COLD SORE DEFINITION
Cold sores — also called fever blisters — are a common viral infection. They are tiny, fluid-filled blisters on and around your lips. These blisters are often grouped together in patches. After the blisters break, a crust forms over the resulting sore. Cold sores usually heal in two to four weeks without leaving a scar.
Cold sores spread from person to person by close contact, such as kissing. They’re caused by a herpes simplex virus (HSV-1) closely related to the one that causes genital herpes (HSV-2). Both of these viruses can affect your mouth or genitals and can be spread by oral sex. Cold sores are contagious even if you don’t see the sores.
There’s no cure for HSV infection, and the blisters may return. Antiviral medications can help cold sores heal more quickly and may reduce how often they return.
COLD SORE CAUSES
Most cases of cold sores are a consequence of infection with HSV-1 (herpes simplex virus type 1). Infection with HSV-2, usually resulting from oral sex with a person who has genital herpes, is a much less common cause of cold sore outbreaks.
HSV-1 is typically passed on in early childhood when a child is kissed by a person with a cold sore. Shared eating utensils, bathroom items, such as towels or razors, may spread the infection. The virus makes its way to the nerves and lies there dormant until some trigger activates it later on.
The following triggers are known to potentially activate the virus:
- Mental stress
- Deep sadness or upset
- An injury to the affected area
- Intense sunlight.
COLD SORE PATHOPHYSIOLOGY
HSV (both types 1 and 2) belongs to the family Herpesviridae and to the subfamily Alphaherpesvirinae. It is a double-stranded DNA virus characterized by the following unique biological properties:
- Neurovirulence (the capacity to invade and replicate in the nervous system)
- Latency (the establishment and maintenance of latent infection in nerve cell ganglia proximal to the site of infection): In orofacial HSV infections, the trigeminal ganglia are most commonly involved, while, in genital HSV infection, the sacral nerve root ganglia (S2-S5) are involved.
- Reactivation: The reactivation and replication of latent HSV, always in the area supplied by the ganglia in which latency was established, can be induced by various stimuli (eg, fever, trauma, emotional stress, sunlight, menstruation), resulting in overt or covert recurrent infection and shedding of HSV. In immunocompetent persons who are at an equal risk of acquiring HSV-1 and HSV-2 both orally and genitally, HSV-1 reactivates more frequently in the oral rather than the genital region. Similarly, HSV-2 reactivates 8-10 times more commonly in the genital region than in the orolabial regions. Reactivation is more common and severe in immunocompromised individuals.
Dissemination of herpes simplex infection can occur in people with impaired T-cell immunity, such as in organ transplant recipients and in individuals with AIDS.
HSV is distributed worldwide. Humans are the only natural reservoirs, and no vectors are involved in transmission. Endemicity is easily maintained in most human communities owing to latent infection, periodic reactivation, and asymptomatic virus shedding.
HSV is transmitted by close personal contact, and infection occurs via inoculation of virus into susceptible mucosal surfaces (eg, oropharynx, cervix, conjunctiva) or through small cracks in the skin. The virus is readily inactivated at room temperature and by drying; hence, aerosol and fomitic spread are rare.
COLD SORE SYMPTOMS
A symptom is something the patient feels and reports, while a sign is something other people, including a doctor or a nurse may detect. For example, pain may be a symptom while a rash may be a sign.
Many people infected with the herpes simplex virus have no symptoms and will never know they are infected, until an outbreak of cold sores occurs (if ever one does). If there are symptoms with a primary infection, they may be severe.
Signs and symptoms of the primary infection
(Primary infection – the original outbreak of an illness against which the body has had no opportunity to build antibodies.)
In the majority of cases there are no detectable signs or symptoms. When they do occur, usually in very young children, they may be severe, and can include:
- Mouth or tongue lesions
- Blisters in the mouth
- Mouth ulcers
- Mouth or tongue pain
- Lip swelling
- Possible swallowing difficulties
- Sore throat
- Swollen glands
- Elevated body temperature
- Dehydration (body does not have enough water)
COLD SORE DIAGNOSIS
To see if you have the virus, your doctor may simply examine the cold sore or may take a culture from it. Your doctor may also test your blood for antibodies to the herpes simplex virus (HSV). A positive antibody test only proves that you have the virus, but does not indicate whether or not the virus is active or when you may have acquired it.
COLD SORE TREATMENT
Cold sores generally clear up without treatment in two to four weeks. Several types of prescription antiviral drugs may speed the healing process. Examples include:
- Acyclovir (Xerese, Zovirax)
- Valacyclovir (Valtrex)
- Famciclovir (Famvir)
- Penciclovir (Denavir)
Some of these products are packaged as pills to be swallowed. Others are creams to be applied to the sores several times a day. In general, the pills work better than the creams. For very severe infections, some antiviral drugs can be given with an injection.