Viral Infections of the Mouth

Introduction

Members of the human herpesvirus (HHV) and human papillomavirus (HPV) families are the most common causes of primary viral infections of the oral cavity. Nonetheless, many other viral infections can affect the oral cavity in humans, either as localized or systemic infections. This article discusses viral conditions of the oral cavity, including HHV infection, HPV infection, coxsackievirus infection, mumps, measles (rubeola), and rubella. See Cutaneous Manifestations of HIV Disease and Cutaneous Manifestations of Hepatitis C for information on these viral infections.

For excellent patient education resources, visit eMedicine's Teeth and Mouth Center and Bacterial and Viral Infections Center. Also, see eMedicine's patient education articles Oral Herpes, Canker Sores, Measles, Mumps, Chemical Burns, and Allergic Reaction.

Human Herpesvirus

Background

HHV infections are common in the oral cavity. They may be primary or recurrent infections. Eight types of HHV have been linked with oral disease. These types have different disease patterns in their hosts.

• HHV-1, also known as herpes simplex virus (HSV)–1, causes primary herpetic gingivostomatitis, or oral herpes. In some hosts, it becomes latent and may periodically recur as a common cold sore.
• HHV-2, also known as HSV-2, causes genital herpes and occasionally causes oral disease that is clinically similar to that of HHV-1 infection.
• HHV-3, also known as varicella-zoster virus (VZV), causes the primary infection chickenpox and the secondary reactivation disease herpes zoster.
• HHV-4, also known as Epstein-Barr virus (EBV), causes the primary infection infectious mononucleosis, and it is implicated in various diseases, such as African Burkitt lymphoma, other immunoproliferative disorders, and nasopharyngeal carcinoma. HHV-4 causes oral hairy leukoplakia in patients who are immunosuppressed.¹
• HHV-5, also known as cytomegalovirus (CMV), causes a primary infection of the salivary glands and other tissues, and it is believed to have a chronic form.
• HHV-6, which can produce acute infection in CD4⁺ T lymphocytes, causes roseola infantum, a febrile illness that affects young children. It is believed to chronically persist in salivary gland tissue in some hosts, and oral shedding is the probable route of disease transmission.
• HHV-7 has been isolated from the saliva of healthy adults and has been implicated as one cause of roseola infantum and febrile seizures in children.
• HHV-8 is associated with Kaposi sarcoma (KS), and evidence links it with body-cavity lymphomas and Castleman disease.

Pathophysiology

Herpesvirus family members are icosahedral DNA viruses. A herpesvirus measures approximately 100 nm without an envelope or 150 nm with an envelope. HHVs replicate in the host cell nucleus. Infected saliva or droplets spread the viruses in the oral cavity. The viruses also may be transmitted via oral-genital contact. Viral shedding has been detected before, during, and after the appearance of clinical lesions in patients with recurrent HHV-1 and HHV-2 infections; therefore, lack of visible lesions does not correlate with lack of potential infectivity. In a localized primary infection, the virus penetrates the mucosal epithelium and invades the cells of the basal layer, where the viral DNA inserts into the host DNA.

In HHV-1 and HHV-2 oral infections, viral replication within the oral epithelium may cause lysis of epithelial cells, with vesicle formation. Shallow ulcers with scabs that then heal without scarring follow the formation of vesicles. Herpesviruses establish latent permanent infections in their hosts, although clinical signs of disease may not be detected.

Frequency

• HHV-1: The seroprevalence is approximately 80% in North American adults.
• HHV-2: The seroprevalence is approximately 20% in North American adults.
• HHV-3: The seroprevalence is approximately 95% in North American adults.
• HHV-4: The seroprevalence is approximately 90% in North American adults.
• HHV-5: The seroprevalence is approximately 70% in North American adults.
• HHV-6: The seroprevalence approaches 100% in North American adults.
• HHV-7: The seroprevalence is approximately 85% in adults.
• HHV-8: The global seroprevalence is estimated at 2-10%, although it has been demonstrated to be greater than 28% in Albanian adults, 25% in Albanian children, 18% in Kosovar adults, and greater than 16% in Kosovar children.²

Mortality/morbidity

In children and adults who are immunocompetent, primary herpetic infections may be annoying and uncomfortable, but they rarely cause significant morbidity or mortality.

