Measles Case Study Quiz

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Questions and Answers

What condition was Moyo diagnosed with upon arrival at the clinic?

Bacterial meningitis

Viral encephalitis (correct)

Pneumonia

Septicemia

What was the significant consequence of the measles epidemic mentioned in the case history?

Increased vaccination rates

Isolation of affected families

A high death toll among the infected (correct)

Development of a new antiviral treatment

What was Moyo's mother's initial response regarding his vaccination status?

She stated he was vaccinated recently.

She was unsure and needed to check records.

She was evasive and admitted he had not been vaccinated. (correct)

She claimed Moyo had been vaccinated multiple times.

Which statement describes the measles virus?

It produces a negative-sense, single-stranded RNA virus. Signup and view all the answers

What action did health officials take in response to the measles cases in the village?

They forcibly vaccinated more than 100 children. Signup and view all the answers

What is the primary function of the epidermis?

To block microbial access to deeper tissues Signup and view all the answers

Which of the following components are found in the dermis?

Blood vessels Signup and view all the answers

Which type of rash is characterized by small, solid, and elevated lesions?

Papular Signup and view all the answers

What is the primary component of mucous membranes that serves as a barrier?

Epithelial tissue Signup and view all the answers

Which part of the eye is considered internal?

Retina Signup and view all the answers

Which type of rash is characterized by small blisters forming?

Vesicular Signup and view all the answers

What does an exanthem refer to?

Widespread skin rash with systemic symptoms Signup and view all the answers

Which layer of the skin contains keratin?

Epidermis Signup and view all the answers

What is the primary virus responsible for cold sores?

HSV-1 Signup and view all the answers

What is the only known reservoir for smallpox?

Humans Signup and view all the answers

Which antiviral medication is commonly used to treat primary infections of herpes?

Acyclovir Signup and view all the answers

What type of contact transmits smallpox?

Direct or indirect contact Signup and view all the answers

Which variant of smallpox is generally more severe?

Variola major Signup and view all the answers

What treatment has not been approved by the FDA for smallpox?

Specific medical treatments Signup and view all the answers

Herpetic keratitis affects which part of the body?

Cornea Signup and view all the answers

How can HSV-2 be transmitted?

Primarily through sexual contact Signup and view all the answers

What is the role of coagulase in Staphylococcus aureus infections?

It coats the bacteria with fibrin, walling off the infection. Signup and view all the answers

Which of the following is a characteristic of Methicillin-resistant Staphylococcus aureus (MRSA)?

It can interfere with cell wall synthesis. Signup and view all the answers

What type of skin infection is folliculitis associated with?

Superficial infection of hair follicles. Signup and view all the answers

What is the primary treatment for Methicillin-resistant Staphylococcus aureus (MRSA) infections?

Vancomycin Signup and view all the answers

Which toxin produced by S. aureus causes a blistering condition known as scalded-skin syndrome?

Exfoliative toxin Signup and view all the answers

What is the most common manifestation of a deep infection of hair follicles caused by S. aureus?

Furuncle Signup and view all the answers

How is Staphylococcus aureus typically able to evade the immune system?

By forming a fibrin wall around the infection. Signup and view all the answers

What type of infections does S. aureus frequently require for treatment?

Surgical drainage and antibiotic therapy. Signup and view all the answers

What is the primary characteristic of dermatophytes?

They mostly affect cool, moist, keratinized tissues. Signup and view all the answers

Which of the following conditions is correctly matched with its location?

Tinea cruris - groin Signup and view all the answers

What is the causative agent of tinea versicolor?

Malassezia Signup and view all the answers

Which type of tinea primarily affects small children?

Tinea capitis Signup and view all the answers

Which of the following correctly describes candidal intertrigo?

It occurs between areas where skin touches and rubs together. Signup and view all the answers

What factor contributes to the hypopigmented lesions seen in tinea versicolor?

Invasion of the stratum corneum Signup and view all the answers

Which species of fungi is part of the normal flora but can also cause disease?

Candida albicans Signup and view all the answers

Which of the following statements is true about the characteristics of fungi?

Fungi can be filamentous or single-celled. Signup and view all the answers

What are the common types of fungi responsible for causing fungal keratitis?

