MICROBIOLOGY 211: HIV AND DENTISTRY

Transcription

1 ICROBIOLOGY 211: Dr. Gillian ccarthy Room DSB Tel Ext 86122; HIV AND DENTISTRY OBJECTIVES: The student will be able to discuss - The epidemiology of HIV/AIDS worldwide and in Canada Transmission of HIV Infectivity of body fluids HIV infection and HIV disease progression General issues related to HIV and dentistry: Transmission from blood and saliva Risk of transmission of HIV and other bloodborne viruses (hepatitis B and hepatitis C) Prevention of transmission in the dental office Ethical and legal considerations related to the treatment of patients with HIV The HIV- infected dentist Importance of dentists in treatment and care of HIV-infected patients: Prevention and early diagnosis of oral infection Diagnosis and management of oral manifestations of HIV disease / immune suppression Appropriate referral of patients for investigation of immune status / HIV Issues related to HIV testing Advice to reduce further transmission of HIV These lectures are aimed to bridge the gap between microbiology and clinical dentistry and to provide relevant information that is required before students start to diagnose and treat patients.

2 BACKGROUND: first cases of unusual immune system failure reported among gay men in the United States acquired immunodeficiency syndrome (AIDS) was initially described the human immunodeficiency virus (HIV) was identified. ost persons with HIV infection or disease do not have AIDS. AIDS includes a group of severe diseases associated with immunosuppression due to HIV. HIV-1 is prevalent in North America, Europe and Africa HIV-2 is prevalent in West Africa and is considered less pathogenic. HIV-1 and HIV-2 co-infections can occur HIV is associated with high rates of re-activation of TB - a major problem where TB is endemic. any persons are unaware that they are infected with HIV- one third are unaware in Canada. Tracking of the epidemic has been based on AIDS cases and underestimates HIV infections. EPIDEIOLOGY OF AIDS The WHO classification of countries is becoming less relevant but shows some differences: Pattern 1 countries - Include Canada, U.S.A. and Western Europe. - Low prevalence of HIV and AIDS - Higher prevalence in males - sex between men has been predominant means of transmission - HIV prevalence in women, transmission as a result of heterosexual activity and IV drug abuse have been increasing recently. Pattern 2 countries - Include Sub-Saharan Africa, and the Caribbean. - Very high prevalence of HIV infection/aids. - Predominant means of transmission are heterosexual contact and perinatal transmission. - Sexes were equally affected, but rates among younger women are becoming a major concern. Pattern 3 countries - Include countries in North Africa, the iddle East, Eastern Europe and Asia. S Onset of epidemic more recent, therefore lower prevalence of AIDS cases S HIV is spreading very rapidly in many of these areas, mainly as a result of drug abuse and heterosexual transmission 2

3 THE PREVALENCE OF AIDS/HIV GLOBAL ESTIATES of number of people living with HIV/AIDS : Total: 40 million Women: 17 million females years Children: 2 million See UNAIDS epidemiology update CANADA: Positive HIV test reports in Canada from November 1985 thru December 2005: 60,200 Positive HIV test reports in Canada in 2005: 2,500 The number of positive HIV test reports has risen 20% in the last five years Over one quarter of positive HIV reports in 2005 were among women. Among the year age group, 29% of those testing positive for HIV were women. HIV transmission rates have been rising among heterosexuals and Aboriginal persons - especially younger women. NB: The accuracy of prevalence rates are limited by factors including non-reporting, late reporting In Canada in 2005, of those testing HIV positive: 20% were among injection drug users 44% were men who have sex with men 31% were due to heterosexual activity It is estimated that one third of those infected with HIV in Canada are unaware (approx. 20,000) See HIV and AIDS in Canada: Surveillance report to December HIV is spread - TRANSISSION OF HIV 1. By unprotected sexual intercourse with an infected person 2. From an infected mother to her infant (perinatal transmission or breastfeeding) 3. By parenteral exposure - including transfusion of blood or blood products; organ transplantation; the sharing of unsterilized injection equipment - IV drug abuse or occupational exposures. 3