In individuals who are immunosuppressed, primary herpetic infections can be severe, and, occasionally, they can cause esophagitis, encephalitis, keratoconjunctivitis, and other diseases. The other forms of HHV can result in death. Herpes infections occasionally trigger erythema multiforme.

Age

Primary herpes infections typically occur during childhood or youth, although occasional cases are observed in older individuals. Recurrent HHV-1 infections typically occur throughout life and are particularly triggered by stress, illness, immune compromise, or other factors. Herpes zoster usually affects patients older than 40 years.

Clinical history

HHV-1

When HHV-1 infection recurs, it has different and distinct oral and perioral presentations from primary herpetic gingivostomatitis.

Primary herpes infection (primary herpetic gingivostomatitis) usually occurs in children or adolescents who have not been previously exposed to the virus. Many primary infections are asymptomatic. Symptomatic primary infection, with multiple, small, clustered vesicles in numerous locations, can occur anywhere in the oral cavity, on the perioral skin, on the pharynx, or on the genitalia. Headache, fever, painful lymphadenopathy, and malaise are common. Antibody production follows, and the virus may become latent in sensory ganglia, often the trigeminal ganglion. Primary herpetic gingivostomatitis usually resolves within approximately 14 days.

Recurrent herpes lesions are commonly referred to as cold sores. Recurrent herpes occurs in approximately one third of patients who have experienced primary herpetic gingivostomatitis. When the disease manifests extraorally, prodromal burning or itching often precedes vesicle formation. Recurrent herpes is a more limited disease than primary herpes. Unlike primary herpes, it occurs on keratinized mucosa (usually the lips, attached gingiva, and/or the hard palate). Vesicles are present in one discrete area, typically the same site every time in any given patient. Such sites include the vermilion border of the lips, the perioral skin, the hard palate, or, occasionally, the gingiva or the dorsal aspect of the tongue. Because vesicles can easily rupture intraorally, only an ulcer may be observed in some cases. Lymphadenopathy and systemic manifestations are much milder than in the primary disease. One case report describes HHV-1 infection manifesting as a mass in the piriform sinus.³

Triggers for recurrence may include sunlight exposure, physical or emotional stress, or systemic illness for extraoral lesions and trauma (eg, a dental procedure) for intraoral lesions.

In immunosuppressed individuals, recurrent herpes lesions may occur on any oral mucosal surface, including nonkeratinized sites. They also may manifest solely as lesions on the dorsal aspect of the tongue. Such a presentation has been variously reported as red or white nodules, painful nonvesicular ulcerations, fissured, and, rarely, as a tongue mass.⁴ Herpes lesions in immunocompromised individuals are often severe. Such atypical presentations in an individual who is immunocompetent may lead the clinician to further investigate the patient's immune status.

Human herpesvirus (HHV) type 1. Primary herpetic gingivostomatitis often affects children or young adults. The initial clinical presentation can be severe, with vesicles throughout the oropharynx and perioral skin, in contrast to the much more limited presentation typical of recurrent herpes. Courtesy of A.K. ElGeneidy, DDS.

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Human herpesvirus (HHV) type 1. Primary herpetic gingivostomatitis often affects children or young adults. The initial clinical presentation can be severe, with vesicles throughout the oropharynx and perioral skin, in contrast to the much more limited presentation typical of recurrent herpes. Courtesy of A.K. ElGeneidy, DDS.

Human herpesvirus (HHV) type 1. Additional intraoral view of the same patient in Image 1. Note the redness around the marginal gingiva, representing healing ulcers, which days earlier would have appeared as vesicles. This extensive ulceration often makes eating painful. Courtesy of A.K. ElGeneidy, DDS.

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Human herpesvirus (HHV) type 1. Additional intraoral view of the same patient in Image 1. Note the redness around the marginal gingiva, representing healing ulcers, which days earlier would have appeared as vesicles. This extensive ulceration often makes eating painful. Courtesy of A.K. ElGeneidy, DDS.

Human herpesvirus (HHV) type 1. Primary herpes can affect the lips, and the ruptured vesicles may appear as bleeding of the lips (same patient as in Images 1-2). Courtesy of A.K. ElGeneidy, DDS.

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Human herpesvirus (HHV) type 1. Primary herpes can affect the lips, and the ruptured vesicles may appear as bleeding of the lips (same patient as in Images 1-2). Courtesy of A.K. ElGeneidy, DDS.

