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Biomedical subjects

N Crofts

Publications and source records attributed to N Crofts.

At least 91 records · Page 5Linked to original sources
PubMed1994

AIDS in Malaysia.

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Acquired Immunodeficiency Syndrome↗
PubMed1993

Hepatitis C virus infection among a cohort of Victorian injecting drug users.

OBJECTIVE: To describe the epidemiology of infection with hepatitis C virus (HCV) among injecting drug users (IDUs) in Victoria. DESIGN AND SUBJECTS: Subjects were current IDUs from a wide spectrum of age, sex and social background, enrolled in a prospective study of injecting drug use. They were contacted by peer workers through their social networks and through community agencies and prisons, and were regularly followed for interview and blood collection in the field. Sera were tested for presence of antibody to HCV (anti-HCV), for the presence of HCV RNA directly in serum, and for measures of liver function. The results were correlated with demographic variables. SETTING: Rural and metropolitan Victoria. MAIN OUTCOME MEASURES: Presence of anti-HCV and demonstration of HCV RNA. RESULTS: Two-thirds (68%, 206/303) of the current cohort of IDUs were seropositive for HCV, risk being particularly associated with duration of injecting, and independently for men with opiate use and prison history, and for women with a history of methadone therapy. HCV RNA was detected in 48% (76/160) by polymerase chain reaction (PCR); 61% (74/122) of these subjects were HCV seropositive and 5% (2/38) seronegative. Of 32 HCV seronegative subjects followed for a mean period of 291 days, five seroconverted to HCV, an incidence of 20 infections per 100 person-years. Those who seroconverted were older, more likely to be male, had been injecting longer, more often reported opiate use, and were more likely to be based in the country. Serum liver enzyme levels were higher and more likely to be abnormal in HCV seropositive than seronegative subjects, and were highest in those seropositive subjects in whom HCV RNA was detected. CONCLUSIONS: This population of IDUs has a very high rate of exposure to HCV, related to duration of injecting and independently to opiate use and prison history, perhaps reflecting increased risk in particular social networks. There is evidence of high rates of carriage of HCV, of continuing transmission of HCV, and of ongoing liver disease among these IDUs. If these IDUs are at all representative of all IDUs in Australia, we estimate that 80,000 current and former IDUs may be at risk of chronic liver disease from HCV, and that 8000-10,000 new infections may be occurring each year. Two subjects who were seronegative had HCV RNA detectable in sera. These data have important implications for screening programs and document the need for further measures to prevent spread of blood-borne viruses including HIV among IDUs.

Adult↗
PubMed1993

An outbreak of hepatitis A among homosexual men in Melbourne.

OBJECTIVE: To describe an outbreak of hepatitis A virus (HAV) infection that occurred in Melbourne in 1991. DESIGN: (i) We reviewed Health Department Victoria surveillance data from 1989 to 1991 (primary surveillance) and identified all notified cases of HAV infection with an onset of illness between 1 January and 31 December 1991 (secondary surveillance data). (ii) We studied HAV seroprevalence in Melbourne among homosexual men attending gay venues. RESULTS: (i) In the two years 1989-1990 there were only 55 notifications of HAV infection to Health Department Victoria, with a male:female ratio of 1.2:1. Of the 495 notifications for 1991, 407 (82%) were male, of whom 210 (52%) were known to be homosexual. Many reported sexual and social contact at Melbourne's gay venues and with the Sydney gay community. (ii) Of men attending gay venues, 27% had serological evidence of past infection with HAV, compared with 45.8% in a 1981 Melbourne study. CONCLUSION: The outbreak of HAV infection in Victoria largely affected homosexual males in their sexually active years. Contact with the Sydney gay community was commonly reported.

Adult↗
PubMed1993

The epidemiology of HIV-1 infection in Victoria. The Victorian Collaborative Group on HIV and AIDS Surveillance (VCGHAS).

