Salmonella Javiana is a Salmonella serotype that is restricted geographically in the United States to the Southeast. During the summer of 2001, the number of reported S. Javiana infections in Mississippi increased sevenfold. To identify sources of infection, we conducted a case-control study, defining a case as an infection with S. Javiana between August and September in a Mississippi resident. We enrolled 55 cases and 109 controls. Thirty (55%) case patients reported exposure to amphibians, defined as owning, touching, or seeing an amphibian on one's property, compared with 30 (29%) controls (matched odds ratio 2·8, P=0·006). Contact with amphibians and their environments may be a risk factor for human infection with S. Javiana. The geographic pattern of S. Javiana infections in the United States mimics the distribution of certain amphibian species in the Southeast. Public health officials should consider amphibians as potential sources of salmonellosis, and promote hand washing after contact with amphibians.

In Spain, vaccination against rubella was initiated in schoolgirls in the mid-1970s. In Gipuzkoa, subsequent extensions to the vaccination schedule culminated in 1992 with the introduction of the two-dose measles, mumps and rubella vaccine in children and adolescents of both sexes. Moreover, in 1985 a programme for the identification and vaccination of non-immune parturient women was implemented in the region's main hospital. The prevalence of rubella-susceptible parturient women decreased from 3·7% at the beginning of the study to <1·5% by 1992. Despite this overall decrease, 4·8% of adolescent parturients were susceptible to rubella during 2001–2002. From 1984, the number of reported cases of rubella (children and adults) progressively decreased until 1997, after which there have been no cases of indigenous rubella. There have been no cases of reported congenital rubella since 1984. These results indicate that the vaccine policy carried out in this geographical area has been effective in achieving considerable progress towards rubella elimination.

Leptospirosis is an important public health problem in the Andaman Islands. The disease is being increasingly reported among children and adolescents in recent times. An attempt was made to find out the level of exposure to leptospires, to estimate the incidence of infection and to identity the risk factors for acquiring infection among children. A sample of 1544 schoolchildren was selected. Presence of anti-leptospiral antibodies was tested using the microscopic agglutination test (MAT). Students were interviewed for behavioural factors. In total, 341 (221 seronegative and 120 seropositive) students were followed up clinically and serologically during a subsequent outbreak. An overall seropositivity rate of 23·6% (95% CI 21·54–25·81) was observed. Infection rate was 33·5% among seronegatives whereas re-infection rate was 16·7% among seropositives during the outbreak that occurred 1 month after the first sample collection. Morbidity and mortality were found to be higher among seronegative individuals than serpositives, More than 90% of leptospiral infections were found to be subclinical or unnoticed. The high level of exposure among the children results in high infection rates and because they have less previous exposure than adults, they do not have sufficient protection to resist clinical illness during outbreaks.

Salmonella Goldcoast (SGC), an uncommon serotype in Germany, was identified in 25 isolates between 1 April and 7 May 2001. To determine the cause of the outbreak, we conducted a matched case-control study including 24 cases and 51 controls. In a multivariable regression model, only consumption of a raw fermented sausage manufactured by a local company remained significant (adjusted odds ratio 20·0, 95% confidence interval 2·7–302·5). SGC isolated from case-patients shared an indistinguishable pulsed-field gel electrophoresis pattern. A part of the produced raw fermented sausage was sold after only 4 days of fermentation. Samples from the premises and products of the company were negative for SGC. However, short-time raw fermented sausage is more likely to contain pathogens. Irradiation of raw ingredients is not accepted by German consumers, thus strict adherence to good manufacturing practices, the use of HACCP programmes as well as on-farm programmes remain crucial to reduce Salmonella.

An outbreak of E. coli O157:H7 infections was identified in November 1999 with a fivefold increase in the occurrence of laboratory-confirmed cases of E. coli O157:H7 infection. A matched case-control study was conducted. Samples of food from cases and from retailers were analysed for the presence of E. coli O157:H7. A total of 143 cases were identified over a 12-week period with the same pulsed-field gel electrophoresis (PFGE) pattern. The case-control study found that Company A salami was significantly associated with illness (Mantel–Haenszel matched odds ratio 10·0, 95% CI 1·4–434, P=0·01). Company A salami tested positive for E. coli O157:H7 and isolates had the same PFGE pattern as case isolates. An immediate voluntary national recall of Company A dry fermented meat products took place. Findings from the investigation of this outbreak suggest that the hold-and-test option may not be adequate to prevent shiga-toxigenic Escherichia coli (STEC) infection in salami consumers.

