# Clinical Cases: Pediatric Infectious Diseases

## Case 1: Kawasaki Disease

### Patient Demographics
- **Age:** 3-year-old male
- **Sex:** Male

### Chief Complaint
"He's had a high fever for 5 days that won't go away."

### History of Present Illness
A 3-year-old previously healthy male presents with 5 days of persistent high fever (39.5-40.5C) despite alternating acetaminophen and ibuprofen. Mother reports he developed a rash on day 2 of illness that began on the trunk and spread to extremities. His eyes became red and "bloodshot" without discharge on day 3. He has been extremely irritable and refusing to eat. Parents noted his lips became cracked and red, and his tongue looked "bumpy." Today they noticed swelling of his hands and feet. He was seen at urgent care on day 3 and started on amoxicillin for presumed strep throat, but the fever has continued. No respiratory symptoms, vomiting, or diarrhea.

### Growth Parameters
- **Height:** 97 cm (60th percentile)
- **Weight:** 15 kg (55th percentile)

### Physical Examination
- **General:** Ill-appearing, irritable child, inconsolable
- **Vital signs:** T 40.1C, HR 140, RR 28, BP 95/60
- **HEENT:**
  - Bilateral bulbar conjunctival injection without exudate
  - Erythematous, dry, cracked lips
  - "Strawberry tongue" - erythematous tongue with prominent papillae
  - Oropharyngeal erythema
  - Unilateral cervical lymphadenopathy (2.5 cm, mobile, tender)
- **Cardiovascular:** Tachycardia, no murmur, bounding pulses
- **Respiratory:** Clear breath sounds
- **Abdomen:** Soft, mildly tender, no hepatosplenomegaly
- **Extremities:** Erythema and edema of hands and feet, induration of palms and soles
- **Skin:** Polymorphous maculopapular rash over trunk and extremities, no vesicles
- **Neurologic:** Irritable but alert

### Workup
- **CBC:** WBC 18,500 (80% neutrophils), Hgb 10.8, Platelets 420,000
- **CMP:** Na 132, otherwise normal
- **ESR:** 85 mm/hr (elevated)
- **CRP:** 14.2 mg/dL (elevated)
- **Urinalysis:** Sterile pyuria (25 WBC/hpf, negative culture)
- **AST/ALT:** 68/72 U/L (mildly elevated)
- **Albumin:** 2.8 g/dL (low)
- **Echocardiogram:** Mild dilation of proximal left coronary artery (LAD z-score +2.7), normal RCA, no pericardial effusion

### Diagnosis
**Kawasaki disease with coronary artery involvement**

### Clinical Reasoning
This child meets classic diagnostic criteria for Kawasaki disease with >=5 days of fever plus 4 of 5 principal features: (1) bilateral conjunctival injection, (2) oral mucosal changes (cracked lips, strawberry tongue), (3) extremity changes (edema/erythema), (4) polymorphous rash, and (5) cervical lymphadenopathy >1.5 cm. Supporting laboratory findings include elevated inflammatory markers, sterile pyuria, thrombocytosis (or normal early in disease), and hypoalbuminemia. The echocardiogram showing coronary artery dilation (z-score >2.5) confirms cardiac involvement, making prompt treatment essential.

### Management
1. **IVIG:** 2 g/kg IV as single infusion over 10-12 hours
2. **High-dose aspirin:** 80-100 mg/kg/day divided q6h until afebrile for 48-72 hours
3. **Then low-dose aspirin:** 3-5 mg/kg/day (antiplatelet) for 6-8 weeks minimum
4. **If IVIG-refractory (fever >36 hours after IVIG):**
   - Second dose of IVIG 2 g/kg, OR
   - IV methylprednisolone
   - Consider infliximab for refractory cases
5. **Cardiac monitoring:**
   - Repeat echocardiogram at 2 weeks and 6-8 weeks
   - If coronary abnormalities persist, long-term cardiology follow-up
   - If coronary aneurysms develop, anticoagulation may be needed
6. **Avoid live vaccines for 11 months after IVIG** (MMR, varicella)

