A prospective seroepidemiological survey was carried out in Luxembourg in 2000–2001 to determine the antibody status of the Luxembourg population against hepatitis A virus (HAV) and hepatitis B virus (HBV). One of the objectives of this survey was to assess the impact of the hepatitis B vaccination programme, which started in May 1996 and included a catch-up campaign for all adolescents aged 12–15 years. Venous blood from 2679 individuals was screened for the presence of antibodies to HAV antigen and antibodies to hepatitis B surface antigen (anti-HBs) using an enzyme immunoassay. Samples positive for anti-HBs were tested for antibody to hepatitis B core antigen (anti-HBc) using a chemiluminiscent microparticle immunoassay to distinguish between individuals with past exposure to vaccine or natural infection. The estimated age-standardized anti-HAV seroprevalence was 42·0% [95% confidence interval (CI) 39·8–44·1] in the population >4 years of age. Seroprevalence was age-dependent and highest in adult immigrants from Portugal and the former Yugoslavia. The age-standardized prevalence of anti-HBs and anti-HBc was estimated at 19·7% (95% CI 18·1–21·3) and 3·16% (95% CI 2·2–4·1) respectively. Anti-HBs seroprevalence exceeding 50% was found in the cohorts targeted by the routine hepatitis B vaccination programme, which started in 1996. Our study illustrates that most young people in Luxembourg are susceptible to HAV infection and that the hepatitis B vaccination programme is having a substantial impact on population immunity in children and teenagers.

In two prisons in Berlin, Germany, provision of sterile injection equipment for injecting drug users (IDUs) started in 1998. To assess the programme's impact, the frequency of injecting drug use and syringe sharing, and the incidence of HIV, HBV, and HCV infection were determined in a follow-up study. Of all IDUs (n=174), 75% continued to inject. After the project start the level of syringe sharing declined from 71% during a 4-month period of previous imprisonment to 11% during the first 4 months of follow-up, and to virtually zero thereafter. Baseline seroprevalences for HIV, HBV, and HCV were 18, 53, and 82%. HIV and HCV seroprevalence at baseline was significantly associated with drug injection in prison prior to the project start. No HIV and HBV seroconversions, but four HCV seroconversions occurred. The provision of syringes for IDUs in appropriate prison settings may contribute to a substantial reduction of syringe sharing. However, the prevention of HCV infection requires additional strategies.

IgM- and IgG-capture ELISAs are widely used as diagnostic tests for confirmation of dengue virus infection. The positive rate of anti-dengue IgM and IgG detection was examined in primary and secondary dengue virus infections in the setting of a provincial hospital using IgM- and IgG-capture ELISAs. Disease day 1 was defined as the day of onset of symptoms. In total, 232 plasma samples were collected from 106 confirmed dengue cases consisting of 12 primary and 94 secondary infections. In primary infection, anti-dengue IgM was detected in 4 out of 5 samples collected on disease day 5 and in all the 21 samples collected on disease day 6 or later. Specific IgG was detected in 2 out of 5 samples collected on day 12, and in 5 out of 6 samples collected on disease days 13–15, but was not detected in samples collected on disease day 10 or earlier. In secondary infection, IgM was not detected in the samples on disease days 2 and 3, but detected in 20 out of 79 samples collected on days 4–6, in 44 out of 65 on disease days 7–11 and in 40 out of 51 samples on disease days 12–14. In contrast, specific IgG was detected in 21 out of 60 samples on disease days 4 and 5, in 13 out of 19 on disease day 6, in 62 out of 65 on disease days 7–11 and in all the samples collected on disease day 12 or later. The result indicate that seroconversion rates of IgM and IgG are different between primary and secondary infections, and suggest that detection of specific IgM and IgG is necessary for determining dengue virus infection and for differentiating primary and secondary dengue infections.

In this study, the sera collected from a variety of mammalian species (ass-mules, cat, cattle, dog, horse, human and sheep) in 10 representative provinces of Turkey, were surveyed for the presence of neutralizing antibodies to West Nile virus (WNV). Overall, 1 of 40 (2·5%) ass-mules, 4 of 100 (4%) cattle, 43 of 114 (37·7%) dogs, 35 of 259 (13·5%) horses, 18 of 88 (20·4%) humans and 1 of 100 (1%) sheep, tested positive for WNV-neutralizing antibodies. The results indicate that a wide range of mammals are exposed to a West Nile-related virus and this could contribute to the long-term survival of this virus in the absence of overt disease.