Aspergillus, Fusarium, and Candida Signup and view all the answers

What diagnostic methods are used for identifying fungal keratitis?

Culturing, PCR amplification, and confocal microscopy Signup and view all the answers

Which of the following treatments are generally used for superficial fungal keratitis?

Natamycin or Amphotericin B Signup and view all the answers

What is a key characteristic of Acanthamoeba species that causes parasitic keratitis?

It exists as a cyst under unfavorable conditions. Signup and view all the answers

What symptom may indicate an Acanthamoeba infection in the eye?

Persistent eye redness, pain, and tearing Signup and view all the answers

In staphylococcal scalded skin syndrome (SSSS), why are no organisms typically found in the blister fluid?

The toxic shock syndrome toxin is secreted from another site. Signup and view all the answers

What characteristic identifies Streptococcus pyogenes in cases of cellulitis?

It is encapsulated and grows in chains. Signup and view all the answers

Which of these pathogens is primarily responsible for non-contact lens related keratitis?

Acanthamoeba species Signup and view all the answers

Study Notes

Chapter 19: Infections of the Skin and Eye

Chapter Objectives:
- Correlate skin and eye anatomy/physiology to infectious processes.
- Differentiate viral, bacterial, and parasitic skin/eye infections by symptoms.
- Relate pathogens' mechanisms to disease prevention strategies.
- Connect pathogen physiology to antimicrobial treatment/prevention.

Rash Ruins Vacation Scenarios

Scenario 1 (Nate):
- 69-year-old type 2 diabetic.
- Awakened with a tingling sensation extending from the spine to the rib cage.
- Discomfort worsened to severe pain.
- Developed small blisters along irritated red skin.
- Referred to a local doctor by hotel.
Scenario 1 (Diagnosis):
- Diagnosed with St. Anthony's fire (shingles).
- Caused by the same virus (VZV) that causes chickenpox.
- VZV had previously nested in a spinal nerve root.
Scenario 1 (Treatment):
- Prescribed antiviral and pain relief medication.
- Instructed to maintain good blood sugar control.
- Advised to follow up with a regular physician.
Scenario 1 (Follow-Up):
- Trip to Italy cut short.
- Diagnosis and treatment plan confirmed in the U.S.
- St. Anthony's fire is another name for shingles.
Scenario 1 (Resolution):
- Recovered from shingles.
- Received antiviral medication and rest.
- Able to return to Italy for a successful later trip.

19.1 Anatomy of Skin and Eye

Section Objectives:
- List skin cell components and functions.
- Describe dermis/epidermis structural differences/similarities.
- Describe skin's role in disease prevention.
- Distinguish between eye's internal/external parts.
Skin (General):
- Largest human organ (16-22 sq ft).
- Acts as a barrier, preventing microbial access to deeper tissues.
Skin Layers:
- Superficial layer (epidermis): 5 layers of dead keratinocytes.
- Deep layer (dermis): connective tissue, cells (blood vessels, nerves, hair follicles, sweat glands).
Eye Structure (External):
- Eyelids, Cornea, Lens, Iris, Pupil, Sclera.
Eye Structure (Internal):
- Retina, Macula, Vitreous humor.

19.2 Viral Infections of the Skin

Section Objectives:
- Classify viruses causing skin rashes by genomic structure.
- Explain viral skin infection sequelae pathogenesis.
- Diagnose viral skin infections based on patient signs/symptoms.
- Recommend treatment/prevention options for viral skin infections.

19.3 Bacterial Infections of the Skin

Section Objectives:
- Name bacterial pathogens causing common skin infections.
- Categorize skin infections by bacterial physiology.
- List clinical/laboratory methods of diagnosing bacterial skin infections.
- Develop treatment/prevention plans for bacterial skin infections.

Staphylococcal Skin Infections

Staphylococcus aureus:
- Normal inhabitant of the nose.
- Causes skin infections.
- Can lead to superficial or deep infections (folliculitis, furuncle, carbuncles).
- Produces enzymes (coagulase) hindering immune system response.
- Produces Exotoxins:
  - Toxic shock syndrome toxin (TSST) causing Toxic shock syndrome.
  - Exfoliative toxin causing scalded skin syndrome.
Methicillin-resistant S. aureus (MRSA):
- Resistant to methicillin.
- Commonly found in hospitals but becoming more common in the community.
- Vancomycin is the treatment of choice.