### Clinical Image
![Kawasaki disease features](case_01_image.jpg)

**Image Description:** Clinical photograph composite demonstrating classic features of Kawasaki disease including conjunctival injection, strawberry tongue, and erythematous cracked lips.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Kawasaki_symptoms_A.png
**License:** CC BY 3.0

---

## Case 2: Bacterial Meningitis

### Patient Demographics
- **Age:** 8-month-old female
- **Sex:** Female

### Chief Complaint
"My baby has had a fever and won't stop crying."

### History of Present Illness
An 8-month-old female presents with 2 days of fever up to 39.8C, progressive irritability, and decreased feeding. She initially had mild upper respiratory symptoms (runny nose, cough) but over the past 12 hours has become increasingly lethargic and inconsolable. She vomited twice today and has had poor urine output. Parents note that she seems uncomfortable when picked up and arches her back when held. She had been well until this illness and is up-to-date on immunizations through 6 months. She attends daycare.

### Growth Parameters
- **Weight:** 8.2 kg (50th percentile)
- **Length:** 68 cm (50th percentile)
- **Head circumference:** 44 cm (75th percentile)

### Physical Examination
- **General:** Ill-appearing, lethargic, high-pitched cry, difficult to console
- **Vital signs:** T 39.5C, HR 180, RR 42, BP 80/50, SpO2 98%
- **HEENT:**
  - Anterior fontanelle full and bulging
  - No papilledema visualized
  - Bilateral otitis media (bulging, erythematous TMs)
- **Neck:** Unable to assess nuchal rigidity (infant crying)
- **Cardiovascular:** Tachycardia, pulses 2+ throughout, cap refill 2 sec
- **Respiratory:** Mild tachypnea, clear breath sounds
- **Abdomen:** Soft, non-distended
- **Skin:** No petechiae or purpura, no rash
- **Neurologic:**
  - Lethargic, weak cry
  - Hypotonia
  - Brudzinski sign not assessable
  - Jitteriness noted

### Workup
- **CBC:** WBC 24,500 (85% neutrophils, 10% bands), Hgb 11.0, Platelets 185,000
- **CMP:** Na 133, glucose 95, otherwise normal
- **Blood culture:** Obtained
- **Procalcitonin:** 8.5 ng/mL (highly elevated)
- **Lumbar puncture CSF analysis:**
  - WBC: 2,850/mcL (92% neutrophils)
  - RBC: 50/mcL
  - Protein: 280 mg/dL (elevated)
  - Glucose: 18 mg/dL (serum glucose 95; ratio 0.19, very low)
  - Gram stain: Gram-positive diplococci
  - Culture: Pending
- **CT head (prior to LP given bulging fontanelle):** No mass lesion, mild meningeal enhancement

### Diagnosis
**Bacterial meningitis, likely Streptococcus pneumoniae**

### Clinical Reasoning
This infant presents with classic signs of bacterial meningitis: fever, irritability progressing to lethargy, bulging fontanelle, vomiting, and CSF findings showing pleocytosis with neutrophil predominance, elevated protein, and markedly decreased glucose (CSF:serum ratio <0.4). Gram-positive diplococci are consistent with Streptococcus pneumoniae, the most common cause of bacterial meningitis in this age group in the post-Hib vaccine era. The concurrent otitis media suggests a potential source of hematogenous spread.

### Management
1. **Empiric antibiotics (started immediately):**
   - Vancomycin 60 mg/kg/day IV divided q6h (covers DRSP)
   - Ceftriaxone 100 mg/kg/day IV divided q12h
2. **Dexamethasone:** 0.15 mg/kg IV q6h x 4 days (started before or with first antibiotic dose to reduce hearing loss risk)
3. **Supportive care:**
   - IV fluids (avoid overhydration - risk of SIADH and cerebral edema)
   - Monitor for seizures
   - Frequent neurologic checks
4. **Narrow antibiotics** when culture and sensitivities return
5. **Duration:** 10-14 days for pneumococcal meningitis
6. **Close contacts:** Not required for pneumococcal meningitis (would be needed for meningococcal)
7. **Follow-up:**
   - Audiology evaluation before discharge (hearing loss is major complication)
   - Neurodevelopmental follow-up
   - Repeat LP not routinely needed if clinically improving

### Clinical Image
![CSF Gram stain pneumococcus](case_02_image.jpg)

**Image Description:** Gram stain of cerebrospinal fluid demonstrating gram-positive diplococci (lancet-shaped) characteristic of Streptococcus pneumoniae.

