Lack of HIV transmission in the practice of a dentist with AIDS

Molecular epidemiology to aid virtual elimination of HIV transmission in Australia

The Global UNAIDS 95/95/95 targets aim to increase the percentage of persons who know their HIV status, receive antiretroviral therapy, and have achieved viral suppression. Achieving these targets requires efforts to improve the public health response to increase access to care for those living with HIV, identify those yet undiagnosed with HIV early, and increase access to prevention for those most at risk of HIV acquisition. HIV infections in Australia are among the lowest globally having recorded significant declines in new diagnoses in the last decade. However, the HIV epidemic has changed with an increasing proportion of newly diagnosed infections among those born outside Australia observed in the last five years. Thus, the current prevention efforts are not enough to achieve the UNAIDS targets and virtual elimination across all population groups. We believe both are possible by including molecular epidemiology in the public health response. Molecular epidemiology methods have been crucial in the field of HIV prevention, particularly in demonstrating the efficacy of treatment as prevention. Cluster detection using molecular epidemiology can provide opportunities for the real-time detection of new outbreaks before they grow, and cluster detection programs are now part of the public health response in the USA and Canada. Here, we review what molecular epidemiology has taught us about HIV evolution and spread. We summarize how we can use this knowledge to improve public health measures by presenting case studies from the USA and Canada. We discuss the successes and challenges of current public health programs in Australia, and how we could use cluster detection as an add-on to identify gaps in current prevention measures easier and respond quicker to growing clusters. Lastly, we raise important ethical and legal challenges that need to be addressed when HIV genotypic data is used in combination with personal data.

No longer 'written off' - times have changed for the BBV-infected dental professional

There is a recognised potential risk of transmission of blood-borne viruses (BBVs) from infected healthcare workers to patients during exposure prone procedures (EPPs). The restrictions placed on performance of EPPs by infected clinicians in the UK have had a particularly significant impact on dentists because of the exposure-prone nature of most dental procedures and the difficulties in identifying alternative career pathways in the profession that do not involve EPPs. More recently, the significant positive impact of antiviral drugs on viral load, together with a re-categorisation of EPPs in dentistry have resulted in evolution of the guidance with a consequent significant improvement to the career prospects of dentists infected with BBVs. This paper provides an update for practitioners on the progress that has been made and outlines the current position with respect to practice restrictions.

Connecting the dots: network data and models in HIV epidemiology

Effective HIV prevention requires knowledge of the structure and dynamics of the social networks across which infections are transmitted. These networks most commonly comprise chains of sexual relationships, but in some populations, sharing of contaminated needles is also an important, or even the main mechanism that connects people in the network. Whereas network data have long been collected during survey interviews, new data sources have become increasingly common in recent years, because of advances in molecular biology and the use of partner notification services in HIV prevention and treatment programmes. We review current and emerging methods for collecting HIV-related network data, as well as modelling frameworks commonly used to infer network parameters and map potential HIV transmission pathways within the network. We discuss the relative strengths and weaknesses of existing methods and models, and we propose a research agenda for advancing network analysis in HIV epidemiology. We make the case for a combination approach that integrates multiple data sources into a coherent statistical framework.

Phylogenetically resolving epidemiologic linkage

Although the use of phylogenetic trees in epidemiological investigations has become commonplace, their epidemiological interpretation has not been systematically evaluated. Here, we use an HIV-1 within-host coalescent model to probabilistically evaluate transmission histories of two epidemiologically linked hosts. Previous critique of phylogenetic reconstruction has claimed that direction of transmission is difficult to infer, and that the existence of unsampled intermediary links or common sources can never be excluded. The phylogenetic relationship between the HIV populations of epidemiologically linked hosts can be classified into six types of trees, based on cladistic relationships and whether the reconstruction is consistent with the true transmission history or not. We show that the direction of transmission and whether unsampled intermediary links or common sources existed make very different predictions about expected phylogenetic relationships: (i) Direction of transmission can often be established when paraphyly exists, (ii) intermediary links can be excluded when multiple lineages were transmitted, and (iii) when the sampled individuals' HIV populations both are monophyletic a common source was likely the origin. Inconsistent results, suggesting the wrong transmission direction, were generally rare. In addition, the expected tree topology also depends on the number of transmitted lineages, the sample size, the time of the sample relative to transmission, and how fast the diversity increases after infection. Typically, 20 or more sequences per subject give robust results. We confirm our theoretical evaluations with analyses of real transmission histories and discuss how our findings should aid in interpreting phylogenetic results.

