Recent trends in pediatric Haemophilus influenzae type B infections in Canada. Immunization Monitoring Program,Active (IMPACT) of the Canadian Paediatric Society and the Laboratory Centre for Disease Control.

OBJECTIVE: To describe changes in the number of cases of Haemophilus influenzae type b (Hib) infections among Canadian children before and after the introductory phases of Hib vaccination. DESIGN: Multicentre case series. SETTING: All 10 pediatric tertiary care centres across Canada participating in the Immunization Monitoring Program, Active (IMPACT) of the Canadian Paediatric Society and the Laboratory Centre for Disease control. PATIENTS: Children with a Hib infection admitted to any of the participating hospitals from 1985 to 1994. Annual case totals from 1985 to 1990 were determined from records of hospital laboratories or coded discharge diagnoses, or both. From 1991 to 1994 intensive case surveillance was conducted on the wards in addition to thorough record searches as above. OUTCOME MEASURES: Estimated annual case totals for 1985-90. For 1991-94 intensive surveillance for quarterly case totals, yearly age distribution of cases, and proportion of recent cases that represent vaccination failures or missed opportunities to prevent infection. RESULTS: The total number of Hib cases from 1985 to 1990 was 2095; from 1991 to 1994, there were 326 laboratory-confirmed cases and 15 probably cases supported by Hib antigen detection. The annual number of cases declined from an estimated 485 in 1985 to 24 in 1994, a decrease of 95.1%. The steepest interannual decrease (63.7%) occurred between 1992 and 1993, following the introduction of infant-based vaccination programs across Canada. The number of Hib cases involving children most at risk (those 6 to 18 months old) decreased from 78 in 1991 to 4 in 1994. Of the 24 cases in 1994, 6 were categorized as preventable, 1 was fatal, and 8 were vaccine failures (2 of which involved currently used vaccines). CONCLUSION: The prevalence of Hib infections reported by the IMPACT centres has declined greatly since the introduction of vaccination programs. However, deaths and complications continue to occur, attesting to the need to vaccinate all eligible infants and children against this virulent pathogen.     

Multiple Forms and Distribution of Calcium/Calmodulin-Stimulated Protein Kinase II in Brain

In recent years, the enzyme Ca²⁺/calmodulin-stimulated protein kinase II¹ (CaM-PK II) as attracted a great deal of interest. CaM-PK II is the most abundant calmodulin-stimulated protein kinase in brain, where it is particularly enriched in neurons (Ouimet et al., 1984; Erondu and Kennedy, 1985; Lin et al., 1987; Scholz et al., 1988). Neuronal CaM-PK II has been suggested to be involved in several phenomena associated with synaptic plasticity (Lisman and Goldring, 1988; Kelly, 1992), including long-term potentiation (Malinow et al., 1988; Malenka et al.,1989), neurotransmission (Nichols et al., 1990; Siekevitz, 1991), and learning (for review, see Rostas, 1991). This enzyme has also been postulated to be selectively vulnerable in several pathological condition, including epilepsy/kindling (Bronstein et al.,1990; Wu et al., 1990), cerebral ischemia (Taft et al., 1988), and organophosphorus toxicity (Abou-Donia and Lapadula, 1990).     

Sexually transmitted diseases and HIV-1 infection among homosexual men in England and Wales.

