Public health and hepatitis C.

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.

Diffuse lamellar keratitis related to endotoxins released from sterilizer reservoir biofilms.

OBJECTIVE: To investigate the risk factors and control mechanisms used to control the outbreak of diffuse lamellar keratitis (DLK) associated with laser in situ keratomileusis (LASIK) and examine the relationship between DLK and endotoxins released from sterilizer biofilm reservoirs. DESIGN: Clinic-based cohort and laboratory study. PARTICIPANTS: All patients undergoing LASIK at our clinic from October 7, 1998 through August 31, 1999. The case definition was a diffuse infiltrate in the interface developing within the first week after surgery. INTERVENTIONS: Biofilm control in the sterilizer, changes in sterilizer, distilled water, instruments, and irrigating fluids. MAIN OUTCOME MEASURES: The incidence of DLK after LASIK surgery. RESULTS: There were 983 evaluable patients, with three whose DLK status was not recorded. There were 52 cases of DLK. Burkholderia pickettii was isolated from the sterilizer reservoir. Potential risk factors and associations, for which there was no significant difference, included age and sex of the patients, surgeon, operating suite temperature or humidity, drapes used, saline solutions used, time of day the surgery was performed, and microkeratome use. Sterilizers 1 and 2, before biofilm control, were compared with sterilizer 3, after control. The relative risk was 9.4 (confidence limits [CL], 7.5-11.8) for sterilizer 1 versus 3 and 18. 7 (CL, 11-32) for sterilizer 2 versus 3. Three cases occurred after biofilm control, but were sporadic in nature and associated with epithelial defects. CONCLUSIONS: Clusters of DLK may be related to endotoxins released from gram-negative biofilms in sterilizer reservoirs. We experienced an outbreak of DLK affecting 52 patients and isolated B. pickettii from the sterilizer reservoir. Epidemiologic investigation showed that biofilm control in the sterilizer reservoirs was associated with a significant reduction in the development of DLK. We encourage any clinics that experience a cluster of DLK to consider microbiologic and epidemiologic investigation for the effectiveness of sterilizer biofilm control.

HIV and hepatitis B surveillance in First Nations alcohol and drug treatment centers in British Columbia, Canada.

Data have been lacking on the prevalence of HIV and hepatitis B (HB) infections in the North American Indian population in Canada. In January 1992, surveillance was introduced into two residential First Nations alcohol and drug treatment centers in British Columbia as part of an AIDS/STD education program. Male and female clients were given the option of participating and submitting serum for testing of HIV, HBsAg, and anti-HBc. As of December 31, 1995, 1,165 Native persons had been tested. There were four positive HIV results--two males and two females--a rate of 3.5/1,000. This compares with an expected rate of 4/1,000 for a British Columbia population not selected for specific risk factors. Similarly, the rate of HB carriage is low at 0.3%, compared to a provincial population rate of 0.5%. Evidence of past hepatitis B infection is 11.3%, double the rate of a British Columbia blood donor population. This study is ongoing.

Continuing investigation and controversy regarding risk of transmission of infection via dental handpieces.

Current epidemiologic evidence indicates that infectious diseases, specifically blood-borne pathogens such as hepatitis B, hepatitis C and HIV, are not transmitted from patient to patient via dental instruments. However, ongoing laboratory investigations suggest that potential pathogens may be retained within dental handpieces, creating a theoretical risk of cross infection. Controversy regarding certain laboratory study results and the clinical implications of these studies continues. Guidelines and regulations for infection control should be rational, and based on a realistic response to a documented risk. Dental professionals should be aware of continuing research focusing on these issues.

Ascaris and Trichuris do not contribute to growth retardation in primary school children.

To access the effectiveness of the treatment of soil-transmitted helminthiasis (STH) on the growth of primary school children, 353 children were block stratified to receive either mebendazole plus pyrantel oxantel pamoate every three months or a placebo. The children were followed for two years with 89% completing the trial. Follow-up stools indicated that the treatment was efficacious for ascariasis and trichuriasis. There was virtually no hookworm infection. The children were malnourished as measured by the number below -2 SD of height and weight standards. There was no difference in height or weight between the treatment and control groups by sex initially or at the end of two years of follow-up. The treatment of Ascaris and Trichuris had no effect on growth parameters. The effect of STH on growth may be mediated through hookworm infections.

Dentistry and tuberculosis in the 1900s.

