[A clinical and epidemiological study of the Trypanosoma cruzi infected population in the north metropolitan area of Barcelona]. / Un estudio clínico-epidemiológico de la población infectada por Trypanosoma cruzi en la zona metropolitana norte de Barcelona.

BACKGROUND: As an inevitable consequence of Latin American immigration to Europe, Spain and other European countries, it is necessary to confront the approach to cases of Chagas infection/disease for which, epidemiologically, there are more questions than answers. This study has aimed to describe all the Chagas-infected population in the north metropolitan area of Barcelona (406,000 inhabitants). PATIENTS AND METHODS: A prospective and multicentric study was performed in 3 hospitals and 1 International Health Unit. It included all patients with Trypanosoma cruzi positive serology, regardless of the requesting reason.Results The 139 diagnosed cases represent an annual incidence of: a) 0.68/10,000 inhabitants and, b) 73.2/10,000 immigrants coming from endemic zones. Of the patients, 80 (57.6%) had alterations in some complementary tests: cardiologic 62 (44.6%), digestive 38 (27.3%) and 20 (14.4%) both. According to the Brazilian Consensus of Chagas cardiomyopathy, they were classified as: 0=84 (60.4%); a=40 (28.7%); b1=4 (2.9%), b2=10 (7.2%) and c/d=1 (0.7%). Treatment with benznidazole (5mg/kg/24h for 60 days) was prescribed in 116 (83.4%) patients, 89 (76.7%) of whom completed it. Secondary effects were recorded in 56 (50.9%), which made it necessary to withdraw it in 21 (19.1%). CONCLUSIONS: Fewer cases of Chagas infection/disease than expected have been diagnosed in the North Metropolitan area of Barcelona. The series contains a high number of patients and there may be an elevated number of immigrants from endemic zones who have the asymptomatic chronic stages of the infection and who were unaware of their condition.

An international trial of quantitative PCR for monitoring Legionella in artificial water systems.

AIMS: To perform an international trial to derive alert and action levels for the use of quantitative PCR (qPCR) in the monitoring of Legionella to determine the effectiveness of control measures against legionellae. METHODS AND RESULTS: Laboratories (7) participated from six countries. Legionellae were determined by culture and qPCR methods with comparable detection limits. Systems were monitored over ≥10 weeks. For cooling towers (232 samples), there was a significant difference between the log mean difference between qPCR (GU l(-1) ) and culture (CFU l(-1) ) for Legionella pneumophila (0·71) and for Legionella spp. (2·03). In hot and cold water (506 samples), the differences were less, 0·62 for Leg. pneumophila and 1·05 for Legionella spp. Results for individual systems depended on the nature of the system and its treatment. In cooling towers, Legionella spp. GU l(-1) always exceeded CFU l(-1) , and usually Legionella spp. were detected by qPCR when absent by culture. The pattern of results by qPCR for Leg. pneumophila followed the culture trend. In hot and cold water, culture and qPCR gave similar results, particularly for Leg. pneumophila. There were some marked exceptions with temperatures ≥50°C, or in the presence of supplementary biocides. Action and alert levels for qPCR were derived that gave results comparable to the application of the European Guidelines based on culture. Algorithms are proposed for the use of qPCR for routine monitoring. CONCLUSIONS: Action and alert levels for qPCR can be adjusted to ensure public health is protected with the benefit that remedial actions can be validated earlier with only a small increase in the frequency of action being required. SIGNIFICANCE AND IMPACT OF THE STUDY: This study confirms it is possible to derive guidelines on the use of qPCR for monitoring the control of legionellae with consequent improvement to response and public health protection.

Clinical, electrocardiographic and echocardiographic abnormalities in Latin American migrants with newly diagnosed Chagas disease 2005-2009, Barcelona, Spain.