Human herpesvirus (HHV) type 1. Recurrent herpes is most often noted clinically as herpes labialis, with clustered vesicles (often coalescing) on the lip vermilion and often on the perioral skin. Recurrences generally occur in the same area each time, although their severity may vary.

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Human herpesvirus (HHV) type 1. Recurrent herpes is most often noted clinically as herpes labialis, with clustered vesicles (often coalescing) on the lip vermilion and often on the perioral skin. Recurrences generally occur in the same area each time, although their severity may vary.

Human herpesvirus (HHV) type 1. Recurrent herpes is occasionally observed intraorally. Inside the oral cavity, recurrent herpes typically affects only keratinized tissues, such as the gingiva or the hard palate. Vesicles often break quickly, so the clinician may observe small clustered ulcers. Courtesy of Sheldon Mintz, DDS.

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Human herpesvirus (HHV) type 1. Recurrent herpes is occasionally observed intraorally. Inside the oral cavity, recurrent herpes typically affects only keratinized tissues, such as the gingiva or the hard palate. Vesicles often break quickly, so the clinician may observe small clustered ulcers. Courtesy of Sheldon Mintz, DDS.

HHV-2⁵

HHV-2 infection is less common in the oral cavity than HHV-1 infection; however, its oral manifestations are clinically indistinguishable from HHV-1 infection. Assessment of HSV-2 shedding by polymerase chain reaction has detected oral HSV-2 shedding in the absence of an oral lesion, but concurrent with genital HSV-2 reactivation. This was more common in HIV-positive males.

HHV-3

HHV-3 is responsible for chickenpox and shingles.

Primary varicella, or chickenpox, usually occurs in children aged 3-6 years who are not immunized at the time of their first exposure to the virus. Itchy vesicles begin on the skin of the trunk and spread to the skin of the head. Intraoral and pharyngeal vesicles may occur. Antibody production follows, and the virus usually becomes latent in the dorsal root ganglia. Healthy children usually recover uneventfully, with a mortality rate of fewer than 2 deaths per 100,000 cases. However, older patients may experience more severe symptoms, and, in patients who are immunocompromised, the mortality rate may approach 18%.

Recurrent varicella, also known as herpes zoster or shingles, usually occurs in adults, and its incidence increases with age. It can occur in any patient who has had chickenpox and only rarely occurs in patients who have received chickenpox immunization. Recurrent varicella may occur when cellular immunity decreases. It results in a vesicular rash that usually affects a single dermatome. Inside the oral cavity, this may be observed as vesicles or ulcerations that stop sharply at the midline. A prodrome of pain, burning, or itching that mimics a toothache may occur.

After resolution of the rash, postherpetic neuralgia may linger for a month or longer, especially in patients who are immunosuppressed or in those older than 50 years.

Unusual complications can include devitalization of teeth, root resorption, osteonecrosis, and root resorption.⁶

Ramsay-Hunt syndrome arises when the virus emerges from latency in the geniculate ganglion. It involves cranial nerve VII (facial nerve), which has both motor and sensory functions. Manifestations may include paralysis that involves the levator palati muscle and the face; hoarseness; loss of secretory function (eg, dry mouth, loss of taste); vertigo; tinnitus; pain; and vesicles involving the pharynx, the eardrum, the external ear, or the tympanic membrane. Persistent facial nerve weakness or deafness may follow.

Human herpesvirus (HHV) type 3. The initial manifestation of Varicella-Zoster Virus infection is chickenpox (varicella), and vesicular lesions may be noted on the oral mucosa in addition to the characteristic and better-known skin lesions.

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Human herpesvirus (HHV) type 3. The initial manifestation of Varicella-Zoster Virus infection is chickenpox (varicella), and vesicular lesions may be noted on the oral mucosa in addition to the characteristic and better-known skin lesions.

Human herpesvirus (HHV) type 3. Intraoral herpes zoster closely resembles recurrent HHV-1 infection, but the lesions generally follow a dermatome and stop sharply at the midline, as shown here. However, the rules for common sites of occurrence of HHV-1 and HHV-3 often do not apply to patients who are immunocompromised. Courtesy of Sheldon Mintz, DDS.