The number of new cases--or incidence--of tuberculosis is increasing in nearly every region of the world. A number of forces have resulted in the increased incidence of TB in developed countries, including the HIV epidemic, homelessness, and emigration from highly endemic regions. Although the number of new cases in Canada is relatively constant, the TB experience in the United States serves as a reminder that this situation could change rapidly. The appearance of multidrug-resistant tuberculosis has added to the urgency of situation. The basic methods of preventing TB transmission include preventing the release of the organism into the air, removing the organism from the air, and preventing the inhalation of the organism. Identifying and appropriately treating every person with active tuberculosis is an extremely important component of the control strategy; adequate ventilation, filtering air, and ultraviolet germicidal irradiation are methods used to remove the organism from the air; and masks and other personal protective devices, such as high-efficiency particulate air filters (HEPA), have been suggested as a means of preventing inhalation of the organism. In addition, identifying new TB infections and using chemoprophylaxis often prevents infection from progressing to active disease. Given the route by which tuberculosis is transmitted, it is necessary for both dentists and allied dental personnel to be aware of the risks they may face in day-to-day practice, and the means by which they can protect themselves and their patients.

Survey to assess dental practitioner's knowledge of infectious disease.

The prerequisite to understanding the need for infection control practices in dentistry is a sound knowledge of infectious disease and the potential for its transmission in the dental setting. To assess the infectious disease knowledge-base of dental practitioners, a questionnaire was developed and distributed to dentists in British Columbia. The survey results showed that many of the mechanisms, routes and risks for the transmission of viral pathogens in the dental setting are not clearly understood by dentists. Continuing education is needed to ensure that compliance with current infection control recommendations, and the provision of appropriate patient care, continues to be based on a clear understanding by dentists of the mechanisms of infection. By identifying the current infectious disease knowledge-base of dentists, this survey may permit more specifically-directed continuing education programs to be offered.

Compliance to recommended infection control procedures: changes over six years among British Columbia dentists.

Over the last decade, in response to the heightened awareness of HBV and HIV infections, world health authorities have produced specific infection control recommendations for dental practices. Surveys have been done in various countries to investigate the level of compliance to these recommendations. This paper reports on the changes in compliance over a six year period among British Columbia dentists, as indicated from four volunteer surveys conducted between 1987 and 1993. During that period, the percentage of dentists who reported taking a medical history for each new patient increased from 70 per cent to 99 per cent. The routine use of gloves increased from 61 per cent to 95 per cent, and of face masks from 49 per cent to 83 per cent. In 1993, most dentists (91 per cent) used a new pair of gloves with each patient, up from 62 per cent three years earlier. Dentists also reported on their sterilization and hygiene methods. Autoclavable handpieces were used by 66 per cent of respondents in 1990, and by 74 per cent in 1993. High-speed autoclavable handpieces were used by 83 per cent of dentists in 1993, but only 62 per cent sterilized these handpieces. Similarly, 65 per cent reported using low-speed autoclavable handpieces, but only 47 per cent sterilized them. It is apparent that disinfection of handpieces and intraoral instruments is still an important part of regular operatory hygiene. Biologic monitors were used by 61.6 per cent of respondents to test the efficiency of their office sterilizer in 1993.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of inspection frequency and food handler education on restaurant inspection violations.

The effectiveness of restaurant inspections and food handler education are not known. Consequently, the optimal frequency of neither has been determined. Thirty randomly selected restaurants from seven health units in three provinces were inspected by one of three senior inspectors. A questionnaire was used to collect the data. The violation score worsened when the time since last inspection was greater than 12 months, but did not worsen when the interval was shorter. Those restaurants in which supervisors and food handlers had completed food handler education courses had better inspection scores than those without. Restaurants whose food handlers had food service education had better scores only for time and temperature violations. These outcomes were all significant in a multiple regression model. The duration of most education courses was under five days. The time since the last food service education course was not significant. Routine inspections should be done yearly. Food service education should be offered to both supervisors and food handlers.

Survey of knowledge of infectious disease and infection control practices of dental specialists.

A questionnaire was developed to assess the knowledge of clinical specialists regarding infectious disease as well as their infection control practices. The questionnaire was mailed to 202 dental specialists in British Columbia. Seventy per cent returned completed surveys. Their responses indicate that the mechanisms, route and risk of transmission of the viral pathogens of importance in dental practice are not clearly understood. However, infection control practices closely follow the guidelines set forth by the Canadian Dental Association and the licensing bodies, including immunization for hepatitis B (82 per cent), glove use (in 89 per cent of non-surgical and 95 per cent of surgical procedures), and sterilization/disinfection of dental handpieces (94 per cent). Compliance with infection control guidelines was similar to that reported in the United States, where strict enforcement has been instituted. The majority of dental specialists (84-88 per cent) were either treating or willing to provide treatment to patients with infectious disease. Continuing education in the area of infectious disease is needed to improve dentists' understanding of the risk of transmission to dental providers and patients. This will ensure that compliance with infection control recommendations and appropriate patient care practices continue.

