Page updated 9 October 2006
Risk from Bloodborne Viruses (BBV) and Infectious Diseases in the Dental Surgery
Introduction
- Infective dose of the organism required to cause infection
- Virulence of the organism and whether it more likely to colonise the host or cause superficial or invasive infection
- Immune status of the host - as the immunocompromised, the very young and old and diabetic patients are more prone to infection
- Portal of entry for infection - intact skin and mucosa act as a barrier to infection and a breach in the skin or mucosa is usually required for infection to take place
- Prevalence of BBV infection in the local community
- Likelihood of an accident / incident taking place during a given dental procedure
- Known seroconversion risk or infection attack rate following an accident/incident
- Fractures (except to fingers and toes)
- Dislocation of the shoulder
- Penetrating injury to the eye
- Acute illness requiring medical treatment where there is reason to believe that this resulted from exposure to a biological agent or its toxins or to infectious material
In the dental surgery environment the dental team and patients may be exposed to a wide variety of microorganisms that are transmitted by blood, saliva, respiratory secretions or from the skin including: - hepatitis B, hepatitis C, HIV, herpes simplex 1 and 2 (cold sores), herpes zoster (shingles), CMV, Mycobacterium tuberculosis , staphylococci and other oral and respiratory viruses and bacteria as well as waterborne environmental species. Of greatest concern are the BBV and respiratory pathogens such as M. tuberculosis as they cause serious disease and may be fatal. When you are carrying a risk assessment on the likelihood of infection arising from a dental procedure consider the following factors:
Host and microorganism characteristics:
Epidemiological risk factors:
Blood-borne Viruses
Blood borne viruses (Hepatitis B (HBV), Hepatitis C (HCV) and HIV) can be transmitted occupationally from infected staff to patients, from infected patients to staff, or from patient to patient via contaminated instruments. The most common route of transmission is from patients with a BBV to a member of staff following a percutaneous sharps injury or splash exposure of the mucous membranes. Infectious patients maybe asymptomatic carriers, or suffering from acute or chronic infection.
The prevalence of blood borne viruses in the UK is HCV of (0.5-1%), for HIV of (0 06%), and for HBV of (0.1 %). However, the implication of these statistics is that most practices will have a small number of patients who are infected either with HCV, HIV or HBV. Hepatitis C is the most common BBV in the UK . Many of these patients are asymptomatic carriers and are unaware that they carry the infection. The majority of cases of both hepatitis C and hepatitis B occur in people younger than 44 years. Intravenous drug use (IDU) and sexual transmission are the most frequently reported known risk factors for transmission of hepatitis B. Hepatitis C transmission is associated with intravenous drug use. Nationally a third (33%) of IDU users show past or current evidence of hepatitis C, a fifth (20%) have markers of hepatitis B and less than 1 percent HIV. Recreational and intravenous drug use is associated with high levels of caries and periodontal disease and such patients often require extensive dental treatment.
Surveys of American and Scottish dental practitioners found that on average they sustained 1.7- 3.3 sharps injuries per year. In the Scottish study 30% of the sustained injuries were assessed as constituting a moderate or high risk for transmission of BBV infection from the patient to the dentist. Dental nurses (DCPs) experience more sharps injuries than dentists, therapists or hygienists as most of the sharp injuries occur during clearing-up between patients and cleaning instruments.
Seroconversion rates following a needlestick or sharps injury are estimated to vary between 7-30% for hepatitis B (the higher figure relates to unvaccinated healthcare workers, the vaccine provides 90-95% protection), 1.8-10% for hepatitis C and 0.3% for HIV. Overall the risk to dental staff of acquiring a BBV occupationally is low. However, you cannot afford to be complacent. Great care must be taken when handling sharps and any injuries should be dealt with promptly as described in section 2. PPE should be used correctly (section 2) and guidance given on decontaminating instruments in section 3 strictly is adhered to.
Tuberculosis
Tuberculosis is spread by respiratory droplets or by direct contact. Tb has been transmitted during dental procedures. 15 cases were linked to an infected dentist. (See section 2 for prevention ). Only those patients with sputum positive pulmonary Tb are likely to cause an infection risk in the dental surgery. The disease has a long incubation period, produces chronic disease with a risk of reactivation especially if patients become immuncompromised due to illness or treatment with corticosteroids. Worldwide TB causes more deaths than any other infectious disease and the incidence of new case in the UK started to rise from 1987 onwards. Currently there are approximately 7,000 new cases per annum. There are marked geographic differences in the incidence of the disease, with London having the highest number of cases per head of population at 41.3 cases /100,000 compared the average figure of 12.8 cases/100,000 for England and Wales in 2003. Infection is more common in those between 15-44 years, in males and in those persons born outside the UK in areas of high endemicity. To view the surveillance data for your region of the country visit www. Hpa.org.uk/infections/topics_az/tb/epidemiology/reports.htm.
There have been recent changes to the national BCG vaccination policy details of which can be found at www.dh.gov.uk gateway reference 5360.
Syphilis
In the last few years syphilis has seen a re-emergence due to series of outbreaks originating in major cities (e.g. London, Dublin, Oslo) across Europe that have mainly affected men who have sex with men. The current outbreak in UK was first identified in 2001 and is still continuing, although the number of new cases is declining. The majority of cases are gay or bisexual men between the ages of 17-64 years, though small numbers of women have also been affected in the outbreak, including a pregnant woman.
Oral sex was identified as the route of transmission in some of the notified cases. Dentists should refer any patients with suspicious oral lesions suggestive of either primary syphilis (presenting as a chancre - an indurated ulcer, often affecting the lips), or secondary syphilis (presenting as oral ulceration and/or mucosal lesions usually affecting the tongue) to their local Genitourinary Medicine Clinic or to the patient's GP.
