7.2 Infectious Disease
Key Takeaways
- Primary herpetic gingivostomatitis (HSV-1) is the most common cause of acute gingivostomatitis in young children and is managed with hydration, soft diet, analgesia and aciclovir 200 mg five times daily for 5 days if severe or within 72 hours of onset
- UK HIV post-exposure prophylaxis (PEP) after a significant sharps injury should start as soon as possible, ideally within 24 hours and no later than 72 hours; the standard regimen is tenofovir/emtricitabine plus raltegravir for 28 days (BASHH/BHIVA 2021, amended 2023)
- Hepatitis B vaccination is recommended for all clinical dental staff in the UK and is given at 0, 1 and 6 months with post-vaccination serology confirming HBs antibody levels above 10 IU/L
- The HIV-specific oral lesion most strongly associated with EBV co-infection is oral hairy leukoplakia - white, corrugated, non-wipeable plaques usually on the lateral border of the tongue
- UK standard infection control uses 'standard precautions' for every patient - treat all blood and body fluids as potentially infectious regardless of perceived risk
Viral Infections
Herpes Simplex Virus (HSV-1)
Primary herpetic gingivostomatitis is the most common manifestation of primary HSV-1 infection, typically in children aged 1-5 years but also in adults. Features include:
- Painful vesicles on the lips, tongue, gingivae and buccal mucosa that rupture to form ulcers.
- Fever, malaise, cervical lymphadenopathy.
- Diffuse gingival inflammation and inability to eat or drink.
Management is supportive - hydration, soft diet, paracetamol, and aciclovir 200 mg five times daily for 5 days if severe or started within 72 hours of onset. Most cases resolve in 10-14 days.
Recurrent HSV produces cold sores (herpes labialis) at the mucocutaneous junction of the lip. Prodromal tingling precedes the vesicular eruption. Avoid dental treatment during an active cold sore to prevent spread and aerosol contamination; if treatment is urgent, consider topical aciclovir and defer elective work until crusting heals.
Varicella Zoster Virus (VZV)
Chickenpox is the primary VZV infection. Herpes zoster (shingles) is reactivation in a dermatomal distribution. In the maxillary or mandibular divisions of the trigeminal nerve, shingles produces unilateral painful vesicles that crust and heal with potential post-herpetic neuralgia. Hutchinson's sign - a vesicle on the tip of the nose (nasociliary branch of V1) - predicts ocular involvement and warrants urgent ophthalmology referral.
Epstein-Barr Virus (EBV)
EBV causes infectious mononucleosis with fever, tonsillar exudate and cervical lymphadenopathy. Ampicillin/amoxicillin produces a characteristic non-allergic maculopapular rash in infectious mononucleosis and should be avoided if EBV is suspected. EBV is also associated with oral hairy leukoplakia in immunosuppressed patients.
HIV and AIDS
Human immunodeficiency virus (HIV) targets CD4 T-helper cells. Untreated it progresses to acquired immunodeficiency syndrome (AIDS). UK patients on effective antiretroviral therapy (ART) with an undetectable viral load cannot transmit HIV sexually (U=U) and pose minimal occupational risk.
Oral Manifestations of HIV
| Lesion | Characteristics |
|---|---|
| Oral candidiasis | Erythematous or pseudomembranous; often the earliest oral sign |
| Oral hairy leukoplakia | White, corrugated, non-wipeable plaques on lateral tongue; EBV-associated; near-pathognomonic of HIV |
| Linear gingival erythema | Distinct red band along free gingival margin; poorly responsive to plaque control |
| Necrotising ulcerative periodontitis | Rapid attachment loss, necrosis, pain; requires urgent referral |
| Kaposi sarcoma | Purple-brown vascular lesions (palate, gingivae); HHV-8-driven |
| Aphthous-like ulcers | Major, persistent; biopsy to exclude lymphoma |
| Non-Hodgkin lymphoma | Firm palatal swelling; urgent biopsy |
HIV-positive patients should receive routine dental care in primary care; there is no need to refer to secondary care solely on the basis of HIV status. Use standard precautions as for every patient.
Hepatitis B, C and D
Hepatitis B (HBV)
A DNA virus transmitted by blood and body fluids, far more infectious than HIV occupationally. Most adults clear the infection; 5-10% become chronic carriers who develop cirrhosis and hepatocellular carcinoma.