Following Latin American migration, Chagas disease has inevitably appeared in non-endemic countries in Europe and elsewhere. New policies are necessary to prevent transmission in those countries but the long, often undetected chronic period of the early stages of the disease also renders epidemiological studies important. The main objective of our study was to determine the presence of clinical, electrocardiogram (ECG) and echocardiographic abnormalities in a population of Latin American migrants infected with Trypanosoma cruzi at the moment of diagnosis. We performed a hospital-based observational study of 100 adult patients with newly diagnosed Chagas infection between January 2005 and December 2009. Thirty-seven patients were classified within the Brazilian Consensus on Chagas cardiomyopathy early cardiac stages (A or B1) and 49 presented pathological findings (stage B2) according to the Panamerican Health Organization Classification. Overall, 49 patients showed ECG and/or echocardiographic alterations. The presence of ECG and ecocardiographic alterations were significantly associated (p=0.038). The most frequent ECG and echocardiographic findings were right bundle branch block (12 cases) and impaired left ventricular wall relaxation (24 cases), respectively. In conclusion, ECG and echocardiographic alterations coherent with Chagas cardiomyopathy were found in a large proportion of newly diagnosed Latin American migrants infected with T. cruzi. In the mid-term, Chagas disease might become an important cause of chronic cadiomyopathy in our attendance area.

The impact of pipeline changes and temperature increase in a hospital historically colonised with Legionella.

Healthcare-related Legionnaires' disease has a devastating impact on high risk patients, with a case fatality rate of 30-50%. Legionella prevention and control in hospitals is therefore crucial. To control Legionella water colonisation in a hospital setting we evaluated the effect of pipeline improvements and temperature increase, analysing 237 samples over a 2-year period (first year: 129, second year: 108). In the first year, 25.58% of samples were positive for Legionella and 16.67% for amoeba. Assessing the distance of the points analysed from the hot water tank, the most distal points presented higher proportion of Legionella colonisation and lower temperatures (nearest points: 6.4% colonised, and temperature 61.4 °C; most distal points: 50% and temperature 59.1 °C). After the first year, the hot water system was repaired and the temperature stabilised. This led to a dramatic reduction in Legionella colonisation, which was negative in all the samples analysed; however, amoeba colonisation remained stable. This study shows the importance of keeping the temperature stable throughout the circuit, at around 60 °C. Special attention should be paid to the most distal points of the circuit; a fall in temperature at these weak points would favour the colonisation and spread of Legionella, because amoeba (the main Legionella reservoir) are not affected by temperature.

Outbreak of Legionnaires' disease associated with a supermarket mist machine.

An outbreak of Legionnaires' disease affected 12 customers of a supermarket in a town in Catalonia, Spain, between August and November 2006. An epidemiological and environmental investigation was undertaken. Preliminary investigation showed that all patients had visited the same supermarket in this town where a mist machine was found in the fish section. Water samples were collected from the machine and from the supermarket's water distribution system when high-risk samples were excluded. Environmental samples from the mist machine and clinical samples from two patients tested positive for L. pneumophila serogroup 1 and had the same molecular pattern. The PFGE pattern detected in the clinical and mist-machine isolates had never previously been identified in Catalonia prior to the outbreak and has not been identified since. Four days after turning off the machine, new cases ceased appearing. Molecular study supports the hypothesis that the mist machine from the fish section of the supermarket was the source of infection. We believe it is essential to include exposure to mist machines in any legionellosis epidemiological survey.

Factors influencing the case-fatality rate of Legionnaires' disease.

SETTING: The extent of the public health problem posed by Legionnaires' disease (LD) is not always well- appreciated. OBJECTIVE: To determine the characteristics and factors associated with the case fatality rate (CFR) of LD in Catalonia, Spain. DESIGN: Confirmed cases of LD reported during 1993-2004 were studied. Age, sex, hospitalisation, the type of diagnostic confirmation test and the personal risk factors for LD of cases were collected. Comparative bivariate and multivariate analyses according to origin (community-acquired or nosocomial) and nature (sporadic or outbreaks) were performed. RESULTS: Of 1938 cases reported, 164 died (case-fatality rate [CFR] 8.5%). The CFR fell from 35% in 1993 to 5.6% in 2004, and was higher in sporadic than in outbreak-associated cases (10% vs. 4.7%) and in nosocomial than community-acquired cases (31.7% vs. 6.8%). In community-acquired cases, the CFR was associated with age >70 years (OR 3.42, 95%CI 2.02-5.79), cancer (OR 4.58, 95%CI 2.36-8.90) and diagnostic confirmation methods other than Legionella urinary antigen test. The CFR of nosocomial cases was not associated with any of these factors. CONCLUSIONS: The CFR of LD fell during the study period due to the incorporation of new diagnostic techniques and improved detection of outbreaks.

Clinical impact and prevalence of MRSA CC398 and differences between MRSA-TetR and MRSA-TetS in an area of Spain with a high density of pig farming: a prospective cohort study.

OBJECTIVES: Tetracycline resistance (TetR) is a phenotypic marker of the livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) CC398 clone. The aim of this study was to analyse the prevalence of MRSA CC398 in patients in contact with healthcare facilities and differences between patients with MRSA-TetR and MRSA tetracycline-susceptible (TetS) strains. METHODS: Patients diagnosed with MRSA from January 2012 to December 2015 were divided into two groups, MRSA-TetR and MRSA-TetS. Epidemiologic and clinical data were evaluated. Molecular analysis was performed (multilocus sequence typing, spa typing) on MRSA-TetR strains. RESULTS: Data from 288 MRSA patients were obtained, and 106 (36.8%) carried MRSA-TetR (93 typed as CC398 (87.7%); the remaining 13 isolates were ascribed to CC9, CC1, CC121, CC30, CC97, CC146 and CC152). The most frequent spa type was t011 (56.6%, 61/106). Detection of MRSA-TetR increased over the years (21.9%, 16/73, in 2012; 50.7%, 36/71, in 2015; p <0.001). Hospital acquisition was found in 16.7% (19/114) of MRSA-TetR patients vs. 83.3% (95/114) in MRSA-TetS patients (p <0.001). Frequency of MRSA-TetR patients in nursing homes was lower than in MRSA-TetS patients (4.7%, 5/106, vs. 27.5%, 50/182, p <0.001). MRSA-TetR as distinct from MRSA-TetS was associated with workers on pig farms (49.0%, 52/106, vs. 1.0%, 2/182; p <0.001), fewer admissions to hospital (46.2%, 49/106, vs. 68.1%, 124/182; p <0.001) and fewer comorbidities (81.1%, 86/106, vs. 59.9%, 109/182; p <0.001). Sixty cases of MRSA-CC398 infection were diagnosed, including, among others, endocarditis, septic arthritis, prosthetic joint infection, pneumonia and bacteraemia. CONCLUSIONS: Prevalence of MRSA-TetR (especially CC398) at the hospital level in a Spanish region with intensive pig farming activity is high and is responsible for severe infections. Significant differences were detected in clinical and epidemiologic characteristics among MRSA-TetR and MRSA-TetS patients.

A community outbreak of Legionnaires' disease: evidence of a cooling tower as the source.

A community outbreak of Legionella pneumonia in the district of Cerdanyola, Mataró (Catalonia, Spain) was investigated in an epidemiological, environmental and molecular study. Each patient was interviewed to ascertain personal risk-factors and the clinical and epidemiological data. Isolates of Legionella from patients and water samples were subtyped by pulsed-field gel electrophoresis. Between 7 August and 25 August 2002, 113 cases of Legionella pneumonia fulfilling the outbreak case definition criteria were reported, with 84 (74%) cases being located within a 500-m radius of the suspected cooling tower source. In this area, the relative risk of being infected was 54.6 (95% CI 25.3-118.1) compared with individuals living far from the cooling tower. Considering the population residing in the Cerdanyola district (28,256 inhabitants) as a reference population, the attack rate for the outbreak was 399.9 cases/100,000 inhabitants, and the case fatality rate was 1.8%. A single DNA subtype was observed among the ten clinical isolates, and one of the subtypes from the cooling tower matched exactly with the clinical subtype. Nine days after closing the cooling tower, new cases of pneumonia caused by Legionella ceased to appear. The epidemiological features of the outbreak, and the microbiological and molecular investigations, implicated the cooling tower as the source of infection.

Has the economic crisis led to a new risk profile for international travellers? / ¿La crisis económica condiciona la aparición de un nuevo perfil de riesgo en viajeros internacionales?

INTRODUCTION: The economic world crisis has led to the migration of European workers to developing countries with a high incidence of infectious diseases. The objective of this study was to assess whether this context has produced an increase in the risks to international travellers for work reasons (TWR). METHODS: Observational, retrospective study. The study population included TWR who were attended before travelling at an International Health Unit in the year 2007 (the year before the initiation of the European crisis) and in the year 2012 (when the structural crisis was established). A comparative socioeconomic analysis was performed as well as an analysis of the risk factors present in both groups. RESULTS: In 2007 and 2012 a total of 9,197 travellers were attended. Of these, there were 344 TWR (3.4%); 101 TWR (2.8%) in 2007 and 243 TWR (4.5%) in 2012 (p<0.001). The average age of the travellers was 38.1 years (SD: 10.57). The most common destination was Sub-Saharan Africa, in 164 (47.6%) of the cases. Malaria chemoprophylaxis was prescribed to 152 travellers (44%) and 80 presented comorbidity (23.25%). The TWR from 2012 presented a significantly greater age (p=0.05), more comorbidity (p=0.018) and a greater proportion of stays in rural areas (p=0.0009) for longer time periods (p=0.001). CONCLUSIONS: At 5 years from the start of the economic crisis, there was a change in the profile of TWR. Their number has increased significantly, as has the proportion who present risk factors for contracting imported diseases. The International Health Units should adapt to these new circumstances and adopt preventive measures for this population.

Presence and chromosomal subtyping of Legionella species in potable water systems in 20 hospitals of Catalonia, Spain.

OBJECTIVE: To investigate the presence and clonal distribution of Legionella species in the water supply of 20 hospitals in Catalonia, Spain. SETTING: 20 hospitals in Catalonia, an area of 32,000 km2, located in northeast Spain. METHODS: Environmental cultures of 186 points of potable water supply and 10 cooling towers were performed for the presence of Legionella species. Following filtration and acid treatment, the samples were seeded in selective MWY (modified Wadowsky Yee)-buffered charcoal yeast extract-alpha agar. All isolates obtained were characterized microbiologically and genotyped by SfiI pulsed-field gel electrophoresis (PFGE). RESULTS: 73 of 196 water samples, representing 17 of the 20 hospitals included in the study, were positive for Legionella pneumophila (serogroups 1, 2-14, or both). The degree of contamination ranged from 200 to 74,250 colony-forming units/L. Twenty-five chromosomal DNA subtypes were detected by PFGE. A single DNA subtype was identified in 10 hospitals, 2 DNA subtypes were observed in 6 hospitals, and 1 hospital exhibited 3 different DNA subtypes. Each hospital had its own Legionella DNA subtype, which was not shared with any other hospitals. CONCLUSIONS: Legionella was present in the water of most of the hospitals studied; each such hospital had a unique, dominant chromosomal DNA subtype. The verification of several genomic DNA restriction profiles in such a small geographic area demonstrates the great genetic diversity of Legionella in the aquatic environment.

Changes in bloodstream infections in HIV-positive patients in a university hospital in Spain (1995-1997).

OBJECTIVES: The Hospital Universitario Germans Trias i Pujol is a 600-bed center serving 700,000 inhabitants including 1800 patients with HIV infection in Catalonia (Spain). Highly active antiretroviral therapy (HAART) became available at the end of 1996. Thus, the period 1995 1997 was considered appropriate for evaluating possible epidemiological changes in bloodstream infections (BSI) in HIV-infected patients. METHODS: All significant bloodstream infections, including mycobacteremia and fungemia, observed in HIV-positive patients from January, 1995 to December, 1997 have been included in the study. RESULTS: One hundred and eighty six cases were evaluated, in whom a decrease in BSI was observed (68 in 1995, 86 in 1996, 32 in 1997). Over time, we observed an improvement in the immunologic situation of the patients (1995: CD4 <50/mm3 73.8% vs 1997: CD4 <50/mm3 45.5% (P=0.05)). The source of BSI was known in 80.7% of the episodes. BSI secondary to catheter and respiratory infections prevailed in 1995, whereas an increase in bacteremias related to intravenous drug use, with or without endocarditis, was seen in 1997. The most frequent isolates were Mycobacterium avium intracellulare (23) (MAI), M. tuberculosis (20), Staphylococcus aureus (20), coagulase-negative staphylococci (16), Salmonella spp. (16) and Streptococcus pneumoniae (15). In 1997, a decrease was observed in the isolation of Gram-negatives and Mycobacterium spp. with S. aureus and enterococci prevailing. CONCLUSIONS: The prevalence of bloodstream infections in HIV-positive patients has decreased since the introduction of HAART and the immunologic state has improved. Furthermore there is a trend to a decrease or disappearance of microorganisms, such as Pseudomonas spp., Mycobacterium tuberculosis, MAI or fungi related to severe immunosuppression. Lastly, bacteremia caused by the active use of intravenous drugs remains stable with the highest percentage in Spain.

[Impact of control measures on the course of an outbreak of methicillin-resistant Staphylococcus aureus]. / Impacto de las medidas de control sobre la evolución de un brote epidémico por Staphylococcus aureus resistente a la meticilina.

BACKGROUND: Outbreaks of nosocomial infection by methicillin resistent Staphylococcus aureus (MRSA) are a problem in many hospitals with the control measures to be adopted being controversial. An outbreak of MRSA in a 550-bed university hospital is herein described and the impact of the adopted control measures on the evolution of the epidemic in the general hospitalization area (GHA) was analyzed. PATIENTS AND METHODS: The adopted control measures in the GHA were: microbiologic surveillance, cutaneous isolation measures, treatment of nasal carrier, and the early discharge of the cases. Hand washing was reinforced and a study of carriers was carried out on detection of sporadic cases (not related to the ICU). A molecular study of 70 strains of MRSA was performed with analysis of total plasmids, plasmid restriction pattern and chromosomic DNA analysis by pulsed field gel electrophoresis (PFGE). RESULTS: From December 1990 to December 1993, 273 cases of MRSA were reported. One hundred seventy-two cases originated in the ICU and 101 cases in the GHA (sporadic cases). The incidence of MRSA in 1991-1993 was 13.6, 14.3, and 6.6% in the ICU and 0.17, 0.36, and 0.15% in the GHA, respectively. Molecular study of MRSA isolates (1991 and 1992) demonstrated two plasmid and two chromosomic patterns. The latter had a similarity coefficient > 0.90, probably belonging to the same "clone". CONCLUSIONS: Despite the control measures adopted in the GHA the outbreak of MRSA originated in the ICU thereafter extending to the GHA. The rates of colonization detected, however, remained stable during the 3 years studied. On the other hand, the observation of a single "clone", responsible for the epidemic, suggest that most of the sporadic cases were autoctonous and due to failure in fulfillment of the established norms.

[Hepatic angiosarcomas]. / Angiosarcomas hepáticos.

The authors describe three cases of hepatic angiosarcoma diagnosed at postmortem examination, two of them being associated to thorium dioxide. The low incidence of these tumors amongst the general population is commented upon, and an update is made on the factors involved in their appearance, with special mention of thorium dioxide. An analysis of the clinical picture of the disease is undertaken, emphasizing its diagnostic difficulties. A tentative diagnosis can be made on the basis of clear-cut epidemiological data and or the presence of increased radiological density over the liver, spleen and paraaortic lymph nodes in the cases associated to thorium dioxide. Two of the reported patients presented hemolytic anemia, and disseminated intravascular coagulation, respectively; these findings, although nonspecific, may suggest the diagnosis in the presence of a toxic clinical picture or one of the above mentioned factors. The diagnosis should be made by the usual techniques utilized clinically to detect space occupying lesions within the liver. The evolution of such patients is rapidly progressive, with a fatal outcome within three to six months after beginning of symptoms.

[Pheochromocytoma and sudden death (author's transl)]. / Feocromocitoma y muerte súbita.

Five cases of pheochromocytoma are described in which sudden death was the form of the initial clinical presentation in almost all of them. After a brief review on the history and the incidence of the tumor within the general population, diverse cases are analyzed from a clinical point of view and in relation to the data appeared in the literature. In the analysis of the symptoms emphasis is placed on the important psychomotor manifestations which are present in the majority of those patients and which causes serious difficulties in the initial diagnosis. All of the patients showed signs of shock at the time of being observed or during the course of this observation, and in the majority of them the presence of acute pulmonary edema was confirmed; facts which we attribute to an initial hypertensive episode associated to a left heart failure. The onset of the crisis in two patients was related to known triggering factors: anesthesia and sulpiride. In other two patients associated conditions were diagnosed: medullary carcinoma of the thyroid gland in one of them, and cystic necrosis of the middle layer of the aorta in the other.

[Haemophilus influenzae pulmonary infection in patients infected with the human immunodeficiency virus]. / Infección pulmonar por Haemophilus influenzae en pacientes infectados por el virus de la inmunodeficiencia humana.