OBJECTIVE: To describe the epidemiology of infection with the human immunodeficiency virus type 1 (HIV-1) in Victoria from 1980 to 1991. DESIGN: Data on HIV-1 infection in Victoria, obtained through routine laboratory-based surveillance, were entered in a database. Missing information was sought by contacting the referring doctor where possible. SETTING: In Victoria, the acquired immunodeficiency syndrome (AIDS) is notifiable to Health Department Victoria by diagnosing doctors, and laboratories are required to notify new diagnoses of HIV-1 infection, without identifiers. All confirmatory testing for HIV-1 has taken place at the State HIV Reference Laboratory at Fairfield Hospital. MAIN OUTCOME MEASURES: Diagnoses of HIV-1 infection, as confirmed at the State HIV Reference Laboratory by western blot immunoassay, and notifications of AIDS to Health Department Victoria. RESULTS: Over six years the annual number of diagnoses of HIV-1 infection in Victoria remained constant despite a substantial increase in the number of tests performed. To the end of 1991, 2679 people had been diagnosed with HIV-1 infection, 686 of whom had developed AIDS. Information on exposure was available for 2379 (88.8%). Homosexual and bisexual men made up 75.5% (85.0% of those for whom exposure had been ascertained); 3.4% were female or heterosexual male injecting drug users; and 3.7% were heterosexuals with no history of injecting drug use. The latter two groups contributed 2.0% in 1985 to the proportion of all new diagnoses for which exposure was known, and 14.3% in 1991; for recipients of contaminated blood or blood products before 1985 this proportion fell from 12.4% to 1.0%. The cumulative incidence of HIV-1 diagnoses was highest in the age group 25-29 years, and 20% of all HIV-1 infected people were under 25 at the time of diagnosis. In 1991, 81 of the 311 people who had been diagnosed with HIV-1 infection had had previous negative or indeterminate results of tests; half of these had acquired infection in the previous year. CONCLUSION: Most HIV-1 infections in Victoria have been acquired through male homosexual contact, with a small but increasing proportion of diagnoses occurring in heterosexuals. Laboratory-based surveillance of voluntary testing, despite its limitations, has provided valuable information on the extent of the HIV-1 epidemic in Victoria. Surveillance of all HIV-1 test results and of seroconverters now supplements routine surveillance of HIV diagnoses and will ensure a more accurate picture of the epidemic in coming years.

Acquired Immunodeficiency Syndrome↗
PubMed1993

HIV infection among injecting drug users in north-east Malaysia, 1992.

Human immunodeficiency virus (HIV) has spread widely among injecting drug users (IDUs) in countries to the north and west of the 'Golden Triangle' region of South-East Asia; it is likely to have spread southwards to Malaysia as well. In order to assess HIV seroprevalence among IDUs in north-east Malaysia and describe risk factors for HIV infection in this population, we performed a cross-sectional seroepidemiological study among 210 IDUs recruited at the detoxification ward of the General Hospital in the capital city of the north-eastern Malaysian state, Kelantan. Subjects were sequential entrants to the detoxification ward, interviewed about HIV risk behaviour, and tested for antibody to HIV and to syphilis. Nearly a third (62/210, 30%) of these IDUs were HIV seropositive. Three-quarters (159/210) had travelled to Thailand in the preceding 5 years, of whom 32% (51/159) were HIV seropositive; this was associated with injecting in Thailand, but not with sexual contact there. Of those who had not left Malaysia in the preceding 5 years, 26% (11/43) were HIV seropositive, a rate not significantly different from those who had travelled. Travel within Malaysia was common (144/210, 69%) among IDUs interviewed, as was unsafe injecting and unsafe sexual behaviour (20% had shared injecting equipment and 21% had had unprotected intercourse) in other states. In every locale, rates of unsafe injecting behaviour were high (55% sharing in last month), even among those who knew they were HIV infected, and rates of condom usage were low (93% of 160 sexually active IDUs had never used a condom). Syphilis was not associated with HIV infection, but with contact with Thai prostitutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

HIV infection among injecting drug users in Asia: an evolving public health crisis.

Injecting drug use is being reported from an increasing number of Asian and other Third World countries. HIV continues to spread globally among and from populations of injecting drug users (IDUs), although the rate of spread appears to have slowed down recently in some industrialized countries. Asia produces two-thirds of the world's supply of opium. In recent years the rapid development of new illicit drug trade routes in efforts to evade detection by law enforcement authorities has exposed new populations in Asia to drug injecting and, thus, the risk of HIV infection. Epidemic spread of HIV has recently commenced in some Asian countries among injecting drug users, and others are at substantial risk of an HIV epidemic among their IDU populations. The speed of spread and the consequences of HIV infection among IDUs in Asian and other Third World countries are even more profound than in western countries. Asian countries attempting to control this component of the epidemic often have greater difficulty than industrialized countries because of their proximity to drug producing areas, scarcity of resources and a greater likelihood of pragmatic policies conflicting with traditional values. Vigorous efforts are urgently required at both a national and international level to raise awareness of the consequences of an uncontrolled epidemic of HIV among IDUs in Asian and other countries, and to support the implementation of policies which are likely to reduce the spread of HIV.

Asia↗
PubMed1993

The effects of methadone on immune function among injecting drug users: a review.