OBJECTIVE--To examine surveillance data for evidence of changing sexual behaviour and continuing transmission of HIV-1 among men who have sex with men. DESIGN--Analytic study of surveillance data on sexually transmitted diseases. SETTING--England and Wales. MAIN OUTCOME MEASURES--Number of cases of rectal gonorrhoea and newly diagnosed HIV infection in homosexual men. RESULTS--New cases of gonorrhoea among men attending genitourinary medicine clinics increased by 7.7% in 1989 and by 4.2% in 1990. Reports of rectal isolates of Neisseria gonorrhoeae also rose and the male to female ratio for patients with rectal gonorrhoea changed from 0.3:1 during 1988-9 to 2.6:1 in 1990-1. Although the overall number of cases of acute hepatitis B fell during 1988-91, 81 and 82 homosexual men were infected in 1990 and 1991 respectively compared with 50 and 42 in 1988 and 1989. 1526 men had HIV-1 infection diagnosed in 1991, the largest number since 1987. Twenty eight of the 97 (29%) men who seroconverted between January 1989 and December 1991 were aged less than 25. The proportion of men aged 15-19 who were found to be infected with HIV-1 at their first test increased from an average of 2.4% up to 1990 to 4.7% in the first nine months of 1991. The prevalence of HIV infection in men under 25 attending genitourinary medicine clinics in London was 17% compared with 7.8% outside London. CONCLUSION--Unsafe sexual behaviour and HIV transmissions have increased among homosexual men after a period of decline. Recent HIV transmissions may disproportionately affect younger men.     

21-Hydroxylase deficiency: screening and incidence in Israel

BACKGROUND: Neonatal screening for congenital adrenal hyperplasia was introduced in 1977. However, even today only a few national screening programs exist and their cost effectiveness is still debatable. This study was conducted in order to evaluate the advisability of a national or regional screening program in Israel. METHODS: From June 1987 until December 1992 we screened a countrywide random sample of 113,846 newborns for 21-hydroxylase (21-OH) deficiency measuring 17alpha-OH progesterone (17-OHP) from blood spotted on filter paper. Between January 1993 and August 1995 we continued the screening program concentrating on the population of northern Israel. A total of 56,958 newborns were screened. We compared these findings with the incidence of 21-OH deficiency in the total population born in Israel during the years 1986-1991. RESULTS: In the countrywide screening program, 4 newborns (2 Arabs and 2 Jews) were found to have levels of 17-OHP between 409 and 2,049 nmol/l (2 males and 2 females). This constitutes a low incidence of 1 in 28,462 live births. In the north-Israel screening program 4 newborns (all Arabs) were detected (2 males and 2 females) constituting a much higher incidence of 1 in 14,240 live births. The data obtained from the archives revealed that the incidence of 21-OH deficiency nationwide during the years 1986-1991 was 1:19,000 live births, 1:30,000 for Jews and 1:8,000 for Arabs. The incidence of 21-OH deficiency among Arab newborns in the northern part of the country was as high as 1:5,000 (14:71,130). The female to male (F:M) ratio was 2.6:1 and the ratio of the salt-losing to the simple virilizing variant was 5:1. Two male patients were diagnosed prenatally, 21 patients (17 F and 4 M) during the first month after birth and 6 others subsequently. CONCLUSIONS: The high F:M ratio of 21-OH deficiency in the total population compared to a 1:1 ratio in our random screening programs suggests that 21-OH-deficient male patients in the general population might have been missed or died early due to a salt-losing crisis. The high incidence of this disease in the northern part of the country and especially among the Arabs, suggests that screening in this part of the country, especially among the Arab population, is warranted and might save the lives of some male patients.     

Cancer morbidity and mortality among the liquidators of the Chernobyl accident: estimation of radiation risks

The work focuses on the results of the analysis of the cancer incidence among the Chernobyl emergency workers residing in Russia during 1991-2001. The analysis is based on the data for the cohort of male emergency workers from 6 regions of Russia including 55718 persons with documented external radiation doses in the range of 0.001-0.3 Gy who worked within the 30-km zone in 1986-1987. The mean age at exposure for these persons was 34.8 years old and the mean external radiation dose 0.13 Gy. In this cohort 1370 cases of solid cancer were diagnosed. Three follow-up periods were considered: 1991-1995, 1996-2001 and 1991-2001. The second follow-up period was chosen to allow for a minimum latency period of 10 years. Risk assessments were performed for two control groups: the first control group ("external") represented incidence rates for corresponding ages in Russia in general and the second control group ("internal") consisted of emergency workers. The estimated standardized incidence ratio (SIR) is in good agreement with that of the control within 95% CI. The values of the excess relative risk per unit dose 1 Gy (ERR/Gy) for solid malignant neoplasms have been estimated to be 0.33 (95% CI: -0.39, 1.22) (internal control) for the follow-up period 1991-2001 and 0.19 (95% CI: -0.66, 1.27) for 1996-2001. The analysis of cancer morbidity was carried out for the cohort of 29003 emergency workers who took part in liquidation of the consequences of the Chernobyl accident from 26 April 1986 to 25 April 1987. It was shown that the excess relative risk of cancer deaths per unit dose 1 Sv (ERR/Sv) is equal to 1.52 (95% CI: 0.20, 2.85).     

