Public health authorities should be vigilant to the potential for outbreaks deliberately caused by biological agents (bioterrorism). Such events require a rapid response and incorporation of non-traditional partners for disease investigation and outbreak control. The astute application of infectious disease epidemiological principles can promote an enhanced index of suspicion for such events. We discuss epidemiological indicators that should be considered during outbreak investigations, and also examine their application during bioterrorism incidents, an accidental release of an agent, outbreaks of infections that were alleged to have been deliberately initiated, and a model scenario. The Grunow & Finke epidemiological assessment tool is used to examine these historical events and the model scenario. The results received from this analysis, coupled with an understanding of epidemiological clues to unnatural events, and knowledge of how to manage such events, can aid in the improved response and resolution of epidemics.

The ongoing worldwide spread of the H5N1 influenza virus in birds has increased concerns of a new human influenza pandemic and a number of surveillance initiatives are planned, or are in place, to monitor the impact of a pandemic in near real-time. Using epidemiological data collected during the early stages of an outbreak, we show how the timing of the maximum prevalence of the pandemic wave, along with its amplitude and duration, might be predicted by fitting a mass-action epidemic model to the surveillance data by standard regression analysis. This method is validated by applying the model to routine data collected in the United Kingdom during the different waves of the previous three pandemics. The success of the method in forecasting historical prevalence suggests that such outbreaks conform reasonably well to the theoretical model, a factor which may be exploited in a future pandemic to update ongoing planning and response.

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

To evaluate the risk of transmission of SARS coronavirus outside of the health-care setting, close household and community contacts of laboratory-confirmed SARS cases were identified and followed up for clinical and laboratory evidence of SARS infection. Individual- and household-level risk factors for transmission were investigated. Nine persons with serological evidence of SARS infection were identified amongst 212 close contacts of 45 laboratory- confirmed SARS cases (secondary attack rate 4·2%, 95% CI 1·5–7). In this cohort, the average number of secondary infections caused by a single infectious case was 0·2. Two community contacts with laboratory evidence of SARS coronavirus infection had mild or sub-clinical infection, representing 3% (2/65) of Vietnamese SARS cases. There was no evidence of transmission of infection before symptom onset. Physically caring for a symptomatic laboratory-confirmed SARS case was the only independent risk factor for SARS transmission (OR 5·78, 95% CI 1·23–24·24).

The aim of this study was to determine changes in the epidemiology of hepatitis A virus (HAV) infection in the Basque Country, Spain, and to evaluate their implications for vaccination strategies. A total of 1356 persons were enrolled in a study of the prevalence of anti-HAV in 2004 and compared with two previous studies (1986–1987 and 1992). The selection method and the characteristics of the population were similar in the three studies. A marked decline in the seroprevalence in all age groups (P<0·001) and in the incidence of cases/100000 inhabitants (from 38·0 in 1986–1988 to 2·9 in 2002–2004) were observed. The mean age of patients with hepatitis A increased from 17·7 years in 1986–1992 to 21·2 years in 1993–1998 and 25·3 years in 1999–2004 (P<0·001). Between 1997 and 2004, 20% of patients were hospitalized. The changes observed have occurred rapidly causing a change in the epidemiological pattern from middle-high endemicity (1986) to low endemicity (2004).

This prospective, multicentre study was conducted between September and October 2003 in 38 French departments of internal medicine, infectious disease and hepatogastroenterology and included 406 consecutive HBV-infected patients (positive HBsAg), half of whom were HIV-infected (53%). The aim was to outline the main characteristics of hepatitis B virus (HBV)-human immunodeficiency virus (HIV) co-infected patients in French hospitals. HBV-HIV co-infected patients (85% were receiving HAART; mean CD4 count 447±245/μl, HIV RNA load <400 copies/ml, 67% of patients), compared to HIV-negative patients, were more often male, injecting drug users, HBeAg-positive and HCV-HIV co-infected (P<10−4). They underwent liver biopsy less often (31% vs. 51%, P<10−4), particularly those with severe immunodeficiency. They received anti-HBV treatment more often (75% vs. 45·7%, P<10−4), mainly lamivudine and tenofovir. Significant improvements in the management of such patients are awaited mainly in the appraisal of liver disease by either liver biopsy or non-invasive alternatives to liver biopsy.

This paper describes sentinel laboratory surveillance of hepatitis C antibody testing in England. Demographic and test result data were supplemented by follow-up questionnaires sent to the requesting clinician. Between October 2002 and September 2003 almost 75000 anti-HCV tests were performed in eight sentinel centres. More males were tested than females and over half of those tested were aged 25–44 years. Overall 5·7% (3333/58144, range 2·8–7·7%) individuals tested positive. Follow-up questionnaire data showed that 82% (1043/1277) of the positives had injecting drug use reported as the main risk exposure. The majority of negative individuals were undergoing routine screening as recommended for specific patient groups. Most individuals were asymptomatic. Antibody prevalence was estimated to be 34% in current injecting drug users and 42% in former injectors. Comparing positives to routine national surveillance suggests that only 53% (1782/3333) of diagnosed cases were reported. Sentinel laboratory data can provide valuable supplementary data to national surveillance.

