Herpes Simplex Virus (HSV)

Microbiology

Epidemiology
- HSV has been prospectively cultured from 78% of ARDS patients -> however, isolation does not imply infection
- May present without any antecedent HSV mucocutaneous lesions
Diagnosis
- FOB:
  - Diffuse Erythema:
  - Pearl-White Fibrinous Plaques:
  - Diffuse Bronchial Wall Edema:
  - BAL Cytology: intranuclear inclusions (dark material in nuclei) and diagnostic triple-M nuclear features of HSV infection:
    - Molding (nuclei abut and line up with each other)
    - Margination (condensation of nuclear chromatin along the margin of nuclei)
    - Multinucleation
Clinical: bronchospasm unresponsive to conventional therapy (see Obstructive Lung Disease, [[Obstructive Lung Disease]])

Risk Factors
- Advanced Age
- Human Immunodeficiency Virus (HIV) (see Human Immunodeficiency Virus, [[Human Immunodeficiency Virus]])
- Immunosuppression
Physiology: spread may occur form oral/labial lesion to airway or esophagus
Diagnosis
- FOB: predominantly central bronchial 5-15 mm heaped-up mucosal ulcerations (slowly progressive and may coalesce) on white or gray base with surrounding erythema
  - Brush of lesion: HSV-DFA may be positive/HSV culture may be positive
- CXR/Chest CT Patterns
  - Normal CXR: usual pattern in elderly cases
Clinical
- Painful Oral/Labial/Pharyngeal Mucosal Ulcerations (see Pharyngitis, [[Pharyngitis]]): usually absent in elderly cases
- Dyspnea
- Wheezing: some elderly cases may present mainly with wheezing (typically refractory bronchospasm) and respiratory failure (notably without previous history of lung disease)
- Chest Pain
- Cough
- Dysphagia (if esophagus involved)
- Diaphoresis
- Fever/Chills
- Hypotension: may occur

Risk Factors
- Burns
- Human Immunodeficiency Virus (HIV) (see Human Immunodeficiency Virus, [[Human Immunodeficiency Virus]])
- Immunosuppression
- Malignancy
- Neonates
- Post-Transplant
Diagnosis
- CXR/Chest CT Patterns
  - Focal or multifocal infiltrates (in cases of direct extension)
  - Diffuse bilateral infiltrates (in cases of hematogenous spread)
Clinical
- Pneumonia-Like Presentation (see Pneumonia, [[Pneumonia]])
- Acute Lung Injury-ARDS (see Acute Lung Injury-ARDS, [[Acute Lung Injury-ARDS]])
- Pleural Effusion (see Pleural Effusion-Exudate, [[Pleural Effusion-Exudate]])

Genital Herpes Simplex Virus (HSV)
- Painful, Genital Ulcers
- Headache
- Fever
- Tender Inguinal Lymphadenopathy

Vesicular Skin Lesions (see Vesicular-Bullous Skin Lesions, [[Vesicular-Bullous Skin Lesions]])
Erythema Multiforme (see Erythema Multiforme, [[Erythema Multiforme]])
Stevens-Johnson Syndrome (SJS)/Toxic Epidermal Necrolysis (TEN) (see Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis, [[Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis]])

Acyclovir (see Acyclovir, [[Acyclovir]])
- Dose/Administration: 5 mg/kg IV q8 hrs (with optimal duration unknown)
- Decrease dose for /CrCl <50 mL/min (high drug levels in these patients may cause encephalopathy, seizures)
- Adverse Effects: N/V/D, headache, rash
- Pregnancy: safe during first trimester
Foscarnet (see Foscarnet, [[Foscarnet]])
- Dose/Administration: 40 mg/kg IV q8 hrs x 14-21 days
- For acyclovir-resistant HSV
Prophylactic Acyclovir (see Acyclovir, [[Acyclovir]])
- Decreases HSV isolation rates in the ICU, but does not impact outcome

Prevention of lower respiratory Herpes simplex virus infection with acyclovir in patients with the adult respiratory distress syndrome. Am Rev Respir Dis 1987; 136:402-405
Herpetic tracheobronchitis. Ann Intern Med 1988; 109:229-233
Herpes simplex virus involvement of the lower respiratory tract following surgery. Chest 1994; 106(suppl):8S-14S [MEDLINE]