The spatial and temporal distribution of hantavirus and arenavirus antibody-positive wild rodents in Trentino, Italy, was studied using immunofluorescence assays (IFA) in two long-term sites trapped in 2000–2003, and six other sites trapped in 2002. The overall hantavirus seroprevalence in the bank voles, Clethrionomys glareolus (n=229) screened for Puumala virus (PUUV) antibodies was 0·4%, and that for Apodemus flavicollis mice (n=1416) screened for Dobrava virus (DOBV) antibodies was 0·2%. Antibodies against lymphocytic choriomeningitis virus (LCMV) were found in 82 (5·6%) of the 1472 tested rodents; the seroprevalence being 6·1% in A. flavicollis (n=1181), 3·3% in C. glareolus (n=276), and 14·3% in Microtus arvalis (n=7). Of the serum samples of 488 forestry workers studied by IFA, 12 were LCMV-IgG positive (2·5%) and one DOBV-IgG positive (0·2%), however, the latter could not be confirmed DOBV-specific with a neutralization assay. Our results show a widespread distribution but low prevalence of DOBV in Trentino, and demonstrate that the arenavirus antibodies are a common finding in several other rodent species besides the house mouse.

Vaccination coverage in 595 adult patients undergoing total splenectomy in the Hospital Clinic of Barcelona during 1992–2002 was studied. The rates of cover for pneumococcal, Haemophilus influenzae type b and meningococcal vaccines were 63, 63 and 61% respectively, during 2000–2002; 32, 17 and 22% in 1997–1999; and 24, 9 and 8% in 1992–1996. Multivariate analysis showed a greater risk of no vaccination in splenectomies due to trauma, malignant neoplasms of solid organs and incidental splenectomy compared with both neoplastic and non-neoplastic haematological disease, and those patients undergoing splenectomy before 2001. Coverage ([ges ]1 vaccine) since 1997 in patients with haematological diseases was 83·5% (71/85), haematological neoplasias 69·2% (18/26), solid organ neoplasms 38·3% (36/94), incidental splenectomy 35·6% (16/45), and traumas 28·4% (21/74). Mandatory hospital admission of patients undergoing splenectomy offers a good opportunity for vaccination of these patients. Specific vaccination policies should be developed to take advantage of this circumstance.

The current WHO policy during measles outbreaks focuses on case management rather than reactive vaccination campaigns in urban areas of resource-poor countries having low vaccine coverage. Vaccination campaigns may be costly, or not timely enough to impact significantly on morbidity and mortality. We explored the time available for intervention during two recent epidemics. Our analysis suggests that the spread of measles in African urban settings may not be as fast as expected. Examining measles epidemic spread in Kinshasa (DRC), and Niamey (Niger) reveals a progression of smaller epidemics. Intervening with a mass campaign or in areas where cases have not yet been reported could slow the epidemic spread. The results of this preliminary analysis illustrate the importance of revisiting outbreak response plans.

Pertussis is an infectious respiratory disease for which mass vaccination is an effective preventive strategy. In many developed countries, where high vaccination coverage has been maintained for approximately 50 years, re-emergence of the disease has been observed in all age groups. In the municipality of Rio de Janeiro (RJ), where vaccination started in the 1980s, surveillance data show no sign of disease re-emergence. We developed a mathematical model that incorporates the major demographic aspects of a large urban centre in a developing nation, in addition to the most important epidemiological aspects of disease transmission. Parameter values were estimated based on RJ demographic and vaccine coverage data. Overall, all vaccination strategies determined a major decrease (over 95% decrease when compared to the pre-vaccine era) in the incidence of primary infections (occurring in individuals who have never been immunized through infection or vaccine). On the other hand, the strategies (a) three doses at age 2–11 months, (b) three doses plus booster at age 12–23 months, (c) three doses plus booster at age 4–5 years, and (d) three doses plus both boosters, differently affected the incidence of secondary infections (occurring in previously infected/vaccinated individuals). Given that the immunity against pertussis wanes with time and that the infectious agent has not been eliminated from the population, it is expected that pertussis will continue to be a problem in RJ. Actually, since immunity acquired from vaccine wanes faster than disease-acquired immunity and the possibility of natural boosters has decreased with mass vaccination, an increase in the incidence of secondary infections among older age groups is expected (and predicted by the model). Possible explanations as to why this dynamics is not captured by the RJ surveillance system are discussed. A poorly effective surveillance system and a lack of awareness regarding loss of immunity and the possibility of pertussis infection in older age groups are among them. Finally, we bring attention to the need of (i) field studies for the measurement of pertussis incidence in adolescents and adults; (ii) better understanding of the transmission dynamics currently occurring in RJ, and (iii) re-evaluation of vaccination strategies with the possible introduction of acellular vaccines for the vaccination of older individuals.