Streptococcal Skin Infections

Streptococcus pyogenes (GAS):
- Inhabits human nasopharynx and skin.
- Causes Necrotizing fasciitis ("flesh-eating" disease).
- Produces Exotoxins:
  - SPEs, which trigger massive inflammation and shock.
- Infections can sometimes be polymicrobial.
Rheumatic fever:
- Develops after a primary GAS infection.
- Autoreactive antibodies against cardiac antigens damage tissues.
Acne vulgaris:
- Affects 60-70% of Americans.
- Results from blocked hair follicles (comedones)
- Common types include; Open comedones (blackheads), Closed comedones (whiteheads). Inflammatory acne, cystic acne.
- Factors contributing; Genetics, Hormones, And Gram-positive bacteria Propionibacterium acnes.
- P. acnes metabolises sebum and leads to inflammation.

19.4 Fungal Infections of the Skin

Section Objectives:
- Outline common fungal skin infections by etiology.
- Compare dermatophytes to other fungi infecting skin.
- Explain how common fungal infections are clinically diagnosed.

Fungi

Dermatophytes:
- Epidermophyton, Trichophyton, Microsporum.
- Infects skin, hair, nails.
- Tinea capitis (scalp), Tinea corporis (body), Tinea cruris (jock itch), Tinea pedis (foot), Tinea unguium (nails).
Tinea versicolor:
- Caused by *Malassezia *.
- Characterised by hypopigmented lesions (lighter coloration).
- Common in warm, humid climates.
Candida:
- Dimorphic yeasts.
- Part of the body's normal flora.
- Can infect skin, mucous membranes, and other organs.
- Can cause inflammation and skin irritation.

19.5 Skin Infections of Special Circumstances

Not included (in this chapter)

19.6 Eye Infections

Section Objectives:
- Identify viral, bacterial, and fungal eye infection causes.
- Describe pink eye (conjunctivitis) symptoms/etiology.
- Explain the pathogenesis of infectious keratitis/endophthalmitis differences.
- Outline the corneal epithelium's relationship to fungal keratits.

Viral Eye Infections

Herpes viruses:
- Major cause of keratitis/keratoconjunctivitis.
- Herpes Simplex 1 (HSV-1) causing most cases.
- Lesions might not cause damage at first but reactivation leads to damage/blindness.
- Treated with antiviral medications (acyclovir, trifluridine).
- Herpes zoster ophthalmicus:
  - Shingles outbreak in the ophthalmic division of the trigeminal nerve.
  - Painful and can also affect eyes.
  - Treated with antiviral medications.

Bacterial Eye Infections

Bacterial conjunctivitis:
- Affects one eye.
- Acute, painful, purulent.
- Caused by pyogenic bacteria (like Staph/Strep) leading to irritation and discharge.
- Can be identified and treated accordingly.
Chlamydia trachomatis:
- Obligate intracellular bacteria.
- Can cause infection through vaginal contact.
- Infants are often treated at birth to avoid potential for eye infections.
- Often affects the conjunctiva.
Trachoma:
- Most common cause of infectious blindness worldwide.
- Often transmitted by direct eye contact.
- Can cause the eyelashes to turn inward (trichiasis).
- Irritates and potentially scars the cornea.
Neisseria gonorrheae:
- Causes ophthalmia neonatorum (eye infection in newborns).
- Transmitted during birth from an infected mother.

Fungal and Parasitic Eye Infections

Fungal keratitis:
- Caused by fungi (Fusarium, Aspergillus, Candida).
- Often originates in environments such as; warm, humid; or from compromised areas.
- Diagnosis requires; Culturing the fungi, Polymerase Chain Reaction (PCR), and Confocal microscopy.
- Frequently requires systemic treatment (antifungals like Natamycin or Amphtericin B).
Parasitic keratitis:
- Due to Acanthamoeba species (protozoa).
- Often found in environments with stagnant water or air conditioning systems.
- If left untreated eye may become progressively irritated and damaged along with potential loss of vision.

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Description

Test your knowledge on the key details of Moyo's case study regarding a measles epidemic. This quiz covers Moyo's diagnosis, vaccination status, and health officials' responses. Challenge yourself to recall significant facts from the scenario presented.