HSV-1 primary infection

The mouth.

Most primary infections with HSV-1 are asymptomatic (no apparent symptoms). However, primary infection can cause a variety of clinical symptoms such as infection of the mouth and gums (gingivostomatitis) and a sore throat (pharyngitis) in children. Lesions may occur anywhere in the oral region and may involve the roof and floor of the mouth, as well as the inside of the cheek (the buccal mucosa). Disease may develop over a few days and can be painful.

The child will often be cranky and irritable, unwilling to eat, drink, and swallow and they may also have swollen lymph nodes and a fever. Sometimes these children become so dehydrated that they require hospitalization. In adolescents and adults, primary HSV-1 infection may present as tonsillitis. The tonsils may be tender and covered with a whitish substance, resembling "strep throat".

The swelling and tenderness of the tonsils may result in swallowing difficulties. Sometimes blisters may also be present in the mouth. In people with normal immunity (immunocompetent) the fever will cease and lesions will heal and crust over in a week. Even when no clinical symptoms of primary HSV-1 infection are apparent, some people will shed virus making them infectious.

The skin.

HSV-1 can also infect skin, but only if the skin is damaged, such as in patients with eczema (atopics). In rare instances, primary HSV-1 infection may become wide-spread in many areas of eczema across the body (eczema herpeticum). This condition requires antiviral treatment to limit its proliferation. Children who suck their thumbs may develop herpes on their finger.

Healthcare workers, such as anesthesiologists and dentists, may also develop herpes infected fingers (digits) from patients with cold sores or oral viral shedding. Herpes infection of the finger is called herpetic whitlow. In the immunocompetent patient, most skin lesions will heal within a few weeks, unless there is a complication with a bacterial infection such as Staphylococcus aureus or Group A Streptococcus, which may require antibiotic treatment.

Primary HSV-1 infection has also been associated with a variety of other skin disorders, such as erythema multiforme and Stevens-Johnson syndrome. These conditions are not thought to be directly caused by the virus, but result from an immunological reaction in the skin at the time of infection.

The eye.

A less common but clinically important primary HSV-1 infection site is the eye. Such infection may occur in one or both eyes as conjunctivitis, or as infection of the eyelid with blisters on the lid margin, swelling of the eyelids, and tearing.

The eye itself may also be more extensively involved (keratoconjunctivitis). Occasionally, children with labial herpes or herpetic whitlow may rub their eyes and spread the virus to their eyes in this fashion (autoinoculation). In immunocompromised patients, HSV-1 eye infection may also involve the retina.

Neonatal herpes.

This is primary infection in the neonate, but is discussed under a separate heading below, in conjunction with herpes infection in pregnancy.