Mechanisms of Infectious Disease

Unit 2 Assignment (160 points)

MN551-2: Apply knowledge of tissue and organ structure and function to physiologic alterations in systems and analyze the cause and effect relationship in response to disease.

Select one of the case studies below. In your discussion be sure to include evidence of your knowledge of tissue and organ structure and function to physiologic alterations in systems and analyze the cause and effect relationship in response to disease.


1. Make sure all of the topics in the case study have been addressed.

2. Cite at least three sources—journal articles, textbooks, or evidenced-based websites—to support the content.

3. All sources must have been written within five years.

4. Do not use .com, Wikipedia, or up-to-date, etc., for your sources.

Case Study 1

Mechanisms of Infectious Disease

Thirty-two–year-old Jason is a general laborer, who fell ill shortly after working on a job digging up old water pipes for the town he lived in. The task involved working around shallow pools of stagnant water. Ten days after the contract ended, Jason developed a fever and aching muscles. He also had nausea, vomiting, and diarrhea. Jason’s friend took him to his physician who listened carefully to Jason’s history. She told him she suspected West Nile fever and ordered serological testing. Jason went home to recover and was feeling better by the end of the week.

1. Jason’s physician ordered serological tests. How would antibody titers assist the doctor in confirming his diagnosis?

2. When Jason was feeling at his worst, he had extreme malaise, vomiting, and diarrhea. What stage of the illness was he experiencing at that time? What are the physiological mechanisms that give rise to the signs and symptoms of infectious illness?

3. West Nile virus has a single-stranded RNA genome. How does this virus replicate? In general terms, what are the various effects viruses can have on host cells?

Case Study 2

Innate and Adaptive Immunity

Melissa is a 15-year-old high school student. Over the last week, she had been feeling tired and found it difficult to stay awake in class. By the time the weekend had arrived, she developed a sore throat that made it difficult to eat and even drink. Melissa was too tired to get out of bed, and she said her head ached. On Monday morning, her mother took her to her doctor. Upon completing the physical exam, he told Melissa the lymph nodes were enlarged in her neck and she had a fever. He ordered blood tests and told Melissa he thought she had mononucleosis, a viral infection requiring much bed rest.

1. Innate and adaptive immune defenses work collectively in destroying invasive microorganisms. What is the interaction between macrophages and T lymphocytes during the presentation of antigen?

2. Melissa’s illness is caused by a virus. Where are type I interferons produced, and why are they important in combating viral infections?

3. Humoral immunity involves the activation of B lymphocytes and production of antibodies. What are the general mechanisms of action that make antibodies a key component of an immune response?

Case Study 3

Disorders of the Immune Response

Ahmed has worked as a phlebotomist in the local hospital for the last 7 years. Last year, he began to complain of watery, nasal congestion and wheezing whenever he went to work. He suspected he was allergic to something at the hospital because his symptoms abated when he was at home over the weekends. One day he arrived at work for the morning shift and put on his gloves. Within minutes, he went into severe respiratory distress requiring treatment in the emergency ward. It was determined at that time his allergic response was due to latex exposure.

1. Ahmed experienced a type I, IgE-mediated hypersensitivity response. How can this be determined by his signs and symptoms? How might another type of latex hypersensitivity reaction present?

2. How do T2H cells, mast cells, and eosinophils function to produce the signs and symptoms typical of a type I hypersensitivity disorder?

3. How is it that someone who does not come into direct contact with latex can still have a hypersensitivity response to the material? What do food allergies have to do with latex allergies?

Case Study 4

Inflammation, Tissue Repair, and Wound Healing

Carlton, a six-year-old boy, was playing on a sandy beach with his mother. He began to run along the shoreline when he stepped on the sharp edge of a shell, giving himself a deep cut on his foot. His mother washed his foot in the lake and put on his running shoe to take him home. One day later, Carlton’s foot looked worse. The gash was red and painful. The foot was warm to touch and appeared swollen. Carlton’s mom put some gauze over the wound and prepared to take him to the local community health clinic.

1. What is the physiologic mechanism causing the wound to become red, hot, swollen, and painful? How is this different than the inflammatory response that might occur in an internal organ?

2. What are the immunologic events that are happening at the local level during Carlton’s acute inflammatory response?

3. Nutrition plays an important factor in wound healing. What stages of wound healing would be affected by a deficiency in vitamins A and C?

Case Study 5

Acquired Immunodeficiency Syndrome

Patience is 29 years old and has been HIV positive for nine years. She has remained asymptomatic and is not taking antiretroviral medication. Recently she was at the drop-in clinic to talk to a public health nurse about having a baby through artificial insemination. She said she had met a man who wanted to marry her and have children with her, but she was concerned about the baby contracting HIV. Her latest blood tests indicated her CD4+ count was 380/µL. The PCR test indicated her viral load was 850. The nurse referred her to the physician to discuss antiretroviral therapy during her pregnancy.