The herald waves of influenza virus infections detected in Sendai and Yamagata cities in 1985-1990

The community surveillance of respiratory virus infections performed during 1985-1987 in Sendai and 1988-1990 in Yamagata has identified a total of five herald waves of influenza virus infections: A/H3N2 virus infections in 1985 and 1989, A/H1N1 virus infections in 1986 and 1988, and type B virus infections in 1989. To investigate the antigenic and genetic relationships between the herald wave and epidemic strains, influenza A/H1N1 viruses isolated during the 1986 and 1988 herald waves were compared with those isolated during the 1986-1987 and 1988-1989 epidemic seasons, respectively, utilizing hemagglutination inhibition tests with anti-hemagglutinin monoclonal antibodies and oligonucleotide mapping of total viral RNAs. The results showed that multiple variants differing in antigenic and genetic properties were cocirculating during the 1986 herald wave as well as during each of the two epidemics (only one strain was isolated in the 1988 herald wave). It was also observed that viruses which had the antigenic and/or genetic characteristics closely similar to those of the viruses circulating in the 1986 and 1988 herald waves, were isolated during the winters of 1986-1987 and 1988-1989, respectively.     

Trap-vaccinate-release and oral vaccination for rabies control in urban skunks, raccoons and foxes.

Two rabies control tactics, trap-vaccinate-release (T-V-R) and oral vaccination were used for the control of rabies in skunks (Mephitis mephitis), raccoons (Procyon lotor), and foxes (Vulpes vulpes) in metropolitan Toronto, Canada. Using T-V-R, a mean of 45% to 72% (95% confidence limits of 40% to 81%) of the skunks and a mean of 17% to 68% (95% confidence limits of 14% to 76%) of the raccoons in a 60 km2 area of Toronto were vaccinated against rabies between 1987 and 1991. The area has been free of skunk rabies from May 1989 to April 1992. Forty-five rabies cases were diagnosed during 1980 to 1986. In contrast, only three skunk cases have been reported since the vaccination program began in July 1987. The T-V-R area also remained rabies free during an epizootic of skunk rabies in metropolitan Toronto during 1991. Following distribution of rabies vaccine-baits throughout the ravines of metropolitan Toronto, June 1989 to December 1991, 46% to 80% of the Toronto fox population was immunized during 1989, 1990 and 1991. Only one case of fox rabies was reported in metropolitan Toronto since vaccination began, compared to 80 cases reported between 1982 and 1988. The area has been free of reported fox rabies from October 1990 to April 1992.     

Changes in prostate cancer incidence,mortality and survival in relation to prostate specific antigen testing in New South Wales,Australia