**Source:** CDC Public Health Image Library
**URL:** https://phil.cdc.gov/Details.aspx?pid=2896
**License:** Public Domain

---

## Case 3: Viral Exanthem - Roseola

### Patient Demographics
- **Age:** 11-month-old female
- **Sex:** Female

### Chief Complaint
"She had a high fever for 3 days, and now she has a rash."

### History of Present Illness
An 11-month-old previously healthy female is brought in because of a new rash. She had high fevers (up to 40.5C) for the past 3 days. She was fussy during the fever but continued to drink and had no other symptoms. Parents gave acetaminophen and ibuprofen around the clock. She was seen in the ED on day 2 of fever; urinalysis and blood work were unremarkable, and she was sent home with instructions for supportive care. This morning, the fever resolved completely, and shortly afterward, parents noticed a red rash appearing first on her trunk that has now spread to her face and extremities. She is now acting like her normal self - playful and eating well.

### Growth Parameters
- **Weight:** 9.0 kg (50th percentile)
- **Length:** 73 cm (50th percentile)
- **Head circumference:** 45 cm (50th percentile)

### Physical Examination
- **General:** Happy, playful infant, no distress
- **Vital signs:** T 37.2C, HR 120, RR 28
- **HEENT:**
  - Anterior fontanelle soft, flat
  - Mild rhinorrhea
  - TMs normal
  - Posterior cervical and occipital lymphadenopathy (small, mobile, non-tender)
- **Cardiovascular:** Normal
- **Respiratory:** Clear
- **Abdomen:** Soft, non-tender
- **Skin:** Discrete, rose-pink, blanching maculopapular rash predominantly on trunk with spread to neck, face, and proximal extremities; non-pruritic; appears similar to rubella rash
- **Neurologic:** Normal, alert, interactive

### Workup
- **No additional workup needed** - classic clinical presentation
- **Previous ED labs (for reference):**
  - CBC: WBC 5,200 (lymphocyte predominant), Hgb 11.5, Platelets 220,000
  - UA: Normal
  - No blood culture obtained

### Diagnosis
**Roseola infantum (Exanthem subitum) - Human Herpesvirus 6 (HHV-6) infection**

### Clinical Reasoning
This is a textbook presentation of roseola: high fever (often 40-40.5C) for 3-4 days in an otherwise well-appearing infant, followed by defervescence and sudden appearance of a characteristic rose-pink macular/maculopapular rash starting on the trunk. The relative leukopenia with lymphocyte predominance is typical. The age (6 months to 2 years) and clinical course are pathognomonic. No laboratory confirmation is needed. The posterior cervical/occipital lymphadenopathy is a supportive finding.

### Management
1. **Reassurance:** This is a benign, self-limited viral illness
2. **Supportive care:**
   - Antipyretics as needed (fever has resolved)
   - Adequate hydration
3. **Education:**
   - Rash will fade within 1-3 days without treatment
   - No isolation needed once afebrile
   - The child is contagious during febrile phase, not during rash phase
4. **Return precautions:**
   - Fever recurrence
   - New symptoms
   - Seizure (febrile seizures can occur with high fever in roseola)
5. **No antibiotics indicated**

### Clinical Image
![Roseola rash](case_03_image.jpg)

**Image Description:** Clinical photograph demonstrating the characteristic rose-pink maculopapular rash of roseola infantum (exanthem subitum) on the trunk of an infant.

**Source:** Wikimedia Commons
**URL:** https://commons.wikimedia.org/wiki/File:Roseola_on_a_21-month-old_girl.jpg
**License:** CC BY 2.0