1. What are the factors that increase the chance of HIV transmission from mother to infant, and how the transmission occurs?

2. Patience was told that after she became pregnant, she would begin HAART therapy. Describe what this therapy is and what particular antiretroviral medication would be particularly useful to her during her pregnancy. What concern is there about administering certain antiretrovirals early in the pregnancy?

3. Individuals with HIV are prone to contracting opportunistic infections. What are opportunistic infections and the risk factors that leave an individual with HIV particularly prone to contracting this type of illness?

Case Study 6

Blood Cells and the Hematopoietic System

Charlie is a 53-year-old man with non-Hodgkin lymphoma. His treatment has been only modestly successful in delaying the progression of the disease, and he has recently relapsed. His medical team decided to administer aggressive chemotherapy. Knowing that the intensive treatment would have a destructive effect on Charlie’s bone marrow, they removed stem cells from his blood before the chemotherapy began. Afterward, the stem cells were returned by IV to reestablish his bone marrow function.

1. What are the therapeutic advantages of an autologous stem cell transplant on Charlie’s bone marrow and immune system?

2. Before harvesting stem cells, a cytokine growth factor is administered to the patient. What is the benefit of this procedure?

3. Non-Hodgkin lymphoma is a disease involving B and T lymphocytes. What aspects of the immune response are these cells responsible for?

4. When considering erythrocytes, how is the body able to meet hematopoietic demand in conditions such as hemolytic anemia or blood loss?

Case Study 7

Disorders of Hemostasis

Leona is 52 years old and smokes. She is also overweight and has atherosclerosis. When she was given a two-week vacation from work, she packed up her bags and flew from Minnesota to Sydney, Australia, for the trip she always wanted to take. Unfortunately, just three days after she arrived, she was hospitalized when her left calf became inflamed, causing her considerable pain. The physician attending to her told her she developed a deep vein thrombosis.

1. Explain, using your knowledge of hypercoagulability, why the trip to Australia contributed to Leona’s DVT? Why was Leona already at risk for thrombus development?

2. How does Leona’s atherosclerosis affect platelet function? Conversely, what is the effect of increased platelet activity on the development of atherosclerosis?

3. How do atherosclerosis and immobility promote changes in blood coagulation?

4. When Leona was in hospital, she received heparin therapy. Explain why this course of action was taken to treat her DVT. Why was she not given heparin tablets to take back to the hotel with her?

Case Study 8

Disorders of Red Blood Cells

Henry is 77 years old and lives with his daughter and son-in-law. He has chronic renal failure, but likes to get out whenever he can to work in his daughter’s backyard garden. Over the last few months, he began to go outside less often. He said he was feeling unusually tired and he was running out of breath doing the simplest of tasks. He also said his head ached and he often felt dizzy. His daughter took him to his doctor who performed a complete physical examination and diagnosed Henry with anemia.

1. From what you know of Henry’s history, what type of anemia do you suspect he has? How would Henry’s red blood cells appear on a peripheral blood smear?

2. What is the physiological basis that would explain why Henry’s anemia would cause him to have the symptoms he is experiencing?

3. Predict the cellular adaptations erythrocytes undergo when chronic hypoxia is present. How would this be evident on an oxygen–hemoglobin dissociation curve?

Case Study 9

Disorders of White Blood Cells and Lymphoid Tissues

Max is a 60-year-old living in Iowa. For the 27 years, he has been working in the agricultural industry, particularly in the management of corn production. Recently he began to feel weak during work and tired easily. During the night he woke up sweating, and he often felt unusually warm during the day. Max was also surprised that, in spite of eating regularly, his weight was declining and his work pants were now too large for him. Upon physical examination, his physician noted his inguinal lymph nodes were swollen although Max said they were not sore. Subsequent laboratory tests confirmed follicular, non-Hodgkin lymphoma. Chemotherapy in conjunction with rituximab was immediately initiated.

1. What are the key cellular differences between non-Hodgkin lymphoma and Hodgkin lymphoma?

2. The early manifestations of non-Hodgkin lymphoma and Hodgkin lymphoma in lymphatic tissue appear differently. In terms of lymphatic presentation, how would these two diseases appear clinically?

3. What are the pharmacologic properties of rituximab, and what is its mechanism of action on malignant cells?

4. Outline the structure of lymph node parenchyma including the areas where B and T lymphocytes reside. Where did Max’s lymphoma arise?

Assignment Requirements:

Before finalizing your work, you should:

· Ensure you have written at least four double-spaced pages.

· be sure to read the Assignment description carefully (as displayed above);

· consult the Grading Rubric (under the Course Home) to make sure you have included everything necessary; and

· utilize spelling and grammar check to minimize errors.

· follow the conventions of Standard American English (correct grammar, punctuation, etc.);

· be well ordered, logical, and unified, as well as original and insightful;

· display superior content, organization, style, and mechanics; and

· use APA 6th Edition format as outlined in the APA Progression Ladder.

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