HIV/AIDS: dental assistants' self-reported knowledge and attitudes in Kuwait

Although several studies have been conducted to assess dentists' knowledge of and attitudes towards human immunodeficiency virus (HIV)/acquired immune-deficiency syndrome (AIDS), few have targeted dental assistants. The main aims of this study were to assess the knowledge of and attitudes towards HIV/AIDS among dental assistants in Kuwait and to compare the knowledge and attitudes of dental assistants at Kuwait University Dental Center (KUDC) with those of dental assistants in Ministry of Health (MoH) hospitals. The secondary objective was to determine if any intervention was needed to provide more information to dental assistants on HIV/AIDS. A cross-sectional study was conducted by distributing questionnaires. The study sample included 85 dental assistants from each of KUDC and the MoH. The questionnaire included questions to assess the assistants' knowledge and attitude towards HIV/AIDS. Statistical data analysis was conducted using SPSS 20.0. Qualitative data were analysed using the Pearson chi-square text for any association or the Z-test for proportion to test the significance of differences. A total of 167 questionnaires were completed, returned and analysed. KUDC dental assistants were found to have significantly more knowledge about HIV/AIDS than their MoH counterparts, whereas the assistants at the MoH clinics displayed a more positive attitude towards patients with HIV/AIDS (P < 0.05). Although dental assistants at KUDC were more knowledgeable than those at the MoH clinics, there are still some misconceptions that need to be addressed, in addition to the negative attitudes displayed by some of the respondents. It would therefore be beneficial to increase awareness about HIV/AIDS patients through lectures, seminars and workshops targeting dental assistants.

Use of non-human DNA analysis in forensic science: a mini review

Analysis of non-human DNA in forensic science, first reported about two decades ago, is now commonplace. Results have been used as evidence in court in a variety of cases ranging from abduction and murder to patent infringement and dog attack. DNA from diverse species, including commonly encountered pets such as dogs and cats, to plants, viruses and bacteria has been used and the sheer potential offered by such analyses has been proven. In this review, using case examples throughout, we detail the considerable literature in this field.

Phylogenetic relatedness of circulating HIV-1C variants in Mochudi, Botswana

BACKGROUND

Determining patterns of HIV transmission is increasingly important for the most efficient use of modern prevention interventions. HIV phylogeny can provide a better understanding of the mechanisms underlying HIV transmission networks in communities.

METHODS

To reconstruct the structure and dynamics of a local HIV/AIDS epidemic, the phylogenetic relatedness of HIV-1 subtype C env sequences obtained from 785 HIV-infected community residents in the northeastern sector of Mochudi, Botswana, during 2010-2013 was estimated. The genotyping coverage was estimated at 44%. Clusters were defined based on relatedness of HIV-1C env sequences and bootstrap support of splits.

RESULTS

The overall proportion of clustered HIV-1C env sequences was 19.1% (95% CI 17.5% to 20.8%). The proportion of clustered sequences from Mochudi was significantly higher than the proportion of non-Mochudi sequences that clustered, 27.0% vs. 14.7% (p = 5.8E-12; Fisher exact test). The majority of clustered Mochudi sequences (90.1%; 95% CI 85.1% to 93.6%) were found in the Mochudi-unique clusters. None of the sequences from Mochudi clustered with any of the 1,244 non-Botswana HIV-1C sequences. At least 83 distinct HIV-1C variants, or chains of HIV transmission, in Mochudi were enumerated, and their sequence signatures were reconstructed. Seven of 20 genotyped seroconverters were found in 7 distinct clusters.

CONCLUSIONS

The study provides essential characteristics of the HIV transmission network in a community in Botswana, suggests the importance of high sampling coverage, and highlights the need for broad HIV genotyping to determine the spread of community-unique and community-mixed viral variants circulating in local epidemics. The proposed methodology of cluster analysis enumerates circulating HIV variants and can work well for surveillance of HIV transmission networks. HIV genotyping at the community level can help to optimize and balance HIV prevention strategies in trials and combined intervention packages.

The HIV positive dentist in the United Kingdom - the dilemma of the undiagnosed clinician

This article considers the position of the HIV positive dentist in the United Kingdom who is unaware of their HIV status, or who at least has had no positive HIV test result. It outlines the current UK guidance that relates to HIV positive dentists, and the challenges to those guidelines. It considers how the behaviour of a practising seropositive dentist who has had no positive test result might be interpreted by regulatory bodies and the courts, and highlights the importance of clinicians being fully aware of their HIV status.

