 7

Morphology of hemoflagellates

Answer 7

They all have a single flagellum that elongates from what is called the kinetoplast. They also have a central nuclei and an undulating membrane that extends the full length of the cell.
- it looks different depending on which part of the life cycle it is in.

Question 8

What are the different life cycle stages of hemoflagellates?

Answer 8

Mnemonic - A PET

Amastigote - kinetoplast is central and there is no flagellum
Promastigote - kinetoplast has moved to anterior part of the cell and a flagella emerged from it.
Epimastigote - kinetoplast migrates centrally and from it there is a short undulating membrane
Trypomastigote - kinetoplast moves to the posterior end of the cell thus elongating the undulating membrane causing it to extend the full length of the cell.

Question 9

Trypanosoma brucei

• epidemiology
• disease
• how does it evade the immune system?
• prevention

Answer 9

Otherwise known as African trypanosomiasis or African Sleeping Sickness
- spread by the bite of the tsetse fly

• 1) starts with a localized inflammatory lesion and the trypanosomes multiply at the site of the tsetse bite and spread to the bloodstream. 2) Once in the bloodstream the disease can be long-lasting and can cause fever, headache, muscle/joint pain, rash, anemia, leukocytosis, weight loss, enlarged lymph nodes - all signs of chronic inflammation. - the enlarged posterior lymph nodes are called Winterbottom’s sign. 3) In the late stage it invades the CNS and causes lassitude, motor and reflex abnormalities, stupor, coma, and death.
• it evades the immune system through phase variation.
• prevention is through control of tsetse flies.

Question 10

Talk about the phase variation of the Trypanosoma brucei

Answer 10

Basically, the outer surface of the bloodstream form is covered with a single protein called Variable Surface Gllycoprotein (VSG). The genome has 1-2 expressed forms but thousands of silent forms. As the immune system reacts to one type of VSG state, a rare recombination event occurs between the active form and one of the silent forms, which causes an entirely new antigenic form.
- This causes repeated IgM flares in infected persons because it is always fighting a new infection.

Question 11

Leishmania

• epidemiology
• disease

Answer 11

• caused by the sandfly and then multiply within macrophages in humans until they are released by cell lysis
• Leishmaniasis is the result of multiplication in the spleen, liver, bone marrow, and other tissues. There is widespread dermotrophic Leishmanias that cause ulcerative dermal lesions at the site of infection. Classic site is the back of the neck. The cutaneous infections could spread from the site of infection to mucous membranes of the oral or nasal cavity which can remain latent for years or decades.

Question 12

Entamoeba histolytica

• what type of eukaryote is it?
• epidemiology
• morphology
• disease
• symptoms

Answer 12

• it is a amoeba
• cysts are ingested in contaminated water and food
• usually we do microscopic examination of stool or abscess contents. They are larger than other species typically in the guy. The cysts are round, medium sized, have 4 nuclei, and not much glycogen.
• the amoebas invade the epithelial wall at the base of the crypt and produces a small ulcer. They they penetrate a deeper layer and spread laterally to produce a disk shaped lesion. Blood and mucus then spread from the lesion into the lumen. Secondary lesions may spread to the peritoneum and to tissues via the bloodstream.
• symptoms usually are diarrhea, cramps, nausea, vomiting, malaise. If it is worse it is bloody stools, fever, abdominal pain, dehydration.

Question 13

Amoebic meningoencaphalitis

Answer 13

Caused by: Naelgeria, Hatmonella, Acanthamoeba.

• infections is usually due to swimming in natural water and then the amoebas enter the brain through the cribiform plate through the ethmoid bone.
• treated with amphotericin + azoles

Question 14

Toxigenic flagellates

Answer 14

Called dinoflagellates - they produce toxins.

- one example is Pfeisteria piscidida

Question 15

Balantidum coli

Answer 15

A type off Ciliate.

• diagnosis is by demonstration of the organism in the stool
• have a kidney shaped nucleus.

Question 16

Apicomplexia

Answer 16

Named for the apical complex used to infect host cells. They multiply intracellularly.

• they undergo multiple nuclear division cycles without cytokinesis to produce large multinucleate forms called schizonts
• they they cleave to produce multiple uninicleate infective progeny cells that are released by lysis of the cell.

Question 17

Plasmodium babesia

Answer 17

A form of Apicomplexia. They are transmitted to humans by the female Anopheles mosquito.

• they first replicate in the liver and then gamete formation occurs in the RBCs.
• the. Mosquito infects us with sporozoite and then the hepatocytes release merozoites into the bloodstream, which are not bad for the liver but are bad for the RBCs.

Question 18

The erythrocytic cycle once infected with merozoite

Answer 18

• a merozoite infects an erythrocytes ad becomes vacuolated.
• then it enrages (trophozuite) and undergoes nuclear cell division (Developing schizoint) and then finally cleaves (schizoint).
• Upon cleavage, many merozoites are made and then released by lysis of the erythrocyte.

Question 19

What are the symptoms of malaria?

Answer 19

There is an incubation period for 1-4 weeks before symptoms develop. This is the liver stage. Then, there are cycles of RBC infection and release of merozoites that become highly synchronized. With each wave there is fever, chills, and then sweats.

• also headache, malaise, nausea, vomiting, anemia, cachexia, and enlargement of the liver and spleen.
• may also cause extensive hemolysis of erythrocytes in the urine.

Question 20

Microsporidia

Answer 20

Three genera: Encephalitozoon, Enterocytoon, Nosemia

• transmission is via contaminated water or food. Life cycle is similar to Apicomplexia. They multiply intracellularly. The spore has a polar filament that can pierce the host cells cell membrane and then due to osmotic flow of water, bring the Microsporidia into the cell and then surround it with membrane.
• cells are very tiny which make them hard to find.
• disease is mostly associated with the intestines, eyes, or systemic infection. An expecting mother can infect her child transplacentally.
• diagnosis via a special stain that detects organisms in stool, exudate, and urine.