BackgroundTo examine changes in prostate cancer incidence and mortality rates, and 5-year relative survival, in relation to changes in the rate of prostate specific antigen (PSA) screening tests and the use of radical prostatectomy (RP) in the Australian population.MethodsProstate cancer stage-specific incidence rates, 5-year relative survival and mortality rates were estimated using New South Wales Cancer Registry data. PSA screening test rates and RP/Incidence ratios were estimated from Medicare Benefits Schedule claims data. We used multiple imputation to impute stage for cases with “unknown” stage at diagnosis. Annual percentage changes (APC) in rates were estimated using Joinpoint regression.ResultsTrends in the age-standardized incidence rates for localized disease largely mirrored the trends in PSA screening test rates, with a substantial ‘spike’ in the rates occurring in 1994, followed by a second ‘spike’ in 2008, and then a significant decrease from 2008 to 2015 (APC −6.7, 95% CI −8.2, −5.1). Increasing trends in incidence rates were observed for regional stage from the early 2000s, while decreasing or stable trends were observed for distant stage since 1993. The overall RP/Incidence ratio increased from 1998 to 2003 (APC 9.6, 95% CI 3.8, 15.6), then remained relatively stable to 2015. The overall 5-year relative survival for prostate cancer increased from 58.4% (95% CI: 55.0–61.7%) in 1981–1985 to 91.3% (95% CI: 90.5–92.1%) in 2011–2015. Prostate cancer mortality rates decreased from 1990 onwards (1990–2006: APC −1.7, 95% CI −2.1, −1.2; 2006–2017: APC −3.8, 95% CI −4.4, −3.1).ConclusionsOverall, there was a decrease in the incidence rate of localized prostate cancer after 2008, an increase in survival over time and a decrease in the mortality rate since the 1990s. This seems to indicate that the more conservative use of PSA screening tests in clinical practice since 2008 has not had a negative impact on population-wide prostate cancer outcomes.     

Multiple sclerosis among immigrants in Greater London.

Among immigrants resident in greater London from Europe, Ireland, the USSR, the old Commonwealth countries of Australia, Canada, and New Zealand, North and South America, Egypt, Turkey, and Iran the incidence of admission to hospital for probable multiple sclerosis (MS) between 1960 and 1972 was high or moderately high. The incidence was the same order as that found in those born in the United Kingdom. Immigrants from India, Pakistan, and other Asian countries and from new Commonwealth Africa and America, which includes the West Indies, had a low incidence of hospital admission for MS. Immigrants from countries where the risk of MS is low whose parents were born in Europe had a reduced incidence of admission to hospital but not the very low incidence found in those parents were also born in these countries. Emigrating to England from low risk parts of the world did not seem to increase the risk of developing MS.     

Trends in incidence of AIDS associated with transfusion of blood and blood products in Europe and the United States, 1985-93.

OBJECTIVE--To quantify patterns and trends in incidence of AIDS associated with transfusion of blood and its products in 14 European countries and the United States. DESIGN--Data were derived from the World Health Organisation''s European non-aggregate AIDS dataset and, for the United States, from the Centers for Disease Control AIDS public information dataset. Rates were standardised by using the world standard populations and adjusted for reporting delays in each country. SUBJECTS--Cases of AIDS in patients with haemophilia and recipients of transfusions. RESULTS--Overall, between 1985 and 1993 almost 6000 cases of AIDS associated with transfusions were registered in the 14 European countries considered and over 8000 in the United States between 1985 and 1992. Most European countries had annual age adjusted rates lower than 0.5 per million children aged 12 or less and between 1 and 2 per million adults. The United States had rates around 1 per million children and 5 per million adults in the most recent period. For children, the highest rates were generally reached in 1985-7, whereas in adults the highest rates were in the late 1980s. France had the highest overall incidence of AIDS related to transfusion in Europe (3.3 per million). Romania had a major epidemic in children (over 30 cases per million children in 1988-90). Incidence rates of AIDS associated with transfusion were still increasing in some southern European countries in the early 1990s. CONCLUSIONS--Apart from in France and Romania it is clear that rates of bloodborne AIDS in European countries are lower than those registered in the United States.     

Changes in incidence of and mortality from breast cancer in England and Wales since introduction of screening. United Kingdom Association of Cancer Registries.