4 E s timates of Efficiency of HIV Transmission per Single Exposure Route or mode of Efficiency per single Comments transmission exposure (%) Blood transfusion > 90 before screening/testing of blood Perinatal developed countries - no ART developing countries- no ART Breastfeeding 16 Sexual intercourse < estimates difficult anogenital 0.2 / 0.8 protected / unprotected vaginal 0.1 orogenital O.04 risk increases with greater frequency Injecting drug use, with contaminated needles Occupational exposures healthcare environment needlestick 0.3 higher if larger bore or high viral load mucous membrane exposures blood splash to eyes, nose or mouth HIV INFECTIVITY OF BODY FLUIDS HIV transmission is known to occur via blood, vaginal secretions, semen and breast milk. HIV has been isolated from tears, saliva, sweat, cerebrospinal fluid, amniotic fluid, faeces, urine Risk of transmission is highest for blood. Risk increases with higher viral load (more circulating virus) Risk is increased if exposed mucosa or skin has abrasions or ulceration - portals of entry. The low risk of transmission of HIV via saliva is due to the: 1. very low concentration of virus in saliva 2. presence of factors in saliva that inhibit HIV-infection of lymphocytes: IgA antibodies, high molecular weight salivary proteins, secretory leukocyte protease inhibitor. 3. hypotonicity of saliva Saliva is frequently contaminated with blood and is considered infectious in the clinical environment 4

5 HIV INFECTION After infection with HIV there is a window period when antibodies cannot be detected. During the window period, the infected patient has high levels of HIV in the blood and high infectivity but antibodies to HIV cannot be demonstrated. Seroconversion usually occurs within 3 to 6 months of infection - antibodies can be detected. Duplicate tests are carried out using Elisa (enzyme linked immunosorbent assay) and Western blot. Viral load (and infectivity of blood) is high before seroconversion and with advanced disease. Stages of HIV Disease Stage and Clinical Features Typical Duration CD4+ Cell Range Acute retroviral syndrome 1-2 wk 1, cells/mm 3 Asymptomatic 10+ yr Early symptomatic 0-5 yr Late symptomatic 0-3 yr Advanced 1-2 yr CDC Revised Classification System for HIV Infection CD4+ CD4+ Clinical Category* count % A B C > 500/ L > 29 A1 B1 C / L A2 B2 C2 < 200/ L < 14 A3 B3 C3 * A = asymptomatic; B - symptomatic, not (A) or (C); C = AIDS 5

6 HIV DISEASE PROGRESSION Progression of HIV-disease is marked by a decline in CD4+ (T4 or helper) lymphocytes and decreased resistance to opportunistic infections. Infection High levels of virus in circulating blood (viral load) shortly after infection Acute retroviral syndrome Occurs approximately 1-3 weeks after infection (range 5 days-3 months) Duration 1-2 weeks Signs and symptoms: Fever, pharyngitis, headache, malaise, diffuse cutaneous erythematous rash, lymphadenopathy Differential diagnosis: Influenza Acute mononucleosis Frequently acute retroviral syndrome is not recognized Asymptomatic disease Latent period frequently lasts >10 years HIV and disease process are primarily confined to lymphoid tissue Lymphadenopathy may be present Early symptomatic disease Non life-threatening infections (e.g. oral candidiasis) Chronic or intermittent symptoms Advanced symptomatic disease Increasingly severe symptoms Life-threatening infections e.g. Pneumocystis carinii pneumonia alignancy e.g. Kaposi s sarcoma, non-hodgkins's lymphoma Increasing viral load with increasing severity of disease Includes AIDS TREATENT: 1. Nucleoside analogues: ZDV (zidovudine), ddc (dideoxycitidine), ddi (dideoxyinosine), 3TC (lamivudine). 2. Protease inhibitors: IDV (indinavir), saquinivir, ritinovir. 3. Highly active antiretroviral treatment (HAART) includes combinations of drugs e.g ZDV, 3TC and IDV for greater antiretroviral activity and delay in onset of AIDS. 6