Confidentiality of the medical records of HIV-positive patients in the United Kingdom - a medicolegal and ethical perspective

This article examines the legal and ethical issues that surround the confidentiality of medical records, particularly in relation to patients who are HIV positive. It records some historical background of the HIV epidemic, and considers the relative risks of transmission of HIV from individual to individual. It explains the law as it pertains to confidentiality, and reports the professional guidance in these matters. It then considers how these relate to HIV-positive individuals in particular.

Source identification in two criminal cases using phylogenetic analysis of HIV-1 DNA sequences

Phylogenetic analysis has been widely used to test the a priori hypothesis of epidemiological clustering in suspected transmission chains of HIV-1. Among studies showing strong support for relatedness between HIV samples obtained from infected individuals, evidence for the direction of transmission between epidemiologically related pairs has been lacking. During transmission of HIV, a genetic bottleneck occurs, resulting in the paraphyly of source viruses with respect to those of the recipient. This paraphyly establishes the direction of transmission, from which the source can then be inferred. Here, we present methods and results from two criminal cases, State of Washington v Anthony Eugene Whitfield, case number 04-1-0617-5 (Superior Court of the State of Washington, Thurston County, 2004) and State of Texas v Philippe Padieu, case numbers 219-82276-07, 219-82277-07, 219-82278-07, 219-82279-07, 219-82280-07, and 219-82705-07 (219th Judicial District Court, Collin County, TX, 2009), which provided evidence that direction can be established from blinded case samples. The observed paraphyly from each case study led to the identification of an inferred source (i.e., index case), whose identity was revealed at trial to be that of the defendant.

The HIV positive dentist in the United Kingdom--a legal perspective

In 1991, the United Kingdom Advisory Panel (UKAP) was set up under the aegis of the Expert Advisory Group on AIDS (EAGA) to consider individual cases of HIV infected healthcare workers. Policy and guidance relating to HIV infected healthcare workers is set out in a Department of Health report. Although more recently the EAGA has advised that an HIV positive dentist may under certain conditions provide clinical treatment for patients who are also HIV positive, the advice from UKAP relating to exposure-prone procedures means, in effect, that dentists who become HIV positive must cease contemporary clinical dentistry. The plight of dentists who become HIV positive and face this situation has been poignantly described as '...the dental practice equivalent of clearing your desk and being escorted off the premises.'

Molecular epidemiological tracing of HIV-1 outbreaks in Hainan island of southern China

OBJECTIVES

To determine the prevalence of HIV in Hainan island and the molecular epidemiological linkages related to risk factors of viral transmission.

METHODS

A governmental HIV/AIDS surveillance program, HIV serological study was conducted in volunteers from several high-risk groups between 1991 and 2006 in Hainan province. By phylogenetic reconstruction, we performed a molecular epidemiological tracing in a representative subset of the HIV-1-seropositive individuals diagnosed during this survey.

RESULTS

Of 499 752 volunteers, 523 (0.1%) accumulated cases of HIV-1 infection (69.2% needle-sharing drug users, 19.3% heterosexually acquired adults, 3.3% receivers of blood transfusion, 0.8% children born from HIV-1-infected mothers, and 7.7% remained unknown) were diagnosed. Among 83 patient samples examined (70 were infected with HIV-1 subtypes CRF01_AE and eight, two, one, one, and one were B', C, CRF08_BC, B, and a new CRF01_AE/B' recombinant, respectively), 66 (79.5%) were segregated into one large cluster (59 sequences) (founder effect) and one small cluster (three sequences) of CRF01_AE, one small cluster (two sequences) of B', and one small cluster (two sequences) of C. Phylogenetic and epidemiological linkages confirmed four heterosexual transmission events and rejected two potential heterosexual transmission suggested by contact tracing. Only two cases of CRF01_AE showed mutations conferring resistance to nucleoside and nonnucleoside reverse transcriptase inhibitors.

CONCLUSION

The reconstruction of current HIV-1 outbreaks by molecular epidemiological tracing is helpful for identifying epidemic sources and for defining prevention strategies.

Healthcare Workers and HIV Health Issues

Should healthcare workers (HCWs) be routinely tested for HIV? The authors reviewed the literature on the risk and incidence of HIV transmission from HCW to patients and offer recommendations for HIV testing in HCWs in Singapore. Management of HCWs who are tested seropositive for HIV infection is also discussed in this paper. Key words: AIDS, HIV testing, occupational, transmission

Molecular tracing of sexual HIV Type 1 transmission in the southwest border of China

Since the first outbreak of HIV-1 was reported in heroin users in China in 1989, HIV-1 has spread steadily among injection drug users, leading to an exponential growth of nationwide outbreaks from 1998 to 2004. However, the impact of sexual transmission on outbreaks of HIV in China's general population is still unclear. Through a governmental HIV/AIDS surveillance program, an HIV serological study was conducted in volunteers between 1996 and 2005 in Xishuangbanna Dai Autonomous Prefecture of Yunnan province. We performed the transmission reconstruction by molecular epidemiological tracing in a subset of the HIV-1-seropositive individuals diagnosed during this survey. Neighbor joining and maximum likelihood trees based on the HIV-1 pol and env genes were implemented to provide information on putative epidemiological links, which were then confirmed by contact tracing. Of 25,390 volunteers, 501 (2%) accumulated cases of HIV-1 infection (21.1% in needle-sharing drug users, 77.3% in heterosexual adults, 0.4% in homosexual adults, and 1.2% in children born from infected mothers) were diagnosed. Among 44 heterosexually infected and antiretroviral-naive local-traceable individuals (27 infected with HIV-1 subtype CRF01_AE, 15 with CRF08_BC, 1 with G, and 1 with a new B/C recombinant), 18 (40.9%) were coclustered into 8 transmission chains with an average size of 2.25 infections per chain. Phylogenetic and epidemiological linkages confirmed eight heterosexual transmission events. This is the first report providing molecular epidemiological evidence of heterosexual transmission of HIV-1 in China's general population. The reconstruction of transmission of current HIV-1 outbreaks by molecular epidemiological tracing is instrumental in identifying sources of the epidemic and in defining prevention strategies.

HIV forensics: pitfalls and acceptable standards in the use of phylogenetic analysis as evidence in criminal investigations of HIV transmission

BACKGROUND

Phylogenetic analysis - the study of the genetic relatedness between HIV strains - has recently been used in criminal prosecutions as evidence of responsibility for HIV transmission. In these trials, the expert opinion of virologists has been of critical importance.

PITFALLS

Phylogenetic analysis of HIV gene sequences is complex and its findings do not achieve the levels of certainty obtained with the forensic analysis of human DNA. Although two individuals may carry HIV strains that are closely related, these will not necessarily be unique to the two parties and could extend to other persons within the same transmission network.

ACCEPTABLE STANDARDS

For forensic purposes, phylogenetic analysis should be conducted under strictly controlled conditions by laboratories with relevant expertise applying rigorous methods. It is vitally important to include the right controls, which should be epidemiologically and temporally relevant to the parties under investigation. Use of inappropriate controls can exaggerate any relatedness between the virus strains of the complainant and defendant as being strikingly unique. It will be often difficult to obtain the relevant controls. If convenient but less appropriate controls are used, interpretation of the findings should be tempered accordingly.

CONCLUSIONS

Phylogenetic analysis cannot prove that HIV transmission occurred directly between two individuals. However, it can exonerate individuals by demonstrating that the defendant carries a virus strain unrelated to that of the complainant. Expert witnesses should acknowledge the limitations of the inferences that might be made and choose the correct language in both written and verbal testimony.

Autochthonous horizontal transmission of a CRF02_AG strain revealed by a human immunodeficiency virus type 1 diversity survey in a small city in inner state of Rio de Janeiro, Southeast Brazil

As part of an ongoing study on the features of AIDS spread towards small cities and rural areas, we present a molecular survey of human immunodeficiency virus type 1 (HIV-1) polymerase sequences recovered between 2004 and 2006 from 71 patients receiving care in the city of Saquarema, inner state of Rio de Janeiro. Phylogenetic reconstructions found the two prevalent lineages in the state (subtypes B [59 strains, 83.1%], F1 [6 strains; 8.4%], and BF1 recombinants [four strains; 5.6%]), as well as two (2.8%) CRF02_AG strains, which seems to be an emerging lineage in the capital. These CRF02_AG sequences were recovered from a married heterosexual couple who never traveled abroad, thus providing the first molecular evidence of autochthonous horizontal transmission of this lineage of major global importance. Also, three phylogenetic clusters of strains recovered from a total of 18.3% of the cohort were uncovered. Their close genetic relatedness suggests they were recovered from patients who probably took part in the same chain of viral spread. In conjunction with our previous surveys from inner Rio de Janeiro, these results suggest that although small cities harbor unique molecular features of HIV-1 infection, they also clearly reflect and may rapidly absorb the diversity recorded in large urban centers.

Limitations to contact tracing and phylogenetic analysis in establishing HIV type 1 transmission networks in Cuba

Sequence analysis can be used to evaluate transmission networks. We have used retrospective samples to examine two HIV-1 transmission networks established by contact tracing. Regions of the HIV-1 region representing segments of gag and env were amplified by RT-PCR from frozen plasma samples and the sequence of each PCR product was determined. Within one of the networks (composed of 38 subjects) we found only a subset of the tested sequence clusters was consistent with the reported epidemiological linkage. Of 15 presumed transmission events where sequence data were available, 9 could be rejected either by subtype mismatch or by phylogenetic tests. In the other network (composed of 89 subjects) we were able to assess sequences for 26 presumed transmission events, 18 of which were rejected based on subtype discordance. Long lags in time between the time of transmission and the time of sequence sampling (ranging from 2 to 18 years) may limit the sensitivity for the detection of sequence linkage. Also, superinfection and incomplete epidemiological information are other factors that will limit the concordance of phylogenetic reconstruction and reported epidemiological linkage.

Hygiene und Infektionsprävention in Zahnarztpraxen

Recommendations for prevention of infection in dentistry have been published in many countries and in Germany as well. In a pilot project in collaboration with the Public Health Service of the City of Frankfurt and the chamber of dentists in Hesse, compliance with these recommendations was studied in dental practices in Frankfurt/M in 2005. After being informed about the recommendations, more than 50% of the 560 Frankfurt dentists agreed to participate in this project, and 127 of these practitioners were visited by experts of the dentist chamber. Hygienic standards in the practices were examined using a checklist. A proper hygiene schedule was observed in 84% of the practices. Facilities for hand hygiene such as dispensers for soap, disinfectant and towels were available in 98, 93 and 92% of the practices, and personal protective equipment such as gloves, masks, eye wear and gowns was found in 98, 100, 98 and 88% of the practices, respectively. Reprocessing of dental instruments was done either manually (52%), manually in combination with ultrasonic cleaning (48%) or by using special reprocessing machines (32%). Steam sterilization was used in all practices; in some practices gravity displacement sterilizers were used (14%), whereas in most of the practices (61%) a high-speed prevacuum sterilizer was available -- especially in dental surgeon practices (77%). Monitoring and documentation of the sterilization process was done automatically (33%) or by hand (55%). In 80% of the practices, pressure, temperature, time and person responsible were documented. Documents of routine maintenance and regular biological testing of the sterilizers could be shown in 93 and 84% of the practices. The Frankfurt pilot project based on information and advice in combination with control has proven to be successful in the majority of practices enrolled. Encouraged by this experience, the chamber of dentists wants to implement this project all over the state of Hesse. The intention is to inform and to visit all 4,500 dental practices in agreement with the local public health services, which in turn could reduce their own control visits in dental practices. Thus, hygiene control visits of the public health services could focus on other practices such as ambulatory surgery or endoscopy.

Molecular analysis of HIV strains from a cluster of worker infections in the adult film industry, Los Angeles 2004

OBJECTIVES

In April 2004, 13 susceptible women were exposed to a single acutely HIV-1-infected man while employed to perform various sex acts for the production of adult films; three women were subsequently found to have acquired HIV infection (23% attack rate). As part of the investigation of this infection cluster, we evaluated whether viral strains collected from infected individuals were significantly related.

METHODS

We determined nucleotide sequences from the C2V3C3 and gp41 region of env and the p17 region of gag in viruses from the three infected individuals from whom specimens were available. We then compared these sequences phylogenetically to comparable sequences from available reference strains. Genotypic and phenotypic antiretroviral drug resistance was determined for plasma virus from the male index case and one female contact at a separate commercial laboratory.

RESULTS

The env and gag sequences of the HIV strains from the male index case and two of the infected women were 100% similar. Genotyping of the male index case's virus identified 12 mutations, which represented known naturally occurring polymorphisms in the subtype B consensus sequence that are not associated with antiretroviral drug resistance. Genotyping of the virus from the female contact identified 10 mutations, all of which were shared by the virus from the male index case. Phenotyping demonstrated that both viruses were susceptible to all antiretroviral drugs tested.

CONCLUSION

Molecular and virological data strongly support the epidemiological conclusion that these women were infected with an identical strain of HIV through occupational exposure to an individual with an acute HIV infection.

Attitudes of a group of Mexico City residents toward HIV/AIDS in the dental office

OBJECTIVE

To ascertain the intention of the public to undergo dental treatment at dental clinics where other patients or a dentist are infected with HIV/AIDS.

STUDY DESIGN

A cross-sectional design was used to interview a stratified sample of persons 18 years and older in Mexico City with use of a standardized questionnaire. Questions included the type of dental service used, the perception of risk for HIV/AIDS contagion in the dental environment, and the reported intention to continue treatment in a dental office where patients or a dentist were affected by HIV/AIDS.

RESULTS

Of the 490 participants, 74.9% were concerned about HIV/AIDS transmission in the dental office. Only 21.2% intended to continue treatment at a dental office where HIV/AIDS patients were treated, and only 20.0% intended to continue treatment when the dentist was HIV-positive. The degree of concern about HIV/AIDS contagion and the modality of dental service used were associated with the stated intention to continue dental treatment.

CONCLUSIONS

There is a need to have good infection control standards in dental practice; to increase public trust in such standards by making them more apparent; and/or to establish educational programs to improve public knowledge and attitudes toward HIV/AIDS risks in dental practice.

Molecular analysis in support of an investigation of a cluster of HIV-1-infected women

An investigation of a possible single-source sexual transmission case was conducted in upstate New York in 1997-1998 (MMWR 1999;48:413-416). Of 42 primary female contacts with the putative male index case, 13 tested positive for HIV infection. Blood was available for DNA sequencing (C2V3C3 region of the env gene and the p17-coding region of gag) from 10 of the 13 women, 1 HIV-infected secondary contact, and 2 HIV-infected persons from the community, but not from the index cam. Phylogenetic and distance analyses were performed with the inclusion of reference HIV subtype strains for both the env and gag gene regions, as was the two regions combined. A high degree of relatedness was found among DNA sequences of the 10 primary contacts that excluded reference strains, the secondary contact, and the community HIV control subjects. In conclusion, phylogenetic analysis of HIV strains in an epidemiologic investigation is highly useful in support of cluster identification, even without sampling from the putative index patient.

Blood-borne pathogens and nosocomial infections

Guidelines to prevent the transmission of blood-borne infections have evolved rapidly since the recognition that "serum hepatitis" could be transmitted to health care personnel via percutaneous exposure to blood. The HIV epidemic focused renewed attention on the problem of protecting health care personnel, culminating in "standard precautions" for patient care, which emphasized the use of gloves for all contact with blood and body fluids. This focus on protection of the health care worker sometimes obscures the other important functions of gloves: protection of patients from microorganisms on the hands of providers and prevention of patient-to-patient transmission of nosocomial pathogens. The risk of infection after percutaneous exposure to the 3 major blood-borne viruses-hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV-varies greatly. The risk for a nonimmune individual exposed to HBV may be >30% if the source is Hb(e)Ag-positive. The average infection rate for HCV is 1.8%. For HIV, the average risk is 0.3%, but is higher with deep injury, when there is visible blood on the device, when a needle has been in an artery or vein, or when the source patient is in the terminal phase of HIV. Prompt administration of anti-HIV therapy reduces risk by about 80%. Mucous membrane and cutaneous exposures carry less risk. Recent efforts to reduce needlestick injuries in hospitals have reduced the risk to health care providers. Surgeons and other health care professionals who are infected with HIV or HCV pose a very small risk to their patients, although a number of outbreaks have been traced to surgeons who are HBV carriers; most have been Hb(e)Ag-positive.

The use of tat and env sequences from human immunodeficiency virus 1 in phylogenetic epidemiological studies

Using nucleotide sequences from the first exon of the tat gene of the human immunodeficiency virus 1 (HIV-1), we tested the hypothesis that a Florida dentist (a common source) infected five of his patients in the course of dental procedures against the null hypothesis that the dentist and each individual of the dental group independently acquired the virus within the local community. This novel approach of analyzing the tat gene region was used because it may, in some circumstances, be more informative for phylogenetic epidemiology than the more commonly used C2-V3 envelope gene region. The first exon of the tat gene was polymerase chain reaction (PCR)-amplified and directly sequenced from uncultured peripheral blood mononuclear cells. Patient's sequences were compared with sequences from six HIV-1 infected heterosexual couples unrelated to the dentist or the five patients, but from the same general geographic area. In addition, a sixth infected dental patient, previously inferred to have acquired HIV-1 from a source other than the dentist, was included. Multiple phylogenetic analyses demonstrated that the sequences of the five patients were significantly more closely related to each other than to sequences of the controls. Our results using tat sequences, combined with envelope sequence data, strongly support a common phylogenetic epidemiological relationship among these five patients, and the HIV-1 infected dentist who treated them. Correct recovery of known epidemiological relationships among couples included in the analysis further strengthens this conclusion.

Risk and management of blood-borne infections in health care workers

Exposure to blood-borne pathogens poses a serious risk to health care workers (HCWs). We review the risk and management of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in HCWs and also discuss current methods for preventing exposures and recommendations for postexposure prophylaxis. In the health care setting, blood-borne pathogen transmission occurs predominantly by percutaneous or mucosal exposure of workers to the blood or body fluids of infected patients. Prospective studies of HCWs have estimated that the average risk for HIV transmission after a percutaneous exposure is approximately 0.3%, the risk of HBV transmission is 6 to 30%, and the risk of HCV transmission is approximately 1.8%. To minimize the risk of blood-borne pathogen transmission from HCWs to patients, all HCWs should adhere to standard precautions, including the appropriate use of hand washing, protective barriers, and care in the use and disposal of needles and other sharp instruments. Employers should have in place a system that includes written protocols for prompt reporting, evaluation, counseling, treatment, and follow-up of occupational exposures that may place a worker at risk of blood-borne pathogen infection. A sustained commitment to the occupational health of all HCWs will ensure maximum protection for HCWs and patients and the availability of optimal medical care for all who need it.

Risk and management of blood-borne infections in health care workers

Exposure to blood-borne pathogens poses a serious risk to health care workers (HCWs). We review the risk and management of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infections in HCWs and also discuss current methods for preventing exposures and recommendations for postexposure prophylaxis. In the health care setting, blood-borne pathogen transmission occurs predominantly by percutaneous or mucosal exposure of workers to the blood or body fluids of infected patients. Prospective studies of HCWs have estimated that the average risk for HIV transmission after a percutaneous exposure is approximately 0.3%, the risk of HBV transmission is 6 to 30%, and the risk of HCV transmission is approximately 1.8%. To minimize the risk of blood-borne pathogen transmission from HCWs to patients, all HCWs should adhere to standard precautions, including the appropriate use of hand washing, protective barriers, and care in the use and disposal of needles and other sharp instruments. Employers should have in place a system that includes written protocols for prompt reporting, evaluation, counseling, treatment, and follow-up of occupational exposures that may place a worker at risk of blood-borne pathogen infection. A sustained commitment to the occupational health of all HCWs will ensure maximum protection for HCWs and patients and the availability of optimal medical care for all who need it.

Nosocomial HIV-transmission in an outpatient clinic detected by epidemiological and phylogenetic analyses

OBJECTIVE

To determine if a case of HIV-infection in a patient (GP) with common variable immunodeficiency, and with no known risk factors for HIV-infection, could be due to horizontal nosocomial transmission.

METHODS

For determination of time of transmission stored serum-samples from GP were analysed for HIV RNA content. Patient records were used to identify patients, who had received intravenous therapy on the same day as GP. Samples from GP and these possible source patients were identified and phylogenetic analyses of the env, gag and RT-encoding region of pol were performed. Furthermore, routines in conjunction with intravenous therapy were examined.

RESULTS

We identified a patient (FDL) harbouring virus almost indistinguishable from the virus isolated from GP. The pairwise nucleotide distance between the C2-V3-C3 region of the env and gag sequences from the two patients were 1.9 and 0.9% respectively. In addition, GP harboured HIV RNA with a foscarnet resistance mutation further lending support to virus from the foscarnet-treated FDL being the source of the infection. Interestingly, GP experienced increases in immunoglobulin production after contracting the HIV-infection, and decreases after antiretroviral-induced viral suppression. A clinical procedure which, under stressful conditions, could lead to breaches in infection control measures was identified. The source of the infection was most likely a contaminated multidose vial.

CONCLUSION

Through epidemiological and phylogenetic analyses a case of horizontal nosocomial HIV-transmission was disclosed. Identification of multidose vials as possible vehicles for horizontal nosocomial transmission recently led to the recommendation of restriction of the use of multidose vials, a recommendation supported by the present study. The study underlies the importance of a constant survey of infection control precautions.

Molecular evidence for nosocomial transmission of human immunodeficiency virus from a surgeon to one of his patients

We have investigated the molecular evidence in favor of the transmission of human immunodeficiency virus (HIV) from an HIV-infected surgeon to one of his patients. After PCR amplification, the env and gag sequences from the viral genome were cloned and sequenced. Phylogenetic analysis revealed that the viral sequences derived from the surgeon and his patient are closely related, which strongly suggests that nosocomial transmission occurred. In addition, these viral sequences belong to group M of HIV type 1 but are divergent from the reference sequences of the known subtypes.

Molecular epidemiological analysis of HIV in sexual networks in Uganda

OBJECTIVE

To investigate the suitability of HIV sequence analysis, based on the p17 region of the gag gene, to characterize the sexual networks in and around a trading town in south-west Uganda.