Recently we identified hepatitis C virus (HCV) genotype 4 as the principle genotype among Lebanese thalassaemics. In an attempt to confirm the predominance of genotype 4 in Lebanon and perhaps in the Middle East, genotyping was attempted on 142 HCV-infected Lebanese patients from five different hospitals in the country. These included 38 HCV-positive patients with symptomatic liver disease who were referred to gastroenterologists and 104 HCV-positive patients with no symptoms of liver disease: 27 patients with thalassaemia, 30 patients on haemodialysis, 32 multi-transfused and 15 intravenous drug users. HCV genotyping was performed on PCR HCV RNA-positive samples using a commercial line probe assay (LiPA; Innogenetics, Ghent, Belgium). HCV genotype 4 is found to be the predominant genotype among HCV-infected Lebanese patients (ranging from 34·2% to 53·3%) followed by 1a (ranging from 12·5% to 43·3%) and 1b (ranging from 8·0% to 34·4%). In patients with symptomatic liver disease, however, genotype 4 (34·2%) was preceded by genotype 1a (39·5%). The predominance of HCV genotype 4 in our population (45·7%) confirms the predominance of HCV genotype 4 in Lebanon and most of the Arab countries in the Middle East but contrasts with data reported from non-Arab Middle Eastern Countries as can be seen from the literature review. Implications of genotyping for clinical outcome of HCV infection, response to treatment as well as for vaccine development are discussed.

It is estimated that of 50000 persons in Scotland (1% of the county's population), infected with the hepatitis C virus (HCV), around 90% injected drugs. This paper reviews data on the prevalence and incidence of HCV, and the methods used to generate such information, among injecting drug users (IDUs), in Scotland. The prevalence estimate for HCV among IDUs in Scotland as a whole (44% in 2000), is comparable with those observed in many European countries. Incidence rates ranged from 11·9 to 28·4/100 person-years. The data have shaped policy to prevent infection among IDUs and have informed predictions of the number of HCV-infected IDUs who will likely progress to, and require treatment and care for, severe HCV-related liver disease. Although harm reduction interventions, in particular needle and syringe exchanges and methadone maintenance therapy, reduced the transmission of HCV among IDUs during the early to mid-1990s, incidence in many parts of the country remains high. The prevention of HCV among IDUs continues to be one of Scotland's major public health challenges.

Contact tracing is a well-established disease control measure that seeks to uncover cases by following chains of infection. This paper examines mathematical models of both single-step and iterative contact tracing schemes and analyses the ability of these procedures to trace core groups and the sensitivity of the intervention to the timescale of tracing. An iterative tracing process is shown to be particularly effective at uncovering high-risk individuals, and thus it provides a powerful public health tool. Further targeting of tracing effort is considered. When the population exhibits like-with-like (assortative) mixing the required effort for eradication can be significantly reduced by preferentially tracing the contacts of high-risk individuals; in populations where individuals have reliable information about their contacts, further gains in efficiency can be realized. Contact tracing is, therefore, potentially an even more potent tool than its present usage suggests.

Scabies outbreaks in England have been reported in hospitals, long-stay wards, acquired immune deficiency syndrome (AIDS) units and residential homes for the elderly. This paper describes the control of an outbreak in a further education college for persons with learning disabilities. In March 2004, four confirmed cases of scabies were reported among a subset of 108 students and 41 staff members. Staff had considerable physical contact with the students who were housed in five groups of homes, individual homes and support centres. Mass prophylaxis was offered to all staff and students, through 39 general practice surgeries. Challenges overcome were: ensuring complete case ascertainment, accessing of up-to-date information about students and staff, achieving a coordinated approach to treatment, securing informed consent and media management. No further outbreaks have been reported. The college has revised its information request form for new students.

We systematically investigated risk factors for typhoid fever in Kamalapur, a poor urban area of Bangladesh, to inform targeted public health measures for its control. We interviewed patients with typhoid fever and two age-matched controls per case about exposures during the 14 days before the onset of illness. The municipal water supply was used by all 41 cases and 81of 82 controls. In multivariate analysis, drinking unboiled water at home was a significant risk factor [adjusted odds ratio (aOR) 12·1, 95% CI 2·2–65·6]. Twenty-three (56%) cases and 21 (26%) controls reported that water from the primary source was foul-smelling (aOR 7·4, 95% CI 2·1–25·4). Eating papaya was associated with illness (aOR 5·2, 95% CI 1·2–22·2). Using a latrine for defecation was significantly protective (aOR 0·1, 95% CI 0·02–0·9). Improved chlorination of the municipal water supply or disinfecting drinking water at the household level may dramatically reduce the risk of typhoid fever in Kamalapur. The protective effect of using latrines, particularly among young children, should be investigated further.

