Parasitology Exam 4: Adaptation & Morphology

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Questions and Answers

What is a characteristic of an 'ideal' parasite?

It causes immediate death to the host.

It is always a bacterium.

It is always easily detected by the host's immune system.

It has a complex life cycle that allows for both asexual and sexual reproduction. (correct)

What is the purpose of the cuticle in nematodes?

To aid in attachment to the host

To provide a surface for absorption of nutrients

To protect the parasite from the host's immune system (correct)

To facilitate movement through the host's tissues

What is the result of a successful immune response to a parasitic infection?

Recovery and immunity (correct)

Death of the host

Increased susceptibility to future infections

Chronic infection

Which of the following parasites avoids the immune system?

Ascaris Signup and view all the answers

What is the role of lymphokines in the immune response to Trichinella spiralis?

To attract White Blood Cells to the site of infection Signup and view all the answers

What is the term for the movement of White Blood Cells from the bloodstream to the tissues during inflammation?

Diapedesis Signup and view all the answers

What is the term for the formation of a collection of immune cells around a foreign substance or parasite?

Granuloma Signup and view all the answers

What is the result of bioaccumulation in the parasite Diphyllobothrium latum?

Accumulation of nutrients from the host Signup and view all the answers

What is the result of the larval deposition in Trichinella life cycle?

Compensation for the 14-day self-cure Signup and view all the answers

What is the most effective against schistosomules?

Antibody and white blood cells Signup and view all the answers

What is the reason for the fluctuation of parasitemia in Trypanosoma gambiensis?

Alternate expression of genes controlling variant specific surface glycoproteins Signup and view all the answers

What is the primary vector of Malaria?

Anopheles mosquito Signup and view all the answers

Which species of Plasmodium is responsible for the most severe and fatal outcomes?

P.falciparum Signup and view all the answers

What is the term for the removal of parasites from the bloodstream?

Blackwater fever Signup and view all the answers

What is the purpose of thick and thin blood smears in Malaria diagnosis?

To detect the presence of parasites Signup and view all the answers

What is the term for the wasting away of the body due to repeated paroxysms of Malaria?

Malarial Cachexia Signup and view all the answers

Study Notes

Adaptation

An "ideal" parasite has adaptations to optimize its survival and reproduction
Morphological adaptations include:
- Size: larger to house reproductive system
- Shape: long and thin, broad and flat, round
- Attachment: suckers, acetabula, hooks, biological holdfast
Body surface adaptations:
- Cuticle: found in nematodes
- Absorptive surface: found in tapeworms

Reproductive System

Reproductive cyst: found in protozoan
Reproductive organs make up majority of body mass
Hermaphroditic: capable of producing both male and female gametes
Complex life cycles allow for asexual and sexual reproduction
Bioaccumulation: seen in Diphyllobothrium latum
Free and parasitic parts of life cycles: seen in Strongyloides

Immunity

Non-specific immunity:
- Phagocytosis and inflammation
- Inflammation: movement and actions of WBCs in inflammation
  - Margination
  - Diapedesis
  - Chemotaxis
  - Ingestion
  - Digestion
  - Granuloma formation
Specific immunity:
- Humoral (immunoglobulin or antibody): B cells
- Cell-mediated immunity: T cells

Parasitic Infection

Can result in:
- Chronic infection
- Recovery and immunity
- Death

Immune Response to Intestinal Nematodes

Ascaris: avoids the immune system
Necator: some inflammation due to partial tissue invasion
Trichinella: tissue invader, good immune response, but leaves larvae behind

Trichinella Spiralis

Immune response involves:
- Worm antigens or foreign materials
- Lymph system
- Lymph nodes
- T cells
- Lymphokines:
  - Stimulatory
  - Chemotactic
  - Arming
- White Blood Cells in inflammation as a result of T-cell lymphokines
Life cycle compensation: larval deposition

Molecular Mimicry

Smithers' Experiment: proves Molecular Mimicry by worm transplants between hosts

Immunity against Schistosomules

Antibody and white blood cells most effective against schistosomules

Trypanosoma Gambiensis

African sleeping sickness
Parasitemia fluctuates due to:
- Specific antibody against glycoprotein coat
- Changing glycoprotein coat
Alternate expression of genes controlling variant specific surface glycoproteins
Variant Specific Glycoprotein (VSG) coat

Malaria

Means "bad air"
Endemic in 90 countries; 1.5B people exposed; 750,000 die mostly in Africa
Vector: Anopheles mosquito
Types:
- Plasmodium vivax (80% of cases, tropics, subtropics, temperate zones)
- Plasmodium falciparum (15% of cases, tropics)
- Plasmodium ovalae (rare, West Africa)
- Plasmodium malaria (rare and spotty in locations)
Human is the intermediate host; Mosquito is the definitive host
Clinical syndromes:
- Acute Benign: P.vivax, P.ovale, P.malaria
- Acute Malignant: P.falciparum
- Cerebral malaria: capillary obstruction and ring hemorrhage
- Blackwater fever: P.falciparum, acute hemolytic syndrome
- Malarial Cachexia: all species, wasting away from repeated paroxysms
General pathologic changes:
- Anemia
- Enlarged spleen and liver
Diagnosis: thick and thin blood smear, response to chemotherapy

Cryptosporidium and Toxoplasma

Cryptosporidium:
- Life cycle
- Symptoms/pathology
- Treatment
- Water treatment considerations
Toxoplasma gondii and Babesia microti:
- Life cycles
- General location/geographic risk
- Symptoms/pathology
- Special precautions or coinfections?