OBJECTIVE--To assess the impact of the NHS breast screening programme on the incidence of and mortality from breast cancer. DESIGN--Comparison of age specific incidence and mortality before and after the introduction of screening in the late 1980s. SETTING--England and Wales. SUBJECTS--Women aged over 30 years. RESULTS--In 1992 the age standardised incidence of breast cancer was 40% higher than in 1979. After the introduction of screening in 1988 recorded incidence rates rose steeply in the screened age group (50-64 year olds) but not in others. In 1992 the rates levelled off at about 25% higher than in 1987. Total mortality from breast cancer has increased steadily since the 1950s; the rates increased earlier in the younger age groups. By the mid-1980s rates had begun to fall in the younger age groups; but total mortality was still among the highest in the world. Age standardised mortality in the 55-69 age group changed little during the first three years of screening but then fell steeply and in 1994 was 12% lower than in 1987. CONCLUSIONS--Since the introduction of screening there have been pronounced increases in recorded incidence in the screened age group. Cancer registries have an essential role in assessing screening programmes and cancer services. The steep decrease in mortality in 55-69 year olds which began three years after screening started is unlikely to be due to screening. The widespread adoption of treatment with tamoxifen during this period may be important. With the reduction in mortality already observed and the expected additional benefits from screening, the Health of the Nation target should be achieved.     

The rising incidence of type 1 diabetes in south-eastern Poland. A study of the 0-29 year-old age group, 1980-1999

INTRODUCTION: Studies carried out over the last few years have provided information about the increase in the incidence of type 1 diabetes in different parts of the world including the European countries bordering Poland. THE AIM OF STUDY: The aim of this study was to determine the long-term trends in the incidence of type 1 diabetes over the 20 years between 1980 and 1999 and to compare the incidence during the decades preceding and following the 1989 economic and political transformation in Poland. MATERIAL AND METHODS: The registration of type 1 diabetes among people aged 0-29 was drawn up according to the DERI recommendations using three data sources. We calculated the age-standardised incidence rates for five-year age groups and determined the long-term trend in the incidence of type 1 diabetes in south-eastern Poland. RESULTS: A significant growth in the incidence of type 1 diabetes was observed among people aged 0-29 in the Rzeszów Province in the period between 1980 and 1999. The mean age-standardised incidence rate was 6.1/100,000, and a statistically significant difference was noted between the 1980s and the 1990s (5.3 [95%CI 4.5-6.0] and 6.8 [95%CI 5.9-7.6]). The male incidence of 6.7 significantly exceeded that for females--5.5/100,000. There was also a higher incidence in the group aged 0-14 in comparison with the group aged 15-29 (6.4 and 5.8/100,000 respectively). The highest incidence was found in boys aged 10-14 (11.5/100,000) and a significantly rising trend was observed in children of 0-4 years old. CONCLUSIONS: The mean incidence of type 1 diabetes among the study population was low. Nevertheless, we demonstrated a significantly increasing trend in the incidence during the 20-year observation period. The incidence in the 1990s, both in general and for males, was significantly higher when compared to the 1980s.     

A serological survey on Bacillus piliformis infection in laboratory rabbits in Japan

A total of 544 rabbit sera obtained from 6 commercial breeding facilities and 9 research institutions during 1985-1990 were tested for Bacillus piliformis antibody by an enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent antibody test (IFAT). The antibody was detected in 53 (14.2%) rabbits from 3 breeding facilities and 30 (17.4%) rabbits from 6 research institutions, indicating the prevalence of B. piliformis infection among laboratory rabbits in Japan. The overall agreement with ELISA for immune status was 96.9% (527/544) with IFAT. In tests of the ability of ELISA and IFAT to quantitate antibody, a correlation coefficient (r) of 0.86 (P less than 0.01) was obtained by plotting the measured average log of the ELISA titer against the corresponding log of the IFAT titer.     

Colonization and succession of submerged macrophytes in shallow Lake Væng during the first five years following fish manipulation

Colonization of submerged macrophytes and changes in species composition were studied in shallow Lake Væng during the first five years (1987–91) following fish manipulation in 1986–1988 and a resultant significant improvement in lake water transparency. No submerged macrophytes were present in the lake from 1981–1986, during which time the summer mean Secchi depth ranged from 0.6 and 0.8 m. From 1987 to 1990, Secchi depth increased from 0.9 m to 1.8 m and macrophyte coverage consequently increased (1 % of the lake area in 1987, 2% in 1988, 50% in 1989, 80% in 1990 and 90% in 1991). At the same time, the macrophytes became taller, and the weedbeds more dense. The macrophytes colonized from the exposed and deeper part of the lake towards the sheltered and more shallow part of the lake, a colonization pattern that was confirmed by transplantation experiments. The delay in colonization of the shallow parts may be caused by waterfowl grazing. The vegetation was initially dominated by Potamogeton crispus L., but there was a gradual change during 1988–1989 and Elodea canadensis Michx became exclusively dominant in 1990–1991.     