Vaccination (recombinant HBsAg) is recommended for all UK clinical dental staff at 0, 1 and 6 months. Post-vaccination serology confirms an HBs antibody level above 10 IU/L. Non-responders receive further courses or HBIG for exposure.
Hepatitis C (HCV)
An RNA virus, the leading cause of chronic hepatitis in the UK from injecting drug use and historically from blood products before 1991. Most are asymptomatic until chronic liver disease develops. Direct-acting antivirals (DAAs) cure over 95% of cases in 8-12 weeks. HCV has no vaccine - post-exposure management relies on testing and, if seroconversion occurs, early DAA therapy.
Tuberculosis and Syphilis
Tuberculosis (TB)
Mycobacterium tuberculosis is primarily pulmonary. Oral TB is rare and usually secondary, presenting as a chronic, painless ulcer often on the tongue dorsum - biopsy any chronic non-healing oral ulcer in an at-risk patient. Pulmonary TB is an aerosol-transmissible disease: defer elective dental treatment for at least 2 weeks after starting effective therapy; urgent care requires FFP3 respirator and negative-pressure where possible.
Syphilis
Treponema pallidum is re-emerging in the UK. Primary syphilis produces a chancre - a painless indurated ulcer at the inoculation site, including the lips or oral mucosa. Secondary syphilis produces mucous patches and maculopapular rashes including palms and soles. Tertiary syphilis causes gumma - granulomatous destructive lesions that may perforate the palate. All stages are treated with penicillin under genitourinary medicine supervision; oral ulcers of uncertain cause that persist beyond 2-3 weeks require biopsy and serology.
Cross-Infection Control and Needlestick Injury
Standard (Universal) Precautions
Treat all patients as potentially infectious. Core measures:
- Hand hygiene before and after each patient (WHO five moments).
- Personal protective equipment - gloves, mask, eye protection, gown.
- Safe sharps handling - do not resheath needles; use safety devices and a rigid sharps bin.
- Sterilisation of reusable instruments by autoclave and tracking.
- Surface disinfection between patients.
- Single-use items discarded appropriately.
Needlestick Injury Management
A significant occupational exposure is percutaneous injury with a hollow-bore needle or a sharp contaminated with blood. Immediate management (BASHH/BHIVA UK 2021, amended 2023):
- Encourage bleeding from the wound - do not scrub.
- Wash thoroughly with soap and water.
- Irrigate mucous membranes with copious water if splashed.
- Report immediately to occupational health / the duty clinician - do not delay.
- Baseline serology of the recipient - HIV 4th-generation Ag/Ab, HBsAg/HBsAb/HBcAb, HCV Ab, plus creatinine/eGFR and ALT; store serum.
- Source testing with consent from a senior member of the source patient's team (not the exposed clinician) - HIV Ag/Ab, HBsAg, HCV Ab.
- Risk-assess for PEP:
- HIV PEP - start as soon as possible, ideally within 24 hours and no later than 72 hours; regimen is tenofovir disoproxil 245 mg / emtricitabine 200 mg once daily plus raltegravir 1,200 mg once daily for 28 days.
- HBV - hepatitis B immunoglobulin (HBIG) plus vaccine booster depending on vaccination status.
- HCV - no PEP; early PCR and DAA treatment if seroconversion detected.
- Follow-up testing at agreed intervals; HIV at minimum 45 days after PEP completion; HBV/HCV per protocol.
- Report the incident to the Health and Safety Executive (HSE) under RIDDOR where applicable.
Local anaesthetic needles are among the most common causes of significant sharps injuries in dentistry - never resheath a used needle by hand.
A 3-year-old presents with sudden onset of fever, drooling, cervical lymphadenopathy and multiple painful vesicles on the gingivae and tongue. The most likely diagnosis is:
A dental nurse sustures a hollow-bore needlestick injury from a known HIV-positive source of unknown viral load. According to UK guidance, HIV PEP should be started:
A newly qualified dentist completes hepatitis B vaccination at 0, 1 and 6 months. Post-vaccination serology is considered satisfactory when the HBs antibody level is:
An HIV-positive patient presents with white, corrugated plaques on the lateral border of the tongue that cannot be wiped off. The lesion is:
A 35-year-old man has a painless, indurated ulcer on the lower lip with regional lymphadenopathy that has persisted for three weeks. The most likely infectious cause is: