Hepatitis C virus: an important occupational hazard?

Infection with Hepatitis C virus (HCV) is estimated to affect 3% of the world's population and is an important cause of liver disease. It is most commonly transmitted by percutaneous exposure. Although current evidence does not suggest an increased prevalence of HCV infection among healthcare workers, transmission of infection following occupational exposure has been demonstrated. An average transmission rate of 1.8%, following percutaneous injury, has been reported. The risk of transmission is higher from patients with viraemia, as measured by a positive polymerase chain reaction for HCV RNA. After exposure to HCV, healthcare workers should be actively followed up, initially using a test to detect viral RNA. This may facilitate earlier diagnosis and treatment. Recent reports in the UK, of transmission of infection to patients from HCV infected healthcare workers, have prompted a review of the appropriateness of HCV infected individuals undertaking exposure prone procedures.     

Die variante Creutzfeldt-Jakob-Krankheit (vCJK)

In the wake of the bovine spongiform encephalopathy (BSE) epidemic, variant Creutzfeldt-Jakob disease (vCJD) has emerged as a previously unknown prion disease of humans. The initial occurrence of vCJD was observed in 1995/1996, and, so far, a total of 219 vCJD cases have been reported worldwide from seven European and four non-European countries. Of these, 172 cases were observed in the United Kingdom. The exact prevalence of sub- or pre-clinical vCJD infections is unclear. Despite effective measures that have been implemented against both BSE in ruminants and its transmission to humans, there is now a theoretical risk of secondary vCJD transmissions from human to human, for example via blood and blood products, organs and tissues, or contaminated surgical instruments and medical devices. Four cases of probable vCJD transmissions via blood have been described, as well as one case of secondary infection via a plasma product. This article provides an overview of the surveillance and epidemiology of vCJD and outlines public health strategies for the risk assessment and risk management of this novel BSE-associated prion disease in humans.     

Chagas Disease and Breast-feeding

Chagas disease (infection by the protozoan Trypanosoma cruzi) is a major parasitic disease of the Americas and one of the main neglected tropical diseases. Although various routes of transmission sre recognized, the risk for transmission of the infection through breast-feeding has not clearly been established. We reviewed the literature on transmission of T. cruzi through breast-feeding to provide breast-feeding mothers with Chagas disease with medical guidance. Although data from animal studies and human studies are scarce, we do not recommend that mothers with Chagas disease discontinue breast-feeding, unless they are experiencing the acute phase of the disease, reactivated disease resulting from immunosuppression, or bleeding nipples. In these cases, thermal treatment of milk before feeding the infant may be considered.     

The risk of accidental transmission of transmissible spongiform encephalopathy: identification of emerging issues

The transmissible spongiform encephalopathies (TSEs), thought to be caused by prions, are fatal neurodegenerative disorders of humans and animals. Despite their rarity, human prion diseases have received prominence because the consumption of prion-contaminated meat from cattle with bovine spongiform encephalopathy (BSE) is thought to be responsible for the emergence of variant Creutzfeldt-Jakob disease (vCJD) in humans. Clinical criteria for the diagnosis of vCJD is now available. Recent, more startling evidence suggests that the clinical presentation of vCJD may vary and that patients may present as classical (sporadic) CJD or may have subclinical infection and be apparently healthy. These patients may still pose a risk of iatrogenic transmission through surgical or medical (blood transfusion) procedures. The aim of future work is to develop preclinical screening tests for the identification of infected but still healthy individuals. The future course of vCJD is still uncertain. Modelling studies to predict the cases of vCJD depend on the date of origin of BSE and time of infection, which is, at best, only approximated. As the number of cases of BSE in the UK declines, the risk of BSE in other countries from imported cattle or meat and bone meal from the UK has been increasing. It is also recognized that other animal species (farmed, domestic and wild animals) other than cows are susceptible to TSEs. The possibility of interspecies transmission of TSEs and the global presence of the disease suggests a need for a co-ordinated worldwide risk management approach to eradicate TSEs.     

The epidemiology of HIV infection, AIDS, and health care worker risk issues.

Acquired immunodeficiency syndrome (AIDS) has been a silent epidemic for 22 years. The 1st documented isolate of the human immunodeficiency virus (HIV) was detected retrospectively in a blood specimen from a young Central African man who had participated in a study in 1959. AIDS cases were 1st reported in 1981. 2 factors kept the AIDS epidemic silent: 1) the long incubation period between the initial infection and the onset of disease; and 2) the relatively recent intrusion of the virus into developed nations. Almost 100,000 people in the US now have AIDS. AIDS was found to be transmitted by blood; therefore, there is concern among health care workers (HCWs) about the risk of AIDS transmission. In the US, AIDS was 1st described in 1981 in 5 sexually active homosexual young men in Los Angeles. Soon, AIDS was describe in clusters of patients in other cities. It is defined as many unusual infections or cancers that suggest a poorly functioning immune system for which no other cause can be found. Statisticians with the US Public Health Service have used mathematical models to estimate the magnitude of HIV infection in the US. They currently estimate this to be 1-1.5 million infected persons. AIDS is not spread by casual transmission. The 3 established transmission routes--sex, contact with blood, and being born to an infected mother--are not equally efficient. It is estimated that all infected persons will sooner or later become seriously ill with HIV-related disease. To date, only 1 drug (Azidothymide or AZT) has been licensed as an effective antiviral drug. In April, 1988 the Centers for Disease Control (CDC) reported that HCWs developed AIDs with the same statistical frequency as the rest of the general population. The number of HCWs who have developed disease as a result of occupational exposure is so small that it is statistically undetectable. This does not mean there is no risk for occupational infection, but only that it is a relatively low risk for most HCWs. The major risk for transmission of HIV infection to HCWs is associated with handling sharp instruments. The major preventive effort should be directed at this problem. The CDC has suggested a system of infection precautions called "Universal Precautions" to protect HCWs from HIV infection. Another approach is "Body Substance Isolation." It is intended to be a complete isolation and precautions system. Reusable instruments should receive disinfection. Management of HCWs with potential exposure to HIV is discussed.     

河南省首例人感染H7N9禽流感病例的流行病学调查

[目的]通过对1例人感染H7N9禽流感病毒患者的调查分析,为人感染H7N9禽流感的科学防控提供依据。[方法]采用流行病学调查方法,调查病例的发病经过、可能的感染来源、传播途径及暴露因素等,医学观察患者的密切接触者,同时对患者进行临床诊治、实验室检测。[结果]确诊1例人感染HTN9禽流感病毒,经救治后痊愈出院。患者有明确的活禽接触史,咽拭子检测H7N9禽流感病毒核酸阳性。患者的密切接触者中均未发现异常临床表现。通过扩大监测流感病例160例和职业人群858例,均未发现H7N9禽流感病毒核酸阳性。当地活禽交易市场鸡咽拭子标本检出2份H7N9禽流感病毒核酸阳性,阳性鸡来源于外省。[结论]活禽暴露是人感染H7N9禽流感病毒的关键风险因素,暂无证据人传人,未发现人群隐性感染和轻症病例。仍需开展扩大监测和流行病学调查,以完善对感染谱的认识。     

Reporting of chlamydial infection--Massachusetts, January-June 2003

Chlamydia trachomatis infection is the most commonly reported sexually transmitted disease (STD) in the United States. An estimated 2.8 million infections occur annually. In 2002, a total of 834,555 cases in the United States, including 10,914 cases in Massachusetts, were reported through the National Notifiable Disease Surveillance System (NNDSS). Chlamydial infection is most often reported in females, particularly those aged 15-24 years, reflecting a higher level of screening in females but also important risk factors. Although the majority of infections are asymptomatic, complications are potentially severe in women and include pelvic inflammatory disease, which can lead to tubal pregnancy, infertility, and chronic pelvic pain. Chlamydial infection during pregnancy can cause illness in the infant (e.g., conjunctivitis and pneumonia). Infection in men can manifest as urethritis and epididymitis. Timely, documented diagnosis and treatment of chlamydial infection are critical to prevent both complications and transmission. Since 1996, a progressive increase has occurred in the number of reported cases of chlamydial infection in Massachusetts, in part because of an increase in screening and use of more sensitive tests. This report summarizes an evaluation of chlamydial-infection reporting in Massachusetts during January-June 2003. The results underscore the need for improvement in both completeness and timeliness of reporting chlamydial infection in Massachusetts.     

Outbreak of serogroup W135 meningococcal disease after the Hajj pilgrimage,Europe, 2000

The 2000 Hajj (March 15-18) was followed by an outbreak of Neisseria meningitidis W135 2a: P1.2,5 in Europe. From March 18 to July 31, 2000, some 90 cases of meningococcal infection were reported from nine countries, mostly the United Kingdom (UK) and France; 14 cases were fatal. Although most early cases were in pilgrims, the outbreak spread to their contacts and then to those with no known pilgrim contact. In France and the UK, the outbreak case-fatality rate was compared with the rate reported from national surveillance. The risk of dying during this outbreak was higher in France and the UK, although the difference was not statistically significant. Prophylaxis for all pilgrims and their household contacts was offered in France; in the UK and other European countries, prophylaxis was recommended only for close contacts. No difference in transmission rates following intervention was detected between France and the UK.     

Variant Creutzfeldt-Jakob disease in France: estimating the number of cases related to travel to the United Kingdom between 1980 and 1995

BACKGROUND: The outbreak of variant Creutzfeldt-Jakob disease (vCJD) cases rose serious concerns about secondary transmission of the disease, particularly through blood transfusion. Protective measures leading to the exclusion of potentially infectious blood donors were settled: in France, donors who had stayed more than one year in the UK were excluded. In this work, which was part of a larger study aiming to estimate the French epidemic of vCJD, the number of vCJD cases who were infected during a trip to the UK was estimated. Those estimates may notably enable the assessment of such exclusion measures. METHODS: The particular age-related structure in vCJD cases is taken into account in our simulations considering birth cohorts in the population. The total French exposure is simulated assuming the main source of infection to be dietary through consumption of mechanically recovered meat (MRM) manufactured from British bovine carcasses. Then, using a "back calculation" algorithm, all infected individuals required to produce a consistent epidemic (6 vCJD cases in 2003) was simulated. This study was exclusively focused on the part of the exposure linked to trips (beef MRM consumed in the UK while traveling) and on cases resulting from this exposure. RESULTS: The influence of exposure linked to trips to the UK was greater in the youngest cohort (6.3% of the total exposure) while it only accounted for 3.3% and 1% in the 1939-69 and in the pre-1939 birth cohorts respectively. Overall, exposure resulting from trips in the UK can be neglected with regards to the exposure linked to the consumption of MRM produced in France from British bovine carcasses. Consequently, French vCJD cases that would have been infected in the UK are very unlikely to occur (median: 0 case, IC 95%: (0-2)). Nevertheless, if such cases occur, they would probably occur in subjects born after 1969 and their onset would take place before 2010. Thus, unlike the situation in BSE-free countries, the causal relationship between travel in the UK and occurrence of vCJD cases cannot be underlined in France, as trips only account for a small part of the French exposure. CONCLUSION: Since trips in the UK slightly contribute to the overall French exposure, excluding people who travelled in the UK from blood donation would not influence the risk of secondary transmission.     

Tuberculosis transmission in a homeless shelter population--New York, 2000-2003

In 2003, the incidence of tuberculosis (TB) cases in the United States declined for the eleventh consecutive year to a record low of 5.1 cases per 100,000 population. In 2003, 6.3% of reported TB cases in the United States were among homeless persons. Compared with the general population, this group has a greater risk for latent TB infection (LTBI) and progression to active disease. This report summarizes a recent outbreak of TB and highlights the challenges of preventing TB among homeless persons, particularly when multiple chains of transmission are occurring and multiple jurisdictions are involved. The findings underscore the complementary role of rapid DNA genotyping in the detection of possible TB transmission in homeless populations. To ensure early detection of unsuspected TB transmission in homeless populations, health department TB-control programs are encouraged to use CDC's universal Mycobacterium tuberculosis rapid genotyping system.     

Methicillin-resistant Staphylococcus aureus and multidrug resistant tuberculosis: Part 2

Drug resistant tuberculosis has been recognized since chemotherapy first became available. However, drug resistance has increased in many countries, and recently strains resistant to both rifampicin and isoniazid (multidrug resistant tuberculosis) have emerged. This review discusses the epidemiology of multidrug resistant tuberculosis (MDRTB), and the control of MDRTB in healthcare facilities. Relevant papers for this review were identified by a systematic literature search on Medline. MDRTB is already established world-wide, and although the overall problem of resistance remains low in the UK, it is of significant clinical importance due to its high case-fatality, higher transmission risk, and complex treatment. The key elements of MDRTB control are prompt recognition, confirmation and treatment of cases, and the institution of strict infection control procedures to reduce the airborne spread of infection from infectious patients to others. This review emphasizes the importance of a multidisciplinary approach to management, with liaison between tuberculosis physicians, the microbiology department, infection control team, consultant in communicable disease, and occupational health.     

Intrauterine West Nile virus infection--New York, 2002

West Nile virus (WNV), a mosquito-borne flavivirus and human neuropathogen, is epidemic in the United States. In 2002, newly recognized mechanisms of person-to-person WNV transmission were described, including possible transmission from mother to infant through breast milk. WNV has not been previously associated with intrauterine infection or adverse birth outcomes. This report describes a case of transplacental WNV transmission. Pregnant women should take precautions to reduce their risk for WNV or other arboviral infection and should undergo diagnostic testing when clinically appropriate.     

Primer on hepatitis C for hospital epidemiologists.

First identified in the late 1980s as the main causative agent of non-A, non-B hepatitis, hepatitis C virus (HCV) infection is now the most common chronic bloodborne infection in the United States. It is likely that the number of deaths attributable to HCV-related chronic liver disease will increase substantially during the next 2 decades, and the potential economic and clinical burden related to HCV is staggering. Accordingly, it is essential to identify risk factors for transmission of HCV and implement appropriate precautions to decrease the prevalence of this emerging infection. The relative importance of the two most common types of exposures associated with transmission of HCV, ie, blood transfusion and injection drug use, has evolved over time. Strict blood-donor selection and the use of reliable serological tests have led to a significant reduction in transfusion-associated risk. Injection drug use is currently the single most important risk factor for HCV infection in the United States. Transmission of HCV poses a serious threat to healthcare workers and patients if infection control techniques or disinfection procedures are inadequate. Potential exposures include contact of the eyes, mucous membranes, broken skin, or needlestick injury. Hospitalized patients may serve as a reservoir for transmission, and the prevalence of anti-HCV seropositivity among such patients can be as high as 20%. The infected healthcare worker is a potential source of transmission. A recent molecular phylogenetic analysis demonstrated that a cardiac surgeon likely transmitted HCV to five of his patients during open heart surgery. In summary, nosocomial transmission has been unequivocally confirmed and underscores the need for strict infection control practices.     

The emergence of human Powassan virus infection in North America

Powassan virus (POWV) is a tickborne flavivirus discovered in Ontario, Canada in 1958 that causes long-term neurological sequelae in about half the reported cases and death in a little more than 10 % of cases. The incidence of POWV disease is rising in the United States but there is limited understanding of the scope and causes of recent changes in POWV epidemiology. We focus on quantifying the increase in human POWV disease incidence and infection prevalence in the United States. We also examine differences in the frequency of symptomatic cases and asymptomatic or mildly symptomatic cases, as well as limitations in national and state surveillance for POWV infection. We searched SCOPUS for all articles containing original POWV prevalence research, case studies, or literature reviews published in English. Case studies were supplemented by Morbidity and Mortality Weekly Report POWV data from the Centers for Disease Control and Prevention (CDC) and surveillance information from state health department websites. An increase in the number of POWV cases has been reported in the United States over the past 50 yr, and the geographic range of human POWV cases has expanded. The age distribution of symptomatic POWV cases has shifted, with significantly more individuals over 40 yr old being diagnosed after 1998. The emergence of POWV is due in large part to: (i) a change in transmission of POWV from a vector that rarely bites people (Ixodes cookei) to a new vector that often bites people (Ixodes scapularis) and has expanded its geographic range, (ii) enhanced surveillance efforts for arboviruses, and (iii) a greater awareness of POWV infection.     

The Impact of Obesity on SARS-CoV-2 Pandemic Mortality Risk

The COVID-19 pandemic has uncovered the increased susceptibility of individuals with obesity to infection and severe disease leading to hospitalization and death. Studies in New York City demonstrated that after advanced age, obesity was the most common risk factor leading to severe disease and death from COVID-19. While the connection has been recognized, there has not been a general recognition of the potential mechanisms for this link between excess body fat and mortality from this viral pandemic including respiratory complications and sequelae of increased activation of the immune system. Despite plans for vaccination of the global population, the risk community spread of COVID-19 and future pandemics will be linked in part to obesity and immunity. This review will detail a number of potential mechanisms through which obesity may contribute to the lethality of this viral infection. These insights will hopefully lead to a greater emphasis on obesity prevention and treatment as part of the global response to this and future pandemic threats.     