Cervical cancer in Croatia: state of the art and possibilities for prevention

In Croatia, there are about 355 incident cases and about 100 deaths from cervical cancer every year. The aim of this study is to present the trends of cervical cancer incidence and mortality and to propose preventive strategies for cervical cancer in Croatia. Age-standardised and age-specific cervical cancer incidence rates were calculated for the period 1985-2004. For cervical cancer mortality data, the WHO Mortality Database was used. After an early decrease of cervical cancer incidence and mortality following the introduction of opportunistic screening in Croatia, no further decrease has been observed since the 1990s. An increase in incidence over the last 20 years was observed in the age-groups 40-44 and 45-49 years. To reduce cervical cancer rates, an organised cervical cancer screening programme is essential. In addition, HPV vaccination should be introduced in the school vaccination programme to achieve further reductions in cervical cancer incidence in the future.     

Understanding Fluctuations in Bobcat Harvest at the Northern Limit of Their Range

ABSTRACT In Quebec, Canada, harvest of bobcats (Lynx rufus) started to decline in 1985 and by 1991, harvest seasons were closed due to concerns of a perceived population decline. Since the closing of harvest season in 1991, the average temperature has increased, snow quantity has decreased, and important changes in agriculture and forest management have occurred. In light of changing conditions, the situation of Quebec bobcats needed reassessment. Thus, we analyzed harvest data to clarify the current status of bobcat populations in Quebec. From 1980 to 1991, bobcat harvest in Quebec was strongly correlated with bobcat harvest in Maine (USA), Nova Scotia (Canada), Ontario (Canada), and Vermont (USA). Extrapolations of harvest in Quebec relative to harvest in Maine, Ontario, Vermont, and Nova Scotia suggested an increase in number of bobcats after 1991. Mass of male and female bobcats before 1991 was less than mass of animals captured after 1991. Percentage of juveniles in the reported harvest before 1991 was higher than after 1991. However, percentage of males and litter sizes in the harvest did not differ before and after 1991. The geographic distribution of bobcats captured has gradually expanded after the closure of the harvest season. Our findings suggest that bobcat populations in Quebec have recovered from the 1985–1991 decline, and that the harvest season for this species could resume. This study also illustrates how managers can rely on data from neighboring jurisdiction to manage species when local harvest data is unavailable.     

Can the fall in Avon's sudden infant death rate be explained by changes in sleeping position?

OBJECTIVE--To examine the impact of changing practice with regard to infant sleeping position on mortality from the sudden infant death syndrome. DESIGN--A population based study of all infants dying suddenly and unexpectedly during February 1990 to July 1991, and two groups of controls; one comprising every 125th baby born to Avon residents and the other comprising pairs of infants matched to each index case for age, neighbourhood, and date of study. Information about sleeping position was collected at home visits soon after the index baby''s death or, for the population based controls, on several occasions in the first six months of life. The design was comparable to that of an earlier study of the same population. SETTING--County of Avon. SUBJECTS--35 infants who died suddenly and unexpectedly (32 of the sudden infant death syndrome), 70 matched controls, and 152 population based controls. RESULTS--The prevalence of prone sleeping in the matched controls was much lower than that found in an earlier study in Avon (28% (18/64) 1990-1 v 58% (76/131) 1987-9; p less than 0.001) and was comparable with the prevalence in population based controls (29%). This would be expected to lead to a reduction in the incidence of the sudden infant death syndrome to 2.0/1000 live births (95% confidence interval 1.8/1000 to 2.5/1000). The actual mortality fell from 3.5/1000 in 1987-9 to 1.7/1000. CONCLUSION--The fall in mortality can be almost entirely accounted for by the reduction in prone sleeping, suggesting a causal relation exists between them. Side and supine positions confer protection but the side position is unstable and the infant may roll prone. We therefore recommend supine as the safest sleeping position for babies.     