Syphilis is most infectious during the early stages of the disease and although the overwhelming majority of cases are spread by sexual contact, syphilis can be spread, by direct contact with an active lesion present on the lips or oral mucosa. Surgical gloves provide an effective barrier to transmission. Treponema pallidum the causative agent of syphilis is carried in the blood and accidental percutaneous inoculation via a needlestick injury could potentially result in transmission. Antibiotic prophylaxis is available following occupational exposure and advice should be sought from your local Community Infection Control Nurse or CCDC.
Mumps
Mumps is an acute viral illness spread by transmission of saliva or aerosolised saliva droplets from an infected person through the respiratory tract, eye or GI tract. In the last few years there has been an increase in the number of new cases in the UK with the peak incidence in those between 15-24 years of age. This particular age group are especially at risk as they were too old to receive the MMR vaccine when it was initially introduced.
Patients with mumps may occasionally present at the dental surgery as in some instances the symptoms are similar to those of acute sialadenitis. Mumps start with a headache and fever for a day or two and then painful swelling of the parotid glands, which may affect one or both glands, although in 10% of cases the submandibular glands are also involved. The swelling of the salivary glands is accompanied by trismus, swelling of the papilla of Stenson's duct, but there is no evidence of xerostomia (dry mouth). The incubation period is 14-21 days. A person with mumps is infectious from on average six days before the swelling starts to around five days after. The treatment for mumps is palliative involving analgesics and adequate hydration.
Mumps is fairly contagious and up to 45% of non-immune family contacts develop the disease and 25% have subclinical infection. Outbreaks have been recorded in hospital, work places and schools. Prevention of mumps is through immunisation with the MMR vaccine and two doses are recommended for maximum protection. Since 1998 MMR has been given to children between 12-15 months and since 1996 it is now also given at around 4 years of age. There is no upper age limit and where required, two doses are given, separated by a three month interval. MMR vaccine will not prevent infection in those already incubating the disease. Most people over the age of 25 years are likely to be immune to mumps through previous exposure to mumps infection. Those dental staff under 25 years old who have not had two doses of MMR vaccine may wish to discuss this with their GP or Occupational Health Department.
Good infection control such as hand hygiene and removal of aerosols with high volume suction is also important in controlling spread of mumps, as well as careful disposal of articles soiled with nose or throat secretions. In the event that a member of the dental team develops mumps they should seek medical advice to confirm the diagnosis. They are advised to stay off work for at least five days after the swelling started.
Influenza and Avian Flu
Outbreaks of influenza affecting many thousands and sometimes millions of people occurred worldwide in 1918, 1957, 1968 and 1977. New subtypes of influenza caused these pandemics, which were probably formed from a combination of genes from both avian and human influenza. Emergence of new highly pathogenic avian influenza with the capacity to infect humans is a concern because it may lead to circumstances where a new subtype of influenza can develop that both causes serious infection and can spread from person to person. Currently there is no human avian influenza vaccine available. Annually produced influenza vaccines against seasonal epidemics of influenza offer no protection against avian flu. Two drugs, the neurominidase inhibitors Ostelamivir and Zanimivir are active against avian flu and will be used in the management and treatment of any future influenza pandemic. In England prescribing of these drugs in primary care is restricted to specific circumstances and to the "at risk groups" specified by NICE (Flu Prophylaxis Guidance). The Department of Health have published a UK contingency plan for responding to an influenza pandemic, which is based on the framework developed by the World Health Organisation (WHO). For the latest information on all aspects of influenza, and avian flu visit the Health Protection Agency Influenza pages.
Reporting of Injuries, Disease & Dangerous Occurrences Regulations (RIDDOR) 1995
It is a statutory requirement that an employer reports to the HSE work related accidents, diseases, and dangerous occurrences (near misses) affecting employees, self-employed person working on your premises or to members of the public who are killed or taken to hospital as a result of the incident. Fatal, major accidents (including physical violence to staff), and over 3 day injuries (results in staff on sick leave for 3 or more days) must be reported immediately to HSE and a completed accident report form (2508) sent to the HSE within 10 days. You must keep a record of all major injuries. The simplest way to do this is to keep a copy of the completed 2508 form. Incident reporting forms are available from The Stationery Office Bookshop or can be downloaded from the Health and Safety Executive website.
Examples of major accident (See HSE RIDDOR leaflet for full list (available as a hard copy or as a downloadable version from their website )
If the incident does not result in a reportable injury but clearly could have done, then it is classed as a dangerous occurrence and must also be reported immediately and a 2508 form completed. A comprehensive list of "dangerous occurrences" and your obligations can be found in the RIDDOR 97 leaflet. If you are unsure whether an accident is notifiable under RIDDOR consult the HSE website.
If the employer (Dentist) is notified by a doctor that an employee suffers from a reportable work related disease or infection (e.g. occupational dermatitis, occupational asthma, Tuberculosis, Hepatitis B, Legionnaires' disease), then a completed disease report form (2508A) must be sent to the HSE.
References
Siew C, Gruninger SE, Miaw CL, Neidle EA. Percutaneous injuries in practicing dentists. A prospective study using a 20-day diary. J Am Dent Assoc 1995; 126: 1227-34.
Gore SM, Felix DH, Bird AG, Wray D. Occupational risk and precautions related to HIV infection among dentists in the Lothian region of Scotland . J Infect 1994; 28: 209-222.
Head MW, Ritchie D, McLoughlin V, Ironside JW. Investigation of PrP res in dental tissues in variant CJD Brit Dent J 2003; 195: 339-343.
Eye of the Needle . Surveillance of Significant Occupational. Exposure to Blood borne Viruses in Healthcare Workers. Seven-year report. January 2005.
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