A 21 year old female patient presents to ED complaining of a painful blistering rash on her genitals and swollen inguinal lymph nodes, following a 3 - 4 day flu-like illness. Which of the following pathogens is most likely responsible for her symptoms:
Herpes simplex virus may be subtype 1 or type 2; HSV-1 is generally associated predominantly with the mouth, eye, and central nervous system and HSV-2 is found most often in the anogenital tract, although this is not mutually exclusive.
Herpes simplex is transmitted through direct contact. It invades skin locally producing skin vesicles by its cytolytic activity. Local multiplication is followed by viraemia and systemic infection (although this may go unnoticed) and subsequent lifelong latent infection.
The virus enters peripheral sensory nerves in primary infection and migrates along axons to sensory ganglia in the CNS where it remains latent. Reactivation may be triggered by physical factors e.g. injury, hormones, UV light, or psychological stress.
Cell-mediated immunity, especially the action of cytotoxic T-cells, is essential in the control of herpesvirus infections and patients with T-cell deficiency are at particular risk of reactivation and severe infection.
Clinical manifestations include:
Diagnosis of herpes simplex by nucleic acid amplification testing (NAAT) of vesicle fluid, genital or mouth swabs is the most sensitive and specific method of diagnosis, although the virus grows readily and can be visualised by electron microscopy (EM).
The ratio between serum and CSF antibody may indicate local production and can help in the diagnosis of HSV encephalitis. CT/MRI of the brain may detect temporal lobe lesions that are typical of herpes encephalitis.
Treatment of herpes simplex infection should start as early as possible and usually within 5 days of the appearance of the infection.
In individuals with good immune function, mild infection of the eye (ocular herpes) and of the lips (herpes labialis or cold sores) is treated with a topical antiviral drug. Primary herpetic gingivostomatitis is managed by changes to diet and with analgesics. Severe infection, neonatal herpes infection or infection in immunocompromised individuals requires treatment with a systemic antiviral drug. Primary or recurrent genital herpes simplex infection is treated with an antiviral drug given by mouth. Persistence of a lesion or recurrence in an immunocompromised patient may signal the development of resistance.
Specialist advice should be sought for systemic treatment of herpes simplex infection in pregnancy.
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Biochemistry | Normal Value |
---|---|
Sodium | 135 – 145 mmol/l |
Potassium | 3.0 – 4.5 mmol/l |
Urea | 2.5 – 7.5 mmol/l |
Glucose | 3.5 – 5.0 mmol/l |
Creatinine | 35 – 135 μmol/l |
Alanine Aminotransferase (ALT) | 5 – 35 U/l |
Gamma-glutamyl Transferase (GGT) | < 65 U/l |
Alkaline Phosphatase (ALP) | 30 – 135 U/l |
Aspartate Aminotransferase (AST) | < 40 U/l |
Total Protein | 60 – 80 g/l |
Albumin | 35 – 50 g/l |
Globulin | 2.4 – 3.5 g/dl |
Amylase | < 70 U/l |
Total Bilirubin | 3 – 17 μmol/l |
Calcium | 2.1 – 2.5 mmol/l |
Chloride | 95 – 105 mmol/l |
Phosphate | 0.8 – 1.4 mmol/l |
Haematology | Normal Value |
---|---|
Haemoglobin | 11.5 – 16.6 g/dl |
White Blood Cells | 4.0 – 11.0 x 109/l |
Platelets | 150 – 450 x 109/l |
MCV | 80 – 96 fl |
MCHC | 32 – 36 g/dl |
Neutrophils | 2.0 – 7.5 x 109/l |
Lymphocytes | 1.5 – 4.0 x 109/l |
Monocytes | 0.3 – 1.0 x 109/l |
Eosinophils | 0.1 – 0.5 x 109/l |
Basophils | < 0.2 x 109/l |
Reticulocytes | < 2% |
Haematocrit | 0.35 – 0.49 |
Red Cell Distribution Width | 11 – 15% |
Blood Gases | Normal Value |
---|---|
pH | 7.35 – 7.45 |
pO2 | 11 – 14 kPa |
pCO2 | 4.5 – 6.0 kPa |
Base Excess | -2 – +2 mmol/l |
Bicarbonate | 24 – 30 mmol/l |
Lactate | < 2 mmol/l |