BACKGROUND: Haemophilus influenzae has frequently been identified as the etiologic agent in pneumonias of patients with the human immunodeficiency virus (HIV) infection. The experience of the authors is reviewed and the significance of isolating this microorganism in respiratory samples commented upon. METHODS: The clinical, radiological and microbiological data of patients with HIV infection in whom H. influenzae was identified in blood, lung tissue, or samples of the lower respiratory tract obtained by fibrobronchoscopy were retrospectively evaluated. RESULTS: Twenty cases were diagnosed with 75% presenting bilateral lung infiltration. In 70% the isolation sample was that of bronchoalveolar lavage. In 40% of the total another microorganism was identified in coinfection with H. influenzae, of which Mycobacterium tuberculosis was the most frequent. Thirty-five percent of the cases presented antecedents of one or several previous pulmonary infections. H. influenzae infection was not observed with either concomitant or previous infections in 20% of the patients. CONCLUSIONS: A high frequency of pneumonias by Haemophilus influenzae with bilateral radiologic presentation have been found. H. influenzae is frequently demonstrated as in coinfection with other agents. The role that this microorganism has in pulmonary infection of patients with HIV infection is not clearly defined.

[Immunoglobulin A and human immunodeficiency virus type 1 infection in parenteral drug abuse addicts]. / Inmunoglobulina A e infección por el virus de la inmunodeficiencia humana tipo 1 en adictos a drogas por vía parenteral.

BACKGROUND: To evaluate the usefulness of serum immunoglobulin A (IgA) as a prognostic marker of human immunodeficiency virus type 1 (HIV-1) in parenteral drug abusers (PDA). METHODS: The serum IgA levels and HIV-1 antibodies were assessed in 374 PDAs admitted for infective diseases or for treatment of addiction. RESULTS: The prevalence of HIV infection was 70%; the frequency of serum IgA above the upper normal limit (440 mg/dl) was 8% in seronegative and 4% in seropositive subjects (NS). The IgA levels in the 274 seropositive subjects, classified for infective stages, were significantly higher in those fulfilling the criteria for acquired immunodeficiency syndrome (AIDS) or AIDS related complex (group IV) than in asymptomatic subjects (group II) or in those with generalized lymphadenopathy (group III) (p less than 0.01). CONCLUSIONS: Serum IgA levels in PDAs with HIV infection may be a useful marker of progression to AIDS.

Sexual transmission of hepatitis C virus and its relation with hepatitis B virus and HIV.

OBJECTIVE: To determine the extent of transmission of hepatitis C virus in sexual partners of intravenous drug misusers and to examine the relation between the prevalences of HIV, hepatitis B virus, and hepatitis C virus infections in homosexual men and intravenous drug misusers and their sexual partners. DESIGN: Serum samples collected between 1984 and 1988 were tested for hepatitis B virus markers and antibodies against hepatitis C virus by enzyme linked immunosorbent assay (ELISA) and for HIV antibody by enzyme immune analysis and western blotting. SETTING: Large referral university hospital with an external AIDS clinic in the metropolitan area of Barcelona, Spain. SUBJECTS: 243 Intravenous drug misusers, 143 of their regular heterosexual partners, and 105 homosexual men. MAIN OUTCOME MEASURES: Prevalences of hepatitis C virus, hepatitis B virus, and HIV infections. RESULTS: In all, 178 of the 243 (73%) intravenous drug misusers, 16 out of 143 (11%) of their partners, and 17 of the 105 (16%) homosexual men had antibodies against hepatitis C virus. The presence of hepatitis C virus infection was unrelated to sex, age, the presence of HIV or hepatitis B virus infections, or the Centers for Disease Control stage of HIV. In sexual partners of intravenous drug misusers there were strong correlations between the presence of hepatitis C virus infection and that of HIV (p = 0.001) and hepatitis B virus (p = 0.013) infections. CONCLUSIONS: Intravenous drug misusers have a high risk of acquiring hepatitis C virus, hepatitis B virus, and HIV infections, but the presence of hepatitis C virus infection seems to be unrelated to the presence of the other two viruses. Homosexual men have a high prevalence of HIV and hepatitis B virus infections with a low prevalence of hepatitis C virus infection, the presence of which is not related to that of the other two infections. Conversely, heterosexual partners of intravenous drug misusers have low prevalences of the three virus infections, but the presence of hepatitis C virus infection correlates significantly with the presence of HIV and hepatitis B infections. The rate of sexual transmission of hepatitis C virus seems to be low, even in partners of people known to be seropositive for this virus.