Herpes simplex

Herpes simplex virus (HSV) is a very common acute, self-limiting vesicular eruption. Humans are the only natural host of HSV and the virus does not survive for long in the external environment (Goodyear, 2000). It is highly contagious and spreads by direct contact with infected individuals when the virus comes into contact with mucosal surfaces or broken skin. In primary infection, a non-immune person is exposed to contaminated saliva or secretions from the pharynx, genitalia or eyes at close contact. The virus penetrates the epidermis and replicates in the epithelial cells at the site of the infection (Gawkrodger, 2003) in the primary infection. The latent non-replicating virus then travels down to the dorsal root ganglion where it can lie dormant. At some later date, following exposure to a trigger it can reactivate and travel back down the sensory nerve and reinfect the epithelial cells at the nerve ending. This ability to recur is a hallmark of HSV infection. It usually happens at the same site, e.g. cold sore. Common triggers are colds, strong sunlight, stress and menstruation (Docherty, 2001). HSV is preceded by tingling or burning in the affected area – the prodromal phase. The highest rate of HSV infections is in the first 5 years of life and then after the onset of sexual maturity (Goodyear, 2000). It is rare under 6 months of age due to passive transfer of maternal antibodies.

There are two types of HSV. Type 1 is usually facial or non-genital and Type 2 is genital due to sexual contact but crossover is seen.

Primary infection usually occurs in children which may often go unrecognised as they are sub-clinical. In those with symptoms, acute inflammation of the gums and mouth (gingivostomatitis) is common. The children have vesicles on their lips and mucous membranes which rapidly erode and are painful. Clusters of vesicles arise on a background of erythema and over about 10–12 days erode to become crusted lesions. Children are miserable, may be pyrexial and can have problems eating and drinking. In severe cases, intravenous fluids may be needed. Some children may also have corneal involvement. There may be local lymphadenopathy. This can last for about 2 weeks.