METHODS

Blood samples were obtained from 54 HIV-seropositive members of three distinct sexual networks and phylogenetic analysis carried out on proviral DNA sequences obtained from the p17 region of gag from 53 individuals.

RESULTS

Despite documented evidence of very little sexual mixing between residents of the trading town, fishing village and surrounding rural area, there was no evidence of clustering of sequences associated with place of residence. More strikingly, known sexual partners failed to show significantly related sequences, and the two pairs of sequences that did show significant similarity came from individuals who had no known social or sexual contact.

CONCLUSIONS

Sequence analyses such as those described here have proved effective in confirming or identifying epidemiological links not only following single transmission events but also within risk groups. However, the results from Uganda contrast markedly with those from Europe and the United States. The length of time that the community has been infected, the number of occasions when the virus has been introduced and the high degree of partner change may contribute to the lack of supportive evidence for sociological studies of sexual networks in Uganda.

The molecular epidemiology of human immunodeficiency virus type 1 in six cities in Britain and Ireland

We have sequenced the p17 coding regions of the gag gene from 211 patients infected either through injecting drug use (IDU) or by sexual intercourse between men from six cities in Scotland, N. England, N. Ireland, and the Republic of Ireland. All sequences were of subtype B. Phylogenetic analysis revealed substantial heterogeneity in the sequences from homosexual men. In contrast, sequence from over 80% of IDUs formed a relatively tight cluster, distinct both from those of published isolates and of the gay men. There was no large-scale clustering of sequences by city in either risk group, although a number of close associations between pairs of individuals were observed. From the known date of the HIV-1 epidemic among IDUs in Edinburgh, the rate of sequence divergence at synonymous sites is estimated to be about 0.8%. On this basis we estimate the date of divergence of the sequences among homosexual men to be about 1975, which may correspond to the origin of the B subtype epidemic.

Maintaining the integrity of human immunodeficiency virus sequence databases

Human immunodeficiency virus type 1 (HIV-1) sequences are accumulating in the literature at a rapid pace. For this ever-expanding resource to be maximally useful, it is critical that researchers strive to maintain a high level of quality assurance, both in experimental design and conduct and in analyses. Here we present detailed analyses of problematic sets of HIV-1 sequences in the database that include sequence anomalies suggestive of mislabeling or sample contamination problems. These data are examined in the context of currently available HIV-1 sequence information to provide an example of how to identify potentially flawed data. Indicators of potential problems with sequences are (i) sequences that are nearly identical that are supposed to be derived from unlinked individuals and that are markedly distinct from other sequences from the putative source or (ii) sequences that are nearly identical to those of laboratory strains. We provide an outline of methods that researchers can use to perform preliminary laboratory and computational analyses that could help identify problematic data and thus help ensure the integrity of sequence databases.

The college student, the dentist, and the North Carolina senator: risk analysis and risk management of HIV transmission from health care worker to patient

The risk of acquiring human immunodeficiency virus (HIV) infection from a health care worker is 2,000 times less than that of dying from a car accident. It is 700 times less probable than perishing from being struck by lightning or suffering a fatal fall. Despite the rarity of this occurrence, reduction of the risk of health-care-worker-to-patient HIV transmission in the workplace has been the focus of congressional, federal, state, and local agencies. If all HIV transmission from health care workers to patients were prevented using current guidelines and legislation, the epidemic of AIDS would be reduced by 0.0006%. Current efforts to prevent HIV transmission from health care workers to patients are the result of incomplete risk analysis and management. In a society of limiting resources and of cherished freedoms, sanctions imposed on health care workers to prevent HIV transmission to patients may benefit no one.

Rapid molecular epidemiology of human immunodeficiency virus transmission

Close sequence homology between strains of HIV-1 have been used to corroborate cases of epidemiologically identified transmission. As an alternative to extensive DNA sequence analysis, genetic relateness between pairs of HIV quasispecies was estimated using the reduced electrophoretic mobilities of HIV-1 envelope DNA heteroduplexes through polyacrylamide gels. All six infections acquired in a dental practice in the late 1980s and four of six infections acquired through blood product transfusions and sexual contact in 1984-1985 could be rapidly identified. A rising level of genetic diversity within HIV-1 subtype B facilitated the detection of later transmission events. Transmission linkages could be detected up to 4 years following infection. The simple and rapid technique of DNA heteroduplex tracking can therefore assist epidemiological investigations of HIV transmission and potentially of other genetically variable infectious agents.