Comments on present-day spread and epidemiology of BSE and prion diseases

Prion diseases of animals and man are neurological diseases with amyloidal deposition of the respective proteins. As to prion disease, the cellular prion protein is in its abnormal isoform(s) an essential component of prion protein aggregates found in affected tissue. In contrast to all neurodegenerative diseases like Morbus Alzheimer or Huntington's disease, prion diseases are transmissible. Therefore, prion diseases were designated Transmissible Spongiform Encephalopathies (TSE). The diseases have been well known for decades. Scrapie was first described around 1750, a BSE case was reported in the 1850-ties most likely a misdiagnosis, and in 1920/1930 the human Creutzfeldt-Jakob disease (CJD) had been described. Transmission of CJD i. e. Kuru had been suspected in the early 1950 s and was erroneously classified as slow virus disease. The CJD transmission posed a problem to humans when transplants from CJD cases were used for treatment. Fortunately, these iatrogenic transmissions remained limited. But with the advent of BSE and appearance of variant CJD cases in the UK and some places in Europe scientists suspected that transmission from cattle to man could have happened. From animal models we know of successful transmission via several routes. Species barriers do not completely prevent transmission. Rather, transmission barriers might exist controlling individual susceptibility against prions. Modes of transmission, susceptibility to transmission, identification of receptor molecules as well as molecular mechanisms of the transmission process are being investigated with great intensity. Current knowledge leads us to assume that inapparent stages of prion infection wrongly suggest a (non-existent) species barrier. This inapparent infection precedes overt disease, and, hence, most research focuses on the development of highly sensitive assay systems for detection of minute amounts of pathological prion protein in suspected cases. Inapparence also should warn us to underestimate BSE or human vCJD cases; at present, approx. 145 cases occurred in Europe and one probable case in Hong Kong (June 2003). Whether BSE had spread to other parts of the world by animal nutrition components or meat can neither be excluded nor confirmed at this time. New data on transmission and consequences of BSE for the human population are summarised in this review.     

Microbiological standards for water and their relationship to health risk

Maintenance of the microbiological quality of water has been used as an important means of preventing waterborne disease throughout the twentieth century. The commonest microbiological tests done on water are for coliforms and Escherichia coli (or faecal coliform). This paper reviews the legislative and other guidance for microbial standards in drinking and bathing waters and considers evidence for the relationship between the microbiological quality of water and risk to human health. In the past measures of the microbiological quality of water correlated well with risks of acquiring gastrointestinal disease. More recent work suggests that gastrointestinal disease is more strongly associated with the presence of enterococci than of E. coli. New diseases such as cryptosporidiosis have been shown to cause outbreaks of waterborne disease when levels of conventional microbiological parameters are satisfactory. In response to this, and because of failure of prosecution in one outbreak, the United Kingdom (UK) Government has introduced new legislation that requires water providers to perform a risk assessment on their water treatment facilities and to implement continuous monitoring for cryptosporidium. A new European directive on drinking water has been introduced and legislation on cryptosporidium in drinking water has been proposed in the UK.     

Hepatitis C in pregnancy

In epidemiologic studies done primarily in Europe and in the United States, antibody to hepatitis C has been present in approximately 1% to 4% of pregnant women. Although close to 50% of infected women have no known risk factors for infection, routine screening of pregnant women is not currently recommended. Hepatitis C virus (HCV) may be transmitted to the newborn at a rate of approximately 5%; it is not clear whether this occurs in utero, intrapartum, or both. Factors that increase the risk of vertical transmission include concomitant HIV infection and a high maternal HCV viral load. Breast feeding does not appear to significantly increase the risk of neonatal HCV infection. There is currently no treatment for HCV infection that is approved for use in pregnancy or for use in the neonate.     

The average cost of measles cases and adverse events following vaccination in industrialised countries

Background  

Even though the annual incidence rate of measles has dramatically decreased in industrialised countries since the implementation of universal immunisation programmes, cases continue to occur in countries where endemic measles transmission has been interrupted and in countries where adequate levels of immunisation coverage have not been maintained. The objective of this study is to develop a model to estimate the average cost per measles case and per adverse event following measles immunisation using the Netherlands (NL), the United Kingdom (UK) and Canada as examples.     

Women and AIDS

This article describes the epidemiology of acquired immunodeficiency syndrome (AIDS) in women in the United States. Comparisons of female and male transmission categories are made and emphasis is placed on the heterosexual transmission and undetermined risk categories for women. Since its onset in 1981, AIDS has affected males predominantly and female AIDS cases have not received as much attention. AIDS education efforts have not targeted women as much as men, despite women's vulnerability to infection, especially through heterosexual transmission. AIDS tends to generate many issues that concern women's sexuality--contraception, pregnancy and abortion among them. Some of the special problems that women with AIDS face are discussed. Women's role as caregiver for persons with AIDS also is examined. Attention is directed to the ways in which AIDS is associated with the traditional female role.