7 HIV AND DENTISTRY Potential for Transmission of HIV in Health Care Situation Transmission of HIV from 3 healthcare workers to patients: There have been three reported cases of transmission of HIV from healthcare workers to patients worldwide since the start of the epidemic: A dentist in Florida was linked to transmission of HIV to 6 patients. An orthopaedic surgeon in France transmitted HIV to 1 patient A nurse transmitted HIV to one patient Transmission of HIV from patient to healthcare worker: The risk of transmission from patient to healthcare worker is greater than the risk of transmission from healthcare worker to patient, however there is minimal risk of acquiring HIV infection as an occupational hazard: Occupationally-acquired HIV infection in healthcare workers as of 1999: Worldwide: 102 documented cases and 217 possible cases Canada: 8 AIDS cases Dental workers: 9 possible cases If recommended infection control practices are used, the risk of occupational exposure to bloodborne pathogens is limited to needle stick injuries and cuts. Risk of HIV infection after a mucous membrane exposure 0.1% This risk can be reduced or eliminated by appropriate use of protective eyewear, masks or faceshield. Risk of infection after a needlestick contaminated with HIV, HCV or HBV. The risk of HIV infection can be reduced by approximately 80% if prophylaxis with zidovudine is given ideally within 2 hours of a significant exposure. Combinations of anti-retroviral drugs may be used for high risk exposures. Estimates of risk of HIV infection are low in comparison to hepatitis B virus or hepatitis C virus Risk of HIV infection after an HIV-contaminated needlestick 0.3% Risk of hepatitis C virus infection after an HCV-contaminated needlestick 3 Risk of hepatitis B virus infection after an HBV-contaminated needlestick : Low infectivity, (source HBV e-antigen-negative) 6 High infectivity (source HBV e-antigen-positive) 30 7

8 PREVENTION OF TRANSISSION OF HIV, HBV OR HCV IN THE DENTAL OFFICE 1. Standard precautions for infection control should be used, and effective HBV immunization. 2. Avoid needle stick injuries and cuts. 3. HIV post-exposure prophylaxis preferably within 2 hours of significant exposure to HIV. Necessity for universal/standard precautions: For maximum safety in the dental office, the same infection control precautions should be used for ALL patients, i.e. all patients should be treated as if they are infected with HBV, HCV or HIV. If our routine infection control procedures are not adequate to protect against HIV or hepatitis viruses, we run the risk of transmission of infection during treatment of persons with undetected infection. This group is likely to include many infected patients. any patients are unaware that they have HIV because of: a) window period before antibodies can be detected b) long incubation period before signs and symptoms of disease c) lack of awareness that they are at risk - no HIV testing d) avoidance of HIV testing by some persons in high risk groups any patients will not disclose their HIV status because of: a) fear of rejection for treatment b) fear of breach of confidentiality c) fear of discrimination ETHICAL AND LEGAL CONSIDERATIONS 1. Refusal or unwillingness to treat patients with HIV (or HCV, HBV) 2. The dentist infected with HIV, HBV or HCV. CDA recommendations; RCDS guidelines; Human Rights legislation (See handouts 1-3 ) ROLE OF DENTISTS 1. Routine dental care 2. Early diagnosis of lesions associated with immune suppression / HIV. If HIV serostatus is unknown, appropriate referral for investigation of immune status, leave discussion of HIV, testing, counselling and treatment to physician with expertise Early diagnosis may a) facilitate treatment and improve prognosis, b) prevent further transmission by counselling to encourage sexual abstinence or safer sex - i.e. condom use for vaginal, anal or oral sex; avoidance of breastfeeding; blood donation /organ transplants; unsafe injection practices. 3. Referral for specialist oral treatment - if the patient is medically compromised or procedure required is outside dentist s normal range of expertise. 4. Early diagnosis and treatment of oral infection in those patients known to have HIV. 5. anagement of oral manifestations of HIV. 6. Prevention of cross-infection 8

9 HANDOUTS: Attached to lecture notes: 1. RCDSO." Policy in respect of the infected/affected dental care provider." 2. Bergin F. Duty to treat. RCDSO Dispatch, supplement. October-November Canadian Dental Association. Statement on the ethical and legal considerations of treating patients with infectious diseases. J Canad Dent Assoc 1999;65: 456 REFERENCE ATERIAL. ccarthy G, Ssali CS, Bednarsh H et al. Transmission of HIV in the dental clinic and elsewhere. Oral Diseases 2002; 8: ccarthy G, Koval JJ, acdonald JK. Occupational injuries and exposures among Canadian Dentists: The result of a national survey. Infect Control Hosp Epidemiol 1999;20: AIDS/HIV epidemic update: Public Health Agency of Canada. HIV and AIDS in Canada. Surveillance report to December : April