We evaluated three established statistical models for automated ‘early warnings’ of disease outbreaks; counted data Poisson CuSums (used in New Zealand), the England and Wales model (used in England and Wales) and SPOTv2 (used in Australia). In the evaluation we used national Swedish notification data from 1992 to 2003 on campylobacteriosis, hepatitis A and tularemia. The average sensitivity and positive predictive value for CuSums were 71 and 53%, for the England and Wales model 87 and 82% and for SPOTv2 95 and 49% respectively. The England and Wales model and the SPOTv2 model were superior to CuSums in our setting. Although, it was more difficult to rank the former two, we recommend the SPOTv2 model over the England and Wales model, mainly because of a better sensitivity. However, the impact of previous outbreaks on baseline levels was less in the England and Wales model. The CuSums model did not adjust for previous outbreaks.

National policies for chemoprophylaxis after single cases of meningococcal disease in day-care or nursery settings vary across Europe. We carried out a multi-national retrospective study to compare the effectiveness of different policies. Countries were divided into those recommending chemoprophylaxis only to close contacts (policy A, close) and those recommending chemoprophylaxis for all children in the same nursery (policy B, mass). Country-specific relative risk (RR) of a cluster was defined as the ratio of the number of clusters observed to the number of clusters expected by chance. In total, 37 clusters were identified between 1 January 1993 and 31 December 2002. After adjusting for marked heterogeneity in RR by country, the ratio of RR between countries suggested possible benefit from mass prophylaxis (RR ratio 3·8, 95% CI 0·7–22·0), although the difference was not statistically significant (P=0·22). The costs of this approach and the low risk of clustering need to be taken into account when deciding national policy.

Enteric illness outbreaks among middle-/high-school students in consecutive semesters of an educational farm programme were investigated with retrospective cohort studies. During the first outbreak, 31/92 (34%) interviewed students were ill. Risk factors included participating in animal science class (RR 8·1, 95% CI 1·2–55·2) and contact with calves (RR 4·2, 95% CI 1·1–16·2). Stool samples from seven students and two calves yielded Cryptosporidium parvum. Students cared for animals in street clothes and practised poor hand washing. During the second outbreak, 37/81 (46%) interviewed animal science students were ill. Risk factors included having visible manure on hands, and wearing coveralls and boots. Stool samples from seven students and eight calves yielded C. parvum. Student hand washing was still inadequate. Coveralls/boots were cleaned infrequently and removed after hand washing. These outbreaks of cryptosporidiosis resulted from calf contact and inadequate hygiene practices. The failure to adequately implement recommended interventions contributed to the second outbreak.

Much data has been gathered by the EWGLINET scheme on the distribution of cases of travel-associated Legionnaires' disease (TALD) by country of infection, but less analysis has been carried out on the distribution of these cases within countries. Travel-associated cases with onset in 2002 linked to France, Italy, Spain and Turkey were mapped. Rates of Legionnaires' disease per 100000 tourists were calculated for internal and foreign visitors for the regions of each country, and mapped. Rates of 1·5 cases/100000 and 2 cases/100000 tourists were classified as ‘high’ and ‘very high’ respectively. Cases of TALD were concentrated in certain regions, but when rates were calculated using tourist data, the results were relatively constant throughout each country. Rates were higher among foreign visitors than internal visitors; three of the countries had at least one region with ‘high’ rates, whilst Turkey additionally had three regions with ‘very high’ rates.

In May 2000, public health authorities in Dublin, Ireland, identified a cluster of unexplained severe illness among injecting drug users (IDUs). Similar clusters were also reported in Scotland and England. Concurrent investigations were undertaken to identify the aetiology and source of the illnesses. In Dublin, 22 IDUs were identified with injection-site inflammation resulting in hospitalization or death; eight (36%) died. Common clinical findings among patients with severe systemic symptoms included leukaemoid reaction and cardiogenic shock. Seventeen (77%) patients reported injecting heroin intramuscularly in the 2 weeks before illness. Of 11 patients with adequate specimens available for testing, two (18%) were positive by 16S rDNA PCR for Clostridium novyi. Clinical and laboratory findings suggested that histotoxic Clostridia caused a subset of infections in these related clusters. Empiric treatment for infections among IDUs was optimized for anaerobic organisms, and outreach led to increased enrolment in methadone treatment in Dublin. Many unique legal, medical, and public health challenges were encountered during the investigation of this outbreak.