Methadone maintenance therapy is advocated as a major preventive strategy for the spread of the human immunodeficiency virus (HIV) and other blood-borne infectious agents among injecting drug users (IDUs) because of its effects in decreasing the frequency of injecting and presumably sharing of equipment. As an opioid agonist, methadone may share the direct and indirect immunoregulatory effects of other opioids, and thus affect susceptibility to, and the natural history of, HIV infection. Available evidence pertaining to methadone and immune function is reviewed. The long-term immunosuppression observed in heroin injectors on present (incomplete) evidence appears to be caused by factors associated with a drug-using lifestyle rather than by a direct action of heroin. Although data are conflicting, it is most likely that methadone does not significantly impair immune function and is safe for HIV-infected IDUs, possibly even allowing some improvement of immune function to occur. The increasing reliance placed on methadone maintenance to control the epidemic of HIV infection in IDUs requires that remaining uncertainties regarding methadone and immune function are clarified urgently.

Antibody Formation↗
PubMed1991

Entry of human immunodeficiency virus infection into a population of injecting drug users, Victoria, 1990.

OBJECTIVE: To investigate the pathway by which the human immunodeficiency virus (HIV) is entering populations of injecting drug users (IDUs) in Victoria. DESIGN: A retrospective case-control study comparing the prevalence of self reported risk behaviour in HIV-infected and uninfected Victorian IDUs. SETTING: Subjects were recruited by trained peer outreach workers from their personal networks, community agencies and Fairfield Hospital outpatients, and by a research worker from the major metropolitan prison. PARTICIPANTS: People who had been resident in Victoria for the past 12 months and had injected an illicit drug more than once in the previous three years were eligible to participate. Sixty-two such people (28 HIV-infected, 34 not infected) were included in the study. MAIN OUTCOME MEASURES: The two main hypothesised portals of entry were from the non-IDU homosexual population in Victoria, and from HIV-infected IDUs elsewhere. RESULTS: male homosexual contact was the most consistent risk factor identified by this study (odds ratio [OR], 6.2; 95% confidence interval [CI], 1.7-23.8). Having lived in or visited Sydney before 1986 was also associated with being infected with HIV (OR, 13.2; 95% CI, 1.5-603), and this was associated with homosexuality. Infected IDUs reported more sharing of injecting equipment than controls (OR, 9.0; 95% CI, 1.5-92.5), particularly with sexual partners; when this was the case, they were more likely to always use the injecting equipment after their partner (61% of cases, 0% of controls; OR, greater than or equal to 4.1; P = 0.0006). CONCLUSION: Men who have a history of both homosexual contact and injecting drug use represent the group of IDUs at highest risk of HIV infection in Victoria. Although heterosexual and homosexual IDUs may have limited contact only, a larger epidemic of HIV infection in heterosexual IDUs could spread from homosexual IDUs through the sharing of injecting equipment.

Adult↗
PubMed1991

Testing of saliva for antibodies to HIV-1.

To determine whether saliva is a potentially useful sample for screening for HIV infection when serum is not obtainable, saliva and serum samples from 50 HIV-infected and 50 uninfected subjects were tested for antibody to HIV-1 (anti-HIV-1) using a second-generation enzyme-linked immunosorbent assay (ELISA; Abbott) and prototype antibody-capture ELISA (Wellcome). Of saliva specimens from HIV-infected people, six gave negative results on the Abbott and one on the Wellcome assays; all specimens from uninfected people were negative by both assays. Sensitivity for the Abbott assay was therefore 88.0% [95% confidence interval (Cl) 76.2-94.4%], an unacceptable level for screening purposes. Sensitivity for the Wellcome assay was 98% (95% Cl 89.5-99.6%), a more satisfactory level for population screening. Further validation of this technique is necessary, and of methods for collection of saliva specimens in particular.

AIDS Serodiagnosis↗
PubMed1989

A possible outbreak of listeriosis caused by an unusual strain of Listeria monocytogenes.

During 1987, a cluster of 23 cases of listeriosis due to an unusual serotype of Listeria monocytogenes was identified. All the 'epidemic' strains (designated serovar 4b(X)) were indistinguishable by serotyping, phage-typing and monoclonal antibody-typing. Clusters of cases due to this type have not been identified previously in Britain at such a high frequency. In an epidemiological survey, patients were interviewed so as to identify risk factors but none common in all cases was identified.

Antibodies, Monoclonal↗
PubMed1988

Evaluation of enzyme-linked immunosorbent assays: a method of data analysis.

Diagnostic tests are usually evaluated in terms of simple qualitative measures of sensitivity and specificity. When comparing different quantitative assays such as ELISAs, it is often more useful to deal with actual values (sample optical density/cut-off optical density ratio (OD ratio] rather than the qualitative relationship to the cut-off, i.e. positive or negative. This allows for a statistical approach to the questions of sensitivity and specificity. The National HIV Reference Laboratory of Australia has developed an approach for determining statistical estimates of sensitivity and specificity in terms of delta (delta). Delta is defined as the distance of the mean OD ratio of the sample population from the cut-off measured in standard deviation units. This paper discusses the derivation of this measurement and its usefulness when evaluating ELISA tests.

Data Interpretation, Statistical↗