Historically, subtype B viruses in men who have sex with men (MSM) and injecting drug users (IDU) dominated the HIV epidemic in the United Kingdom, whereas non-B heterosexual infections dominate globally. Heterosexual contact is now the most common route of transmission in the United Kingdom. Here we monitor HIV subtype in Scotland, and link it to origin of infection. HIV-1 sequence was generated from new diagnoses and the subtype thus obtained linked with demographic data. Virus was subtyped from 80% (137/171) of all new diagnoses in Scotland. Of 58 individuals infected by heterosexual contact, 74% (43) harboured non-B viruses, contrasting with 7% (5/68) of those infected by IDU or MSM. Eighty-four per cent of non-Bs (46/55) were probably acquired outside the United Kingdom, but nine individuals probably acquired their non-B infection in the United Kingdom. Non-B subtypes of HIV-1 predominate in recently diagnosed, heterosexually acquired infections in Scotland and are present in all risk groups, even those with no exposure outside the United Kingdom.

An epidemiological model was developed for rabies, linking the risk of disease in a secondary species (cats) to the temporal dynamics of disease in a wildlife reservoir (raccoons). Data were obtained from cats, raccoons, and skunks tested for rabies in the northeastern United States during 1992–2000. An epizootic algorithm defined a time-series of successive intervals of epizootic and inter-epizootic raccoon rabies. The odds of diagnosing a rabid cat during the first epizootic of raccoon rabies was 12 times greater than for the period prior to epizootic emergence. After the first raccoon epizootic, the risk for cat rabies remained elevated at levels six- to seven-fold above baseline. Increased monthly counts of rabid raccoons and skunks and decreasing human population density increased the probability of cat rabies in most models. Forecasting of the public health and veterinary burden of rabies and assessing the economics of control programmes, requires linking outcomes to dynamic, but predictable, changes in the temporal evolution of rabies epizootics.

In the light of food safety and the control of Salmonella at chicken farms, fermented liquid feed (FLF) was studied. This moistened feed reduced the susceptibility of chickens for Salmonella. To assess the effect of the fermented feed on the transmission of Salmonella between chickens, a transmission experiment was performed. Salmonella shedding was followed within groups of two susceptible chickens together with two previously inoculated chickens. The between-chicken transmission was quantified by calculating a reproduction ratio (R0) and a transmission rate parameter (β). R0 and β in the FLF-treated groups were reduced, but a typical infectious chicken fed with FLF, could on average still infect more than one new infectious case. FLF can therefore reduce the transmission of Salmonella in chicken flocks, but it will not prevent the occurrence of major outbreaks.

A serological prevalence survey was carried out in Luxembourg during 2000–2001 to determine the antibody status of the Luxembourg population against vaccine-preventable infections including varicella-zoster virus (VZV). ELISA tests performed on 2679 sera indicated that 96 (3·6%) of the study population were seronegative. Age-specific seroprevalence rose rapidly from approximately 70% at age 4 years to 90% at age 6 years to 95% at age 12 years. Significant heterogeneity of seroprevalence was observed between the six different primary schools. For age groups 0–5, 6–11 and 12+ years, we estimated an annual force of infection of 0·361 [95% confidence interval (CI) 0·31–0·415)], 0·204 (95% CI 0·12–0·29) and 0·05 (95% CI 0·024–0·082) respectively. Our results indicate that transmission of VZV is highest in children below the age of 6 years and that much lower levels of VZV transmission occur in secondary schools and throughout adulthood.

In Europe, the number of reported sporadic human cases of Salmonella Livingstone infection is low, and outbreaks are rare. We report the largest S. Livingstone outbreak described in the literature having an identified source of infection. In February 2001, an increased incidence of infection caused by S. Livingstone was observed in Norway and Sweden. By July 2001, 44 cases were notified in Norway and 16 in Sweden. The median age was 63 years, and 40 were women. There were three deaths, and 22 patients were hospitalized. Based on standardized questionnaires and retrospective studies of S. Livingstone strains in Norway and Sweden, food items with egg powder were suspected, and S. Livingstone was subsequently recovered from a processed fish product at the retail level. Analysis by pulsed-field gel electrophoresis documented that isolates from the fish product belonged to the same clone as the outbreak strain.

Salmonellosis is a major cause of gastroenteritis in the United States and can lead to septicaemia, and other extra-intestinal illness including urinary tract infections (UTIs). To examine trends in Salmonella bacteriuria in the United States, surveillance data from the National Salmonella Surveillance System from 1980 to the end of 1999 were reviewed. Overall, 17442 urinary Salmonella isolates were reported, representing 2% of all Salmonella isolates from a known source. This proportion increased from 2% during 1980–1984 to 4% during 1995–1999. The median age of persons from whom these isolates came was 51 years; 12176 (70%) were women. Compared to the last national survey conducted between 1968 and 1979, the rate of Salmonella bacteriuria increased among women, from 2·0 per million persons in 1980 to 3·7 in 1999; the highest rate occurring in women [ges ]70 years. National reporting of Salmonella bacteriuria increased in absolute incidence and as a proportion of all Salmonella, especially in elderly women and may represent an increase in the incidence of Salmonella UTIs. Better understanding of the uropathogenicity of Salmonella serotypes may further clarify the mechanisms of Salmonella UTIs.