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Human herpesvirus (HHV) type 3. Intraoral herpes zoster closely resembles recurrent HHV-1 infection, but the lesions generally follow a dermatome and stop sharply at the midline, as shown here. However, the rules for common sites of occurrence of HHV-1 and HHV-3 often do not apply to patients who are immunocompromised. Courtesy of Sheldon Mintz, DDS.

HHV-4

HHV-4 is most commonly known as the agent that causes infectious mononucleosis, although it has been linked to African Burkitt lymphoma, other lymphoproliferative diseases, and some nasopharyngeal carcinomas.

Primary infection, infectious mononucleosis (colloquially referred to as mono or kissing disease), occurs on first exposure to the virus, usually during young adulthood. It is often a subclinical infection. The virus (usually acquired from infected saliva) replicates in the cells of the mucosa and salivary glands and spreads to B lymphocytes and the bloodstream. If the patient is immunocompetent, cytotoxic T cells become activated and a characteristic lymphadenopathy (notably involving the posterior cervical nodes) accompanies tonsillitis and hepatosplenomegaly. Tonsillitis may be severe and may encroach on the airway. Thrombocytopenia may complicate the infection, and petechiae may be noted at the junction of the hard and soft palates. The patient may report headache, fever, malaise, myalgia, and fatigue. Severe abdominal pain may indicate splenic rupture.

A 21-year-old woman with infectious mononucleosis presents with a petechial lesion on her palate.

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A 21-year-old woman with infectious mononucleosis presents with a petechial lesion on her palate.

Latent infection of B lymphocytes follows acute disease. EBV has been detected in saliva as long as 18 months after recovery from clinically evident disease.

Hairy leukoplakia, caused by EBV, primarily occurs in adults who are immunosuppressed. Hairy leukoplakia manifests as asymptomatic white lesions on the lateral border of the tongue, often bilaterally. The lesions may be observed on the adjacent dorsal or ventral surface of the tongue. Occasionally, lesions are present in other sites, such as the buccal mucosa near the commissures. The lesions have a corrugated, linear appearance and may appear granular or nodular or may have hairlike projections. Hairy leukoplakia may be the first manifestation of immunosuppression and may prompt the clinician to test the patient's HIV status. The presence of hairy leukoplakia is significantly associated with an HIV viral load of at least 3000 copies/μ L.^7,8

EBV has been detected in aggressive periodontal lesions more often than in less diseased periodontal tissues, and EBV has also been detected in periapical lesions. The significance of these findings is unclear.

HHV-5

Primary CMV infection is usually asymptomatic in patients who are immunocompetent. The virus is shed by glandular secretions, including saliva. It occasionally is shed in urine. Primary CMV infection can be asymptomatic, but it can also mimic mononucleosis. Clinical disease is more common in neonates and in patients who are immunosuppressed than in other individuals.

CMV can persist indefinitely in the host. Reactivation of latent infection can occur in patients who are immunosuppressed, including most patients who have undergone organ transplantation and as many as 90% of patients with AIDS. Latent CMV infection may cause esophagitis, which is occasionally accompanied by oral ulcerations or erythema. The disease can also affect many other body systems, including the colon, eyes, liver, lungs, or brain. The oral ulcerations are clinically nonspecific, and a biopsy is required for definitive diagnosis. A patient with HIV infection who develops CMV oral ulcerations is at high risk for progression to AIDS.

Congenital CMV infection affects 0.5-2.2% of newborns. It is frequently asymptomatic, but oral manifestations may include enamel hypoplasia of the primary teeth.

HHV-7^9,10

HHV-7 infection has been associated with roseola infantum, acute hemiplegia of childhood, respiratory tract infections, and hepatitis. It has also been linked to seizures in children with febrile illnesses. HHV-7 has been identified in the saliva of adults, and this is most likely where the virus persists chronically.

HHV-8

DNA sequences of HHV-8 have been identified in persons with KS. HHV-8, also termed KS-associated herpesvirus, may be important in causing and/or maintaining KS lesions. KS in the oral cavity follows the same disease pattern as KS in other body sites, and, initially, the lesion may appear as a red, purple, or dusky patch that enlarges into a plaque and later progresses into a tumorous mass. It is observed most frequently in immunosuppressed patients and rarely occurs in children. In the oral cavity, early KS may mimic an amalgam tattoo. The palate is the initial site of intraoral KS in approximately half the cases; other favored sites include the gingiva, the tongue, and the tonsillar area.