Hepatitis: Patrick DM

Mackie CO, Buxton JA, Tadwalkar S, Patrick DM. · Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario. · CMAJ. · Pubmed #19153395 links to  free full text

This publication has no abstract.

Patrick DM, Buxton JA, Bigham M, Mathias RG. · Communicable Disease Epidemiology Services, UBC Centre for Disease Control, Vancouver. · Can J Public Health. · Pubmed #11059125 No free full text.

Abstract: This paper reviews key public health aspects related to surveillance, transmission and primary prevention of hepatitis C. Hepatitis C is now a reportable disease in all Canadian provinces and territories. Although prevalence in Canada is estimated at under 1%, that associated with injection drug use (IDU) approaches 90%. The epidemiology of new HCV infections in Canada is now primarily defined by IDU behaviour, with annual incidence rates among new drug injectors exceeding 25%. HCV is less efficiently transmitted through other routes of exposure. An effective vaccine against HCV remains elusive. Some jurisdictions offer hepatitis A and hepatitis B vaccine to HCV-infected persons. An array of harm reduction strategies targeting IDU has been implemented but underdeployed across Canada, and has been ineffective to date in controlling the HCV epidemic. Public policy alternatives, such as legalization and regulation of injection drugs, are being debated. Improved HCV preventive strategies are urgently required and need careful evaluation.

Ochnio JJ, Scheifele DW, Marion SA, Bigham M, Patrick DM, Ho M, Mozel M. · University of British Columbia, Department of Pediatrics, Vaccine Evaluation Centre, Vancouver. · Can J Public Health. · Pubmed #17278676 No free full text.

Abstract: BACKGROUND: Although population-based serosurveys offer an optimal measure of cumulative infection rates, they are seldom performed due to high cost and complex logistics. Use of participant self-collected oral fluid as a diagnostic specimen and mail for specimen delivery has the potential of generating reliable, population-representative data at limited cost. METHODS: A survey of oral fluid HAV-specific immunoglobulin G (an indicator of past HAV infection) was undertaken in a provincially representative sample of 20-39 year olds as a pilot study. A provincial administrative database served as the sampling frame. Potential participants were invited by mail to collect oral fluid and complete a questionnaire at home and return both by mail. Additional telephone prompting was directed at slow responders. Oral fluid was tested using a validated ELISA. RESULTS: From among 2,448 potential participants, contact by mail or telephone was made with 1,009 eligible subjects; 59% (585) participated. Materials withstood mailing and the quality of self-collected specimens was excellent. A positive test result was found in 22.1% overall and in 15.7% of self-reported non-vaccinated subjects. Among Canadian-born, non-vaccinated individuals, the positive test rate increased progressively from 1.2% (95% CI: 0-6.3) in 20-24 year olds to 16.4% (95% CI: 9.5-23.3) in 35-39 year olds. Antibody prevalence was higher among Canadian-born non-immunized 20-29 year olds who reported travel to developing countries (33.3%, 95% CI: 11.6-55.1) than in non-travellers (2.5%, 95% CI: 0.7-6.2). CONCLUSIONS: Mail-based population surveys of infection markers in oral fluid are feasible provided an appropriate sampling frame is used. This survey revealed a high anti-HAV antibody prevalence in young Canadian adults, increasing with age and travel to developing countries.

Patrick DM, Bigham M, Ng H, White R, Tweed A, Skowronski DM. · Epidemiology Services, University of British Columbia Centre for Disease Control, Vancouver, Canada. · Pediatr Infect Dis J. · Pubmed #14551487 No free full text.