To understand the dynamics of transmission of Shiga toxin-producing Escherichia coli O157:H7 (STEC O157) in beef calves, serum samples were obtained from calves in a beef cow-calf herd approximately every 6 weeks from birth until weaning for three consecutive years. The presence of specific anti-O157 antibodies in these serum samples was detected using a blocking ELISA assay incorporating an anti-O157 monoclonal antibody. Using seroconversion data, the basic reproduction ratio (R0) was estimated for each of the three years as well as in aggregate using both deterministic and Martingale methods. R0 for STEC O157 infection in range beef calves by deterministic methods varied from 2·9–5·6, with an average of 4·3 (95% CI 2·8–5·9). Martingale estimates of R0 ranged from 3·5–7·4, or 5·3 (95% CI 3·9–6·6), for data from all three years. Given the above estimate of R0, it is predicted that 65–86% of a herd of calves must be effectively vaccinated, or must be rendered non-susceptible through other means, to eliminate STEC O157 infection from a herd.

Considerable and reproducible differences were observed in the amount and duration of faecal excretion when in-bred lines of chickens were infected orally with S. enterica serovar Typhimurium at 6 weeks of age after being given a gut flora preparation when newly hatched. Similar but less pronounced results were observed with S. Enteritidis or S. Infantis. Differences in the viable numbers of the inoculated bacteria in caecal contents were detectable within 24 h of inoculation. No major differences were seen in Salmonella-specific serum IgA or IgG titres. Small differences were seen in the numbers of circulating heterophilic cells. Caecal contents taken from the more resistant lines immediately prior to challenge appeared to be no more inhibitory for Salmonella in vivo than contents taken from susceptible lines. The more resistant lines showed a slightly higher rate of intestinal flow, as indicated by the rate of production of faecal droppings, although there was no difference in the rate of emptying of the caeca. In an F1 generation resistance was dominant and not sex-linked. There was no MHC linkage or any association with SAL1, the gene implicated in resistance to systemic salmonellosis in chickens, or NRAMP1.

Thirty-one viruses causing SAT-2 outbreaks in seven West African countries between 1974 and 1991, and four viruses representative of East and Central Africa were genetically characterized in this study. Four major viral lineages (I–IV) were identified by phylogenetic analysis of an homologous 480 nucleotide region corresponding to the C-terminus end of VP1. Lineage I comprised two West African genotypes with viruses clustering according to year of isolation rather than geographical origin. Lineage II was represented by viruses isolated between 1979 and 1983 in two neighbouring West African countries, Senegal and The Gambia. Viruses from Nigeria and Eritrea, representative of West and East Africa respectively, constituted lineage III, whilst lineage IV, comprising viruses from Central and East Africa, was regionally and genetically distinct. This study revealed that unrestricted animal movement in West Africa is a major factor in disease dissemination and has also provided the first indication of trans-regional virus transmission.

This is the first large-scale study to investigate the seroprevalence of varicella zoster (VZV) in the general population of England and Wales. The study focused on those aged 1–20 years, that age group in whom most infections occur. Prevalence rose rapidly with age, with 53% of children showing evidence of prior infection by the age of 5 years and most young adults having experienced infection. In addition to using a fixed cut-off recommended by the manufacturer, a mixture modelling technique was also used to define the proportion of the population seropositive in each age group. This was shown to be a more accurate approach to categorizing data from an epidemiological perspective.

In order to evaluate the incidence and risk factors of infection by hepatitis C virus (HCV) among injecting drug users (IDUs), we conducted a prospective cohort study of HCV- and human immunodeficiency virus (HIV)-negative IDUs in the North and East of France. A total of 231 HCV and HIV IDUs who had injected drugs at least once in their lifetime were followed up every 3 months over a 12-month period. Serum anti-HCV and anti-HIV were tested at inclusion in the study and at the end of the follow-up. Data on injecting practices were collected at inclusion and at each visit. Of the 231 participants included, 165 (71·4%) underwent a final HCV and HIV serum test. The incidence was nil for HIV infection and 9/100 person-years (95% CI 4·6–13·4) for HCV infection. In a multivariable analysis, we found that syringe and cotton sharing were the only independent predictive factors of HCV seroconversion.