Incidence of insulin dependent diabetes in England: a study in the Oxford region, 1985-6.

OBJECTIVE--To determine the incidence of insulin dependent diabetes mellitus up to the age of 21 in a geographically defined population in England with independent validation of completeness of case ascertainment. DESIGN--Prospective registration of newly diagnosed cases supplemented by centralised hospital discharge records and death certificates. Validation of ascertainment from general practitioners. SETTING--Oxford Regional Health Authority area (population 2.4 million). PATIENTS--All patients with insulin dependent diabetes diagnosed below age 21 during 1985-6 and resident in the region at the time of diagnosis. INTERVENTIONS--None. END POINT--Validation of a method of case ascertainment for assessing temporal variation in incidence of insulin dependent diabetes. MEASUREMENTS AND MAIN RESULTS--The overall yearly incidence of newly diagnosed insulin dependent diabetes mellitus in people under 21 was 15.6 cases/100,000 (95% confidence interval 13.6 to 17.6). Among males the incidence was 16.8 cases (14.0 to 19.7)/100,000 and among females 14.3 cases (11.6 to 17.1)/100,000. The highest incidence, in the 10-14 year age group, was 26.4 (20.9 to 31.8) new cases/100,000 population yearly. Case ascertainment was greater than 95%. CONCLUSIONS--The incidence of insulin dependent diabetes in England is considerably higher than reported from large scale studies. It is consistent with described patterns of geographical variation. The figures provide a baseline for assessing temporal change.     

Risk of HIV infection from blood transfusion in Montreal

OBJECTIVES: To determine the incidence (including associated donor characteristics and time trends) of HIV infection among repeat blood donors and to estimate the risk of HIV transmission from blood transfusion in Montreal and in Canada as a whole. DESIGN: Retrospective cohort analysis. SETTING: Montreal Centre Blood Transfusion Service. PARTICIPANTS: People who donated blood at least twice after Nov. 1, 1985, and at least once from Apr. 1, 1989, to Mar. 31, 1993. INTERVENTION: Blood was screened for HIV by enzyme-linked immunosorbent assay and results were confirmed by Western blot analysis. OUTCOME MEASURES: Incidence density (the incidence rate per person-time) of HIV infection among repeat blood donors by sex, age group and region of residence, and incidence density and risk among first-time donors and for Canada as whole. RESULTS: There were 200,196 eligible donors and 432,631 person-years (PY) of observation. From 1989 to 1993, there were 18 HIV seroconversions among repeat donors. The crude incidence density was 3.3 per 100,000 PY (95% confidence interval [CI] 1.8 to 5.4 per 100,000 PY); it was 4.9 per 100,000 PY among men and 0.61 per 100,000 PY among women. Age-specific incidence per 100,000 PY was 2.5 among those 12-29 years of age, 5.1 among those 30-49, 2.9 among those 40-49, and 1.4 among those 50 and older. Based on an estimated mean "window period" (from when a donor''s blood is capable of transmitting HIV until detectable antibody appears) of 25 days, the current risk of HIV infection from repeat donors in the window period is estimated at 1 in 440,000. Inclusion of blood units from first-time donors produces an overall risk of 1 in 390,000 (95% CI 1 in 250,000 to 655,000). The estimated risk per blood unit in Canada as a whole is 1 in 913000 (95% CI 1 in 507,000 to 2,050,000). CONCLUSIONS: This "sentinel" population of repeat blood donors is subject to important trends in HIV spread. Therefore, estimating the incidence density of HIV infection in repeat donors provides insight into the epidemiologic characteristics of HIV infection at minimal expense. As a result of measures to improve blood safety, including HIV testing, the incidence of HIV infection among blood donors in Canada is low and the risk of HIV transmission from transfusion is extremely small, although not zero.