Abstract: BACKGROUND: British Columbia introduced a preadolescent hepatitis B (HB) immunization program in 1992. This study documents trends in the reported rate of acute HB disease since 1992 and examines factors bearing on the rate of infection throughout the period of program implementation. METHODS: All Grade 6 students were eligible for immunization. Vaccine uptake was reported annually for every school. Acute HB infections were reported by physicians and by biomedical laboratories. Year-to-year trends were analyzed overall and by age group using the electronic public health information system and S-plus. Likelihood ratio tests were used to establish whether a variable was associated with the rate of acute HB in a given cohort. Poisson regression was applied to determine which variables were independently associated with the rate of acute HB. RESULTS: Immunization coverage ranged between 90 and 93% for each year between 1993 and 2001. The overall rate of reported acute HB declined from 7 per 100,000 to just more than 2 per 100,000, whereas that in 12- to 21-year-olds declined from 1.7 to 0 per 100,000 over this one decade period. In the final Poisson regression model, the rate of acute HB infection was significantly associated with year, urban region and lower vaccine uptake. There was an interaction between region and vaccine uptake such that higher vaccine uptake appeared more protective in rural than in urban regions. CONCLUSIONS: Acute HB has been eliminated in the immunized adolescent cohort. A higher carrier rate in urban regions most likely explains the apparent difference in program effectiveness between urban and rural regions.

Dawar M, Patrick DM, Bigham M, Cook D, Krajden M, Ng H. · First Nations and Inuit Health Branch, Medical Programs, Pacific Region, Health Canada, Vancouver, BC. · CMAJ. · Pubmed #12642425 links to  free full text

Abstract: Countries with a low risk of hepatitis B (HB) lack data on the effectiveness of universal HB vaccination programs for children. British Columbia began a program in 1992, offering HB vaccination to 11 year olds. We conducted an anonymous, unlinked serologic survey 7 years later, analyzing a random sample of specimens (n = 1215) from women aged 15-44 years who had undergone antenatal rubella testing. Among those aged 15-19 years inclusive there was no evidence of chronic HB (HB surface antigen), the proportion with evidence of acute HB (anti-HB core antibody) was only 0.6% (compared with 6.5% for the entire sample), and evidence of protective immunity was strong: the prevalence of anti-HB surface antibody (anti-HBs) was 79.1% (compared with 41.4% for the entire sample) and the geometric mean titre was 34.9 IU/mL (compared with 0.6-0.8 IU/mL for the older groups [p < 0.001]).

Patrick DM, Tyndall MW, Cornelisse PG, Li K, Sherlock CH, Rekart ML, Strathdee SA, Currie SL, Schechter MT, O'Shaughnessy MV. · University of British Columbia Centre for Disease Control, University of British Columbia, Vancouver, BC. · CMAJ. · Pubmed #11599327 links to  free full text

Abstract: BACKGROUND: Beginning in 1994, Vancouver experienced an explosive outbreak of HIV infection among injection drug users (IDUs). The objectives of this study were to measure the prevalence and incidence of hepatitis C virus (HCV) infection in this context and to examine factors associated with HCV seroconversion among IDUs. METHODS: IDUs recruited through a study site and street outreach completed interviewer-administered questionnaires covering subjects' characteristics, behaviour, health status and service utilization and underwent serologic testing for HIV and HCV at baseline and semiannually thereafter. A Cox proportional hazards model was used to identify independent correlates of HCV seroconversion. RESULTS: As of Nov. 30, 1999, 1345 subjects had been recruited into the study cohort. The prevalence of anti-HCV antibodies was 81.6% (95% confidence interval [CI] 79.6% to 83.6%) at enrollment. Sixty-two HCV seroconversions occurred among 155 IDUs who were initially HCV negative and who returned for follow-up, for an overall incidence density rate of 29.1 per 100 person-years (95% CI 22.3 to 37.3). The HCV incidence remained above 16 per 100 person-years over 3 years of observation (December 1996 to November 1999), whereas HIV incidence declined from more than 19 to less than 5 per 100 person-years. Independent correlates of HCV seroconversion included female sex, cocaine use, injecting at least daily and frequent attendance at a needle exchange program. INTERPRETATION: Because of high transmissibility of HCV among those injecting frequently and using cocaine, the harm reduction initiatives deployed in Vancouver during the study period proved insufficient to eliminate hepatitis C transmission in this population.