Nine different arboviruses are known to be transmitted by, or associated with, mosquitoes in Europe, and several (West Nile, Sindbis and Tahyna viruses) are reported to cause outbreaks of human disease. Although there have been no reported human cases in Great Britain (GB), there have been no published in-depth serological surveys for evidence of human infection. This paper investigates the ecological and entomological factors that could influence or restrict transmission of these viruses in GB, suggesting that in addition to West Nile virus, Sindbis and Tahyna viruses could exist in enzootic cycles, and that certain ecological factors could facilitate transmission to humans. However, the level of transmission is likely to be lower than in endemic foci elsewhere in Europe due to key ecological differences related to spatial and temporal dynamics of putative mosquito vectors and presence of key reservoir hosts. Knowledge of the potential GB-specific disease ecology can aid assessments of risk from mosquito-borne arboviruses.

The epidemic of type 2 diabetes in the United States prompted us to explore the association between diabetes and tuberculosis (TB) on the South Texas–Mexico border, in a large population of mostly non-hospitalized TB patients. We examined 6 years of retrospective data from all TB patients (n=5049) in South Texas and northeastern Mexico and found diabetes self-reported by 27·8% of Texan and 17·8% of Mexican TB patients, significantly exceeding national self-reported diabetes rates for both countries. Diabetes comorbidity substantially exceeded that of HIV/AIDS. Patients with TB and diabetes were older, more likely to have haemoptysis, pulmonary cavitations, be smear positive at diagnosis, and remain positive at the end of the first (Texas) or second (Mexico) month of treatment. The impact of type 2 diabetes on TB is underappreciated, and in the light of its epidemic status in many countries, it should be actively considered by TB control programmes, particularly in older patients.

In September 2004, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTI) was reported among members of a religious community. We conducted a retrospective cohort study on all 175 community members; performed a nasal carriage survey, and environmental swab testing. We identified 24 MRSA cases (attack rate 14%). In multivariate analysis, sauna use [odds ratio (OR) 19·1, 95% confidence interval (CI) 2·7–206·1] and antimicrobial use within 12 months before infection (OR 11·7, 95% CI 2·9–47·6) were risk factors for infection. MRSA nasal carriage rate was 0·6% (1/174). Nine of 10 clinical isolates and an isolate from an administrative office within the community had the pulsed-field gel electrophoresis type USA300. Targeted hygiene improvement, wound care, and environmental cleaning were implemented. We describe the first reported outbreak of MRSA SSTI in a religious community. Adherence to appropriate personal and environmental hygiene might be critical factors in controlling transmission.

In99, a possible ancestor of In100, is a class 1 integron associated with carbenicillinase (blaPSE) and aminoglycoside resistance genes [aac(6′)-Ib and aadA2]. In99 was present in 8 of 81 clinical isolates of Pseudomonas aeruginosa from unrelated patients collected in different years. The strains fell into two clonal groups and exhibited resistance to β-lactams and aminoglycosides.

Health risks in the effluents of seven swine abattoirs and of seven poultry abattoirs were evaluated with regard to environment degradation and to dissemination of pathogenic microorganisms during the rainy and dry seasons. Supply-water samples from affluents and effluents of the treatment systems at different sites within the abattoir processing system were analysed. Similarly, water samples from the three recipient sites (emission point, 100 m upstream, 100 m downstream) were also analysed. Temperature, free residual chlorine (FRC), total coliform bacteria, Escherichia coli, enterococci, identification and serotyping of salmonellae were assessed. Scalding is the most significant stage in the slaughtering chain (P<0·05) when temperature is taken into account. Temperatures at effluents and at the sampled sites in the water bodies accorded to state and federal legislation standards. Supply waters did not meet the standards for FRC and microbial count standards according to the Ministry of Health and within limits imposed by the Industrial and Sanitary Inspection Regulations for Animal Products. Feather plucking and evisceration in poultry slaughter and the cleansing of carcasses and facilities in poultry and swine slaughtering had the highest contamination impact. The three loci at the water bodies were above the microbiological standards for classes II and III sites, in conformity with Law 8468 of the state of São Paulo, Brazil and Conama. Salmonella was found at several sites during slaughter, at both types of abattoirs, including in the effluent treatment system. This showed that these sites were the dissemination sources of the microorganism.

Wild boars are important disease reservoirs. It is well known that abundance estimates are needed in wildlife epidemiology, but the expense and effort required to obtain them is prohibitive. We evaluated a simple method based on the frequency of faecal droppings found on transects (FBII), and developed a spatial aggregation index, based on the runs test statistic. Estimates were compared with hunting data, and with porcine circovirus and Aujeszky's disease virus seroprevalences and Mycobacterium tuberculosis complex and Metastrongylus spp. prevalence. The FBII and the aggregation index were correlated with the hunting index, but both of the former estimates correlated better than the latter with the disease prevalences. Hence, at least in habitats with high wild boar densities, the FBII combined with the aggregation index constitutes a cheap and reliable alternative for wild boar abundance estimation that can be used for epidemiological risk assessment, even outside the hunting season and in areas with no available data on hunting activities.