Although cattle are reservoirs, no validated method exists to monitor Shiga toxin-producing Escherichia coli O157 (STEC O157) on farms. In 29 Midwestern United States feedlot pens we compared culturing faeces from the individual cattle to: (1) culturing rope devices that cattle rub or chew; and (2) culturing a composite of faecal pats. Eighty-six per cent (68–96%) of pens were classified correctly using rope devices to detect pens with at least 16% of the cattle shedding STEC O157 [sensitivity=82% (57–96%); specificity=92% (62–100%)]. Ninety per cent of pens (73–98%) were classified correctly using composite faeces to detect pens with at least 37% of the cattle shedding STEC O157 [sensitivity=86% (42–100%); specificity=91% (71–99%)]. Ranking pens into three risk levels based on parallel interpretation of the pen-test results correlated (Spearman's r=0·76, P<0·0001) with the pen's prevalence. This strategy could identify pens of cattle posing a higher risk to food safety.

Surveillance and control are important aspects of food safety assurance strategies at the pre-harvest level of pork production. Prior to implementation of a Salmonella surveillance and control programme, it is important to have knowledge on the dynamics and epidemiology of Salmonella infections in pig herds. For this purpose, 17 finishing pig herds initially classified as seropositive and 15 as seronegative, were followed for a 2-year period through serological and bacteriological sampling. The study included 10 herds from Denmark, 13 from The Netherlands, 4 from Germany and 5 from Sweden and was performed between October 1996 and May 1999. The Salmonella status of finishing pig herds was determined by an initial blood sampling of approximately 50 finishing pigs close to market weight per herd. The development of the Salmonella status of the selected herds was assessed at seven subsequent sampling rounds of 25 blood samples from finishing pigs, 25 blood samples from grower pigs and 10 pen faecal samples each, approximately 3 months apart. The odds for testing finishers seropositive, given that growers were found seropositive previously were 10 times higher than if growers were seronegative (OR 10·0, 95% CI 3·2–32·8). When Salmonella was isolated from pen faecal samples, the herd was more likely to be classified seropositive in the same sampling round, compared to no Salmonella being detected (OR 4·0, 95% CI 1·1–14·6). The stability of an initially allocated Salmonella status was found to vary noticeably with time, apparently irrespective of a seropositive or seronegative classification at onset of the study. Given the measured dynamics in the occurrence of Salmonella in pig herds, regular testing is necessary to enable producers, advisors and authorities to react to sudden increases in the Salmonella prevalence in single herds or at a national level.

Isolated reports of brucellosis among family members have been documented. The aim of this study is to determine if active serological screening of the households' members of acute brucellosis cases will detect additional unrecognized cases. From May 2000 to October 2001, patients with acute brucellosis were enrolled and their household members were serologically screened for brucellosis using the Standard Agglutination Test (SAT). Fifty-five index cases with acute brucellosis and 404 household members were enrolled. The majority of index cases (48%) were young adults, and 79% were illiterate. Ownership of animals and ingestion of unpasteurized raw milk were reported by 45 and 75% of the index cases respectively. Of the 55 families screened, 23 (42%) had two family members or more with serological evidence of brucellosis and 32 (58%) had only the index case. Households of [ges ]5 members and a history of raw-milk ingestion by family members were risk factors associated with the seropositives (P<0·05). Of the 404 household members screened, 53 (13%) were seropositive; of these 39 (74%) were symptomatic, and 9 (35%) had brucella bacteraemia. Symptomatic seropositives tended to have bacteraemia and higher brucella antibody titres compared to asymptomatic seropositives (P[les ]0·05). Screening family members of an index case of acute brucellosis will detect additional cases.

Inclusion of live varicella vaccine in the routine occupational health vaccination schedule requires knowledge of the natural immunity to varicella zoster virus (VZV) among high-risk occupations. This study aims were to evaluate VZV antibody positivity among health-care workers (HCWs) and day-care-centre workers (DCWs) and to assess its association with potential risk factors. Three groups of workers were tested for VZV antibody positivity: hospitals and community clinic HCWs (n=335), DCWs (n=117) and blue-collar workers as controls (n=121). The total VZV antibody positivity was 94·4%. There was no significant difference in VZV antibody positivity among study groups. DCWs had the lowest VZV seroprevalence (90·9%, 95% CI 85·7–96·1) and controls the highest (96·6%, 95% CI 93·2–99·9). This high VZV antibody positivity suggests that no special occupational measures are indicated in health-care or day-care occupational settings in Israel. On-going monitoring of the natural immunity to VZV is necessary to detect trends over time.