Long-term follow-up of hepatitis B vaccine in infants of carrier mothers.

A program of immunization against hepatitis B, consisting of one dose of hepatitis B immune globulin within 12 hours of birth and three doses of hepatitis B vaccine at 0, 1, and 6 months of age for all infants of carrier mothers, has been operating in British Columbia, Canada, since 1984. The authors report on a survey conducted in 1992 of children immunized between 1984 and 1989. The survey included blood tests obtained from the children and interviews of the mothers. A total of 770 of 1,135 eligible children participated. Thirty-one percent of the mothers had been positive for hepatitis B e antigen prior to the birth of the child. At follow-up, the overall antibody against hepatitis B surface antigen seropositivity rate for children was 87.9 percent. A total of 5.1 percent of children had evidence of previous hepatitis B infection, and 2.3 percent were hepatitis B surface antigen positive. In multiple logistic regression analysis, a delay in the initial dose of vaccine was associated with increased risk of infection, but the age of the child was not, even though antibodies against hepatitis B surface antigen declined with age. The authors conclude that most infections occurred early and resulted from prenatal infection, initial nonresponse, or a delay in the initial dose of vaccine, not from waning immunity. A booster dose of vaccine, at least up to age 8 years, is not necessary.

Prevalence of HIV infection in provincial prisons in British Columbia.

OBJECTIVE: To ascertain the prevalence of HIV infection among people entering provincial adult prisons in British Columbia and to study associations between HIV infection and specific demographic and behavioural characteristics. DESIGN: Prospective, unlinked, voluntary survey involving HIV antibody testing of saliva specimens. SETTING: All adult provincial prisons in British Columbia through which inmates are admitted to the provincial correctional system. PARTICIPANTS: All adult inmates admitted to provincial prisons in British Columbia between Oct. 1 and Dec. 31, 1992. OUTCOME MEASURES: Rate of HIV positivity. Independent variables included sex, native status (native or non-native), self-reported HIV status, age group and history of injection drug use. RESULTS: A total of 2482 (91.3%) of 2719 eligible inmates volunteered for testing. Refusal was not associated with sex, native status, self-reported HIV status or age group; inmates who reported a history of injection drug use were more likely than the others to refuse HIV antibody testing (12.9% v. 6.8%; p < 0.001). The 2482 inmates who were tested for HIV were similar to the general inmate population with regard to sex, native status and age group. A total of 28 inmates were confirmed to be HIV positive, for an overall prevalence rate in the study population of 1.1% (95% confidence interval 0.8% to 1.6%). The prevalence rates were higher among the women than among the men (3.3% v. 1.0%; p = 0.023, Fisher's exact test) and among the inmates who reported a history of injection drug use than among those who did not report such a history (2.4% v. 0.6%; p < 0.001). There was no association between HIV status and native status or age group. Logistic regression analysis revealed the higher prevalence rate among the women to be explained by more of the women than of the men reporting a history of injection drug use. Of the 30 people who stated that they were HIV positive and who were tested, 19 (63.3%) had a negative result; conversely, 17 who reported that they were HIV negative or had not been tested had a positive result. CONCLUSIONS: Unlinked, voluntary HIV antibody testing of inmates can achieve high participation rates. The overall prevalence rate of 1.1% and the rate among the female inmates of 3.3% confirm that HIV infection is a reality in prisons and that the virus has established a clear foothold in inmate populations. Harm-reduction interventions should include a comprehensive education program for inmates on infectious diseases, the availability of condoms throughout prisons and the distribution of bleach for sterilizing needles and syringes. From a public health perspective, these data suggest an urgent need for access to sterile injection equipment in addition to other preventive measures.

The evaluation of the effectiveness of routine restaurant inspections and education of food handlers: critical appraisal of the literature.

Literature databases were scanned to locate articles pertaining to food handler education and restaurant inspection. Papers which met pre-established criteria, as described in the generic protocol produced by the Community Health Practice Guidelines Project (CHPG), were evaluated by standardized consideration of criteria. Studies were rated on a scale of one to three. There were eight papers related to the intervention of education, four papers dealing with the intervention of restaurant inspection, and one pertaining to both. the evidence presented in the papers regarding the effectiveness of food handler training in improving food establishment sanitation was weak, but it appeared that some training resulted in improved inspection scores. It appeared that inspections were beneficial, although it was not clear whether three or more inspections were better than two. No inspections appeared to result in worse inspection scores.